CBFilter Class

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The CBFilter class allows applications to intercept and control filesystem requests.

Syntax

cbfsfilter.CBFilter

Remarks

The CBFilter class gives applications the ability to intercept filesystem requests, allowing them to be altered, handled, or blocked. Applications use standard filter rules to specify which requests they are interested in intercepting; and special filter rules to enforce access restrictions and redirect requests to different files.

To learn more about the class's capabilities, please refer to the product's General Information topics.

Getting Started

1. If the class's system driver has not been installed yet, call the Install method to do so. This needs to be done only once.
   • In production, the driver can be installed (or updated) ahead of time with the application's installation script using the Installer DLL. Please refer to the Driver Installation topic for more information.
2. Call the Initialize method to initialize the CBFilter class. This must be done each time the application starts.
3. Add one or more filter rules using methods like AddFilterRule. (Rules can also be added or removed after the filter is started.)
4. Call the StartFilter method to start filtering filesystem requests.
5. When finished, call the StopFilter method to stop filtering filesystem requests.
6. To uninstall the class's system driver, call the Uninstall method. This should not be done as part of the driver upgrade process.
   • In production, the driver can be uninstalled by the application's uninstallation script using the Installer DLL. Please refer to the Driver Installation topic for more information.

Property List

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The following is the full list of the properties of the class with short descriptions. Click on the links for further details.

Method List

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The following is the full list of the methods of the class with short descriptions. Click on the links for further details.

Event List

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The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.

Config Settings

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The following is a list of config settings for the class with short descriptions. Click on the links for further details.

Active Property (CBFilter Class)

This property notes whether the class is active and processing requests.

Syntax

public boolean isActive();

Default Value

False

Remarks

This property reflects whether the class is active and currently processing requests. It will be true after the filter has been attached successfully via a call to StartFilter.

This property is read-only and not available at design time.

Altitude Property (CBFilter Class)

This property specifies the altitude the class's system driver should use .

Syntax

public String getAltitude();


public void setAltitude(String altitude);

Default Value

""

Remarks

This property specifies the altitude that the class's system driver should use . A driver's altitude determines its absolute position in the stack of filter drivers; drivers with higher altitudes are attached toward the top of the stack, closer to the user mode, which allows them to process requests earlier.

Microsoft manages and assigns filesystem minifilter driver altitudes directly, so an application-specific altitude value must be obtained from Microsoft before an application is deployed in production. Please refer to the Driver Altitudes topic for more information. During development, an appropriate arbitrary value, such as 360000 (which is not registered with Microsoft), can be used.

If this property is queried before an altitude has been set (via this property or the Install method), it will return an empty string.

Note: This property cannot be changed when Active is true. Additionally, the Initialize method must be called before attempting to get or set this property's value, which is stored in the registry.

DefaultRules Property (CBFilter Class)

This property includes the collection of default rules.

Syntax

public FileDefaultRuleList getDefaultRules();

Remarks

This property holds a collection of FileDefaultRule objects, each of which represents a default rule. Please refer to the Default Rules topic for more information.

Use the following methods to manage default rules:

• AddDefaultRule
• DeleteDefaultRule
• SuspendDefaultRules

Note: Because default rules are managed by the class's system driver, this collection is not populated by default, nor is it updated by any of the aforementioned methods. Applications can call the CreateDefaultRulesSnapshot method to populate this collection; and must call the CloseDefaultRulesSnapshot method when finished working with it to release the associated memory.

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

This property is read-only and not available at design time.

Please refer to the FileDefaultRule type for a complete list of fields.

FileFlushingBehavior Property (CBFilter Class)

This property specifies the file flushing and closing behavior that the class's system driver should enforce.

Syntax

public int getFileFlushingBehavior();


public void setFileFlushingBehavior(int fileFlushingBehavior);

Default Value

0

Remarks

This property specifies what file flushing and closing behaviors the class's system driver should enforce.

Applications that modify file data as it is being read or written may need to change this property's value to function correctly. For example, applications that provide on-the-fly encryption should choose the proper flags to ensure that other applications that have opened the files being encrypted cannot accidentally write nonencrypted data to the disk.

Applications that do not modify file data as it is being read or written can leave this property unchanged.

The value of this property should be constructed by ORing together zero or more of the following flags:

FilterRules Property (CBFilter Class)

This property includes a collection of filter rules.

Syntax

public FileFilterRuleList getFilterRules();

Remarks

This property holds a collection of FileFilterRule objects, each of which represents a standard filter rule, access rule, or both. Please refer to the File and Registry Filter Rules and Access Rules topics for more information.

Use the following methods to manage the rules in this collection:

• AddFilterRule
• AddFilterRuleEx
• DeleteFilterRule
• DeleteAllFilterRules

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

This property is read-only and not available at design time.

Please refer to the FileFilterRule type for a complete list of fields.

FireVolumeEvents Property (CBFilter Class)

This property specifies the events that should be fired when a filesystem volume is mounted to or unmounted from the system.

Syntax

public int getFireVolumeEvents();


public void setFireVolumeEvents(int fireVolumeEvents);

Default Value

0

Remarks

This property specifies the events that the class should fire when a filesystem volume is mounted to or unmounted from the system. Possible values are as follows:

Note: The aforementioned events are fired only for volumes mounted/unmounted after the StartFilter method is called. Typically, applications use these events to dynamically add or remove volume-specific filter rules that target removable volumes (e.g., USB drives) as well as to create virtual files on such volumes. Please refer to the File Masks topic for more information.

NormalizeShortFileNames Property (CBFilter Class)

CBFILTER_NORMALIZE_SHORT_FILE_NAMES_NEVER 0 CBFILTER_NORMALIZE_SHORT_FILE_NAMES_LOCAL_FS 1 CBFILTER_NORMALIZE_SHORT_FILE_NAMES_ALWAYS 2, TBD.

Syntax

public int getNormalizeShortFileNames();


public void setNormalizeShortFileNames(int normalizeShortFileNames);

Default Value

0

Remarks

TBD.

PassthroughRules Property (CBFilter Class)

This property includes a collection of passthrough rules.

Syntax

public FilePassthroughRuleList getPassthroughRules();

Remarks

This property holds a collection of FilePassthroughRule objects, each of which represents a passthrough rule. Please refer to the Passthrough Rules topic for more information.

Use the following methods to manage the rules in this collection:

• AddPassthroughRule
• AddPassthroughRuleEx
• DeletePassthroughRule
• DeleteAllPassthroughRules

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

This property is read-only and not available at design time.

Please refer to the FilePassthroughRule type for a complete list of fields.

ProcessCachedIORequests Property (CBFilter Class)

This property specifies whether cached file read/write requests should be processed.

Syntax

public boolean isProcessCachedIORequests();


public void setProcessCachedIORequests(boolean processCachedIORequests);

Default Value

False

Remarks

This property specifies whether the class's system driver should process cached file read/write requests (i.e., fire *ReadFile and *WriteFile events for them). Please refer to the Cached and Non-Cached Requests topic for more information.

Note: This property cannot be changed when Active is true.

ProcessFailedRequests Property (CBFilter Class)

This property specifies whether failed requests should be processed.

Syntax

public boolean isProcessFailedRequests();


public void setProcessFailedRequests(boolean processFailedRequests);

Default Value

False

Remarks

This property specifies whether the class's system driver should process failed requests (i.e., fire After* or Notify* events for them).

When this property is enabled, applications can inspect the Status parameter of the aforementioned events to determine whether an operation has failed. If an operation fails, then the corresponding event's Status parameter will contain a nonzero native status code. Applications generally can use the NtStatusToWin32Error method to convert these status codes into Win32 error codes (but keep in mind that not all native status codes have direct Win32 error code mapping).

ReparseRules Property (CBFilter Class)

This property includes a collection of reparse rules.

Syntax

public FileReparseRuleList getReparseRules();

Remarks

This property holds a collection of FileReparseRule objects, each of which represents a reparse rule. Please refer to the Reparse Rules topic for more information.

Use the following methods to manage reparse rules:

• AddReparseRule
• DeleteReparseRule
• DeleteAllReparseRules
• GetReparseRuleByMask

Note: Because reparse rules are managed by the class's system driver, this collection is not populated by default, nor is it updated by any of the aforementioned methods. Applications can call the CreateReparseRulesSnapshot method to populate this collection; and must call the CloseReparseRulesSnapshot method when finished working with it to release the associated memory.

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

This property is read-only and not available at design time.

Please refer to the FileReparseRule type for a complete list of fields.

SerializeEvents Property (CBFilter Class)

Whether events should be fired on a single worker thread, or many.

Syntax

public int getSerializeEvents();


public void setSerializeEvents(int serializeEvents);


Enumerated values:
  public final static int seOnMultipleThreads = 0;
  public final static int seOnOneWorkerThread = 1;

Default Value

0

Remarks

This property specifies whether the class should fire all events serially on a single worker thread, or concurrently on multiple worker threads. The possible values are:

Please refer to the Threading and Concurrency topic for more information.

Note: This property cannot be changed when Active is true, and it cannot be changed within events.

Tag Property (CBFilter Class)

This property stores application-defined data specific to a particular instance of the class.

Syntax

public long getTag();


public void setTag(long tag);

Default Value

0

Remarks

This property can be used to store data specific to a particular instance of the class.

VirtualFiles Property (CBFilter Class)

This property includes a collection of virtual files.

Syntax

public VirtualFileList getVirtualFiles();

Remarks

This property holds a collection of VirtualFile objects, each of which represents a virtual file.

Use the following methods to manage virtual files in this collection:

• AddVirtualFile
• UpdateVirtualFile
• RemoveVirtualFile

This property is read-only and not available at design time.

Please refer to the VirtualFile type for a complete list of fields.

AddDefaultRule Method (CBFilter Class)

This method adds a default rule.

Syntax

public boolean addDefaultRule(String mask, int accessFlags, String productGUID);

Remarks

This method adds a default rule for the files and directories that match the specified Mask. Each rule in a ruleset is uniquely identified by its mask; if a rule with the specified mask already exists, the new rule's parameters are merged into it.

If the rule is added successfully, this method returns true; otherwise, it returns false.

Default rules, like access rules, instruct the class's system driver to apply certain access restrictions to matching files and directories. However, unlike access rules, default rules are managed by the driver directly; they are activated as soon as the driver loads at boot time, and then continue to be enforced at all times, regardless of whether the application that added them is open.

The Mask parameter must be a valid file mask according to the File Masks topic. Only the files and directories that match the specified mask will be covered by the rule.

The AccessFlags parameter specifies which access restrictions the class's system driver should apply to matching files and directories. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The ProductGUID parameter identifies the application that the rule should be associated with in the registry. In most cases, the value passed for this parameter should be the same one that was used to call the Initialize method.

This method requires administrative rights to execute successfully. If the user account of the process that calls this method doesn't have such rights, the call will fail with an ERROR_PRIVILEGE_NOT_HELD (0x0522) error. Please refer to the Default Rules topic for more information.

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

AddFilterRule Method (CBFilter Class)

This method adds a standard filter rule or access rule.

Syntax

public boolean addFilterRule(String mask, int accessFlags, long controlFlags, long notifyFlags);

Remarks

This method adds a standard filter rule or access rule for the files and directories that match the specified Mask. Each rule in a ruleset is uniquely identified by its mask; if a rule with the specified mask already exists, the new rule's parameters are merged into it.

If the rule is added successfully, this method returns true; otherwise, it returns false.

Standard filter rules determine which filesystem operations, of those performed on matching files and directories, the class should fire its events for. Access rules instruct the class's system driver to apply certain access restrictions to matching files and directories.

The Mask parameter must be a valid file mask according to the File Masks topic. Only the files and directories that match the specified mask will be covered by the rule.

The AccessFlags parameter specifies which access restrictions the class's system driver should apply to matching files and directories. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The ControlFlags parameter specifies which filesystem operations the class should fire Control Events for. For example, if the FS_CE_BEFORE_READ and FS_CE_AFTER_READ flags are present, the BeforeReadFile and AfterReadFile events will fire before and after a read operation is performed on any file that matches Mask. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The NotifyFlags parameter specifies which filesystem operations the class should fire Notification Events for. For example, if the FS_NE_READ flag is present, the NotifyReadFile event will fire after a read operation is performed on any file that matches Mask. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

AddFilterRuleEx Method (CBFilter Class)

This method adds a standard filter rule or access rule with additional match qualifiers.

Syntax

public boolean addFilterRuleEx(String mask, String eaName, int accessFlags, long controlFlags, long notifyFlags, long minSize, long maxSize, long includedAttributes, long excludedAttributes);

Remarks

This method adds a standard filter rule or access rule for the files and directories that match the specified Mask (which must be provided), and other qualifiers (which are optional). Each rule in a ruleset is uniquely identified by its mask; if a rule with the specified mask already exists, the new rule's parameters are merged into it.

If the rule is added successfully, this method returns true; otherwise, it returns false.

Standard filter rules determine which filesystem operations, of those performed on matching files and directories, the class should fire its events for. Access rules instruct the class's system driver to apply certain access restrictions to matching files and directories.

The Mask parameter must be a valid file mask according to the File Masks topic. Only the files and directories that match the specified mask will be covered by the rule.

The EaName parameter specifies the name of an extended attribute that a file or directory must have to qualify as a match; wildcards are not allowed. Pass an empty string if this parameter should not be used as a match qualifier.

The AccessFlags parameter specifies which access restrictions the class's system driver should apply to matching files and directories. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The ControlFlags parameter specifies which filesystem operations the class should fire Control Events for. For example, if the FS_CE_BEFORE_READ and FS_CE_AFTER_READ flags are present, the BeforeReadFile and AfterReadFile events will fire before and after a read operation is performed on any file that matches Mask. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The NotifyFlags parameter specifies which filesystem operations the class should fire Notification Events for. For example, if the FS_NE_READ flag is present, the NotifyReadFile event will fire after a read operation is performed on any file that matches Mask. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The MinSize and MaxSize parameters specify the minimum and maximum size, in bytes, that a file can be to qualify as a match. Pass -1 for either parameter if it should not be used as a match qualifier.

The IncludedAttributes and ExcludedAttributes parameters specify which file attributes a file or directory must have or not have to qualify as a match. Pass 0 for either parameter if it should not be used as a match qualifier.

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

AddPassthroughRule Method (CBFilter Class)

This method adds a passthrough rule.

Syntax

public boolean addPassthroughRule(String mask, int accessFlags, long controlFlags, long notifyFlags);

Remarks

This method adds a passthrough rule for the files and directories that match the specified Mask. Each rule in a ruleset is uniquely identified by its mask; if a rule with the specified mask already exists, the new rule's parameters are merged into it.

If the rule is added successfully, this method returns true; otherwise, it returns false.

Passthrough rules exclude matching files and directories from being processed by other filter rules.

The Mask parameter must be a valid file mask according to the File Masks topic. Only the files and directories that match the specified mask will be covered by the rule.

The AccessFlags parameter specifies which access restrictions the class's system driver should lift from matching files and directories. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The ControlFlags parameter specifies which filesystem operations the class should not fire Control Events for. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The NotifyFlags parameter specifies which filesystem operations the class should not fire Notification Events for. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

AddPassthroughRuleEx Method (CBFilter Class)

This method adds a passthrough rule with additional match qualifiers.

Syntax

public boolean addPassthroughRuleEx(String mask, String eaName, int accessFlags, long controlFlags, long notifyFlags, long minSize, long maxSize, long includedAttributes, long excludedAttributes);

Remarks

This method adds a passthrough rule for the files and directories that match the specified Mask (which must be provided) and other qualifiers (which are optional). Each rule in a ruleset is uniquely identified by its mask; if a rule with the specified mask already exists, the new rule's parameters are merged into it.

If the rule is added successfully, this method returns true; otherwise, it returns false.

Passthrough rules exclude matching files and directories from being processed by other filter rules.

The Mask parameter must be a valid file mask according to the File Masks topic. Only the files and directories that match the specified mask will be covered by the rule.

The EaName parameter specifies the name of an extended attribute that a file or directory must have to qualify as a match; wildcards are not allowed. Pass an empty string if this parameter should not be used as a match qualifier.

The AccessFlags parameter specifies which access restrictions the class's system driver should lift from matching files and directories. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The ControlFlags parameter specifies which filesystem operations the class should not fire Control Events for. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The NotifyFlags parameter specifies which filesystem operations the class should not fire Notification Events for. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The MinSize and MaxSize parameters specify the minimum and maximum size, in bytes, that a file can be to qualify as a match. Pass -1 for either parameter if it should not be used as a match qualifier.

The IncludedAttributes and ExcludedAttributes parameters specify which file attributes a file or directory must have or not have to qualify as a match. Pass 0 for either parameter if it should not be used as a match qualifier.

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

AddReparseRule Method (CBFilter Class)

This method adds a reparse rule.

Syntax

public boolean addReparseRule(String mask, String reparseMask, String productGUID, int flags);

Remarks

This method adds a reparse rule for the files and directories that match the specified Mask. Each rule in a ruleset is uniquely identified by its mask; if a rule with the specified mask already exists, the new rule replaces it.

If the rule is added successfully, this method returns true; otherwise, it returns false.

Reparse rules are used to redirect access from a file or directory covered by Mask to another location in the filesystem, specified by ReparseMask.

The Mask and ReparseMask parameters must be valid file masks according to the File Masks topic. Only the files and directories that match Mask will be covered by the rule (i.e., redirected to the path specified by ReparseMask). For example, passing *.txt for Mask and *_1.txt for ReparseMask would cause, for example, test.txt to be redirected to test_1.txt.

More generally, for each wildcard (* or ?) present in Mask, there must be a corresponding wildcard (of the same type) in ReparseMask; and the wildcards in ReparseMask must appear in the same order as they do in Mask. For example, if Mask is 20??_Budget.*, then 20??_Budget_Report.* would be a legal value for ReparseMask; but 20??_Budget_Report.xls would not be, nor would 20*_Budget_Report.*.

The ProductGUID parameter identifies the application that the rule should be associated with in the registry. In most cases, the value passed for this parameter should be the same one that was used to call the Initialize method.

The Flags parameter specifies how, exactly, the redirection should be performed. Possible values are as follows:

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

AddVirtualFile Method (CBFilter Class)

This method adds a virtual file to the list of virtual entries and makes it visible in the filesystem.

Syntax

public boolean addVirtualFile(String fileName, java.util.Date creationTime, java.util.Date lastAccessTime, java.util.Date lastWriteTime, java.util.Date changeTime, long size, int attributes);

Remarks

This method creates or opens a virtual file and adds it to the list of virtual entries, managed by the class. If the class is active, the virtual file also appears in the filesystem. Virtual directories are not supported.

The class stores the creation parameters in the list. Adding the same file name several times will create only one list entry for each distinct file name, and subsequent calls to AddVirtualFile with different parameters will be ignored. To update properties of the file that is already in the list, use the UpdateVirtualFile method. To remove the file from the list, use the RemoveVirtualFile method.

The FileName parameter must contain the full path and name of the file being added. The drive on which the file resides may be referenced in one of following formats:

• A volume GUID, formatted like Volume{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} . A path may start with the \\?\ prefix, such as "\\?\Volume{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}".
• A DOS name, formatted like C:\.
• A volume NT-native name, formatted like \Device\HarddiskVolumeX\, where X is the number of the volume.

To successfully add a virtual file, the volume in the path must already be present on the system.

Note: if an application adds multiple files to the same drive, it is more efficient to convert a GUID-based or a DOS-name-based volume name to the NT-native format using the GetNTPathName method, then use the obtained NT-native volume name in the calls to this AddVirtualFile method.

CreationTime, LastAccessTime, LastWriteTime, ChangeTime must specify the corresponding time values for the file, specified in UTC.

Size must be set to the size of the file. It may be 0 for an empty file or a positive value.

Attributes must be set to the file's attributes. Please refer to Microsoft's File Attribute Constants article for attribute descriptions.

The method will return true if the file was added to the list and false if the file is already present in the list. An error will be reported if adding the file failed on the driver side.

CloseDefaultRulesSnapshot Method (CBFilter Class)

This method closes the previously created default rules snapshot.

Syntax

public void closeDefaultRulesSnapshot();

Remarks

This method closes the default rules snapshot previously created by CreateDefaultRulesSnapshot, releasing the memory associated with it. Please refer to that method's documentation for more information.

Note: This method cannot be called within events.

The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

CloseReparseRulesSnapshot Method (CBFilter Class)

This method closes the previously created reparse rules snapshot.

Syntax

public void closeReparseRulesSnapshot();

Remarks

This method closes the reparse rules snapshot previously created by CreateReparseRulesSnapshot, releasing the memory associated with it. Please refer to that method's documentation for more information.

Note: This method cannot be called within events.

The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

Config Method (CBFilter Class)

Sets or retrieves a configuration setting.

Syntax

public String config(String configurationString);

Remarks

Config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

CreateDefaultRulesSnapshot Method (CBFilter Class)

This method creates a snapshot of information about the default rules that have been added.

Syntax

public void createDefaultRulesSnapshot(String productGUID);

Remarks

This method creates a snapshot of information about all default rules that have been added by the application identified by ProductGUID. This information is then used to populate the DefaultRules collection property.

When the application is finished working with the default rules snapshot, it must close it by calling the CloseDefaultRulesSnapshot method to release the associated memory. If this method is called again before an existing snapshot is closed, the class will attempt to close it before creating a new one.

Note: This method cannot be called within events.

The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

CreateFileDirect Method (CBFilter Class)

This method creates or opens a file or directory by passing the request directly to the filesystem.

Syntax

public long createFileDirect(String fileName, boolean synchronize, int desiredAccess, int shareMode, int creationDisposition, int flagsAndAttributes, boolean closeImmediately, boolean sendViaStack);

Remarks

This method should be used instead of the Windows API's CreateFile function to create or open a file or directory when an application needs to access this file without sending requests through the complete filesystem filter driver stack.

The parameters of this method correspond to the parameters of the CreateFile function.

If the file or directory is created or opened successfully, this method returns a file handle for it; otherwise, it returns INVALID_HANDLE_VALUE. The returned handle, if valid, must be closed using the Windows API's CloseHandle function when the application is finished with it. See the "Use of Handle" section below for details of how to use the handle.

If CloseImmediately is true, this method will create or open the specified file or directory and then immediately close the resulting handle. In this case, the handle will still be returned to indicate the success of the operation, but it will not be usable in any file operations.

The SendViaStack parameter specifies how the driver should send the request for opening the file as well as other requests that will be sent using the opened file handle. When this parameter is false, requests made by the application using the handle, created by the CreateFileDirect method, are sent directly to the filesystem. When some filter drivers are located lower in the driver stack than the CBFilter driver, such requests will bypass that filter drivers with possibly unexpected consequences (e.g., requests going to the wrong file, wrong data being read or written). Set this parameter to true to make the driver pass these requests down the filter stack, letting them reach other filter drivers before the filesystem.

When the SendViaStack parameter is false, requests against the returned file handle are routed directly to the filesystem (bypassing all filter drivers, including the class's); applications can use it to call the Windows File API functions (ReadFile, WriteFile) within filesystem-related events without causing a system deadlock. However, pay special attention to the Synchronize parameter's documentation, which is given below.

The FileName, DesiredAccess, CreationDisposition, and FlagsAndAttributes parameters correspond to the lpFileName, dwDesiredAccess, dwCreationDisposition, and dwFlagsAndAttributes parameters of the Windows API's CreateFile function (respectively).

Please refer to Microsoft's documentation for more information about how to set these parameters appropriately.

The CreationDisposition parameter should be set to one of the valid values and may not be 0. If any of these requirements is not met, the ERROR_INVALID_PARAMETER error is returned.

The ShareMode parameter should be set by ORing together zero or more of the following flags:

The Synchronize parameter specifies whether this method and operations with the resulting handle should be synchronized with the thread that originated the underlying filesystem request associated with the current event (i.e., the event that this method was called from).

The parameter is applicable only when a caller uses it to open the file, for which the event was fired, when isolation is not used. If the file create/open operation is isolated (the handler sets the Isolate parameter of the corresponding event to true), the application may safely set Synchronize to false. Also, the parameter should not be set to true when this method is called from the AfterCloseFile event; when the event is fired, no file is open to synchronize operations with.

It is recommended to set Synchronize to true when the method is called from AfterCreateFile and AfterOpenFile event handlers. This helps prevent possible deadlocks in other filter drivers.

Please refer to Direct File operations for additional information about the use of a handle or a stream obtained using this method.

CreateFileDirectAsStream Method (CBFilter Class)

This method creates or opens a file by passing the request directly to the filesystem.

Syntax

public CBFSFilterStream createFileDirectAsStream(String fileName, boolean synchronize, int desiredAccess, int shareMode, int creationDisposition, int flagsAndAttributes, boolean sendViaStack, long handle[]);

Remarks

This method should be used instead of the Windows API's CreateFile function to create or open a file when an application needs to access this file without sending requests through the complete filesystem filter driver stack.

The parameters of this method correspond to the parameters of the CreateFile function.

If the file is created or opened successfully, this method returns a stream object that provides access to its data; otherwise, it returns null.

Upon success, the Handle parameter is populated with the file handle value. This handle value does not need to be closed - the class will do this automatically when the stream is closed. See the "Use of Handle" section below for details of how to use the handle.

The SendViaStack parameter specifies how the driver should send the request for opening the file as well as other requests that will be sent using the opened file handle. When this parameter is false, requests made by the application using the handle, created by the CreateFileDirect method, are sent directly to the filesystem. When some filter drivers are located lower in the driver stack than the CBFilter driver, such requests will bypass that filter drivers with possibly unexpected consequences (e.g., requests going to the wrong file, wrong data being read or written). Set this parameter to true to make the driver pass these requests down the filter stack, letting them reach other filter drivers before the filesystem.

When the SendViaStack parameter is false, requests against the opened file are routed directly to the filesystem (bypassing all filter drivers, including the class's); applications can use it within filesystem-related events without causing a system deadlock. However, pay special attention to the Synchronize parameter's documentation, which is given below.

The FileName, DesiredAccess, CreationDisposition, and FlagsAndAttributes parameters correspond to the lpFileName, dwDesiredAccess, dwCreationDisposition, and dwFlagsAndAttributes parameters of the Windows API's CreateFile function (respectively).

Please refer to Microsoft's documentation for more information about how to set these parameters appropriately.

The CreationDisposition parameter should be set to one of the valid values and may not be 0. If any of these requirements is not met, the ERROR_INVALID_PARAMETER error is returned.

The ShareMode parameter should be set by ORing together zero or more of the following flags:

The Synchronize parameter specifies whether this method and operations with the resulting handle should be synchronized with the thread that originated the underlying filesystem request associated with the current event (i.e., the event that this method was called from).

The parameter is applicable only when a caller uses it to open the file, for which the event was fired, when isolation is not used. If the file create/open operation is isolated (the handler sets the Isolate parameter of the corresponding event to true), the application may safely set Synchronize to false. Also, the parameter should not be set to true when this method is called from the AfterCloseFile event; when the event is fired, no file is open to synchronize operations with.

It is recommended to set Synchronize to true when the method is called from AfterCreateFile and AfterOpenFile event handlers. This helps prevent possible deadlocks in other filter drivers.

Please refer to Direct File operations for additional information about the use of a handle or a stream obtained using this method.

CreateReparseRulesSnapshot Method (CBFilter Class)

This method creates a snapshot of information about the reparse rules that have been added.

Syntax

public void createReparseRulesSnapshot(String productGUID);

Remarks

This method creates a snapshot of information about all reparse rules that have been added by the application identified by ProductGUID. This information is then used to populate the ReparseRules collection property.

When the application is finished working with the reparse rules snapshot, it must close it by calling the CloseReparseRulesSnapshot method to release the associated memory. If this method is called again before an existing snapshot is closed, the class will attempt to close it before creating a new one.

Note: This method cannot be called within events.

The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

DeleteAllFilterRules Method (CBFilter Class)

This method deletes all standard filter rules and access rules.

Syntax

public boolean deleteAllFilterRules();

Remarks

This method deletes all standard filter rules and access rules that are currently present.

If the rules are deleted successfully, this method returns true; otherwise, it returns false.

To delete standard filter rules or access rules individually, use the DeleteFilterRule method instead.

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

DeleteAllPassthroughRules Method (CBFilter Class)

This method deletes all passthrough rules.

Syntax

public boolean deleteAllPassthroughRules();

Remarks

This method deletes all passthrough rules that are currently present.

If the rules are deleted successfully, this method returns true; otherwise, it returns false.

To delete passthrough rules individually, use the DeletePassthroughRule method instead.

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

DeleteAllReparseRules Method (CBFilter Class)

This method deletes all reparse rules.

Syntax

public boolean deleteAllReparseRules(String productGUID);

Remarks

This method deletes all reparse rules associated with the application identified by ProductGUID.

If the rules are deleted successfully, this method returns true; otherwise, it returns false.

In most cases, the value passed for the ProductGUID parameter should be the same one that was used to call the Initialize method. Please refer to the AddReparseRule method's documentation for more information.

To delete reparse rules individually, use the DeleteReparseRule method instead.

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

DeleteDefaultRule Method (CBFilter Class)

This method deletes a particular default rule.

Syntax

public boolean deleteDefaultRule(String mask, int accessFlags, String productGUID);

Remarks

This method deletes the specified AccessFlags from the default rule identified by Mask and associated with the application identified by ProductGUID. If AccessFlags includes all flags currently present in the rule, then the entire rule is deleted; otherwise, the flags specified by AccessFlags are simply removed from the rule.

If the flags or this rule are deleted successfully, this method returns true; otherwise, it returns false.

The Mask parameter must be the file mask of an existing rule. If a rule with the specified mask cannot be found, this method will fail.

The AccessFlags parameter specifies which access restrictions should be removed from the rule. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

In most cases, the value passed for the ProductGUID parameter should be the same one that was used to call the Initialize method. Please refer to the AddDefaultRule method's documentation for more information.

This method requires administrative rights to execute successfully. If the user account of the process that calls this method doesn't have such rights, the call will fail with an ERROR_PRIVILEGE_NOT_HELD (0x0522) error. Please refer to the Default Rules topic for more information.

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

DeleteFilterRule Method (CBFilter Class)

This method deletes a particular standard filter rule or access rule.

Syntax

public boolean deleteFilterRule(String mask, int accessFlags, long controlFlags, long notifyFlags);

Remarks

This method deletes the specified AccessFlags, ControlFlags, and/or NotifyFlags from the standard filter rule and/or access rule identified by Mask. If the aforementioned parameters include all flags currently present in the rule, then the entire rule is deleted; otherwise, the specified flags are simply removed from the rule.

If the flags or this rule are deleted successfully, this method returns true; otherwise, it returns false.

The Mask parameter must be the file mask of an existing rule. If a rule with the specified mask cannot be found, this method will fail.

The AccessFlags parameter specifies which access restrictions should be removed from the rule. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The ControlFlags parameter specifies which Control Event flags should be removed from the rule. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The NotifyFlags parameter specifies which Notification Event flags should be removed from the rule. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

To delete all standard filter rules and access rules, use the DeleteAllFilterRules method instead.

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

DeletePassthroughRule Method (CBFilter Class)

This method deletes a particular passthrough rule.

Syntax

public boolean deletePassthroughRule(String mask, int accessFlags, long controlFlags, long notifyFlags);

Remarks

This method deletes the specified AccessFlags, ControlFlags, and/or NotifyFlags from the passthrough rule identified by Mask. If the aforementioned parameters include all flags currently present in the rule, then the entire rule is deleted; otherwise, the specified flags are simply removed from the rule.

If the flags or this rule are deleted successfully, this method returns true; otherwise, it returns false.

The Mask parameter must be the file mask of an existing rule. If a rule with the specified mask cannot be found, this method will fail.

The AccessFlags parameter specifies which access restrictions should be removed from the rule. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The ControlFlags parameter specifies which Control Event flags should be removed from the rule. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

The NotifyFlags parameter specifies which Notification Event flags should be removed from the rule. The value passed for this parameter should be constructed by ORing together zero or more of the following flags:

To delete all passthrough rules, use the DeleteAllPassthroughRules method instead.

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

DeleteReparseRule Method (CBFilter Class)

This method deletes a particular reparse rule.

Syntax

public boolean deleteReparseRule(String mask, String productGUID);

Remarks

This method deletes the ReparseRules identified by Mask and associated with the application identified by ProductGUID.

If the flags or this rule are deleted successfully, this method returns true; otherwise, it returns false.

The Mask parameter must be the file mask of an existing rule. If a rule with the specified mask cannot be found, this method will fail.

In most cases, the value passed for the ProductGUID parameter should be the same one that was used to call the Initialize method. Please refer to the AddReparseRule method's documentation for more information.

To delete all reparse rules, use the DeleteAllReparseRules method instead.

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

FileMatchesMask Method (CBFilter Class)

This method checks whether a particular file or directory name matches the specified mask.

Syntax

public boolean fileMatchesMask(String mask, String fileName, boolean caseSensitive);

Remarks

This method checks whether the file or directory name specified by FileName matches Mask; if it does, this method returns true. The CaseSensitive parameter controls whether a case-sensitive match should be performed.

Note: This method does not handle so-called DOS_* wildcards (DOS_STAR, DOS_QM, DOS_DOT). The explanation about the characters can be found in the MSDN article. If you have a mask that includes one of those characters on Windows, you can use the RtlIsNameInExpression function of Windows API.

Note: As the explanation states, "When you do a case-insensitive search and do not provide a translation table, the name is converted to uppercase."

GetDriverStatus Method (CBFilter Class)

This method retrieves the status of the class's system driver.

Syntax

public int getDriverStatus(String productGUID);

Remarks

This method retrieves the status of the class's system driver. This status can then be used to verify whether it has been properly installed and is ready for use.

The value returned by the method corresponds to the dwCurrentState field of the SERVICE_STATUS structure from the Windows API. It will be one of the following:

ProductGUID is used to distinguish among driver installations performed by different applications. Such information is necessary to guard against unexpected situations, such as the driver being uninstalled by one application despite other applications still needing it.

Therefore, to ensure proper operation, it is critical that each individual application have its own unique ProductGUID value, and that applications (and their installation scripts) use that value when calling any of the following methods:

• Install
• Uninstall
• GetDriverStatus
• GetDriverVersion
• Initialize

This method is available in both the class API and the Installer DLL included with the product; please refer to the Driver Installation topic for more information about the latter.

Note: This method cannot be called within events.

GetDriverVersion Method (CBFilter Class)

This method retrieves the version of the class's system driver.

Syntax

public long getDriverVersion(String productGUID);

Remarks

This method retrieves the version of the class's system driver. The value is returned as a 64-bit integer composed of four 16-bit words that each correspond to a piece of the overall module version. For example, a version of 2.32.6.28 would cause the value 0x000200200006001C to be returned.

If the class's system driver is not installed, this method returns 0.

ProductGUID is used to distinguish among driver installations performed by different applications. Such information is necessary to guard against unexpected situations, such as the driver being uninstalled by one application despite other applications still needing it.

Therefore, to ensure proper operation, it is critical that each individual application have its own unique ProductGUID value, and that applications (and their installation scripts) use that value when calling any of the following methods:

• Install
• Uninstall
• GetDriverStatus
• GetDriverVersion
• Initialize

This method is available in both the class API and the Installer DLL included with the product; please refer to the Driver Installation topic for more information about the latter.

Note: This method cannot be called within events.

GetEventFileName Method (CBFilter Class)

This method retrieves the name of the file or directory, to which the event applies.

Syntax

public String getEventFileName();

Remarks

This method can be called within event handlers of events, related to the file or directory operations, to retrieve the name of the file or directory, to which the operation applies. If the query fails or an event does not have an associated file name, this method returns an empty string.

GetHandleCreatorProcessId Method (CBFilter Class)

This method retrieves the Id of the process (PID) that opened the file handle.

Syntax

public int getHandleCreatorProcessId();

Remarks

This method can be called within certain events to retrieve the Id of the process (PID) that opened the file handle. If the query fails, this method returns 0.

Note: PIDs are not unique and may be reused by different processes over time (although in practice, this is uncommon).

Applications cannot use this method to retrieve information about remote processes accessing drives shared on the network. Windows does not provide such information due to the nature of remote access.

Note: This method can be called only within the AfterCreateFile and AfterOpenFile events, and must be called in the same thread that the event was originally fired on. Applications that need the information that this method returns during other events can do the following:

1. Call this method within the AfterCreateFile or AfterOpenFile event.
2. Store the information somewhere, and store a reference to it in the event's HandleContext parameter.
3. In a later event, access the information through the reference stored in HandleContext.

Please refer to the Contexts topic for more information on how to use events' context parameters.

Note: This method cannot be used from CleanupContext event handlers.

GetHandleCreatorProcessName Method (CBFilter Class)

This method retrieves the name of the process that opened the file handle.

Syntax

public String getHandleCreatorProcessName();

Remarks

This method can be called within certain events to retrieve the name of the process that opened the file handle. If the query fails, this method returns an empty string.

Applications cannot use this method to retrieve information about remote processes accessing drives shared on the network. Windows does not provide such information due to the nature of remote access.

Note: This method can be called only within the AfterCreateFile and AfterOpenFile events, and must be called in the same thread that the event was originally fired on. Applications that need the information that this method returns during other events can do the following:

1. Call this method within the AfterCreateFile or AfterOpenFile event.
2. Store the information somewhere, and store a reference to it in the event's HandleContext parameter.
3. In a later event, access the information through the reference stored in HandleContext.

Please refer to the Contexts topic for more information on how to use events' context parameters.

Note: This method cannot be used from CleanupContext event handlers.

GetHandleCreatorThreadId Method (CBFilter Class)

This method retrieves the Id of the thread that opened the file handle.

Syntax

public int getHandleCreatorThreadId();

Remarks

This method can be called within certain events to retrieve the Id of the thread that opened the file handle. If the query fails, this method returns 0.

Notes: Thread Ids are not unique and may be reused by different threads over time.

Note: This method can be called only within the AfterCreateFile and AfterOpenFile events, and must be called in the same thread that the event was originally fired on. Applications that need the information that this method returns during other events can do the following:

1. Call this method within the AfterCreateFile or AfterOpenFile event.
2. Store the information somewhere, and store a reference to it in the event's HandleContext parameter.
3. In a later event, access the information through the reference stored in HandleContext.

Please refer to the Contexts topic for more information on how to use events' context parameters.

Note: This method cannot be used from CleanupContext event handlers.

GetHandleCreatorToken Method (CBFilter Class)

This method retrieves the security token associated with the process that opened the file handle.

Syntax

public long getHandleCreatorToken();

Remarks

This method can be called within certain events to retrieve the security token associated with the process that opened the file handle. If the query fails, this method returns INVALID_HANDLE_VALUE.

The security token returned by this method can be passed to the Windows API's GetTokenInformation function to obtain more information about the process.

Note: When applications are finished using the returned security token, they must close it using the Windows API's CloseHandle function.

Network Access Notes

Applications monitoring a drive shared on the network may wish to obtain information about the network users accessing it (e.g., account names). Drives can be shared in several modes in Windows, which can affect the information retrievable via the security token this method returns:

• Authenticated mode, in which case the network redirector (which, in general, is responsible for relaying remote drive requests to and from the system driver) will impersonate the network user, allowing that account's actual information to be retrieved.
• Guest mode, in which case the retrievable information is for the system's GUEST account.
• Administrative shares (those which exist by default and whose names end with '$'; e.g., C$, ADMIN$, etc.), in which case the retrievable information is for the LOCAL_SYSTEM account.

Note: This method can be called only within the AfterCreateFile and AfterOpenFile events, and must be called in the same thread that the event was originally fired on. Applications that need the information that this method returns during other events can do the following:

1. Call this method within the AfterCreateFile or AfterOpenFile event.
2. Store the information somewhere, and store a reference to it in the event's HandleContext parameter.
3. In a later event, access the information through the reference stored in HandleContext.

Please refer to the Contexts topic for more information on how to use events' context parameters.

Note: This method cannot be used from CleanupContext event handlers.

GetOperationTime Method (CBFilter Class)

This method returns the time at which the request was received by the filter driver.

Syntax

public java.util.Date getOperationTime();

Remarks

This method can be called within operation-related events to retrieve the time at which the filter driver received the request. The time is recorded before an event is fired but only when the RecordOperationTime configuration setting is enabled.

The timestamps returned by this method are specified in UTC.

GetOriginatorProcessId Method (CBFilter Class)

Retrieves the Id of the process (PID) that initiated the operation.

Syntax

public int getOriginatorProcessId();

Remarks

This method can be called within events fired for filesystem operations to retrieve the Id of the process (PID) that initiated the operation. If the query fails, this method returns 0.

Please note that PIDs are not unique, and may be reused by different processes over time (though in practice, this is uncommon).

Applications cannot use this method to retrieve information about remote processes accessing drives shared on the network. Windows does not provide such information due to the nature of remote access.

Note: This method can be called only within events, and it must be called in the same thread that the event was originally fired on. However, it must not be called within events that work with opened files since such events can be initiated by system components (e.g., the cache manager, memory manager, etc.). If applications need the information this method returns during such events, they may do the following:

1. Call this method within the CreateFile or OpenFile event.
2. Store the information somewhere, and store a reference to it in the event's HandleContext parameter.
3. In a later event, access the information via the reference stored in HandleContext.

Please refer to the Contexts topic for more information on how to use events' context parameters.

Note: Renaming and deletion of files is performed after the file is opened. Thus, access checks should be performed during file opening as described above.

Note: This method cannot be used from CleanupContext event handlers.

GetOriginatorProcessName Method (CBFilter Class)

Retrieves the name of the process that initiated the operation.

Syntax

public String getOriginatorProcessName();

Remarks

This method can be called within events fired for filesystem operations to retrieve the name of the process that initiated the operation. If the query fails, this method returns empty string.

Applications cannot use this method to retrieve information about remote processes accessing drives shared on the network. Windows does not provide such information due to the nature of remote access.

Note: This method can be called only within events, and it must be called in the same thread that the event was originally fired on. However, it must not be called within events that work with opened files since such events can be initiated by system components (e.g., the cache manager, memory manager, etc.). If applications need the information this method returns during such events, they may do the following:

1. Call this method within the CreateFile or OpenFile event.
2. Store the information somewhere, and store a reference to it in the event's HandleContext parameter.
3. In a later event, access the information via the reference stored in HandleContext.

Please refer to the Contexts topic for more information on how to use events' context parameters.

Note: Renaming and deletion of files is performed after the file is opened. Thus, access checks should be performed during file opening as described above.

Note: This method cannot be used from CleanupContext event handlers.

GetOriginatorThreadId Method (CBFilter Class)

Retrieves the Id of the thread that initiated the operation.

Syntax

public int getOriginatorThreadId();

Remarks

This method can be called within events fired for filesystem operations to retrieve the Id of the thread that initiated the operation. If the query fails, this method returns 0.

Please note that thread Ids are not unique, and may be reused by different threads over time.

Note: This method can be called only within events, and it must be called in the same thread that the event was originally fired on. However, it must not be called within events that work with opened files since such events can be initiated by system components (e.g., the cache manager, memory manager, etc.). If applications need the information this method returns during such events, they may do the following:

1. Call this method within the CreateFile or OpenFile event.
2. Store the information somewhere, and store a reference to it in the event's HandleContext parameter.
3. In a later event, access the information via the reference stored in HandleContext.

Please refer to the Contexts topic for more information on how to use events' context parameters.

Note: Renaming and deletion of files is performed after the file is opened. Thus, access checks should be performed during file opening as described above.

Note: This method cannot be used from CleanupContext event handlers.

GetOriginatorToken Method (CBFilter Class)

Retrieves the security token associated with the process that initiated the operation.

Syntax

public long getOriginatorToken();

Remarks

This method can be called within synchronous, i.e., Before* and After* events fired for filesystem operations to retrieve the security token associated with the process that initiated the operation. If the query fails, this method returns INVALID_HANDLE_VALUE. Note: This method will not work properly when called from Notify* event handlers because security tokens are not kept for possible later use. If you need to obtain security information about a request, use corresponding After* events.

The security token returned by this method can be passed to the Windows API's GetTokenInformation function to obtain more information about the process.

Important: When applications are finished using the returned security token, they must close it using the Windows API's CloseHandle function.

Network Access Notes

Applications monitoring a drive shared on the network may wish to obtain information about the network users accessing it (e.g., account names). Drives can be shared in several modes in Windows, which can affect the information retrievable via the security token this method returns:

• Authenticated mode, in which case the network redirector (which, in general, is responsible for relaying remote drive requests to and from the system driver) will impersonate the network user, allowing that account's actual information to be retrieved.
• Guest mode, in which case the retrievable information is for the system's GUEST account.
• Administrative shares (those which exist by default and whose names end with '$'; e.g., C$, ADMIN$, etc.), in which case the retrievable information is for the LOCAL_SYSTEM account.

Note: This method can be called only within events, and it must be called in the same thread that the event was originally fired on. However, it must not be called within events that work with opened files since such events can be initiated by system components (e.g., the cache manager, memory manager, etc.). If applications need the information this method returns during such events, they may do the following:

1. Call this method within the CreateFile or OpenFile event.
2. Store the information somewhere, and store a reference to it in the event's HandleContext parameter.
3. In a later event, access the information via the reference stored in HandleContext.

Please refer to the Contexts topic for more information on how to use events' context parameters.

Note: Renaming and deletion of files is performed after the file is opened. Thus, access checks should be performed during file opening as described above.

Note: This method cannot be used from CleanupContext event handlers.

GetRemoteAccessInformation Method (CBFilter Class)

This method returns networking-related information about the operation.

Syntax

public void getRemoteAccessInformation(String shareName[], long clientSocketAddressBuffer, int clientSocketAddressBufferSize[]);

Remarks

Call this method from *CreateFile/*OpenFile events to retrieve the collected networking details information related to the filesystem operation performed across the network.

Note: The information will be available only when the CollectRemoteOpenInformation configuration setting is enabled.

This method returns the contents of one of two structures, SRV_OPEN_ECP_CONTEXT or NFS_OPEN_ECP_CONTEXT. These structures contain various networking information that differs depending on the remote access type. Please refer to MSDN for additional information.

Depending on the type of remote access, the information is extracted from one of those structures. When the method returns, ShareName will contain the value of either ShareName or ExportAlias field of the corresponding structure. ClientSocketAddressBuffer will contain the value of the SocketAddress or ClientSocketAddress field of the corresponding structure. This field is a structure of the SOCKADDR_STORAGE_NFS type.

When calling the method, an application needs to prepare the buffer of the required size and specify this size of the ClientSocketAddressBuffer buffer in the ClientSocketAddressBufferSize argument.

GetReparseRuleByMask Method (CBFilter Class)

This method retrieves the reparse rule associated with the specified file mask.

Syntax

public String getReparseRuleByMask(String mask, String productGUID);

Remarks

This method retrieves the reparse rule identified by Mask and associated with the application identified by ProductGUID. If such a reparse rule is found, this method returns its reparse mask (see AddReparseRule); otherwise, it returns empty string.

The Mask parameter must be the file mask of an existing rule.

In most cases, the value passed for the ProductGUID parameter should be the same one that was used to call the Initialize method.

Note: The methods and properties related to rule management are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads (e.g., during the AfterFilterAttachToVolume and AfterFilterDetachFromVolume events) are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of the rule lists both occur in a thread-safe manner.

GetVolumeGUID Method (CBFilter Class)

This method retrieves the volume GUID of the device targeted by a filesystem operation.

Syntax

public String getVolumeGUID();

Remarks

This method can be called within events fired for filesystem operations to retrieve the volume GUID of the device targeted by the operation, returned in the Volume{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} format. If the query fails, this method returns an empty string.

Volume GUIDs can be used to enumerate the mounting points of a device using the Windows API's GetVolumePathNamesForVolumeName function.

Note: This method can be called only within events.

Initialize Method (CBFilter Class)

This method initializes the class.

Syntax

public void initialize(String productGUID);

Remarks

This method initializes the class and must be called each time the application starts before attempting to call any of the class's other methods with the exception of installation-related methods.

ProductGUID is used to distinguish among driver installations performed by different applications. Such information is necessary to guard against unexpected situations, such as the driver being uninstalled by one application despite other applications still needing it.

Therefore, to ensure proper operation, it is critical that each individual application have its own unique ProductGUID value, and that applications (and their installation scripts) use that value when calling any of the following methods:

• Install
• Uninstall
• GetDriverStatus
• GetDriverVersion
• Initialize

If the required driver was not installed using the Install method with the same value of ProductGUID, Initialize will return a ERROR_FILE_NOT_FOUND error (Win32 error code 2).

If the loaded kernel-mode driver is older than the user-mode API, Initialize will return a ERROR_INVALID_KERNEL_INFO_VERSION error (Win32 error code 340). In this situation, an update of the driver using the Install method is required before the class can be used.

Install Method (CBFilter Class)

This method installs (or upgrades) the class's system driver.

Syntax

public boolean install(String cabFileName, String productGUID, String pathToInstall, String altitude, int flags, String allowedControllers);

Remarks

This method is used to install or upgrade the class's system driver. If the system must be rebooted to complete the installation process, this method returns true; otherwise, it returns false.

Important: To upgrade the class's driver, use only the Install method. Previously installed versions of the driver should not be uninstalled first. Calling the Install method will upgrade the previously installed version.

Please refer to the Driver Installation topic for more information.

CabFileName must be the path of the cbfilter.cab file containing the class's system driver.

Note: This .cab file must remain on the target system (or be available in some other way) after installation, as it is required to uninstall the driver from the system.

ProductGUID is used to distinguish among driver installations performed by different applications. Such information is necessary to guard against unexpected situations, such as the driver being uninstalled by one application despite other applications still needing it.

Therefore, to ensure proper operation, it is critical that each individual application have its own unique ProductGUID value, and that applications (and their installation scripts) use that value when calling any of the following methods:

• Install
• Uninstall
• GetDriverStatus
• GetDriverVersion
• Initialize

PathToInstall controls where the driver is installed. Pass empty string (highly recommended) to automatically install them to the appropriate Windows system directory.

Altitude specifies the driver altitude to use . During development, you can use any acceptable altitude value. For deployment, an altitude value must be assigned by Microsoft before deploying a filesystem minifilter in production. After installation, the altitude can be changed at any time using the Altitude property. Please refer to the Driver Altitudes topic for more information.

Flags specifies various installation options. It should contain zero or more of the following flags, ORed together:

Note: Enabling the AlwaysPrepareFiles and/or SendRequestsViaDriverStack configuration settings before calling this method will cause the corresponding flags to be added automatically. These configuration settings can also be used to toggle the corresponding options at any time after installation.

AllowedControllers is the optional parameter that makes it possible to limit communication with the driver to just the predefined set of processes. When the caller specifies one or more names of the executable files, filtering can be started with the specified ProductGUID only when filtering is initiated by the process created from one of the listed executable files. If the name of the caller process does not match any of the allowed names, the call to StartFilter will fail with an error.

The parameter may be either empty or contain one or more EXE file names with complete paths. Separate names/paths should be separated by the LF character (numeric code 10).

This method is available in both the class API and the Installer DLL included with the product; please refer to the Driver Installation topic for more information about the latter.

This method requires administrative rights to execute successfully. If the user account of the process that calls this method doesn't have such rights, the call will fail with an ERROR_PRIVILEGE_NOT_HELD (0x0522) error.

Note: This method cannot be called within events.

IsFileFiltered Method (CBFilter Class)

This method checks whether a particular file or directory is covered by any filter rules.

Syntax

public boolean isFileFiltered(String fileName);

Remarks

This method checks whether the file or directory specified by FileName is covered by any of the standard filter rules active currently (i.e., whether the class would fire its events for one or more kinds of filesystem operations performed on it). If the specified file or directory matches any of the active standard filter rules, this method returns true; otherwise, it returns false.

Applications should use this method anytime they want to create/open some file or directory from within an event handler. If this method returns true, then the file or directory must be created/opened using the class's CreateFileDirect method rather than the Windows API's CreateFile function, because the latter could trigger recursion and cause a system deadlock.

NtStatusToWin32Error Method (CBFilter Class)

This method converts a native status code to a Win32 error code.

Syntax

public int ntStatusToWin32Error(int status);

Remarks

This method converts the native status code specified by Status to a Win32 error code. If the specified native status code does not map directly to a Win32 error code, this method returns ERROR_MR_MID_NOT_FOUND (317).

QueryFileInformationDirect Method (CBFilter Class)

This method returns various kinds of information about a file object.

Syntax

public void queryFileInformationDirect(long fileHandle, byte[] fileInformation, int fileInformationClass, int bytesTransferred[]);

Remarks

Applications may call this method to query various kinds of information about the file or directory using the open handle. The method uses the NtQueryInformationFile Windows API function to retrieve the information.

The FileHandle parameter specifies the file that should be updated. The value passed for this parameter must be a file handle obtained from the CreateFileDirect method; please refer to its documentation for more information.

The InformationClass parameter specifies the class of information to be query. For the list of supported classes, please refer to the documentation of the Windows API's NtQueryInformationFile function.

FileInformation is a buffer that must contain the information queried. The exact size and format of the information depend on InformationClass and are described in the NtQueryInformationFile help topic.

BytesTrasferredThe actual bytes of information received on completion.

QueryFileSecurityDirect Method (CBFilter Class)

This method retrieves security information of a file.

Syntax

public void queryFileSecurityDirect(long fileHandle, int securityInformation, byte[] securityDescriptor, int lengthNeeded[]);

Remarks

Applications may call this method to query security attributes of the file or directory using the open handle. The method uses the NtQuerySecurityObject Windows API function to change the security attributes.

The FileHandle parameter specifies the file that should be queried. The value passed for this parameter must be a file handle obtained from the CreateFileDirect method; please refer to its documentation for more information.

The SecurityInformation parameter specifies the information to be queried as a combination of one or more of the following:

• OWNER_SECURITY_INFORMATION
• GROUP_SECURITY_INFORMATION
• DACL_SECURITY_INFORMATION
• SACL_SECURITY_INFORMATION

Please refer to Microsoft's SECURITY_INFORMATION data type documentation for more information about possible values.

The SecurityDescriptor parameter points to the memory buffer that receives the requested data. It is available only if the length of the buffer is greater than 0. The data must be formatted as a SECURITY_DESCRIPTOR structure in self-relative format. Please refer to these articles for more information about self-relative security descriptors.

The LengthNeeded parameter points to a caller-allocated variable that receives the number of bytes required to store the copied security descriptor.

RemoveVirtualFile Method (CBFilter Class)

This method removes a virtual file from the list of virtual entries.

Syntax

public boolean removeVirtualFile(String fileName);

Remarks

This method removes a previously added virtual file identified by FileName from the list of virtual entries, managed by the class.

The FileName parameter must contain the same value as the one used to add a virtual file earlier.

The method will return true if the file was found and removed from the list and false if the file was not found in the list. An error will be reported if removal of the file failed on the driver side.

ResetTimeout Method (CBFilter Class)

This method resets the timeout duration for the current event handler.

Syntax

public boolean resetTimeout(int timeout);

Remarks

When event timeouts are being enforced, this method can be called within an event handler to inform the class that request processing is taking longer than expected.

If called successfully, this method returns true, and the current event handler's timeout timer is immediately reset to 0; when it reaches the number of milliseconds specified by Timeout, the driver will either "release" the underlying request and pass it onwards, or cancel it by reporting an error; whichever is most appropriate for the event in question. Please refer to the Timeouts topic for more information.

Passing 0 for Timeout disables the timeout timer for the current event handler, allowing it to take as long as it needs to complete.

Note: When several events are fired for the same file concurrently (if the SerializeAccess configuration setting is disabled), and ResetTimeout is called from one of the handlers of these events, this method will reset the timer for all currently executed event handlers.

Note: This method can be called only within events.

SetFileInformationDirect Method (CBFilter Class)

This method sets the file information of a file opened using CreateFileDirect.

Syntax

public void setFileInformationDirect(long fileHandle, int informationClass, byte[] fileInformation);

Remarks

Applications may call this method to change various kinds of information about a file that was opened using the CreateFileDirect method.

The FileHandle parameter specifies the file that should be updated. The value passed for this parameter must be a file handle obtained from the CreateFileDirect method; please refer to its documentation for more information.

The InformationClass parameter specifies the class of information to be set. For the list of supported classes, please refer to the documentation of the Windows API's FltSetInformationFile function.

Note: Only a limited subset of classes comparing to similar functions like NtSetInformationFile or NtQueryInformationFile is supported by this function.

FileInformation is a buffer that must contain the information to be set. The exact size and format of the information depend on InformationClass and are described in the FltSetInformationFile help topic.

SetFileSecurityDirect Method (CBFilter Class)

This method sets security information of a file.

Syntax

public void setFileSecurityDirect(long fileHandle, int securityInformation, byte[] securityDescriptor);

Remarks

Applications may call this method to set security attributes of the file or directory using the open handle. The method uses the NtSetSecurityObject Windows API function to query the security attributes.

The FileHandle parameter specifies the file that should be updated. The value passed for this parameter must be a file handle obtained from the CreateFileDirect method; please refer to its documentation for more information.

The SecurityInformation parameter indicates which pieces of security information must be set. This value is a bitfield; possible flags include (but are not limited to):

• OWNER_SECURITY_INFORMATION
• GROUP_SECURITY_INFORMATION
• DACL_SECURITY_INFORMATION
• SACL_SECURITY_INFORMATION

Please refer to Microsoft's SECURITY_INFORMATION data-type documentation for more information about possible values.

The SecurityDescriptor parameter points to a memory buffer that contains data indicated by SecurityInformation. The data are formatted as a SECURITY_DESCRIPTOR structure in self-relative format. Please refer to those articles for more information about self-relative security descriptors.

SetFileSizeDirect Method (CBFilter Class)

This method resizes a file by passing the request directly to the filesystem.

Syntax

public boolean setFileSizeDirect(long fileHandle, long size);

Remarks

Applications can call this method in filesystem-related event handlers to resize a file without sending the request through the filesystem filter driver stack. If the file is resized successfully, this method returns true; otherwise, it returns false.

The FileHandle parameter specifies the file that should be resized. The value passed for this parameter must be a file handle obtained from the CreateFileDirect method; please refer to its documentation for more information.

The Size parameter specifies the new file size, in bytes.

To set file allocation size or valid file length, you may use the SetFileInformationDirect method.

Note: This method can be called only within events.

ShutdownSystem Method (CBFilter Class)

Shuts down or reboots the operating system.

Syntax

public boolean shutdownSystem(String shutdownPrompt, int timeout, boolean forceCloseApps, boolean reboot);

Remarks

This method shuts down or (if Reboot is true) reboots the operating system. If the appropriate privileges cannot be obtained, or if the InitiateSystemShutdown system call returns false, then this method will return false; otherwise, it returns true. This method can be used if the installation or uninstallation function requires the system to be rebooted in order to complete.

ShutdownPrompt, if non-empty, specifies a message that the OS should display to the user for Timeout seconds. If empty string is passed for ShutdownPrompt, no message is displayed and the Timeout parameter's value is ignored.

ForceCloseApps specifies whether the OS should forcefully close all applications. Please keep in mind that forceful closing of applications with unsaved data can lead to data loss.

Reboot specifies whether the OS should reboot (true) or just shut down (false).

This method is available in both the class API and the Installer DLL included with the product; please refer to the Driver Installation topic for more information about the latter.

Note: This method cannot be called within events.

StartFilter Method (CBFilter Class)

This method starts filtering filesystem operations.

Syntax

public void startFilter(int timeout);

Remarks

This method attaches the filter, causing the class's system driver to start filtering filesystem operations according to the filter rules currently present. Rules can be added and removed both before and after this method is called, so long as the Initialize method is called before doing anything else.

This method can fail for a number of reasons, including (but not limited to) the following:

• If the class's system driver has not been properly installed, or is awaiting a system reboot (as indicated by the return value of Install), this method fails with an ERROR_FILE_NOT_FOUND (2) error code.
• If the Initialize method has not been called yet, this method fails with an ERROR_NOT_READY (21) error code.
• If the filter is already Active, this method fails with an ERROR_CONNECTION_ACTIVE (1230) error code.
• If an invalid value is passed for Timeout, this method fails with an ERROR_IMPLEMENTATION_LIMIT (1292) error code.

Timeout

Timeout specifies how many milliseconds the driver should wait for events to execute before releasing or cancelling the underlying OS requests; please refer to the Timeouts topic for more information. Valid values are 0, which disables event timeouts, and values greater than or equal to 3000. When event timeouts are in effect, event handlers can call ResetTimeout to reset the timer if they require additional time to complete.

StopFilter Method (CBFilter Class)

This method stops filtering filesystem operations.

Syntax

public void stopFilter();

Remarks

This method detaches the filter, causing the class's system driver to stop filtering filesystem operations. This method will block until all pending requests have been completed and the filter has been detached.

SuspendDefaultRules Method (CBFilter Class)

This method suspends all default rules until the application exits.

Syntax

public boolean suspendDefaultRules(String productGUID);

Remarks

This method suspends (i.e., deactivates) all default rules associated with the application identified by ProductGUID until the application exits. If the rules are suspended successfully, this method returns true; otherwise, it returns false.

In most cases, the value passed for the ProductGUID parameter should be the same one that was used to call the Initialize method.

When the application exits, the class's system driver will reactivate the suspended rules and start enforcing them once again.

SuspendFileEvents Method (CBFilter Class)

This method suspends all events for a particular file or directory until all of its handles have been closed.

Syntax

public void suspendFileEvents();

Remarks

Applications can call this method from an AfterCreateFile or AfterOpenFile event to suspend all further events for the file or directory that the event fired for. The suspension will remain in effect until all handles to said file or directory have been closed, at which point the class will once again fire events for it (if it is accessed again).

Typically, this method should be used only as a "last resort"; that is, when the application cannot achieve the same outcome through the use of more granular standard filter rules. Said another way, it is almost always more efficient for an application to exclude files or directories implicitly using standard filter rules, if possible, than it is to exclude them explicitly using this method.

Note: This method can be called only within the AfterCreateFile and AfterOpenFile events.

ToggleProcessProtection Method (CBFilter Class)

This method enables or disables termination protection for the application.

Syntax

public boolean toggleProcessProtection(boolean enabled);

Remarks

This method controls the termination protection mechanism, which applications can enable to prevent their process and threads from being terminated. If successful, this method returns true; otherwise, it returns false.

The Enabled parameter specifies whether termination protection should be enabled (true) or disabled (false); it is disabled by default. If termination protection is enabled, an application must disable it before attempting to exit.

Note: When developing a GUI-based application, please keep in mind that the termination protection mechanism does not intercept Windows' notifications like WM_CLOSE or WM_QUIT; applications must intercept and handle such messages themselves if they wish to protect their UI. Please refer to Microsoft's Window Notifications articles for more information.

Uninstall Method (CBFilter Class)

This method uninstalls the class's system driver.

Syntax

public boolean uninstall(String cabFileName, String productGUID, String installedPath, int flags);

Remarks

This method is used to uninstall the class's system driver. If the system must be rebooted to complete the uninstallation process, this method returns true; otherwise, it returns false.

Important: To upgrade the class's driver, use only the Install method. Previously installed versions of the driver should not be uninstalled first. Calling the Install method will upgrade the previously installed version.

Please refer to the Driver Installation topic for more information.

The same values must be passed for the CabFileName, ProductGUID, and InstalledPath parameters as were passed when Install was called; please refer to its documentation for more information.

Flags specifies which versions of the class's system driver should be uninstalled and which should be set by ORing together one or more of the following values:

This method is available in both the class API and the Installer DLL included with the product; please refer to the Driver Installation topic for more information about the latter.

This method requires administrative rights to execute successfully. If the user account of the process that calls this method doesn't have such rights, the call will fail with an ERROR_PRIVILEGE_NOT_HELD (0x0522) error.

Note: This method cannot be called within events.

UpdateVirtualFile Method (CBFilter Class)

This method updates known information about a virtual file .

Syntax

public boolean updateVirtualFile(String fileName, java.util.Date creationTime, java.util.Date lastAccessTime, java.util.Date lastWriteTime, java.util.Date changeTime, long size, int attributes);

Remarks

This method updates the information about the virtual file identified by FileName.

The FileName parameter must contain the same value as the one used to add a virtual file earlier.

CreationTime, LastAccessTime, LastWriteTime, ChangeTime should contain new time values for the file, specified in UTC; any of the time values may be January 1, 1601 00:00:00 UTC to indicate that the existing value of the corresponding time must remain unchanged.

Size must be set to the new size of the file to update the known file size or to -1 to indicate that the size didn't change.

Attributes must be set to new file's attributes. Set this parameter to 0 to indicate that the existing attributes must remain unchanged.

• FILE_ATTRIBUTE_NORMAL: This attribute is valid only when used alone; it "resets" a file's attributes.
• Please refer to Microsoft's File Attribute Constants article for attribute descriptions.

The method will return true if the file was found and updated and false if the file was not found in the list. An error will be reported if updating the file failed on the driver side.

AfterCanFileBeDeleted Event (CBFilter Class)

This event fires after the OS marks a file or directory for deletion or removes such a mark.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterCanFileBeDeleted(CBFilterAfterCanFileBeDeletedEvent e) {}
  ...
}

public class CBFilterAfterCanFileBeDeletedEvent {
  public String fileName;
  public int requestType;
  public boolean canDelete;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after the OS marks the file or directory specified by FileName for deletion or removes such a mark. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

If the file or directory is marked for deletion, they will not be removed immediately but will actually be removed when the last handle is closed. Moreover, it is possible that a future call to a system function will remove the mark, so this event is not a final indicator that the file or directory will be deleted.

Files and directories can be deleted in two ways: (1) a file or directory can be opened with the FILE_FLAG_DELETE_ON_CLOSE flag, or (2) some process may call Windows API's NtSetInformationFile function with FILE_DISPOSITION_INFORMATION or FILE_DISPOSITION_INFORMATION_EX structure as a parameter.

If the file or directory is created or opened with the FILE_FLAG_DELETE_ON_CLOSE flag, this event is fired shortly after the AfterCreateFile or AfterOpenFile event.

The RequestType indicates which kind of system request resulted in firing this event. It can be one of the following:

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_CAN_DELETE flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The CanDelete parameter reflects whether the file or directory will be deleted.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterCleanupFile Event (CBFilter Class)

This event fires after a file or directory handle is closed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterCleanupFile(CBFilterAfterCleanupFileEvent e) {}
  ...
}

public class CBFilterAfterCleanupFileEvent {
  public String fileName;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after a handle to the file or directory specified by FileName is closed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. This event differs from AfterCloseFile in that AfterCleanupFile fires immediately after an open handle to the specified file or directory is closed by a process, whereas AfterCloseFile may be fired much later when the OS decides that the file or directory can be formally closed.

Other events may fire for the file or directory in the time between when this event fires and when the AfterCloseFile event fires. For example, system components, such as the memory manager or cache manager, may cause the AfterReadFile and AfterWriteFile events to fire.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_CLEANUP flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterCloseEnumeration Event (CBFilter Class)

This event fires after a directory enumeration operation finishes.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterCloseEnumeration(CBFilterAfterCloseEnumerationEvent e) {}
  ...
}

public class CBFilterAfterCloseEnumerationEvent {
  public String directoryName;
  public long directoryContext;
  public long handleContext;
  public long enumerationContext;
  public int resultCode; //read-write
}

Remarks

This event fires after enumeration of the directory specified by DirectoryName finishes. For more information about the DirectoryName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_CLOSE flag (directory enumerations are typically closed immediately before a directory is closed).

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The EnumerationContext parameter is a placeholder for application-defined data associated with the enumeration. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterCloseFile Event (CBFilter Class)

This event fires after a file or directory is closed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterCloseFile(CBFilterAfterCloseFileEvent e) {}
  ...
}

public class CBFilterAfterCloseFileEvent {
  public String fileName;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after the file or directory specified by FileName is closed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_CLOSE flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

If the file or directory was marked for deletion earlier, the AfterDeleteFile will fire shortly before this event.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterCreateFile Event (CBFilter Class)

This event fires after a file or directory is created.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterCreateFile(CBFilterAfterCreateFileEvent e) {}
  ...
}

public class CBFilterAfterCreateFileEvent {
  public String fileName;
  public int existingAttributes;
  public boolean isolate;
  public String backendFileName;
  public int desiredAccess;
  public int attributes;
  public int shareMode;
  public int options;
  public int createDisposition;
  public ByteBuffer securityDescriptor;
  public int length;
  public int status; //read-write
  public int creationStatus; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after the file or directory specified by FileName is created. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. Please refer to the File Create/Open Events topic for more information about how the class determines whether to fire this event or AfterOpenFile.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_CREATE flag.

Note: Applications must have the FilterOwnRequests configuration setting enabled if they wish to filter their own file/directory creation requests.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

When extended rules are used or the AlwaysRequestAttributesOnOpen configuration setting is enabled, the driver requests attributes of the entity from the filesystem and passes them to ExistingAttributes. If the attributes are not requested, this parameter contains 0.

If Isolate was set to true in the BeforeCreateFile or BeforeOpenFile events, the value of the Isolate and BackendFileName parameters in this event will contain the values initially set in those events. Additionally, if a file was added using the AddVirtualFile method Isolate will be true.

The DesiredAccess, Attributes, ShareMode, and CreateDisposition parameters reflect the values that were passed for the similarly named parameters of the Windows API's CreateFile function (or, more accurately, the values carried by the IRP_MJ_CREATE IRP).

DesiredAccess may contain one or more of the following access flags:

Attributes may contain one or more of the following attributes:

ShareMode may contain zero or more of the following share mode flags:

CreateDisposition may contain one of the following values:

Options contains the flags that are described in the CreateOptions parameter of the native API's ZwCreateFile function. Most of those flags correspond to flags passed in the FlagsAndAttributes parameter of the Windows API's CreateFile function, but some flags are specific to the native API. If you need those flags, check both functions' descriptions.

Please refer to Microsoft's documentation for detailed information about these constants.

To determine whether the request was for a file or a directory, compare Attributes against the FILE_SYS_ATTR_DIRECTORY constant, as follows: // Check whether the request is for a file or a directory. bool isDirectory = Attributes & FILE_SYS_ATTR_DIRECTORY == FILE_SYS_ATTR_DIRECTORY; FILE_SYS_ATTR_DIRECTORY will be present if it was specified by the calling process or if the existing filesystem entry is a directory.

To determine whether a file will be deleted when its last handle is closed, compare Options against the Windows API's FILE_FLAG_DELETE_ON_CLOSE constant, as follows: // Check whether the file will be deleted on close. bool deleteOnClose = Options & FILE_FLAG_DELETE_ON_CLOSE == FILE_FLAG_DELETE_ON_CLOSE; Note: Because files can be deleted in different ways, do not use this check to take actions related to tracking file deletion operations. Instead, use the events related to file deletion.

When a file or directory is created using the CreateFile() Windows API function, a caller can specify the security descriptor with the security information. This security information should be applied to a newly created file or directory. The class passes this security information in the SecurityInformation and SecurityDescriptor parameters, when the PassSecurityInFileOpenEvents configuration setting is enabled. If this configuration setting is omitted, the corresponding parameters are empty.

The SecurityInformation parameter reflects which pieces of security information, of those present in SecurityDescriptor, are valid and should have been applied. Please refer to Microsoft's SECURITY_INFORMATION data type documentation for more information about possible values.

The SecurityDescriptor parameter points to a memory buffer that contains the security information. The Length parameter reflects the length of this data, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted as a SECURITY_DESCRIPTOR structure in self-relative format; please refer to the Microsoft's documentation for more information.

If the Options contains the FILE_FLAG_DELETE_ON_CLOSE flag, the AfterCanFileBeDeleted event will fire after this event.

If the file is created with Extended Attributes passed in the request, the AfterSetEa event will fire after this event.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The CreationStatus parameter indicates whether the file was created or opened and can be one of the following values:

Applications may change this parameter's value if they want a different creation status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

When the ProcessFailedRequests property is enabled, this event may fire even if the specified file or directory has not been created or opened, in which case the Status parameter will be non-zero. When this occurs, applications must not alter the FileContext and HandleContext parameters.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterCreateHardLink Event (CBFilter Class)

This event fires after a hard link is created.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterCreateHardLink(CBFilterAfterCreateHardLinkEvent e) {}
  ...
}

public class CBFilterAfterCreateHardLinkEvent {
  public String fileName;
  public String linkName;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after a hard link to the file specified by FileName is created. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. Please refer to Microsoft's Hard Links article for more information about hard links.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_CREATE_HARD_LINK flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The LinkName parameter reflects the name of the created hard link.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterDeleteFile Event (CBFilter Class)

This event fires after a file or directory is deleted.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterDeleteFile(CBFilterAfterDeleteFileEvent e) {}
  ...
}

public class CBFilterAfterDeleteFileEvent {
  public String fileName;
  public int requestType;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after the file or directory specified by FileName is deleted. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. More specifically, this event is fired after the final IRP_MJ_CLOSE IRP is processed by the filesystem (i.e., after the last handle to the file or directory is closed and the file or directory is gone) and before AfterCloseFile fires.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_DELETE flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The RequestType indicates which kind of system request resulted in firing this event. It can be one of the following:

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterDeleteReparsePoint Event (CBFilter Class)

This event fires after the OS deletes a reparse point from a file or directory.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterDeleteReparsePoint(CBFilterAfterDeleteReparsePointEvent e) {}
  ...
}

public class CBFilterAfterDeleteReparsePointEvent {
  public String fileName;
  public ByteBuffer reparseBuffer;
  public int bufferLength;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after the OS deletes a reparse point from a file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Note: The file or directory is not deleted, only a reparse point is.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_DELETE_REPARSE_POINT flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The ReparseBuffer parameter points to a memory buffer that specifies the known reparse point information. This information is provided for convenience. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

Please refer to the Reparse Points topic for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterEnumerateDirectory Event (CBFilter Class)

This event fires after a directory entry is returned during directory enumeration.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterEnumerateDirectory(CBFilterAfterEnumerateDirectoryEvent e) {}
  ...
}

public class CBFilterAfterEnumerateDirectoryEvent {
  public String directoryName;
  public int flags;
  public int index;
  public String fileName; //read-write
  public java.util.Date creationTime; //read-write
  public java.util.Date lastAccessTime; //read-write
  public java.util.Date lastWriteTime; //read-write
  public java.util.Date changeTime; //read-write
  public long size; //read-write
  public long allocationSize; //read-write
  public long fileId; //read-write
  public int attributes; //read-write
  public int status; //read-write
  public long directoryContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public long enumerationContext; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires after a directory entry (i.e., a file or subdirectory) is returned during enumeration of the directory specified by DirectoryName. For more information about the DirectoryName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications may use this event to modify the entry's metadata before it gets reported to the requestor or even to prevent the entry from being reported in the first place.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_ENUMERATE_DIRECTORY flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Flags parameter specifies supplementary information about enumeration. It is a combination of zero or more values:

If the Flags parameter contains FS_ENUM_INDEX_SPECIFIED, the Index parameter contains the index as provided by the OS.

The FileName parameter reflects the name of the directory entry. .

The CreationTime, LastAccessTime, LastWriteTime, and ChangeTime parameters specify the entry's time values, specified in UTC.

The Size parameter specifies the size of the file, in bytes; it must always be 0 for subdirectories.

The AllocationSize parameter specifies the amount of space allocated for the file, in bytes; it must always be 0 for subdirectories.

The FileId parameter specifies the unique Id of the entry, as reported by the filesystem (or, for virtual files, by the application itself). This Id is used by the network redirector, and some third-party applications, to open files and directories by Id instead of by name. The root directory always uses the predefined Id 0x7FFFFFFFFFFFFFFF.

The Attributes parameter specifies the entry's attributes; please refer to Microsoft's File Attribute Constants article for attribute descriptions.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The DirectoryContext, HandleContext, and EnumerationContext parameters are placeholders for application-defined data associated with the directory, specific handle, and enumeration, respectively. (For general-purpose events, the DirectoryContext is called FileContext instead.) DirectoryContext corresponds to the FileContext in the file/directory creation, opening, and closing events. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the directory entry should actually be reported to the requestor; it is true by default. Setting this parameter to false will "hide" the directory entry (i.e., prevent it from being reported).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterFilterAttachToVolume Event (CBFilter Class)

This event fires after the filter attaches to a newly mounted filesystem volume.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterFilterAttachToVolume(CBFilterAfterFilterAttachToVolumeEvent e) {}
  ...
}

public class CBFilterAfterFilterAttachToVolumeEvent {
  public String volumeName;
  public String volumeNameNT;
  public int resultCode; //read-write
}

Remarks

This event fires after the filter attaches to the newly mounted filesystem volume specified by VolumeNameNT and, when possible, VolumeName. Please refer to the FireVolumeEvents property for more information.

Applications need to handle this event only if the FireVolumeEvents property includes the FS_MOUNT_CONTROL flag.

Note: This event won't fire for any volumes skipped during the BeforeFilterAttachToVolume event; please refer to its documentation for more information.

VolumeNameNT contains the name of the volume in the NT-native format, as received from the system. If the ResolveNtDeviceToDriveLetter configuration setting is enabled, and if it was possible to convert the NT name to the DOS format with a drive letter, VolumeName will contain the name in this format; otherwise, it will be empty.

Applications can obtain additional information about a volume by retrieving its GUID using the GetVolumeGUID method, and then using that GUID to call various Windows API functions.

Applications can use this event to add volume-specific rules for the volume that has been mounted (keeping in mind that this event does not fire for volumes that are already present when StartFilter is called). Applications that intend to do so must ensure that proper thread synchronization techniques are used when manipulating or enumerating the rule lists, because this event's handler will always execute in the context of some worker thread. Note: if a path-based rule is added or removed, such a path should use the value from VolumeNameNT to avoid a possible deadlock, which may occur during resolving a DOS name to the NT format.

Applications must be aware that this event fires as a direct response to a filesystem state change (mount or unmount). Various system components or third-party actors can perform supplementary filesystem mounting and unmounting during main unmount operations (e.g., Volume Service is one such component). This can cause seemingly excessive events to be fired, and sometimes they can be fired out of order (such as two *Attach or *Detach events fired in a row).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterFilterDetachFromVolume Event (CBFilter Class)

This event fires after the filter detaches from a filesystem volume.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterFilterDetachFromVolume(CBFilterAfterFilterDetachFromVolumeEvent e) {}
  ...
}

public class CBFilterAfterFilterDetachFromVolumeEvent {
  public String volumeName;
  public String volumeNameNT;
  public int resultCode; //read-write
}

Remarks

This event fires after the filter detaches from the filesystem volume specified by VolumeNameNT and, when possible, VolumeName, typically because of the volume being unmounted. Please refer to the FireVolumeEvents property for more information.

Applications need to handle this event only if the FireVolumeEvents property includes the FS_MOUNT_CONTROL flag.

Note: This event won't fire for any volumes skipped during the BeforeFilterAttachToVolume event; please refer to its documentation for more information.

Applications should use this event to remove volume-specific rules for the volume that has been unmounted. Applications that intend to do so must ensure that proper thread synchronization techniques are used when manipulating or enumerating the rule lists, because this event's handler will always execute in the context of some worker thread. Note: if a path-based rule is added or removed, such a path should use the value from VolumeNameNT to avoid a possible deadlock, which may occur during resolving a DOS name to the NT format.

Applications must be aware that this event fires as a direct response to a filesystem state change (mount or unmount). Various system components or third-party actors can perform supplementary filesystem mounting and unmounting during main unmount operations (e.g., Volume Service is one such component). This can cause seemingly excessive events to be fired, and sometimes they can be fired out of order (such as two *Attach or *Detach events fired in a row).

VolumeNameNT contains the name of the volume in the NT-native format, as received from the system. If the ResolveNtDeviceToDriveLetter configuration setting is enabled, and if it was possible to convert the NT name to the DOS format with a drive letter, VolumeName will contain the name in this format; otherwise, it will be empty.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterFsctl Event (CBFilter Class)

This event fires after an IRP_MJ_FILE_SYSTEM_CONTROL request is processed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterFsctl(CBFilterAfterFsctlEvent e) {}
  ...
}

public class CBFilterAfterFsctlEvent {
  public String fileName;
  public int fsControlCode;
  public ByteBuffer inBuffer;
  public int inBufferLength;
  public int inBufferValidBytes;
  public ByteBuffer outBuffer;
  public int outBufferLength;
  public int outBufferValidBytes; //read-write
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after an IRP_MJ_FILE_SYSTEM_CONTROL (FSCTL) request is processed. Such requests are sent using the Windows API's DeviceIoControl function (user mode), or ZwFsControlFile function (kernel mode); please refer to Microsoft's documentation for more information.

Applications may use this event to modify the output data (if there are any) before the response is returned to the requestor. Applications that choose to do this must:

1. copy no more than OutBufferLength bytes into OutBuffer; and
2. update the OutBufferValidBytes parameter's value afterward so that it correctly reflects the amount of data in OutBuffer.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_FSCTL flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The FileName parameter reflects the file, directory, or volume targeted by the request.

The FsControlCode parameter reflects the requested filesystem control code (FSCTL).

The InBuffer parameter points to a memory buffer that contains the data required to perform the operation. The InBufferLength and InBufferValidBytes parameters reflect the capacity of InBuffer and the length of the data it contains (respectively), in bytes; InBufferValidBytes may be less than InBufferLength (unless the request did not include data, in which case both will be 0).

The OutBuffer parameter points to a memory buffer that contains the data returned by the operation. The OutBufferLength and OutBufferValidBytes parameters reflect the capacity of OutBuffer and the length of the data it contains (respectively), in bytes; OutBufferValidBytes may be less than OutBufferLength (unless the operation did not return data, in which case both will be 0).

Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterGetFileSecurity Event (CBFilter Class)

This event fires after a file or directory's security attributes are retrieved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterGetFileSecurity(CBFilterAfterGetFileSecurityEvent e) {}
  ...
}

public class CBFilterAfterGetFileSecurityEvent {
  public String fileName;
  public int securityInformation;
  public ByteBuffer securityDescriptor;
  public int length;
  public int lengthNeeded; //read-write
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after security attributes are retrieved for the file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Note: This event will not fire every time a file or directory is accessed. To check file security upon each access to a file or directory, implement the file create and open events and perform the necessary checks there instead.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_GET_SECURITY flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The SecurityInformation parameter indicates which pieces of security information were requested. Please refer to Microsoft's SECURITY_INFORMATION data-type documentation for more information about possible values.

The SecurityDescriptor parameter points to a memory buffer that, if the request was successful, contains the requested security information. The Length parameter reflects the length of this data, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted as a SECURITY_DESCRIPTOR structure in self-relative format; please refer to the Microsoft's documentation for more information.

Applications that wish to modify the security information may do so by replacing the data in the SecurityDescriptor buffer. If the current Length is too small to accommodate the new security information, set LengthNeeded to the number of bytes necessary to hold the data and return the ERROR_INSUFFICIENT_BUFFER error code via ResultCode.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterGetFileSizes Event (CBFilter Class)

This event fires after a file's size information is retrieved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterGetFileSizes(CBFilterAfterGetFileSizesEvent e) {}
  ...
}

public class CBFilterAfterGetFileSizesEvent {
  public String fileName;
  public long size; //read-write
  public long allocationSize; //read-write
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires after size information is retrieved for the file specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications that intend to modify a file's contents should use this event to modify the file's actual size or allocation size as necessary. Applications that make use of virtual files should use this event to report the size of the virtual files.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_GET_SIZES flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Size parameter specifies the actual size of the file, in bytes.

The AllocationSize parameter specifies the amount of space allocated for the file, in bytes.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterGetReparsePoint Event (CBFilter Class)

This event fires after a file or directory's reparse point information is retrieved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterGetReparsePoint(CBFilterAfterGetReparsePointEvent e) {}
  ...
}

public class CBFilterAfterGetReparsePointEvent {
  public String fileName;
  public ByteBuffer reparseBuffer;
  public int bufferLength;
  public int dataLength; //read-write
  public int lengthNeeded; //read-write
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after reparse point information is retrieved for the file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_GET_REPARSE_POINT flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The ReparseBuffer parameter points to a memory buffer that, if the request was successful, contains the requested reparse point information. The DataLength parameter reflects the length of this data, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

Please refer to the Reparse Points topic for more information.

Applications that wish to modify the reparse point information may do so by replacing the data in the ReparseBuffer buffer. If the current BufferLength is too small to accommodate the new information, the application should write as much data as possible, set LengthNeeded appropriately, and return the STATUS_BUFFER_OVERFLOW status code via Status.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

Depending on how the request originator accessed the specified file or directory, it may or may not currently be open. The FileContext and HandleContext parameters will be absent if it is not open, in which case they will be 0.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterIoctl Event (CBFilter Class)

This event fires after an IRP_MJ_DEVICE_CONTROL request is processed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterIoctl(CBFilterAfterIoctlEvent e) {}
  ...
}

public class CBFilterAfterIoctlEvent {
  public String fileName;
  public int ioControlCode;
  public ByteBuffer inBuffer;
  public int inBufferLength;
  public int inBufferValidBytes;
  public ByteBuffer outBuffer;
  public int outBufferLength;
  public int outBufferValidBytes; //read-write
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after an IRP_MJ_DEVICE_CONTROL (IOCTL) request is processed. Such requests are sent using the Windows API's DeviceIoControl function (user mode), or ZwDeviceIoControlFile function (kernel mode). Please refer to Microsoft's documentation for more information.

Applications may use this event to modify the output data (if there are any) before the response is returned to the requestor. Applications that choose to do this must:

1. copy no more than OutBufferLength bytes into OutBuffer; and
2. update the OutBufferValidBytes parameter's value afterward so that it correctly reflects the amount of data in OutBuffer.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_IOCTL flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The FileName parameter reflects the file, directory, or volume targeted by the request.

The IoControlCode parameter reflects the requested I/O control code (IOCTL).

The InBuffer parameter points to a memory buffer that contains the data required to perform the operation. The InBufferLength and InBufferValidBytes parameters reflect the capacity of InBuffer and the length of the data it contains (respectively), in bytes; InBufferValidBytes may be less than InBufferLength (unless the request did not include data, in which case both will be 0).

The OutBuffer parameter points to a memory buffer that contains the data returned by the operation. The OutBufferLength and OutBufferValidBytes parameters reflect the capacity of OutBuffer and the length of the data it contains (respectively), in bytes; OutBufferValidBytes may be less than OutBufferLength (unless the operation did not return data, in which case both will be 0).

Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterLock Event (CBFilter Class)

This event fires after a range of bytes in a file is locked.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterLock(CBFilterAfterLockEvent e) {}
  ...
}

public class CBFilterAfterLockEvent {
  public String fileName;
  public long offset;
  public long length;
  public long key;
  public boolean failImmediately;
  public boolean exclusiveLock;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after a range of bytes in the file specified by FileName is locked. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. This request is made either by the OS, or on behalf of a user mode application that called the Windows API's LockFile or LockFileEx function.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_LOCK_CONTROL flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Offset parameter reflects the byte offset where the byte range lock starts.

The Length parameter reflects the length of the byte range lock.

The Key parameter reflects the key that the byte range lock is associated with. This key is used to identify the byte range lock in later unlock-by-key requests.

The FailImmediately parameter indicates whether the request was to fail if the lock could not be granted immediately.

The ExclusiveLock parameter indicates whether the byte range lock was to be exclusive (true) or shared (false).

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterOpenFile Event (CBFilter Class)

This event fires after a file or directory is opened.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterOpenFile(CBFilterAfterOpenFileEvent e) {}
  ...
}

public class CBFilterAfterOpenFileEvent {
  public String fileName;
  public int existingAttributes;
  public boolean isolate;
  public String backendFileName;
  public int desiredAccess;
  public int attributes;
  public int shareMode;
  public int options;
  public int createDisposition;
  public ByteBuffer securityDescriptor;
  public int length;
  public int status; //read-write
  public int creationStatus; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after the file or directory specified by FileName is opened. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. Please refer to the File Create/Open Events topic for more information about how the class determines whether to fire this event or AfterCreateFile.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_OPEN flag.

Note: Applications must have the FilterOwnRequests configuration setting enabled if they wish to filter their own file/directory open requests.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

When extended rules are used or the AlwaysRequestAttributesOnOpen configuration setting is enabled, the driver requests attributes of the entity from the filesystem and passes them to ExistingAttributes. If the attributes are not requested, this parameter contains 0.

If Isolate was set to true in the BeforeCreateFile or BeforeOpenFile events, the value of the Isolate and BackendFileName parameters in this event will contain the values initially set in those events. Additionally, if a file was added using the AddVirtualFile method Isolate will be true.

The DesiredAccess, Attributes, ShareMode, and CreateDisposition parameters reflect the values that were passed for the similarly named parameters of the Windows API's CreateFile function (or, more accurately, the values carried by the IRP_MJ_CREATE IRP).

DesiredAccess may contain one or more of the following access flags:

Attributes may contain one or more of the following attributes:

ShareMode may contain zero or more of the following share mode flags:

CreateDisposition may contain one of the following values:

Options contains the flags that are described in the CreateOptions parameter of the native API's ZwCreateFile function. Most of those flags correspond to flags passed in the FlagsAndAttributes parameter of the Windows API's CreateFile function, but some flags are specific to the native API. If you need those flags, check both functions' descriptions.

Please refer to Microsoft's documentation for detailed information about these constants.

To determine whether the request was for a file or a directory, compare Attributes against the FILE_SYS_ATTR_DIRECTORY constant, as follows: // Check whether the request is for a file or a directory. bool isDirectory = Attributes & FILE_SYS_ATTR_DIRECTORY == FILE_SYS_ATTR_DIRECTORY; FILE_SYS_ATTR_DIRECTORY will be present if it was specified by the calling process or if the existing filesystem entry is a directory.

To determine whether a file will be deleted when its last handle is closed, compare Options against the Windows API's FILE_FLAG_DELETE_ON_CLOSE constant, as follows: // Check whether the file will be deleted on close. bool deleteOnClose = Options & FILE_FLAG_DELETE_ON_CLOSE == FILE_FLAG_DELETE_ON_CLOSE; Note: Because files can be deleted in different ways, do not use this check to take actions related to tracking file deletion operations. Instead, use the events related to file deletion.

When a file or directory is created using the CreateFile() Windows API function, a caller can specify the security descriptor with the security information. This security information should be applied to a newly created file or directory. The class passes this security information in the SecurityInformation and SecurityDescriptor parameters, when the PassSecurityInFileOpenEvents configuration setting is enabled. If this configuration setting is omitted, the corresponding parameters are empty.

The SecurityInformation parameter reflects which pieces of security information, of those present in SecurityDescriptor, are valid and should have been applied. Please refer to Microsoft's SECURITY_INFORMATION data type documentation for more information about possible values.

The SecurityDescriptor parameter points to a memory buffer that contains the security information. The Length parameter reflects the length of this data, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted as a SECURITY_DESCRIPTOR structure in self-relative format; please refer to the Microsoft's documentation for more information.

If the Options contains the FILE_FLAG_DELETE_ON_CLOSE flag, the AfterCanFileBeDeleted event will fire after this event.

If the file is opened with extended attributes passed in the request, the AfterSetEa event will fire after this event.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The CreationStatus parameter indicates whether the file was created or opened and can be one of the following values:

Applications may change this parameter's value if they want a different creation status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

When the ProcessFailedRequests property is enabled, this event may fire even if the specified file or directory has not been created or opened, in which case the Status parameter will be non-zero. When this occurs, applications must not alter the FileContext and HandleContext parameters.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterQueryEa Event (CBFilter Class)

This event fires after information about extended attributes of a file is retrieved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterQueryEa(CBFilterAfterQueryEaEvent e) {}
  ...
}

public class CBFilterAfterQueryEaEvent {
  public String fileName;
  public ByteBuffer buffer;
  public int bufferLength;
  public boolean returnSingleEntry;
  public ByteBuffer eaList;
  public int eaListLength;
  public int eaIndex;
  public boolean restartScan;
  public int lengthReturned; //read-write
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after information about extended attributes of the file specified by FileName is retrieved using the ZwQueryEaFile or FltQueryEaFile function of the system API. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_QUERY_EA flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Buffer parameter points to a memory buffer that, if the request was successful, contains the requested information. The data in the buffer are formatted as a FILE_FULL_EA_INFORMATION structure; please refer to the Microsoft's documentation for more information. The Length parameter reflects the length of this buffer, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

ReturnSingleEntry specifies that the filesystem had to return only the first entry it has found.

EaList is an optional parameter that points to a caller-supplied memory buffer specifying the extended attributes to be queried. The data in the buffer are formatted as a FILE_GET_EA_INFORMATION structure; please refer to the Microsoft's documentation for more information. The EaListLength parameter reflects the length of this data, in bytes. If the caller of the FltQueryEaFile function did not specify any value, it will contain 0.

EaIndex is an optional parameter that specifies the starting index of the attribute, information about which was requested. This parameter is ignored by the filesystem if EaList points to a nonempty list. If the caller of the FltQueryEaFile function did not specify any value, the parameter will contain -1.

The RestartScan parameter instructs the filesystem to restart enumeration of extended attributes from the first entry. If the parameter is false, retrieval of the extended attributes is resumed by the filesystem after a previous request.

LengthReturned is an optional parameter that contains the size, in bytes, of the information, returned in the Buffer.

A handler may modify the contents of the Buffer given that the size of the modified data does not exceed the length of the buffer. When modifying the data, a handler should update LengthReturned accordingly.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterQueryFileInfo Event (CBFilter Class)

This event fires after information about a file or directory is retrieved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterQueryFileInfo(CBFilterAfterQueryFileInfoEvent e) {}
  ...
}

public class CBFilterAfterQueryFileInfoEvent {
  public String fileName;
  public int fileInformationClass;
  public ByteBuffer buffer;
  public int bufferLength;
  public int validBytes; //read-write
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after information about the file or directory specified by FileName is retrieved. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. This event typically fires in response to the Windows API's NtQueryInformationFile function.

Applications may use this event to modify the output data before the response is returned to the requestor. Applications that choose to do this must:

1. copy no more than BufferLength bytes into Buffer; and
2. update the ValidBytes parameter's value afterward so that it correctly reflects the amount of data in Buffer.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_QUERY_FILE_INFO flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The FileInformationClass parameter indicates what kind of file information was requested. Please refer to the NtQueryInformationFile function's documentation for more information about possible values.

The Buffer parameter points to a memory buffer that, if the request was successful, contains the requested file information. The BufferLength and ValidBytes parameters reflect the capacity of Buffer and the length of the data it contains (respectively), in bytes; ValidBytes may be less than BufferLength. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The format of the data is determined by the specified FileInformationClass; please refer to the NtQueryInformationFile function's documentation for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterReadFile Event (CBFilter Class)

This event fires after data are read from a file.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterReadFile(CBFilterAfterReadFileEvent e) {}
  ...
}

public class CBFilterAfterReadFileEvent {
  public String fileName;
  public long position;
  public ByteBuffer buffer;
  public int bufferLength;
  public int bytesToRead;
  public int reserved;
  public int direction;
  public int bytesRead; //read-write
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after data are read from the file specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications may use this event to modify the data that were read from the file before it is returned to the requestor. Applications that choose to do this must:

1. enable the ModifiableReadWriteBuffers configuration setting (i.e., before this event fires);
2. copy no more than BytesToRead bytes into Buffer; and
3. update the BytesRead parameter's value afterward so that it correctly reflects the amount of data in Buffer.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_READ flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Position parameter reflects the byte offset in the file at which reading started.

The Buffer parameter points to a memory buffer that, if the request was successful, contains the data that were read from the file. The BufferLength parameter reflects the capacity of Buffer, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The BytesToRead parameter reflects how many bytes were to be read from the file (i.e., how many bytes the requestor expects will be read).

The Direction parameter indicates the request direction; please refer to the Cached and Non-Cached Requests topic for more information. Possible values are as follows:

The BytesRead parameter specifies how many bytes were actually read from the file, and thus the length of the data in Buffer. This parameter's value must not exceed BufferLength (and should not exceed BytesToRead; please refer to BeforeReadFile for more information).

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information. (If the system's cache manager or memory manager initiated the operation, HandleContext may be absent, in which case it will be 0.)

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterRenameOrMoveFile Event (CBFilter Class)

This event fires after a file or directory is renamed or moved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterRenameOrMoveFile(CBFilterAfterRenameOrMoveFileEvent e) {}
  ...
}

public class CBFilterAfterRenameOrMoveFileEvent {
  public String fileName;
  public String newFileName;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after the file or directory specified by FileName is renamed or moved to NewFileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_RENAME flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

A rule's mask is matched against both previous and new file names, and the event will fire when either of the names matches the mask.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterSetAllocationSize Event (CBFilter Class)

This event fires after a file's allocation size is changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterSetAllocationSize(CBFilterAfterSetAllocationSizeEvent e) {}
  ...
}

public class CBFilterAfterSetAllocationSizeEvent {
  public String fileName;
  public long allocationSize;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after the allocation size of the file specified by FileName is changed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_SET_SIZES flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The AllocationSize parameter reflects the new allocation size, in bytes. A file's allocation size is typically larger than its actual size because filesystem operations often reserve space on disk before writing additional data to a file.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information. (If the system's cache manager or memory manager initiated the operation, HandleContext may be absent, in which case it will be 0.)

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterSetEa Event (CBFilter Class)

This event fires after extended attributes of a file are changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterSetEa(CBFilterAfterSetEaEvent e) {}
  ...
}

public class CBFilterAfterSetEaEvent {
  public String fileName;
  public ByteBuffer buffer;
  public int bufferLength;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after extended attributes are changed for the file specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

If the file is created or opened with extended attributes passed in the request, this event will fire shortly after the AfterCreateFile or AfterOpenFile event.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_SET_EA flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Buffer parameter points to a memory buffer that specifies the extended attribute information. The Length parameter reflects the length of this buffer, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted as a FILE_FULL_EA_INFORMATION structure; please refer to the Microsoft's documentation for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterSetFileAttributes Event (CBFilter Class)

This event fires after a file or directory's attributes or times are changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterSetFileAttributes(CBFilterAfterSetFileAttributesEvent e) {}
  ...
}

public class CBFilterAfterSetFileAttributesEvent {
  public String fileName;
  public java.util.Date creationTime;
  public java.util.Date lastAccessTime;
  public java.util.Date lastWriteTime;
  public java.util.Date changeTime;
  public int attributes;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after the attributes or times of the file or directory specified by FileName are changed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_SET_ATTRIBUTES flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The CreationTime, LastAccessTime, LastWriteTime, and ChangeTime parameters reflect the new time values, specified in UTC. A value of January 1, 1601 00:00:00 UTC indicates that the corresponding time value was not included in the request.

The Attributes parameter reflects the new attributes; please refer to Microsoft's File Attribute Constants article for attribute descriptions.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterSetFileInfo Event (CBFilter Class)

This event fires after information about a file or directory is changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterSetFileInfo(CBFilterAfterSetFileInfoEvent e) {}
  ...
}

public class CBFilterAfterSetFileInfoEvent {
  public String fileName;
  public int fileInformationClass;
  public ByteBuffer buffer;
  public int bufferLength;
  public int validBytes;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after information about the file or directory specified by FileName is changed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. This event typically fires in response to the Windows API's NtSetInformationFile function.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_SET_FILE_INFO flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The FileInformationClass parameter indicates what kind of file information was set. Please refer to the NtSetInformationFile function's documentation for more information about possible values.

The Buffer parameter points to a memory buffer that, if the request was successful, contains the new file information. The BufferLength and ValidBytes parameters reflect the capacity of Buffer and the length of the data it contains (respectively), in bytes; ValidBytes may be less than BufferLength. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The format of the data is determined by the specified FileInformationClass; please refer to the NtSetInformationFile function's documentation for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterSetFileSecurity Event (CBFilter Class)

This event fires after a file or directory's security attributes are changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterSetFileSecurity(CBFilterAfterSetFileSecurityEvent e) {}
  ...
}

public class CBFilterAfterSetFileSecurityEvent {
  public String fileName;
  public int securityInformation;
  public ByteBuffer securityDescriptor;
  public int length;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after security attributes are changed for the file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_SET_SECURITY flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The SecurityInformation parameter reflects which pieces of security information, of those present in SecurityDescriptor, were to be set. Please refer to Microsoft's SECURITY_INFORMATION data-type documentation for more information about possible values.

The SecurityDescriptor parameter points to a memory buffer that contains the new security information. The Length parameter reflects the length of this data, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted as a SECURITY_DESCRIPTOR structure in self-relative format; please refer to the Microsoft's documentation for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterSetFileSize Event (CBFilter Class)

This event fires after a file is resized.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterSetFileSize(CBFilterAfterSetFileSizeEvent e) {}
  ...
}

public class CBFilterAfterSetFileSizeEvent {
  public String fileName;
  public long size;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after the file specified by FileName is resized, whether explicitly (e.g., truncation) or implicitly (i.e., as data are appended). For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_SET_SIZES flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Size parameter reflects the new file size, in bytes.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information. (If the system's cache manager or memory manager initiated the operation, HandleContext may be absent, in which case it will be 0.)

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterSetReparsePoint Event (CBFilter Class)

This event fires after the OS creates or updates a reparse point on a file or directory.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterSetReparsePoint(CBFilterAfterSetReparsePointEvent e) {}
  ...
}

public class CBFilterAfterSetReparsePointEvent {
  public String fileName;
  public long reparseTag;
  public ByteBuffer reparseBuffer;
  public int bufferLength;
  public int dataLength;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after the OS creates or updates a reparse point on a file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_SET_REPARSE_POINT flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The ReparseTag parameter contains the reparse tag, which is the value the system uses to identify the format of the reparse point data. This value is also present in the ReparseBuffer data; the class extracts it and provides it separately for convenience.

The ReparseBuffer parameter points to a memory buffer that specifies the new reparse point information. The DataLength parameter reflects the length of the data contained in the buffer, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

Please refer to the Reparse Points topic for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterUnlockAll Event (CBFilter Class)

This event fires after all locked byte ranges in a file are unlocked.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterUnlockAll(CBFilterAfterUnlockAllEvent e) {}
  ...
}

public class CBFilterAfterUnlockAllEvent {
  public String fileName;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after all locked byte ranges in the file specified by FileName are unlocked. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_LOCK_CONTROL flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterUnlockAllByKey Event (CBFilter Class)

This event fires after all locked byte ranges in a file, associated with a particular key, are unlocked.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterUnlockAllByKey(CBFilterAfterUnlockAllByKeyEvent e) {}
  ...
}

public class CBFilterAfterUnlockAllByKeyEvent {
  public String fileName;
  public long key;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after all locked byte ranges in the file specified by FileName, and associated with the specified Key, are unlocked. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_LOCK_CONTROL flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Key parameter contains the key value specified when the byte ranges were locked. Please refer to the AfterLock event's documentation for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterUnlockSingle Event (CBFilter Class)

This event fires after a particular locked byte range in a file is unlocked.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterUnlockSingle(CBFilterAfterUnlockSingleEvent e) {}
  ...
}

public class CBFilterAfterUnlockSingleEvent {
  public String fileName;
  public long offset;
  public long length;
  public long key;
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after a particular locked byte range in the file specified by FileName is unlocked. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_LOCK_CONTROL flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Offset, Length, and Key parameters contain the starting byte offset, length, and key values (respectively) specified when the byte range was locked. Please refer to the AfterLock event's documentation for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

AfterWriteFile Event (CBFilter Class)

This event fires after data are written to a file.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void afterWriteFile(CBFilterAfterWriteFileEvent e) {}
  ...
}

public class CBFilterAfterWriteFileEvent {
  public String fileName;
  public long position;
  public ByteBuffer buffer;
  public int bufferLength;
  public int bytesToWrite;
  public int direction;
  public int bytesWritten; //read-write
  public int status; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext;
  public int resultCode; //read-write
}

Remarks

This event fires after data are written to the file specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications may use this event to inspect the data that were written to the file, but must not attempt to alter said data. If, during BeforeWriteFile, an application causes less data than requested to be written to the file, it should use this event to set BytesWritten back to the expected value (i.e., BytesToWrite) to prevent the requestor from behaving unexpectedly.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_AFTER_WRITE flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Position parameter reflects the byte offset in the file at which writing started. A value of -1 means "append to the end of the file".

The Buffer parameter points to a memory buffer that contains the data that, if the request was successful, were written to the file. The BufferLength parameter reflects the capacity of Buffer, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The BytesToWrite parameter reflects how many bytes were to be written to the file (i.e., how many bytes the requestor expects will be written).

The Direction parameter indicates the request direction; please refer to the Cached and Non-Cached Requests topic for more information. Possible values are as follows:

The BytesWritten parameter specifies how many bytes were actually written to the file. This parameter's value must not exceed BufferLength (and should not exceed BytesToWrite; please refer to BeforeWriteFile for more information).

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information. (If the system's cache manager or memory manager initiated the operation, HandleContext may be absent, in which case it will be 0.)

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeCanFileBeDeleted Event (CBFilter Class)

This event fires before the OS attempts to mark a file or directory for deletion or remove such a mark.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeCanFileBeDeleted(CBFilterBeforeCanFileBeDeletedEvent e) {}
  ...
}

public class CBFilterBeforeCanFileBeDeletedEvent {
  public String fileName;
  public int requestType;
  public boolean canDelete; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before the OS marks the file or directory specified by FileName for deletion or removes such a mark. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Files and directories can be deleted in two ways: (1) a file or directory can be opened with the FILE_FLAG_DELETE_ON_CLOSE flag, or (2) some process may call Windows API's NtSetInformationFile function with FILE_DISPOSITION_INFORMATION or FILE_DISPOSITION_INFORMATION_EX structure as a parameter.

If the file or directory is created or opened with the FILE_FLAG_DELETE_ON_CLOSE flag, this event is fired shortly before the BeforeCreateFile or BeforeOpenFile event.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_CAN_DELETE flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The RequestType indicates which kind of system request resulted in firing this event. It can be one of the following:

The CanDelete parameter specifies whether the file or directory will be deleted. This parameter can be true or false depending on which request the OS has sent. Applications may prevent deletion of the file or directory by setting CanDelete to false. Changing CanDelete from false to true may or may not have the effect on the file being deleted later, so such a change should be avoided.

Note: If the file is opened with FILE_FLAG_DELETE_ON_CLOSE flag set and the event handler permits file deletion, such flag cannot be removed later (even with the call to NtSetInformationFile() API function).

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

The effect of ProcessRequest depends on what operation caused the event to fire:

• If the event fires during the file open operation where the FILE_FLAG_DELETE_ON_CLOSE flag is set,
  • setting CanDelete to false and ProcessRequest to true causes the FILE_FLAG_DELETE_ON_CLOSE flag to be removed and the file open request to be passed further to the filesystem; and
  • setting CanDelete to false and ProcessRequest to false causes the file open request to fail with ACCESS_DENIED error.
• If the event fires in the context of the call to NtSetInformationFile Windows API function, setting CanDelete to false causes the DeleteFlag parameter to be set to false and the request to be passed further to the filesystem. This combination effectively resets the file deletion state, known to the filesystem, to the false ("do not delete") value. The value of ProcessRequest in this case does not matter as the new value must reach the filesystem.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information. (If the specified file or directory was not opened before the request, both contexts will be absent, in which case these parameters will be 0.)

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeCleanupFile Event (CBFilter Class)

This event fires before a file or directory handle is closed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeCleanupFile(CBFilterBeforeCleanupFileEvent e) {}
  ...
}

public class CBFilterBeforeCleanupFileEvent {
  public String fileName;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before a handle to the file or directory specified by FileName is closed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. This event differs from BeforeCloseFile in that BeforeCleanupFile fires immediately before an open handle to the specified file or directory is closed by a process, whereas BeforeCloseFile may be fired much later when the OS itself decides that the file or directory can be formally closed.

Other events may fire for the file or directory in the time between when this event fires and when the BeforeCloseFile event fires. For example, system components such as the memory manager or cache manager may cause the BeforeReadFile and BeforeWriteFile events to fire.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_CLEANUP flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeCloseFile Event (CBFilter Class)

This event fires before a file or directory is closed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeCloseFile(CBFilterBeforeCloseFileEvent e) {}
  ...
}

public class CBFilterBeforeCloseFileEvent {
  public String fileName;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before the file or directory specified by FileName is closed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_CLOSE flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

If the file or directory was marked for deletion earlier, the BeforeDeleteFile will fire shortly before this event.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeCreateFile Event (CBFilter Class)

This event fires before a file or directory is created.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeCreateFile(CBFilterBeforeCreateFileEvent e) {}
  ...
}

public class CBFilterBeforeCreateFileEvent {
  public String fileName;
  public int existingAttributes;
  public boolean isolate; //read-write
  public String backendFileName; //read-write
  public int desiredAccess; //read-write
  public int attributes; //read-write
  public int shareMode; //read-write
  public int options; //read-write
  public int createDisposition; //read-write
  public ByteBuffer securityDescriptor;
  public int length;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before the file or directory specified by FileName is created. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. Please refer to the File Create/Open Events topic for more information about how the class determines whether to fire this event or BeforeOpenFile.

Applications may use this event to modify the request's parameters, or to block the request entirely. To do the latter, set ProcessRequest to false; and set Status to the desired NT status (the parameter is set to STATUS_ACCESS_DENIED before the event is fired).

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_CREATE flag.

Note: Applications must have the FilterOwnRequests configuration setting enabled if they wish to filter their own file/directory creation requests.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

When extended rules are used or the AlwaysRequestAttributesOnOpen configuration setting is enabled, the driver requests attributes of the entity from the filesystem and passes them to ExistingAttributes. If the attributes are not requested, this parameter contains 0.

To redirect file access to another location, or to provide custom file content, set Isolate to true. For instance if Process A and Process B both access a file, isolation allows returning different content to each process. When Isolate is set to true the BackendFileName parameter determines if the file is redirected, and to where.

When requests are redirected to an existing file on disk a dedicated cache is created for the isolated file by the CBFilter driver. This cache ensures that the data it holds do not interfere with the data read from or written to the file when it is opened without isolation. Please see the File Isolation topic for further details.

To ensure that isolation works properly, on Windows 11, the BypassIORequest event is fired when the OS makes a request to enable BypassIO on this file, giving a way for the application to forbid BypassIO with an application-specific error code and explanation.

Requests may also be redirected to another file or directory via the ReparseFileName event which is fired before this event. In order for the ReparseFileName event to fire, a standard filter rule must exist that includes the FS_CE_REPARSE_FILENAME flag. For more details, please see the ReparseFileName topic.

The initial values of DesiredAccess, Attributes, ShareMode, and CreateDisposition parameters reflect the values that were passed for the similarly named parameters of the Windows API's CreateFile function (or, more accurately, the values carried by the IRP_MJ_CREATE Internet Relay Programming).

DesiredAccess may contain one or more of the following access flags:

Attributes may contain one or more of the following attributes:

ShareMode may contain zero or more of the following share mode flags:

When the file being created or opened is virtual, the event handler must inspect and handle the value of the ShareMode parameter as a filesystem would normally do it.

CreateDisposition may contain one of the following values:

When the file being created or opened is virtual, the event handler must inspect and handle the value of the CreateDisposition parameter as a filesystem would normally do it. This includes adjusting the file size and updating the time attributes depending on the flag. For a virtual file, the driver returns the CreationStatus value that is derived from CreateDisposition as follows: If the event handler needs to change the returned CreationStatus, it should change the value of the CreateDisposition to the FILE_DISPOSITION_*** value that leads to the desired CreationStatus value (e.g. set the value to FILE_DISPOSITION_OPEN_EXISTING so that the driver returns CREATION_STATUS_OPENED).

Options contains the flags that are described in the CreateOptions parameter of the Native API's ZwCreateFile function. Most of those flags correspond to flags passed in the FlagsAndAttributes parameter of the Windows API's CreateFile function, but some flags are specific to Native API. If you need those flags, check both functions' descriptions.

Please refer to Microsoft's documentation for detailed information about these constants.

To determine whether the request is for a file or a directory, compare Attributes against the FILE_SYS_ATTR_DIRECTORY constant, as follows: // Check whether the request is for a file or a directory. bool isDirectory = Attributes & FILE_SYS_ATTR_DIRECTORY == FILE_SYS_ATTR_DIRECTORY; FILE_SYS_ATTR_DIRECTORY will be present only if it was specified by the calling process; its presence or absence does not indicate the real presence of the attribute on the file or directory on disk.

To determine whether a file will be deleted when its last handle is closed, compare Options against the Windows API's FILE_FLAG_DELETE_ON_CLOSE constant, as follows: // Check whether the file will be deleted on close. bool deleteOnClose = Options & FILE_FLAG_DELETE_ON_CLOSE == FILE_FLAG_DELETE_ON_CLOSE;

Note: Files can be deleted in different ways, so do not use this check to take actions related to tracking file deletion operations. Instead, use the events related to file deletion.

To prevent a file or directory from being opened, set the ResultCode parameter to a non-zero value (typically ERROR_ACCESS_DENIED (5)).

When a file or directory is created using the CreateFile() Windows API function, a caller can specify the security descriptor with the security information. This security information should be applied to a newly created file or directory. The class passes this security information in the SecurityInformation and SecurityDescriptor parameters, when the PassSecurityInFileOpenEvents configuration setting is enabled. If this configuration setting is omitted, the corresponding parameters are empty.

The SecurityInformation parameter reflects which pieces of security information, of those present in SecurityDescriptor, are valid and should have been applied. Please refer to Microsoft's SECURITY_INFORMATION data type documentation for more information about possible values.

The SecurityDescriptor parameter points to a memory buffer that contains the security information. The Length parameter reflects the length of this data, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted as a SECURITY_DESCRIPTOR structure in self-relative format; please refer to the Microsoft's documentation for more information.

If an application needs to alter the security information, it can do this by placing up to Length bytes of information into the SecurityDescriptor buffer.

Note: Changing the security data is possible only when the PassSecurityInFileOpenEvents configuration setting is enabled.

If the capacity reflected by the Length parameter is not enough to accommodate the security information, set LengthNeeded to the number of bytes necessary to hold the data, and return the ERROR_INSUFFICIENT_BUFFER error code via ResultCode.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

If the Options contains the FILE_FLAG_DELETE_ON_CLOSE flag, the BeforeCanFileBeDeleted event will fire before this event.

If the file is opened with extended attributes passed in the request, the BeforeSetEa event will fire after this event.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeCreateHardLink Event (CBFilter Class)

This event fires before a hard link is created.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeCreateHardLink(CBFilterBeforeCreateHardLinkEvent e) {}
  ...
}

public class CBFilterBeforeCreateHardLinkEvent {
  public String fileName;
  public String linkName;
  public boolean replaceIfExists; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before a hard link to the file specified by FileName is created. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. Please refer to Microsoft's Hard Links article for more information about hard links.

Applications may use this event to modify the request's parameters, or to block the request entirely. To do the latter, set ProcessRequest to false.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_CREATE_HARD_LINK flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The LinkName parameter reflects the name of the new hard link.

The ReplaceIfExists parameter specifies what to do if a hard link with the specified LinkName already exists. If this parameter is true, the new hard link will replace the existing hard link; if this parameter is false, the operation will fail.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeDeleteFile Event (CBFilter Class)

This event fires before a file or directory is deleted.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeDeleteFile(CBFilterBeforeDeleteFileEvent e) {}
  ...
}

public class CBFilterBeforeDeleteFileEvent {
  public String fileName;
  public int requestType;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before the file or directory specified by FileName is deleted. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. More specifically, this event is fired before the final IRM_MJ_CLOSE Internet Relay Programming (IRP) is processed by the filesystem and before BeforeCloseFile fires.

Applications may use this event to obtain information about the specified file or directory, which still exists at the time this event fires. This event cannot be used to prevent a deletion; use the BeforeCanFileBeDeleted event instead.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_DELETE flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The RequestType indicates which kind of system request resulted in firing this event. It can be one of the following:

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeDeleteReparsePoint Event (CBFilter Class)

This event fires when the OS wants to delete a reparse point from a file or directory.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeDeleteReparsePoint(CBFilterBeforeDeleteReparsePointEvent e) {}
  ...
}

public class CBFilterBeforeDeleteReparsePointEvent {
  public String fileName;
  public ByteBuffer reparseBuffer;
  public int bufferLength;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before the OS deletes a reparse point from a file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Note: The file or directory is not deleted, only the reparse point is.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_DELETE_REPARSE_POINT flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The ReparseBuffer parameter points to a memory buffer that specifies the known reparse point information. This information is provided for convenience. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

Please refer to the Reparse Points topic for more information.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeEnumerateDirectory Event (CBFilter Class)

This event fires when an enumeration request is sent by the OS.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeEnumerateDirectory(CBFilterBeforeEnumerateDirectoryEvent e) {}
  ...
}

public class CBFilterBeforeEnumerateDirectoryEvent {
  public String directoryName;
  public int flags;
  public String mask;
  public int index;
  public long directoryContext; //read-write
  public long handleContext; //read-write
  public long enumerationContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires when the OS sends a request for reading one or more entries of the directory specified by DirectoryName. For more information about the DirectoryName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications may use this event to record the request and optionally block it.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_ENUMERATE_DIRECTORY flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Flags parameter specifies supplementary information about enumeration. It is a combination of zero or more values:

If the Flags parameter contains FS_ENUM_INDEX_SPECIFIED, the Index parameter contains the index as provided by the OS.

The Mask parameter contains the mask for the enumeration. This value may contain any combination of valid file name characters and wildcards (the * and ? characters). Alternatively, it may be an exact file name (i.e., a value without any wildcards), as some applications query file information by specifying an exact file name in an enumeration. When TranslateDOSCharsInEnumMasks is false, this parameter may contain a so-called DOS wildcard (please, refer to the description of this setting for more information). The mask can also be empty in rare cases: this happens when the OS request is a continuation of a previous enumeration with a valid non-zero Index.

The DirectoryContext, HandleContext, and EnumerationContext parameters are placeholders for application-defined data associated with the directory, specific handle, and enumeration, respectively. (For general-purpose events, the DirectoryContext is called FileContext instead.) DirectoryContext corresponds to the FileContext in the file/directory creation, opening, and closing events. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeFilterAttachToVolume Event (CBFilter Class)

This event fires before the filter attaches to a newly mounted filesystem volume.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeFilterAttachToVolume(CBFilterBeforeFilterAttachToVolumeEvent e) {}
  ...
}

public class CBFilterBeforeFilterAttachToVolumeEvent {
  public String volumeName;
  public String volumeNameNT;
  public boolean skipVolume; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before the filter attaches to the newly mounted filesystem volume specified by VolumeNameNT and, when possible, VolumeName. Please refer to the FireVolumeEvents property for more information.

Applications need to handle this event only if the FireVolumeEvents property includes the FS_MOUNT_CONTROL flag.

VolumeNameNT contains the name of the volume in the NT-native format, as received from the system. If the ResolveNtDeviceToDriveLetter configuration setting is enabled, and if it was possible to convert the NT name to the DOS format with a drive letter, VolumeName will contain the name in this format; otherwise, it will be empty.

Applications can obtain additional information about a volume by retrieving its GUID using the GetVolumeGUID method, and then using that GUID to call various Windows API functions.

The SkipVolume parameter specifies whether the class's system driver should skip the specified volume (i.e., not attach the filter to it). Setting this parameter to true will cause all filesystem operations that target to volume to be completely ignored by the class's system driver. It also will prevent any of the following events from firing for the volume:

• AfterFilterAttachToVolume
• NotifyFilterAttachToVolume
• AfterFilterDetachFromVolume
• NotifyFilterDetachFromVolume

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

Applications must be aware that this event fires as a direct response to a filesystem state change (mount or unmount). Various system components or third-party actors can perform supplementary filesystem mounting and unmounting during main unmount operations (e.g., Volume Service is one such component). This can cause seemingly excessive events to be fired, and sometimes they can be fired out of order (such as two *Attach or *Detach events fired in a row).

BeforeFsctl Event (CBFilter Class)

This event fires before an IRP_MJ_FILE_SYSTEM_CONTROL request is processed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeFsctl(CBFilterBeforeFsctlEvent e) {}
  ...
}

public class CBFilterBeforeFsctlEvent {
  public String fileName;
  public int fsControlCode;
  public ByteBuffer inBuffer;
  public int inBufferLength;
  public int inBufferValidBytes; //read-write
  public ByteBuffer outBuffer;
  public int outBufferLength;
  public int outBufferValidBytes; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before an IRP_MJ_FILE_SYSTEM_CONTROL (FSCTL) request is processed. Such requests are sent using the Windows API's DeviceIoControl function (user mode), or ZwFsControlFile function (kernel mode); please refer to Microsoft's documentation for more information.

Applications may use this event to modify the input data (if there are any) before the request continues onward. Applications that choose to do this must do the following:

1. Copy no more than InBufferLength bytes into InBuffer.
2. Update the InBufferValidBytes parameter's value afterward so that it correctly reflects the amount of data in InBuffer.

Alternatively, applications may use this event to handle the request (preventing it from continuing onward), in which case they must do the following:

1. Copy no more than OutBufferLength bytes into OutBuffer.
2. Update the OutBufferValidBytes parameter's value afterward so that it correctly reflects the amount of data in OutBuffer.
3. Set ProcessRequest to false to indicate that the request has been handled and should not continue onward.

(The first two steps are not applicable if the requested operation is not expected to return data.)

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_FSCTL flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The FileName parameter reflects the file, directory, or volume targeted by the request.

The FsControlCode parameter reflects the requested filesystem control code (FSCTL).

The InBuffer parameter points to a memory buffer that contains the data required to perform the operation. The InBufferLength and InBufferValidBytes parameters reflect the capacity of InBuffer and the length of the data it contains (respectively), in bytes; InBufferValidBytes may be less than InBufferLength (unless the request did not include data, in which case both will be 0).

The OutBuffer parameter points to a memory buffer that receives the data returned by the operation. The OutBufferLength and OutBufferValidBytes parameters reflect the capacity of OutBuffer and the length of the data it contains (respectively), in bytes; OutBufferValidBytes may be less than OutBufferLength (unless the operation is not expected to return data, in which case both will be 0).

Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeGetFileSecurity Event (CBFilter Class)

This event fires before a file or directory's security attributes are retrieved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeGetFileSecurity(CBFilterBeforeGetFileSecurityEvent e) {}
  ...
}

public class CBFilterBeforeGetFileSecurityEvent {
  public String fileName;
  public int securityInformation;
  public ByteBuffer securityDescriptor;
  public int length;
  public int lengthNeeded; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before security attributes are retrieved for the file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Note: This event will not fire every time a file or directory is accessed. To check file security upon each access to a file or directory, implement the file create and open events and perform the necessary checks there instead.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_GET_SECURITY flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The SecurityInformation parameter indicates which pieces of security information are requested. Please refer to Microsoft's SECURITY_INFORMATION data-type documentation for more information about possible values.

The SecurityDescriptor parameter points to a memory buffer that receives the requested security information. The buffer referenced by the SecurityDescriptor parameter may be modified by the event handler if the operation is completed without passing it further to other filters and the filesystem driver. The Length parameter reflects the capacity of the SecurityDescriptor buffer, in bytes.

If the capacity reflected by the Length parameter is not sufficient to accommodate the security information, set LengthNeeded to the number of bytes necessary to hold the data, and return the ERROR_INSUFFICIENT_BUFFER error code via ResultCode.

Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The returned data will be formatted as a SECURITY_DESCRIPTOR structure in self-relative format; please refer to the Microsoft's documentation for more information.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeGetReparsePoint Event (CBFilter Class)

This event fires when the OS wants to read a reparse point for a file or directory.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeGetReparsePoint(CBFilterBeforeGetReparsePointEvent e) {}
  ...
}

public class CBFilterBeforeGetReparsePointEvent {
  public String fileName;
  public ByteBuffer reparseBuffer;
  public int reparseBufferLength; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires when the OS wants to read a reparse point for the file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_GET_REPARSE_POINT flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

If an application desires to handle the event and does not pass the request further, it needs to fill ReparseBuffer with the reparse point data associated with the specified file or directory and set ReparseBufferLength to the number of bytes written. The ReparseBufferLength parameter's initial value reflects the capacity of the memory buffer pointed to by ReparseBuffer. If the buffer is too small to hold all of the reparse point data, then the application should write as much data to it as possible, set ReparseBufferLength appropriately, and return the ERROR_MORE_DATA error code via ResultCode.

Please refer to the Reparse Points topic for more information.

Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

Depending on how the request originator accessed the specified file or directory, it may or may not currently be open. The FileContext and HandleContext parameters will be absent if it is not open, in which case they will be 0.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeIoctl Event (CBFilter Class)

This event fires before an IRP_MJ_DEVICE_CONTROL request is processed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeIoctl(CBFilterBeforeIoctlEvent e) {}
  ...
}

public class CBFilterBeforeIoctlEvent {
  public String fileName;
  public int ioControlCode;
  public ByteBuffer inBuffer;
  public int inBufferLength;
  public int inBufferValidBytes; //read-write
  public ByteBuffer outBuffer;
  public int outBufferLength;
  public int outBufferValidBytes; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before an IRP_MJ_DEVICE_CONTROL (IOCTL) request is processed. Such requests are sent using the Windows API's DeviceIoControl function (user mode), or ZwDeviceIoControlFile function (kernel mode). Please refer to Microsoft's documentation for more information.

Applications may use this event to modify the input data (if there are any) before the request continues onward. Applications that choose to do this must do the following:

1. Copy no more than InBufferLength bytes into InBuffer.
2. Update the InBufferValidBytes parameter's value afterward so that it correctly reflects the amount of data in InBuffer.

Alternatively, applications may use this event to handle the request (preventing it from continuing onward), in which case they must do the following:

1. Copy no more than OutBufferLength bytes into OutBuffer.
2. Update the OutBufferValidBytes parameter's value afterward so that it correctly reflects the amount of data in OutBuffer.
3. Set ProcessRequest to false to indicate that the request has been handled and should not continue onward.

(The first two steps are not applicable if the requested operation is not expected to return data.)

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_IOCTL flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The FileName parameter reflects the file, directory, or volume targeted by the request.

The IoControlCode parameter reflects the requested I/O control code (IOCTL).

The InBuffer parameter points to a memory buffer that contains the data required to perform the operation. The InBufferLength and InBufferValidBytes parameters reflect the capacity of InBuffer and the length of the data it contains (respectively), in bytes; InBufferValidBytes may be less than InBufferLength (unless the request did not include data, in which case both will be 0).

The OutBuffer parameter points to a memory buffer that receives the data returned by the operation. The OutBufferLength and OutBufferValidBytes parameters reflect the capacity of OutBuffer and the length of the data it contains (respectively), in bytes; OutBufferValidBytes may be less than OutBufferLength (unless the operation is not expected to return data, in which case both will be 0).

Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeLock Event (CBFilter Class)

This event fires before a range of bytes in a file is locked.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeLock(CBFilterBeforeLockEvent e) {}
  ...
}

public class CBFilterBeforeLockEvent {
  public String fileName;
  public long offset; //read-write
  public long length; //read-write
  public long key;
  public boolean failImmediately; //read-write
  public boolean exclusiveLock; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before a range of bytes in the file specified by FileName is locked. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. This request is made either by the OS, or on behalf of a user mode application that called the Windows API's LockFile or LockFileEx function.

Applications may use this event to modify the request's parameters.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_LOCK_CONTROL flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Offset parameter specifies the byte offset where the byte range lock should start.

The Length parameter specifies the length of the byte range lock.

The Key parameter reflects the key that the byte range lock will be associated with. This key is used to identify the byte range lock in later unlock-by-key requests.

The FailImmediately parameter specifies whether the request should fail if the lock cannot be granted immediately.

The ExclusiveLock parameter specifies whether the byte range lock should be exclusive (true) or shared (false).

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeOpenFile Event (CBFilter Class)

This event fires before a file or directory is opened.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeOpenFile(CBFilterBeforeOpenFileEvent e) {}
  ...
}

public class CBFilterBeforeOpenFileEvent {
  public String fileName;
  public int existingAttributes;
  public boolean isolate; //read-write
  public String backendFileName; //read-write
  public int desiredAccess; //read-write
  public int attributes; //read-write
  public int shareMode; //read-write
  public int options; //read-write
  public int createDisposition; //read-write
  public ByteBuffer securityDescriptor;
  public int length;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before the file or directory specified by FileName is opened. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. Please refer to the File Create/Open Events topic for more information about how the class determines whether to fire this event or BeforeCreateFile.

Applications may use this event to modify the request's parameters, or to block the request entirely. To do the latter, set ProcessRequest to false; and set Status to the desired NT status (the parameter is set to STATUS_ACCESS_DENIED before the event is fired).

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_OPEN flag.

Note: Applications must have the FilterOwnRequests configuration setting enabled if they wish to filter their own file/directory open requests.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

When extended rules are used or the AlwaysRequestAttributesOnOpen configuration setting is enabled, the driver requests attributes of the entity from the filesystem and passes them to ExistingAttributes. If the attributes are not requested, this parameter contains 0.

To redirect file access to another location, or to provide custom file content, set Isolate to true. For instance if Process A and Process B both access a file, isolation allows returning different content to each process. When Isolate is set to true the BackendFileName parameter determines if the file is redirected, and to where.

When requests are redirected to an existing file on disk a dedicated cache is created for the isolated file by the CBFilter driver. This cache ensures that the data it holds do not interfere with the data read from or written to the file when it is opened without isolation. Please see the File Isolation topic for further details.

To ensure that isolation works properly, on Windows 11, the BypassIORequest event is fired when the OS makes a request to enable BypassIO on this file, giving a way for the application to forbid BypassIO with an application-specific error code and explanation.

Requests may also be redirected to another file or directory via the ReparseFileName event which is fired before this event. In order for the ReparseFileName event to fire, a standard filter rule must exist that includes the FS_CE_REPARSE_FILENAME flag. For more details, please see the ReparseFileName topic.

The initial values of DesiredAccess, Attributes, ShareMode, and CreateDisposition parameters reflect the values that were passed for the similarly named parameters of the Windows API's CreateFile function (or, more accurately, the values carried by the IRP_MJ_CREATE Internet Relay Programming).

DesiredAccess may contain one or more of the following access flags:

Attributes may contain one or more of the following attributes:

ShareMode may contain zero or more of the following share mode flags:

When the file being created or opened is virtual, the event handler must inspect and handle the value of the ShareMode parameter as a filesystem would normally do it.

CreateDisposition may contain one of the following values:

When the file being created or opened is virtual, the event handler must inspect and handle the value of the CreateDisposition parameter as a filesystem would normally do it. This includes adjusting the file size and updating the time attributes depending on the flag. For a virtual file, the driver returns the CreationStatus value that is derived from CreateDisposition as follows: If the event handler needs to change the returned CreationStatus, it should change the value of the CreateDisposition to the FILE_DISPOSITION_*** value that leads to the desired CreationStatus value (e.g. set the value to FILE_DISPOSITION_OPEN_EXISTING so that the driver returns CREATION_STATUS_OPENED).

Options contains the flags that are described in the CreateOptions parameter of the Native API's ZwCreateFile function. Most of those flags correspond to flags passed in the FlagsAndAttributes parameter of the Windows API's CreateFile function, but some flags are specific to Native API. If you need those flags, check both functions' descriptions.

Please refer to Microsoft's documentation for detailed information about these constants.

To determine whether the request is for a file or a directory, compare Attributes against the FILE_SYS_ATTR_DIRECTORY constant, as follows: // Check whether the request is for a file or a directory. bool isDirectory = Attributes & FILE_SYS_ATTR_DIRECTORY == FILE_SYS_ATTR_DIRECTORY; FILE_SYS_ATTR_DIRECTORY will be present only if it was specified by the calling process; its presence or absence does not indicate the real presence of the attribute on the file or directory on disk.

To determine whether a file will be deleted when its last handle is closed, compare Options against the Windows API's FILE_FLAG_DELETE_ON_CLOSE constant, as follows: // Check whether the file will be deleted on close. bool deleteOnClose = Options & FILE_FLAG_DELETE_ON_CLOSE == FILE_FLAG_DELETE_ON_CLOSE;

Note: Files can be deleted in different ways, so do not use this check to take actions related to tracking file deletion operations. Instead, use the events related to file deletion.

To prevent a file or directory from being opened, set the ResultCode parameter to a non-zero value (typically ERROR_ACCESS_DENIED (5)).

When a file or directory is created using the CreateFile() Windows API function, a caller can specify the security descriptor with the security information. This security information should be applied to a newly created file or directory. The class passes this security information in the SecurityInformation and SecurityDescriptor parameters, when the PassSecurityInFileOpenEvents configuration setting is enabled. If this configuration setting is omitted, the corresponding parameters are empty.

The SecurityInformation parameter reflects which pieces of security information, of those present in SecurityDescriptor, are valid and should have been applied. Please refer to Microsoft's SECURITY_INFORMATION data type documentation for more information about possible values.

The SecurityDescriptor parameter points to a memory buffer that contains the security information. The Length parameter reflects the length of this data, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted as a SECURITY_DESCRIPTOR structure in self-relative format; please refer to the Microsoft's documentation for more information.

If an application needs to alter the security information, it can do this by placing up to Length bytes of information into the SecurityDescriptor buffer.

Note: Changing the security data is possible only when the PassSecurityInFileOpenEvents configuration setting is enabled.

If the capacity reflected by the Length parameter is not enough to accommodate the security information, set LengthNeeded to the number of bytes necessary to hold the data, and return the ERROR_INSUFFICIENT_BUFFER error code via ResultCode.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

If the Options contains the FILE_FLAG_DELETE_ON_CLOSE flag, the BeforeCanFileBeDeleted event will fire before this event.

If the file is opened with extended attributes passed in the request, the BeforeSetEa event will fire after this event.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeQueryEa Event (CBFilter Class)

This event fires before information about extended attributes of a file is retrieved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeQueryEa(CBFilterBeforeQueryEaEvent e) {}
  ...
}

public class CBFilterBeforeQueryEaEvent {
  public String fileName;
  public ByteBuffer buffer;
  public int bufferLength;
  public boolean returnSingleEntry; //read-write
  public ByteBuffer eaList;
  public int eaListLength; //read-write
  public int eaIndex; //read-write
  public boolean restartScan; //read-write
  public int lengthReturned; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before information about extended attributes of the file specified by FileName is retrieved using the ZwQueryEaFile or FltQueryEaFile function of the system API. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_QUERY_EA flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Buffer parameter points to a memory buffer, into which, if the request is successful, the filesystem will place the requested information. The data in the buffer are formatted as a FILE_FULL_EA_INFORMATION structure; please refer to the Microsoft's documentation for more information. The BufferLength parameter reflects the length of this buffer, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

ReturnSingleEntry specifies that the filesystem had to return only the first entry it has found.

EaList is an optional parameter that points to a caller-supplied memory buffer specifying the extended attributes to be queried. The data in the buffer are formatted as a FILE_GET_EA_INFORMATION structure; please refer to the Microsoft's documentation for more information. The EaListLength parameter reflects the length of this data, in bytes. If the caller of the FltQueryEaFile function did not specify any value, it will contain 0. The list may be modified by an event handler, if needed, provided that the size of the new or modified data does not exceed the value of the EaListLength parameter.

EaIndex is an optional parameter that specifies the starting index of the attribute, information about which is requested. This parameter is ignored by the filesystem if EaList points to a nonempty list. If the caller of the FltQueryEaFile function did not specify any value, the parameter will contain -1.

The RestartScan parameter instructs the filesystem to restart enumeration of extended attributes from the first entry. If the parameter is false, retrieval of the extended attributes is resumed by the filesystem after a previous request. The parameter may be modified by an event handler if needed.

LengthReturned is an optional parameter that contains the size, in bytes, of the information, returned in the Buffer.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

Applications may use this event to modify the request's data before it continues onward, or to handle the request entirely (preventing it from continuing onward). In these cases, applications must do the following:

1. Copy no more than BufferLength bytes into Buffer.
2. Update the LengthReturned parameter's value afterward so that it correctly reflects the amount of data in Buffer.
3. If the request has been handled and should not continue onward, set ProcessRequest to false.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeQueryFileInfo Event (CBFilter Class)

This event fires before information about a file or directory is retrieved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeQueryFileInfo(CBFilterBeforeQueryFileInfoEvent e) {}
  ...
}

public class CBFilterBeforeQueryFileInfoEvent {
  public String fileName;
  public int fileInformationClass;
  public ByteBuffer buffer;
  public int bufferLength;
  public int validBytes; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before information about the file or directory specified by FileName is retrieved. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. This event typically fires in response to the Windows API's NtQueryInformationFile function.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_QUERY_FILE_INFO flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The FileInformationClass parameter indicates what kind of file information is requested. Please refer to the NtQueryInformationFile function's documentation for more information about possible values.

The Buffer parameter points to a memory buffer that receives the requested file information. The BufferLength and ValidBytes parameters reflect the capacity of Buffer and the length of the data it contains (respectively), in bytes; ValidBytes may be less than BufferLength. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The format of the data is determined by the specified FileInformationClass; please refer to the NtQueryInformationFile function's documentation for more information.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

Applications may use this event to modify the request's data before it continues onward, or to handle the request entirely (preventing it from continuing onward). In these cases, applications must do the following:

1. Copy no more than BufferLength bytes into Buffer.
2. Update the ValidBytes parameter's value afterward so that it correctly reflects the amount of data in Buffer.
3. If the request has been handled and should not continue onward, set ProcessRequest to false.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeReadFile Event (CBFilter Class)

This event fires before data are read from a file.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeReadFile(CBFilterBeforeReadFileEvent e) {}
  ...
}

public class CBFilterBeforeReadFileEvent {
  public String fileName;
  public long position; //read-write
  public ByteBuffer buffer;
  public int bufferLength;
  public int bytesToRead; //read-write
  public int reserved; //read-write
  public int direction;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before data are read from the file specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications that intend to modify a file's data after it is read may use this event to modify the request's parameters, if necessary (e.g., to ensure that the correct data are read from the file and made available for postprocessing during the AfterReadFile event). Applications may also use this event to block the request entirely by returning an appropriate error code (e.g., ACCESS_DENIED) via ResultCode.

Alternatively, applications may use this event to handle the underlying request, in which case they must do the following:

1. Enable the ModifiableReadWriteBuffers configuration setting (i.e., before this event fires).
2. Copy no more than BufferLength bytes into Buffer.
3. Update the BytesToRead parameter's value afterward so that it correctly reflects the amount of data in Buffer.
4. Set ProcessRequest to false to indicate that the request has been handled and should not continue onward.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_READ flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Position parameter specifies the byte offset in the file at which reading should start.

The Buffer parameter points to a memory buffer that receives the data read from the file. The BufferLength parameter reflects the capacity of Buffer, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The BytesToRead parameter's initial value reflects how many bytes should be read from the file (i.e., how many bytes the requestor expects will be read). This parameter's value may be changed (for either of the reasons discussed above), but it must not exceed BufferLength.

Note: However, reading more or less data than requested is not expected behavior and likely will cause the requestor to misbehave. Applications that change BytesToRead, for any reason, should use the AfterReadFile event to "cover up" such behavior; please refer to its documentation for more information.

The Direction parameter indicates the request direction; please refer to the Cached and Non-Cached Requests topic for more information. Possible values are as follows:

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information. (If the system's cache manager or memory manager initiated the operation, HandleContext may be absent, in which case it will be 0.)

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeRenameOrMoveFile Event (CBFilter Class)

This event fires before a file or directory is renamed or moved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeRenameOrMoveFile(CBFilterBeforeRenameOrMoveFileEvent e) {}
  ...
}

public class CBFilterBeforeRenameOrMoveFileEvent {
  public String fileName;
  public String newFileName;
  public boolean replaceIfExists; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before the file or directory specified by FileName is renamed or moved to NewFileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications may use this event to modify the request's parameters, or to block the request entirely. To do the latter, set ProcessRequest to false.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_RENAME flag. A rule's mask is matched against both previous and new file names, and the event will fire when either of the names matches the mask.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The ReplaceIfExists parameter specifies what to do if a file with the specified NewFileName already exists. If this parameter is true, the existing file will be overwritten by the file being renamed/moved; if this parameter is false, the operation will fail.

Note: Windows only allows files to be overwritten; if the destination is an existing directory, the request will be denied regardless of this parameter's value.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeSetAllocationSize Event (CBFilter Class)

This event fires before a file's allocation size is changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeSetAllocationSize(CBFilterBeforeSetAllocationSizeEvent e) {}
  ...
}

public class CBFilterBeforeSetAllocationSizeEvent {
  public String fileName;
  public long allocationSize; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before the allocation size of the file specified by FileName is changed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications may use this event to modify the request's parameters.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_SET_SIZES flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The AllocationSize parameter specifies the new allocation size, in bytes. A file's allocation size is typically larger than its actual size because filesystem operations often reserve space on disk before writing additional data to a file. Applications may track such situations and avoid reallocating disk space where possible to improve performance.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information. (If the system's cache manager or memory manager initiated the operation, HandleContext may be absent, in which case it will be 0.)

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeSetEa Event (CBFilter Class)

This event fires before extended attributes of a file are changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeSetEa(CBFilterBeforeSetEaEvent e) {}
  ...
}

public class CBFilterBeforeSetEaEvent {
  public String fileName;
  public ByteBuffer buffer;
  public int bufferLength;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before extended attributes are changed for the file specified by FileName using the ZwSetEaFile or FltSetEaFile function of the system API. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

If the file is created or opened with extended attributes passed in the request, this event will fire shortly after the BeforeCreateFile or BeforeOpenFile event.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_SET_EA flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Buffer parameter points to a memory buffer that specifies the extended attribute information. The buffer referenced by the Buffer parameter may be modified when needed if the request is to be passed further to other filters and the filesystem driver. The Length parameter reflects the length of this buffer, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted as a FILE_FULL_EA_INFORMATION structure; please refer to Microsoft's documentation for more information.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeSetFileAttributes Event (CBFilter Class)

This event fires before a file or directory's attributes or times are changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeSetFileAttributes(CBFilterBeforeSetFileAttributesEvent e) {}
  ...
}

public class CBFilterBeforeSetFileAttributesEvent {
  public String fileName;
  public java.util.Date creationTime; //read-write
  public java.util.Date lastAccessTime; //read-write
  public java.util.Date lastWriteTime; //read-write
  public java.util.Date changeTime; //read-write
  public int attributes; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before the attributes or times of a file or directory specified by FileName are changed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications may use this event to modify the request's parameters.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_SET_ATTRIBUTES flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The CreationTime, LastAccessTime, LastWriteTime, and ChangeTime parameters specify the new time values, specified in UTC. A value of January 1, 1601 00:00:00 UTC indicates that the corresponding time value is not included in the request.

The Attributes parameter specifies the new attributes; please refer to Microsoft's File Attribute Constants article for attribute descriptions.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeSetFileInfo Event (CBFilter Class)

This event fires before information about a file or directory is changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeSetFileInfo(CBFilterBeforeSetFileInfoEvent e) {}
  ...
}

public class CBFilterBeforeSetFileInfoEvent {
  public String fileName;
  public int fileInformationClass;
  public ByteBuffer buffer;
  public int bufferLength;
  public int validBytes; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before information about the file or directory specified by FileName is changed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. This event typically fires in response to the Windows API's NtSetInformationFile function.

Applications may use this event to modify the request's data before it continues onward, in which case they must do the following:

1. Copy no more than BufferLength bytes into Buffer.
2. Update the ValidBytes parameter's value afterward so that it correctly reflects the amount of data in Buffer.

Alternatively, applications may use this event to handle the underlying request, preventing it from continuing onward, by setting ProcessRequest to false.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_SET_FILE_INFO flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The FileInformationClass parameter indicates what kind of file information is to be changed. Please refer to the NtSetInformationFile function's documentation for more information about possible values.

The Buffer parameter points to a memory buffer that specifies the new file information. The BufferLength and ValidBytes parameters reflect the capacity of Buffer and the length of the data it contains, respectively, in bytes; ValidBytes may be less than BufferLength. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The format of the data is determined by the specified FileInformationClass; please refer to the NtSetInformationFile function's documentation for more information.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeSetFileSecurity Event (CBFilter Class)

This event fires before a file or directory's security attributes are changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeSetFileSecurity(CBFilterBeforeSetFileSecurityEvent e) {}
  ...
}

public class CBFilterBeforeSetFileSecurityEvent {
  public String fileName;
  public int securityInformation;
  public ByteBuffer securityDescriptor;
  public int length;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before security attributes are changed for the file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_SET_SECURITY flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The SecurityInformation parameter reflects which pieces of security information, of those present in SecurityDescriptor, will be set. Please refer to Microsoft's SECURITY_INFORMATION data-type documentation for more information about possible values.

The SecurityDescriptor parameter points to a memory buffer that specifies the new security information. The buffer referenced by the SecurityDescriptor parameter may be modified when needed if the request is to be passed further to other filters and the filesystem driver. The Length parameter reflects the length of this data, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted as a SECURITY_DESCRIPTOR structure in self-relative format; please refer to the Microsoft's documentation for more information.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeSetFileSize Event (CBFilter Class)

This event fires before a file is resized.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeSetFileSize(CBFilterBeforeSetFileSizeEvent e) {}
  ...
}

public class CBFilterBeforeSetFileSizeEvent {
  public String fileName;
  public long size; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before the file specified by FileName is resized, whether explicitly (e.g., truncation) or implicitly (i.e., as data are appended). For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications may use this event to modify the request's parameters.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_SET_SIZES flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Size parameter specifies the new file size, in bytes.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information. (If the system's cache manager or memory manager initiated the operation, HandleContext may be absent, in which case it will be 0.)

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeSetReparsePoint Event (CBFilter Class)

This event fires when the OS wants to create or update a reparse point on a file or directory.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeSetReparsePoint(CBFilterBeforeSetReparsePointEvent e) {}
  ...
}

public class CBFilterBeforeSetReparsePointEvent {
  public String fileName;
  public long reparseTag;
  public ByteBuffer reparseBuffer;
  public int bufferLength;
  public int dataLength; //read-write
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before the OS creates or updates a reparse point on a file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_SET_REPARSE_POINT flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The ReparseTag is the reparse tag, which is the value the system uses to identify the format of the reparse point data. This value is also present in the ReparseBuffer data; for convenience, the class extracts it and provides it separately. If the event handler needs to change the reparse tag, it may do so in ReparseBuffer.

The ReparseBuffer parameter points to a memory buffer that specifies the new reparse point information. The buffer referenced by the ReparseBuffer parameter may be modified when needed if the request is to be passed further to other filters and the filesystem driver. The DataLength parameter initially reflects the length of the data contained in the buffer, in bytes. If the event handler updates the data in the ReparseBuffer, it should adjust DataLength to the size of the new data, placed to the buffer. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

Please refer to the Reparse Points topic for more information.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeUnlockAll Event (CBFilter Class)

This event fires before all locked byte ranges in a file are unlocked.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeUnlockAll(CBFilterBeforeUnlockAllEvent e) {}
  ...
}

public class CBFilterBeforeUnlockAllEvent {
  public String fileName;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before all locked byte ranges in the file specified by FileName are unlocked. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_LOCK_CONTROL flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeUnlockAllByKey Event (CBFilter Class)

This event fires before all locked byte ranges in a file, associated with a particular key, are unlocked.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeUnlockAllByKey(CBFilterBeforeUnlockAllByKeyEvent e) {}
  ...
}

public class CBFilterBeforeUnlockAllByKeyEvent {
  public String fileName;
  public long key;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before all locked byte ranges in the file specified by FileName, and associated with the specified Key, are unlocked. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_LOCK_CONTROL flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Key parameter contains the key value specified when the byte ranges were locked. Please refer to the BeforeLock event's documentation for more information.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeUnlockSingle Event (CBFilter Class)

This event fires before a particular locked byte range in a file is unlocked.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeUnlockSingle(CBFilterBeforeUnlockSingleEvent e) {}
  ...
}

public class CBFilterBeforeUnlockSingleEvent {
  public String fileName;
  public long offset; //read-write
  public long length; //read-write
  public long key;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before a particular locked byte range in the file specified by FileName is unlocked. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications may use this event to modify the request's parameters.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_LOCK_CONTROL flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Offset, Length, and Key parameters contain the starting byte offset, length, and key values, respectively, specified when the byte range was locked. Please refer to the BeforeLock event's documentation for more information.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BeforeWriteFile Event (CBFilter Class)

This event fires before data are written to a file.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void beforeWriteFile(CBFilterBeforeWriteFileEvent e) {}
  ...
}

public class CBFilterBeforeWriteFileEvent {
  public String fileName;
  public long position; //read-write
  public ByteBuffer buffer;
  public int bufferLength;
  public int bytesToWrite; //read-write
  public int reserved; //read-write
  public int direction;
  public long fileContext; //read-write
  public long handleContext; //read-write
  public long eventContext; //read-write
  public int status; //read-write
  public boolean processRequest; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires before data are written to the file specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications may use this event to modify the request's parameters or data. Applications that choose to modify the request's data must do the following:

1. Enable the ModifiableReadWriteBuffers configuration setting (i.e., before this event fires).
2. Copy no more than BufferLength bytes into Buffer.
3. Update the BytesToWrite parameter's value afterward so that it correctly reflects the amount of data in Buffer.

Applications may also use this event to block the request entirely by returning an appropriate error code (e.g., ACCESS_DENIED) via ResultCode.

Alternatively, applications may use this event to handle the underlying request, in which case they must do the following:

1. Write the data pointed to by Buffer to the desired location (after preprocessing it, if necessary).
2. Update the BytesToWrite parameter's value afterward so that it correctly reflects the amount of data that were written.
3. Set ProcessRequest to false to indicate that the request has been handled and should not continue onward.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_BEFORE_WRITE flag.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

The Position parameter specifies the byte offset in the file at which writing should start. A value of -1 means "append to the end of the file".

The Buffer parameter points to a memory buffer that contains the data to write to the file. The BufferLength parameter reflects the capacity of Buffer, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The BytesToWrite parameter's initial value reflects how many bytes should be written to the file (i.e., how many bytes the requestor expects will be written). This parameter's value may be changed (for either of the reasons discussed above), but it must not exceed BufferLength.

Note: However, writing more or less data than requested is not expected behavior and likely will cause the requestor to misbehave. Applications that change BytesToWrite, for any reason, should use the AfterWriteFile event to "cover up" such behavior; please refer to its documentation for more information.

The Direction parameter indicates the request direction; please refer to the Cached and Non-Cached Requests topic for more information. Possible values are as follows:

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information. (If the system's cache manager or memory manager initiated the operation, HandleContext may be absent, in which case it will be 0.)

The ProcessRequest parameter controls whether the request is sent onward for further processing by subsequent filter drivers and the filesystem; it is true by default.

When ProcessRequest to false (which means that the request was handled), the handler may additionally specify the status of the handling by setting the Status parameter to the required NT status code (this is not a Win32 error code!).

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

BypassIORequest Event (CBFilter Class)

This event fires when the OS sends one of BypassIO commands.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void bypassIORequest(CBFilterBypassIORequestEvent e) {}
  ...
}

public class CBFilterBypassIORequestEvent {
  public String fileName;
  public int requestCode;
  public long fileContext;
  public long handleContext;
  public int status; //read-write
  public String reason; //read-write
}

Remarks

This event fires when the OS sends a BypassIO request to a file specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

If BypassIO is enabled successfully future operations on the specified file handle will not be visible to the class. To ensure all future operations on the file are visible to the class BypassIO should not be enabled. BypassIO is present in Windows 11; it is not used in Windows 10 and earlier systems, and also is not used in Server systems.

Applications need to handle this event only if they have added a standard filter rule that includes the any of the following flags: FS_BYPASS_IO (it should be passed among notification flags), FS_CE_BEFORE_READ, FS_CE_AFTER_READ, FS_CE_BEFORE_WRITE, FS_CE_AFTER_WRITE.

The RequestCode parameter contains the code of the request. The code may be the one of the following:

When the request code is BPIO_OP_ENABLE, an application is able to block BypassIO by specifying a non-zero value for Status and a description of the reason in the Reason parameter. If the application does so, it should return the same status and reason in response to BPIO_OP_QUERY requests to let the caller know that enabling would not be possible. BPIO_OP_QUERY requests are used, in particular, by diagnostics tools. Other operations may not be denied, and when the event is fired for one of those other operations, the class ignores the values returned in the Status and Reason parameters.

The Status value should be one of the NTStatus codes defined in Windows SDK (Windows 11 SDK defines a group of STATUS_NOT_SUPPORTED_WITH_* constants for this).

The Reason should be set to a human-readable text that explains why BypassIO was blocked.

The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

CleanupContext Event (CBFilter Class)

This event fires when the application-defined data stored in one or more contexts need to be cleaned up.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void cleanupContext(CBFilterCleanupContextEvent e) {}
  ...
}

public class CBFilterCleanupContextEvent {
  public long fileContext;
  public long handleContext;
  public int resultCode; //read-write
}

Remarks

This event fires after a file or directory is closed, just before any contexts related to it are discarded, giving applications a chance to clean up any information stored in them.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.

When a handle to some file or directory is closed, this event will fire if the HandleContext associated with that handle is not 0. When the last handle to the file or directory is closed, this event will fire if the HandleContext associated with that handle or the FileContext associated with that file or directory is not 0. After this event fires, the applicable contexts are set back to 0 automatically.

Applications that need to know the name of the file or directory this event is firing for should store a copy of that name in the context during an earlier event.

This event is optional; it will fire regardless of whether any filter rules are present, but only if FileContext, HandleContext, or both, are not already 0. Applications that clean up their contexts (and set them back to 0) when a file is being closed, or earlier, do not need to handle this event.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

Error Event (CBFilter Class)

This event fires if an unhandled error occurs during an event.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void error(CBFilterErrorEvent e) {}
  ...
}

public class CBFilterErrorEvent {
  public int errorCode;
  public String description;
}

Remarks

This event fires if an unhandled error occurs during another event. Developers can use this information to track down unhandled errors in an application's event handlers.

Note: Not everything is possible or allowed in the event handlers. For details, see the Recursive Calls topic.

FilterStart Event (CBFilter Class)

This event fires once the filter has attached and filtering has started.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void filterStart(CBFilterFilterStartEvent e) {}
  ...
}

public class CBFilterFilterStartEvent {
  public int resultCode; //read-write
}

Remarks

This event fires once the filter has attached and filtering has started; please refer to the StartFilter method for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

FilterStop Event (CBFilter Class)

This event fires once filtering has stopped and the filter has detached.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void filterStop(CBFilterFilterStopEvent e) {}
  ...
}

public class CBFilterFilterStopEvent {
  public int resultCode; //read-write
}

Remarks

This event fires once filtering has stopped and the filter has detached.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

NotifyCanFileBeDeleted Event (CBFilter Class)

This event fires when the OS marks a file or directory for deletion or removes such a mark.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyCanFileBeDeleted(CBFilterNotifyCanFileBeDeletedEvent e) {}
  ...
}

public class CBFilterNotifyCanFileBeDeletedEvent {
  public String fileName;
  public int requestType;
  public boolean canDelete;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when the OS marks the file or directory specified by FileName for deletion or removes such a mark. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Files and directories can be deleted in two ways: (1) a file or directory can be opened with the FILE_FLAG_DELETE_ON_CLOSE flag, or (2) some process may call Windows API's NtSetInformationFile function with FILE_DISPOSITION_INFORMATION or FILE_DISPOSITION_INFORMATION_EX structure as a parameter.

If the file or directory is created or opened with the FILE_FLAG_DELETE_ON_CLOSE flag, this event is fired shortly after the NotifyCreateFile or NotifyOpenFile event.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_CAN_DELETE flag.

The RequestType indicates which kind of system request resulted in firing this event. It can be one of the following:

The CanDelete parameter reflects whether or not the file or directory can be deleted.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyCleanupFile Event (CBFilter Class)

This event fires when a file or directory handle has been closed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyCleanupFile(CBFilterNotifyCleanupFileEvent e) {}
  ...
}

public class CBFilterNotifyCleanupFileEvent {
  public String fileName;
  public int resultCode; //read-write
}

Remarks

This event fires when a handle to the file or directory specified by FileName has been closed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. This event differs from NotifyCloseFile in that NotifyCleanupFile fires when an open handle to the specified file or directory is closed by a process, whereas NotifyCloseFile may be fired much later when the OS itself decides that the file or directory can be formally closed.

Other events may fire for the file or directory in the time between when this event fires and when the NotifyCloseFile event fires. For example, system components, such as the memory manager or cache manager, may cause the NotifyReadFile and NotifyWriteFile events to fire.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_CLEANUP flag.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyCloseFile Event (CBFilter Class)

This event fires when a file or directory has been closed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyCloseFile(CBFilterNotifyCloseFileEvent e) {}
  ...
}

public class CBFilterNotifyCloseFileEvent {
  public String fileName;
  public int resultCode; //read-write
}

Remarks

This event fires when the file or directory specified by FileName has been closed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_CLOSE flag.

If the file or directory was marked for deletion earlier, the NotifyDeleteFile will fire shortly before this event.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyCreateFile Event (CBFilter Class)

This event fires when a file or directory has been created.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyCreateFile(CBFilterNotifyCreateFileEvent e) {}
  ...
}

public class CBFilterNotifyCreateFileEvent {
  public String fileName;
  public int existingAttributes;
  public int desiredAccess;
  public int attributes;
  public int shareMode;
  public int options;
  public int createDisposition;
  public ByteBuffer securityDescriptor;
  public int length;
  public int status;
  public int creationStatus;
  public int resultCode; //read-write
}

Remarks

This event fires when the file or directory specified by FileName has been created. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. Please refer to the File Create/Open Events topic for more information about how the class determines whether to fire this event or NotifyOpenFile.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_CREATE flag.

Note: Applications must have the FilterOwnRequests configuration setting enabled if they wish to filter their own file/directory creation requests.

When extended rules are used or the AlwaysRequestAttributesOnOpen configuration setting is enabled, the driver requests attributes of the entity from the filesystem and passes them to ExistingAttributes. If the attributes are not requested, this parameter contains 0.

The DesiredAccess, Attributes, ShareMode, and CreateDisposition parameters reflect the values that were passed for the similarly named parameters of the Windows API's CreateFile function (or, more accurately, the values carried by the IRP_MJ_CREATE IRP).

DesiredAccess may contain one or more of the following access flags:

Attributes may contain one or more of the following attributes:

ShareMode may contain zero or more of the following share mode flags:

CreateDisposition may contain one of the following values:

Options contains the flags that are described in the CreateOptions parameter of the native API's ZwCreateFile function. Most of those flags correspond to flags passed in the FlagsAndAttributes parameter of the Windows API's CreateFile function, but some flags are specific to the native API. If you need those flags, check both functions' descriptions.

Please refer to Microsoft's documentation for detailed information about these constants.

To determine whether the request was for a file or a directory, compare Attributes against the FILE_SYS_ATTR_DIRECTORY constant, as follows: // Check whether the request is for a file or a directory. bool isDirectory = Attributes & FILE_SYS_ATTR_DIRECTORY == FILE_SYS_ATTR_DIRECTORY; FILE_SYS_ATTR_DIRECTORY will be present if it was specified by the calling process or if the existing filesystem entry is a directory.

To determine whether a file will be deleted when its last handle is closed, compare Options against the Windows API's FILE_FLAG_DELETE_ON_CLOSE constant, as follows: // Check whether the file will be deleted on close. bool deleteOnClose = Options & FILE_FLAG_DELETE_ON_CLOSE == FILE_FLAG_DELETE_ON_CLOSE; Note: Because files can be deleted in different ways, do not use this check to take actions related to tracking file deletion operations. Instead, use the events related to file deletion.

When a file or directory is created using the CreateFile() Windows API function, a caller can specify the security descriptor with the security information. This security information should be applied to a newly created file or directory. The class passes this security information in the SecurityInformation and SecurityDescriptor parameters, when the PassSecurityInFileOpenEvents configuration setting is enabled. If this configuration setting is omitted, the corresponding parameters are empty.

The SecurityInformation parameter reflects which pieces of security information, of those present in SecurityDescriptor, are valid and should have been applied. Please refer to Microsoft's SECURITY_INFORMATION data type documentation for more information about possible values.

The SecurityDescriptor parameter points to a memory buffer that contains the security information. The Length parameter reflects the length of this data, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted as a SECURITY_DESCRIPTOR structure in self-relative format; please refer to the Microsoft's documentation for more information.

If the Options contains the FILE_FLAG_DELETE_ON_CLOSE flag, the NotifyCanFileBeDeleted event will fire after this event.

If the file is created with extended attributes passed in the request, the NotifySetEa event will fire after this event.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The CreationStatus parameter indicates whether the file was created or opened and can be one of the following values:

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyCreateHardLink Event (CBFilter Class)

This event fires when a hard link has been created.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyCreateHardLink(CBFilterNotifyCreateHardLinkEvent e) {}
  ...
}

public class CBFilterNotifyCreateHardLinkEvent {
  public String fileName;
  public String linkName;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when a hard link to the file specified by FileName has been created. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. Please refer to Microsoft's Hard Links article for more information about hard links.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_CREATE_HARD_LINK flag.

The LinkName parameter reflects the name of the created hard link.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyDeleteFile Event (CBFilter Class)

This event fires when a file or directory has been deleted.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyDeleteFile(CBFilterNotifyDeleteFileEvent e) {}
  ...
}

public class CBFilterNotifyDeleteFileEvent {
  public String fileName;
  public int requestType;
  public int resultCode; //read-write
}

Remarks

This event fires when the file or directory specified by FileName has been deleted. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. More specifically, this event is queued for delivery after the final IRP_MJ_CLOSE I/O request packet (IRP) has been processed by the filesystem (i.e., after the last handle to the file or directory is closed and the file or directory is gone) and before NotifyCloseFile is queued.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_DELETE flag.

The RequestType indicates which kind of system request resulted in firing this event. It can be one of the following:

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyDeleteReparsePoint Event (CBFilter Class)

This event fires when a file or directory's reparse point has been deleted.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyDeleteReparsePoint(CBFilterNotifyDeleteReparsePointEvent e) {}
  ...
}

public class CBFilterNotifyDeleteReparsePointEvent {
  public String fileName;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when a reparse point has been deleted from the file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Note: The file or directory was not deleted, only a reparse point was.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_DELETE_REPARSE_POINT flag.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyEnumerateDirectory Event (CBFilter Class)

This event fires when a directory entry has been returned during directory enumeration.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyEnumerateDirectory(CBFilterNotifyEnumerateDirectoryEvent e) {}
  ...
}

public class CBFilterNotifyEnumerateDirectoryEvent {
  public String directoryName;
  public int flags;
  public int index;
  public String fileName;
  public java.util.Date creationTime;
  public java.util.Date lastAccessTime;
  public java.util.Date lastWriteTime;
  public java.util.Date changeTime;
  public long size;
  public long allocationSize;
  public long fileId;
  public int attributes;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when a directory entry (i.e., file or subdirectory) has been returned during enumeration of the directory specified by DirectoryName. For more information about the DirectoryName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_ENUMERATE_DIRECTORY flag.

The Flags parameter specifies supplementary information about enumeration. It is a combination of zero or more values:

If the Flags parameter contains FS_ENUM_INDEX_SPECIFIED, the Index parameter contains the index as provided by the OS.

The FileName parameter reflects the name of the directory entry.

The CreationTime, LastAccessTime, LastWriteTime, and ChangeTime parameters reflect the entry's time values, specified in UTC.

The Size parameter reflects the size of the file, in bytes; it is always 0 for subdirectories.

The AllocationSize parameter reflects the amount of space allocated for the file, in bytes; it is always 0 for subdirectories.

The FileId parameter reflects the unique Id of the entry, as reported by the filesystem. This Id is used by the network redirector, and some third-party applications, to open files and directories by Id instead of by name. The root directory always uses the predefined Id 0x7FFFFFFFFFFFFFFF.

The Attributes parameter reflects the entry's attributes; please refer to Microsoft's File Attribute Constants article for attribute descriptions.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyFilterAttachToVolume Event (CBFilter Class)

This event fires when the filter has been attached to a newly mounted filesystem volume.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyFilterAttachToVolume(CBFilterNotifyFilterAttachToVolumeEvent e) {}
  ...
}

public class CBFilterNotifyFilterAttachToVolumeEvent {
  public String volumeName;
  public String volumeNameNT;
  public int resultCode; //read-write
}

Remarks

This event fires when the filter has been attached to the newly mounted filesystem volume specified by VolumeNameNT and, when possible, VolumeName. Please refer to the FireVolumeEvents property for more information.

Applications need to handle this event only if the FireVolumeEvents property includes the FS_MOUNT_NOTIFY flag.

Note: This event won't fire for any volumes skipped during the BeforeFilterAttachToVolume event; please refer to its documentation for more information.

VolumeNameNT contains the name of the volume in the NT-native format, as received from the system. If the ResolveNtDeviceToDriveLetter configuration setting is enabled, and if it was possible to convert the NT name to the DOS format with a drive letter, VolumeName will contain the name in this format; otherwise, it will be empty.

Applications that use volume-specific rules should typically add such rules during the AfterFilterAttachToVolume event, which is fired synchronously, rather than this one.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

Applications must be aware that this event fires as a direct response to a filesystem state change (mount or unmount). Various system components or third-party actors can perform supplementary filesystem mounting and unmounting during main unmount operations (e.g., Volume Service is one such component). This can cause seemingly excessive events to be fired, and sometimes they can be fired out of order (such as two *Attach or *Detach events fired in a row).

NotifyFilterDetachFromVolume Event (CBFilter Class)

This event fires when the filter has been detached from a filesystem volume.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyFilterDetachFromVolume(CBFilterNotifyFilterDetachFromVolumeEvent e) {}
  ...
}

public class CBFilterNotifyFilterDetachFromVolumeEvent {
  public String volumeName;
  public String volumeNameNT;
  public int resultCode; //read-write
}

Remarks

This event fires when the filter has been detached from the filesystem volume specified by VolumeNameNT and, when possible, VolumeName, typically as a result of the volume being unmounted. Please refer to the FireVolumeEvents property for more information.

Applications need to handle this event only if the FireVolumeEvents property includes the FS_MOUNT_NOTIFY flag.

Note: This event won't fire for any volumes skipped during the BeforeFilterAttachToVolume event; please refer to its documentation for more information.

VolumeNameNT contains the name of the volume in the NT-native format, as received from the system. If the ResolveNtDeviceToDriveLetter configuration setting is enabled, and if it was possible to convert the NT name to the DOS format with a drive letter, VolumeName will contain the name in this format; otherwise, it will be empty.

Applications that use volume-specific rules typically should remove such rules during the AfterFilterDetachFromVolume event, which is fired synchronously, rather than this one.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

Applications must be aware that this event fires as a direct response to a filesystem state change (mount or unmount). Various system components or third-party actors can perform supplementary filesystem mounting and unmounting during main unmount operations (e.g., Volume Service is one such component). This can cause seemingly excessive events to be fired, and sometimes they can be fired out of order (such as two *Attach or *Detach events fired in a row).

NotifyFsctl Event (CBFilter Class)

This event fires when an IRP_MJ_FILE_SYSTEM_CONTROL operation has occurred.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyFsctl(CBFilterNotifyFsctlEvent e) {}
  ...
}

public class CBFilterNotifyFsctlEvent {
  public String fileName;
  public int fsControlCode;
  public ByteBuffer inBuffer;
  public int inBufferLength;
  public int inBufferValidBytes;
  public ByteBuffer outBuffer;
  public int outBufferLength;
  public int outBufferValidBytes;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when an IRP_MJ_FILE_SYSTEM_CONTROL (FSCTL) operation has occurred. Such requests are sent using the Windows API's DeviceIoControl function (user mode), or ZwFsControlFile function (kernel mode); please refer to Microsoft's documentation for more information.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_FSCTL flag.

The FileName parameter reflects the file, directory, or volume targeted by the request.

The FsControlCode parameter reflects the requested filesystem control code (FSCTL).

The InBuffer parameter points to a memory buffer that contains the data required to perform the operation. The InBufferLength and InBufferValidBytes parameters reflect the capacity of InBuffer and the length of the data it contains (respectively), in bytes; InBufferValidBytes may be less than InBufferLength (unless the request did not include data, in which case both will be 0).

The OutBuffer parameter points to a memory buffer that contains the data returned by the operation. The OutBufferLength and OutBufferValidBytes parameters reflect the capacity of OutBuffer and the length of the data it contains (respectively), in bytes; OutBufferValidBytes may be less than OutBufferLength (unless the operation did not return data, in which case both will be 0).

Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyGetFileSecurity Event (CBFilter Class)

This event fires when a file or directory's security attributes have been retrieved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyGetFileSecurity(CBFilterNotifyGetFileSecurityEvent e) {}
  ...
}

public class CBFilterNotifyGetFileSecurityEvent {
  public String fileName;
  public int securityInformation;
  public ByteBuffer securityDescriptor;
  public int length;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when security attributes have been retrieved for the file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Note: This event will not fire every time a file or directory is accessed. To check file security upon each access to a file or directory, implement the file create and open events and perform the necessary checks there instead.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_GET_SECURITY flag.

The SecurityInformation parameter indicates which pieces of security information were requested. Please refer to Microsoft's SECURITY_INFORMATION data-type documentation for more information about possible values.

The SecurityDescriptor parameter points to a memory buffer that, if the request was successful, contains the requested security information. The Length parameter reflects the length of this data, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted as a SECURITY_DESCRIPTOR structure in self-relative format; please refer to the Microsoft's documentation for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyGetFileSizes Event (CBFilter Class)

This event fires when a file's size information has been retrieved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyGetFileSizes(CBFilterNotifyGetFileSizesEvent e) {}
  ...
}

public class CBFilterNotifyGetFileSizesEvent {
  public String fileName;
  public long size;
  public long allocationSize;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when size information has been retrieved for the file specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_GET_SIZES flag.

The Size parameter reflects the actual size of the file, in bytes.

The AllocationSize parameter reflects the amount of space allocated for the file, in bytes.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyGetReparsePoint Event (CBFilter Class)

This event fires when a file or directory's reparse point information has been retrieved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyGetReparsePoint(CBFilterNotifyGetReparsePointEvent e) {}
  ...
}

public class CBFilterNotifyGetReparsePointEvent {
  public String fileName;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when reparse point information has been retrieved for the file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_GET_REPARSE_POINT flag.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyIoctl Event (CBFilter Class)

This event fires when an IRP_MJ_DEVICE_CONTROL operation has occurred.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyIoctl(CBFilterNotifyIoctlEvent e) {}
  ...
}

public class CBFilterNotifyIoctlEvent {
  public String fileName;
  public int ioControlCode;
  public ByteBuffer inBuffer;
  public int inBufferLength;
  public int inBufferValidBytes;
  public ByteBuffer outBuffer;
  public int outBufferLength;
  public int outBufferValidBytes;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when an IRP_MJ_DEVICE_CONTROL (IOCTL) operation has occurred. Such requests are sent using the Windows API's DeviceIoControl function (user mode), or ZwDeviceIoControlFile function (kernel mode). Please refer to Microsoft's documentation for more information.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_IOCTL flag.

The FileName parameter reflects the file, directory, or volume targeted by the request.

The IoControlCode parameter reflects the requested I/O control code (IOCTL).

The InBuffer parameter points to a memory buffer that contains the data required to perform the operation. The InBufferLength and InBufferValidBytes parameters reflect the capacity of InBuffer and the length of the data it contains (respectively), in bytes; InBufferValidBytes may be less than InBufferLength (unless the request did not include data, in which case both will be 0).

The OutBuffer parameter points to a memory buffer that contains the data returned by the operation. The OutBufferLength and OutBufferValidBytes parameters reflect the capacity of OutBuffer and the length of the data it contains (respectively), in bytes; OutBufferValidBytes may be less than OutBufferLength (unless the operation did not return data, in which case both will be 0).

Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyLock Event (CBFilter Class)

This event fires when a range of bytes in a file has been locked.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyLock(CBFilterNotifyLockEvent e) {}
  ...
}

public class CBFilterNotifyLockEvent {
  public String fileName;
  public long offset;
  public long length;
  public long key;
  public boolean failImmediately;
  public boolean exclusiveLock;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when a range of bytes in the file specified by FileName has been locked. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. This request is made either by the OS, or on behalf of a user mode application that called the Windows API's LockFile or LockFileEx function.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_LOCK_CONTROL flag.

The Offset parameter reflects the byte offset where the byte range lock starts.

The Length parameter reflects the length of the byte range lock.

The Key parameter reflects the key that the byte range lock is associated with. This key is used to identify the byte range lock in later unlock-by-key requests.

The FailImmediately parameter indicates whether the request was to fail if the lock could not be granted immediately.

The ExclusiveLock parameter indicates whether the byte range lock was to be exclusive (true) or shared (false).

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyOpenFile Event (CBFilter Class)

This event fires when a file or directory has been opened.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyOpenFile(CBFilterNotifyOpenFileEvent e) {}
  ...
}

public class CBFilterNotifyOpenFileEvent {
  public String fileName;
  public int existingAttributes;
  public int desiredAccess;
  public int attributes;
  public int shareMode;
  public int options;
  public int createDisposition;
  public ByteBuffer securityDescriptor;
  public int length;
  public int status;
  public int creationStatus;
  public int resultCode; //read-write
}

Remarks

This event fires when the file or directory specified by FileName has been opened. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. Please refer to the File Create/Open Events topic for more information about how the class determines whether to fire this event or NotifyCreateFile.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_OPEN flag.

Note: Applications must have the FilterOwnRequests configuration setting enabled if they wish to filter their own file/directory open requests.

When extended rules are used or the AlwaysRequestAttributesOnOpen configuration setting is enabled, the driver requests attributes of the entity from the filesystem and passes them to ExistingAttributes. If the attributes are not requested, this parameter contains 0.

The DesiredAccess, Attributes, ShareMode, and CreateDisposition parameters reflect the values that were passed for the similarly named parameters of the Windows API's CreateFile function (or, more accurately, the values carried by the IRP_MJ_CREATE IRP).

DesiredAccess may contain one or more of the following access flags:

Attributes may contain one or more of the following attributes:

ShareMode may contain zero or more of the following share mode flags:

CreateDisposition may contain one of the following values:

Options contains the flags that are described in the CreateOptions parameter of the native API's ZwCreateFile function. Most of those flags correspond to flags passed in the FlagsAndAttributes parameter of the Windows API's CreateFile function, but some flags are specific to the native API. If you need those flags, check both functions' descriptions.

Please refer to Microsoft's documentation for detailed information about these constants.

To determine whether the request was for a file or a directory, compare Attributes against the FILE_SYS_ATTR_DIRECTORY constant, as follows: // Check whether the request is for a file or a directory. bool isDirectory = Attributes & FILE_SYS_ATTR_DIRECTORY == FILE_SYS_ATTR_DIRECTORY; FILE_SYS_ATTR_DIRECTORY will be present if it was specified by the calling process or if the existing filesystem entry is a directory.

To determine whether a file will be deleted when its last handle is closed, compare Options against the Windows API's FILE_FLAG_DELETE_ON_CLOSE constant, as follows: // Check whether the file will be deleted on close. bool deleteOnClose = Options & FILE_FLAG_DELETE_ON_CLOSE == FILE_FLAG_DELETE_ON_CLOSE; Note: Because files can be deleted in different ways, do not use this check to take actions related to tracking file deletion operations. Instead, use the events related to file deletion.

When a file or directory is created using the CreateFile() Windows API function, a caller can specify the security descriptor with the security information. This security information should be applied to a newly created file or directory. The class passes this security information in the SecurityInformation and SecurityDescriptor parameters, when the PassSecurityInFileOpenEvents configuration setting is enabled. If this configuration setting is omitted, the corresponding parameters are empty.

The SecurityInformation parameter reflects which pieces of security information, of those present in SecurityDescriptor, are valid and should have been applied. Please refer to Microsoft's SECURITY_INFORMATION data type documentation for more information about possible values.

The SecurityDescriptor parameter points to a memory buffer that contains the security information. The Length parameter reflects the length of this data, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted as a SECURITY_DESCRIPTOR structure in self-relative format; please refer to the Microsoft's documentation for more information.

If the Options contains the FILE_FLAG_DELETE_ON_CLOSE flag, the NotifyCanFileBeDeleted event will fire after this event.

If the file is opened with extended attributes passed in the request, the NotifySetEa event will fire after this event.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The CreationStatus parameter indicates whether the file was created or opened and can be one of the following values:

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyQueryEa Event (CBFilter Class)

This event fires when information about the extended attributes of a file has been retrieved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyQueryEa(CBFilterNotifyQueryEaEvent e) {}
  ...
}

public class CBFilterNotifyQueryEaEvent {
  public String fileName;
  public ByteBuffer buffer;
  public int bufferLength;
  public boolean returnSingleEntry;
  public ByteBuffer eaList;
  public int eaListLength;
  public int eaIndex;
  public boolean restartScan;
  public int lengthReturned;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when information about the extended attributes of a file specified by FileName has been retrieved. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_QUERY_EA flag.

The Buffer parameter points to a memory buffer that, if the request was successful, contains the requested information. The data in the buffer are formatted as a FILE_FULL_EA_INFORMATION structure; please refer to the Microsoft's documentation for more information. The Length parameter reflects the length of this buffer, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

ReturnSingleEntry specifies that the filesystem had to return only the first entry it has found.

EaList is an optional parameter that points to a caller-supplied memory buffer specifying the extended attributes to be queried. The data in the buffer are formatted as a FILE_GET_EA_INFORMATION structure; please refer to the Microsoft's documentation for more information. The EaListLength parameter reflects the length of this data, in bytes. If the caller of the FltQueryEaFile function did not specify any value, it will contain 0.

EaIndex is an optional parameter that specifies the starting index of the attribute, information about which was requested. This parameter is ignored by the filesystem if EaList points to a nonempty list. If the caller of the FltQueryEaFile function did not specify any value, the parameter will contain -1.

The RestartScan parameter instructs the filesystem to restart enumeration of extended attributes from the first entry. If the parameter is false, retrieval of the extended attributes is resumed by the filesystem after a previous request.

LengthReturned is an optional parameter that contains the size, in bytes, of the information, returned in the Buffer.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyQueryFileInfo Event (CBFilter Class)

This event fires when information about a file or directory has been retrieved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyQueryFileInfo(CBFilterNotifyQueryFileInfoEvent e) {}
  ...
}

public class CBFilterNotifyQueryFileInfoEvent {
  public String fileName;
  public int fileInformationClass;
  public ByteBuffer buffer;
  public int bufferLength;
  public int validBytes;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when information about a file or directory specified by FileName has been retrieved. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. This event typically fires in response to the Windows API's NtQueryInformationFile function.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_QUERY_FILE_INFO flag.

The FileInformationClass parameter indicates what kind of file information was requested. Please refer to the NtQueryInformationFile function's documentation for more information about possible values.

The Buffer parameter points to a memory buffer that, if the request was successful, contains the requested file information. The BufferLength and ValidBytes parameters reflect the capacity of Buffer and the length of the data it contains (respectively), in bytes; ValidBytes may be less than BufferLength. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The format of the data is determined by the specified FileInformationClass; please refer to the NtQueryInformationFile function's documentation for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyReadFile Event (CBFilter Class)

This event fires when data have been read from a file.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyReadFile(CBFilterNotifyReadFileEvent e) {}
  ...
}

public class CBFilterNotifyReadFileEvent {
  public String fileName;
  public long position;
  public int bytesToRead;
  public int direction;
  public int bytesRead;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when data have been read from a file specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_READ flag.

The Position parameter reflects the byte offset in the file at which reading started.

The BytesToRead parameter reflects how many bytes were to be read from the file.

The Direction parameter indicates the request direction; please refer to the Cached and Non-Cached Requests topic for more information. Possible values are as follows:

The BytesRead parameter reflects how many bytes were actually read from the file.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyRenameOrMoveFile Event (CBFilter Class)

This event fires when a file or directory has been renamed or moved.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyRenameOrMoveFile(CBFilterNotifyRenameOrMoveFileEvent e) {}
  ...
}

public class CBFilterNotifyRenameOrMoveFileEvent {
  public String fileName;
  public String newFileName;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when a file or directory specified by FileName has been renamed or moved to NewFileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_RENAME flag. A rule's mask is matched against both previous and new file names, and the event will fire when either of the names matches the mask.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifySetAllocationSize Event (CBFilter Class)

This event fires when a file's allocation size has been changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifySetAllocationSize(CBFilterNotifySetAllocationSizeEvent e) {}
  ...
}

public class CBFilterNotifySetAllocationSizeEvent {
  public String fileName;
  public long allocationSize;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when the allocation size of the file specified by FileName has been changed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_SET_SIZES flag.

The AllocationSize parameter reflects the new allocation size, in bytes. A file's allocation size is typically larger than its actual size because filesystem operations often reserve space on disk before writing additional data to a file.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifySetEa Event (CBFilter Class)

This event fires when information about the extended attributes of a file has been changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifySetEa(CBFilterNotifySetEaEvent e) {}
  ...
}

public class CBFilterNotifySetEaEvent {
  public String fileName;
  public ByteBuffer buffer;
  public int bufferLength;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when information about the extended attributes of a file specified by FileName has been changed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

If the file is created or opened with extended attributes passed in the request, this event will fire shortly after the NotifyCreateFile or NotifyOpenFile event.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_SET_EA flag.

The Buffer parameter points to a memory buffer that specifies the extended attribute information. The Length parameter reflects the length of this buffer, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted as a FILE_FULL_EA_INFORMATION structure; please refer to the Microsoft's documentation for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifySetFileAttributes Event (CBFilter Class)

This event fires when a file or directory's attributes or times have been changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifySetFileAttributes(CBFilterNotifySetFileAttributesEvent e) {}
  ...
}

public class CBFilterNotifySetFileAttributesEvent {
  public String fileName;
  public java.util.Date creationTime;
  public java.util.Date lastAccessTime;
  public java.util.Date lastWriteTime;
  public java.util.Date changeTime;
  public int attributes;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when the attributes or times of the file or directory specified by FileName have been changed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_SET_ATTRIBUTES flag.

The CreationTime, LastAccessTime, LastWriteTime, and ChangeTime parameters reflect the new time values, specified in UTC. A value of January 1, 1601 00:00:00 UTC indicates that the corresponding time value was not included in the request.

The Attributes parameter reflects the new attributes; please refer to Microsoft's File Attribute Constants article for attribute descriptions.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifySetFileInfo Event (CBFilter Class)

This event fires when information about a file or directory has been changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifySetFileInfo(CBFilterNotifySetFileInfoEvent e) {}
  ...
}

public class CBFilterNotifySetFileInfoEvent {
  public String fileName;
  public int fileInformationClass;
  public ByteBuffer buffer;
  public int bufferLength;
  public int validBytes;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when information about a file or directory specified by FileName has been changed. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic. This event typically fires in response to the Windows API's NtSetInformationFile function.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_QUERY_FILE_INFO flag.

The FileInformationClass parameter indicates what kind of file information was set. Please refer to the NtSetInformationFile function's documentation for more information about possible values.

The Buffer parameter points to a memory buffer that, if the request was successful, contains the new file information. The BufferLength and ValidBytes parameters reflect the capacity of Buffer and the length of the data it contains (respectively), in bytes; ValidBytes may be less than BufferLength. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The format of the data is determined by the specified FileInformationClass; please refer to the NtSetInformationFile function's documentation for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifySetFileSecurity Event (CBFilter Class)

This event fires when a file or directory's security attributes have been changed.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifySetFileSecurity(CBFilterNotifySetFileSecurityEvent e) {}
  ...
}

public class CBFilterNotifySetFileSecurityEvent {
  public String fileName;
  public int securityInformation;
  public ByteBuffer securityDescriptor;
  public int length;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when security attributes have been changed for a file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_SET_SECURITY flag.

The SecurityInformation parameter reflects which pieces of security information, of those present in SecurityDescriptor, were to be set. Please refer to Microsoft's SECURITY_INFORMATION data-type documentation for more information about possible values.

The SecurityDescriptor parameter points to a memory buffer that contains the new security information. The Length parameter reflects the length of this data, in bytes. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted as a SECURITY_DESCRIPTOR structure in self-relative format; please refer to the Microsoft's documentation for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifySetFileSize Event (CBFilter Class)

This event fires when a file has been resized.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifySetFileSize(CBFilterNotifySetFileSizeEvent e) {}
  ...
}

public class CBFilterNotifySetFileSizeEvent {
  public String fileName;
  public long size;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when the file specified by FileName has been resized, whether explicitly (e.g., truncation) or implicitly (i.e., as data are appended). For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_SET_SIZES flag.

The Size parameter reflects the new file size, in bytes.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifySetReparsePoint Event (CBFilter Class)

This event fires when a file or directory's reparse point has been created or updated.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifySetReparsePoint(CBFilterNotifySetReparsePointEvent e) {}
  ...
}

public class CBFilterNotifySetReparsePointEvent {
  public String fileName;
  public long reparseTag;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when a reparse point has been created or updated for a file or directory specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_SET_REPARSE_POINT flag.

The ReparseTag parameter contains the reparse tag, which is the value the system uses to identify the format of the reparse point data.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyUnlockAll Event (CBFilter Class)

This event fires when all locked byte ranges in a file have been unlocked.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyUnlockAll(CBFilterNotifyUnlockAllEvent e) {}
  ...
}

public class CBFilterNotifyUnlockAllEvent {
  public String fileName;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when all locked byte ranges in the file specified by FileName have been unlocked. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_LOCK_CONTROL flag.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyUnlockAllByKey Event (CBFilter Class)

This event fires when all locked byte ranges in a file, associated with a particular key, have been unlocked.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyUnlockAllByKey(CBFilterNotifyUnlockAllByKeyEvent e) {}
  ...
}

public class CBFilterNotifyUnlockAllByKeyEvent {
  public String fileName;
  public long key;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when all locked byte ranges in the file specified by FileName, and associated with the specified Key, have been unlocked. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_LOCK_CONTROL flag.

The Key parameter contains the key value specified when the byte ranges were locked. Please refer to the NotifyLock event's documentation for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyUnlockSingle Event (CBFilter Class)

This event fires when a particular locked byte range in a file has been unlocked.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyUnlockSingle(CBFilterNotifyUnlockSingleEvent e) {}
  ...
}

public class CBFilterNotifyUnlockSingleEvent {
  public String fileName;
  public long offset;
  public long length;
  public long key;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when a particular locked byte range in a file specified by FileName has been unlocked. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_LOCK_CONTROL flag.

The Offset, Length, and Key parameters contain the starting byte offset, length, and key values, respectively, specified when the byte range was locked. Please refer to the NotifyLock event's documentation for more information.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

NotifyWriteFile Event (CBFilter Class)

This event fires when data have been written to a file.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void notifyWriteFile(CBFilterNotifyWriteFileEvent e) {}
  ...
}

public class CBFilterNotifyWriteFileEvent {
  public String fileName;
  public long position;
  public int bytesToWrite;
  public int direction;
  public int bytesWritten;
  public int status;
  public int resultCode; //read-write
}

Remarks

This event fires when data have been written to the file specified by FileName. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_NE_WRITE flag.

The Position parameter reflects the byte offset in the file at which writing started. A value of -1 means "append to the end of the file".

The BytesToWrite parameter reflects how many bytes were to be written to the file.

The Direction parameter indicates the request direction; please refer to the Cached and Non-Cached Requests topic for more information. Possible values are as follows:

The BytesWritten parameter reflects how many bytes were actually written to the file.

The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method.

Note: This event will not fire for failed requests unless the ProcessFailedRequests property is enabled.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason, set it to a non-zero value to report an appropriate error.

Note: This event fires after the operation has already completed, so reporting an error will not actually affect the operation itself. Please refer to the Error Handling topic for more information.

This event is fired asynchronously; please refer to the Event Types topic for more information.

ReparseFileName Event (CBFilter Class)

This event fires to allow file access to be dynamically redirected to another location.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void reparseFileName(CBFilterReparseFileNameEvent e) {}
  ...
}

public class CBFilterReparseFileNameEvent {
  public String fileName;
  public int desiredAccess;
  public String reparsedFileName;
  public String newFileName; //read-write
  public long eventContext; //read-write
  public int resultCode; //read-write
}

Remarks

Applications can use this event to dynamically redirect access to the file or directory specified by FileName to another location. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

The event fires before a file or directory is created or opened (before the corresponding BeforeCreateFile or BeforeOpenFile events fire).

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_REPARSE_FILENAME flag.

The DesiredAccess parameter reflects the value that was passed for the similarly named parameter of the Windows API's CreateFile function. Please refer to Microsoft's documentation for more information.

The ReparsedFileName parameter reflects the default redirection destination. If the specified file or directory matches an existing reparse rule, this parameter's value is generated based on said rule; otherwise, this parameter will reflect the same value as FileName.

The NewFileName parameter specifies an application-defined redirection destination. This parameter's value, if set, must be less than 1024 characters in length.

If the application sets NewFileName to a nonempty value, it will be used as the redirection destination. Otherwise, the value reflected by ReparseFileName will be used as the redirection destination.

The EventContext parameter makes it possible to pass information between Before* and After* events that are related to the same OS request. The value assigned to EventContext by the event handler will reach BeforeCreateFile/BeforeOpenFile events and other events involved in the opening of the file.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

ReparseWithTag Event (CBFilter Class)

This event fires if an open operation returns STATUS_REPARSE so that the application can respond to the reparse point.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void reparseWithTag(CBFilterReparseWithTagEvent e) {}
  ...
}

public class CBFilterReparseWithTagEvent {
  public String fileName;
  public String newFileName;
  public int reparseTag;
  public ByteBuffer reparseBuffer;
  public int reparseBufferLength;
  public long fileContext;
  public long handleContext;
  public long eventContext;
  public boolean reissueIO; //read-write
  public int resultCode; //read-write
}

Remarks

This event fires if a STATUS_REPARSE result is returned when the OS attempts to open the file or directory specified by FileName, which indicates that a reparse point is associated with said file or directory or one of its parents. More specifically, it fires immediately after the open operation returns such a result. For more information about the FileName parameter and what it may contain, please refer to the Filenames In Events topic.

It is possible for applications to add reparse points to specific files/directories so that the filesystem will return STATUS_REPARSE when someone attempts to open them. Such applications can then use this event to perform some operation on the file/directory, assuming that the specified ReparseTag belongs to the application. Please refer to Microsoft's Reparse Point articles for more information.

Applications need to handle this event only if they have added a standard filter rule that includes the FS_CE_REPARSE_TAG flag.

If the reparse tag was recognized by the filesystem or some filesystem filter, NewFileName can contain the new path, to which the request should be sent.

The ReparseTag parameter reflects the reparse point's tag, which is the value the system uses to identify the format of the reparse point data. This value is also present in the ReparseBuffer data; the class extracts it and provides it separately for convenience.

The ReparseBuffer parameter points to a memory buffer that contains the full reparse point data. The ReparseBufferLength parameter reflects the length of ReparseBuffer. Please see the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The data are formatted using either a REPARSE_GUID_DATA_BUFFER structure or (for certain Microsoft-reserved tags) a REPARSE_DATA_BUFFER structure; please refer to Microsoft's documentation for more information.

If the part of the path contained in FileName constitutes a symbolic link or a junction point (both of which are handled by the filesystem), the structure in ReparseBuffer will contain the new path that is to replace a part of the original path. In such a case, the Reserved field of the REPARSE_DATA_BUFFER structure will contain the length in bytes in the original file name buffer that remains unchanged. This value, divided by 2, is the number of characters at the end of FileName that you must append to the new path, contained in ReparseBuffer.

ReissueIO can be set to true to instruct the OS to resend the original request again from the beginning. This may be necessary if the reparse tag is removed from the file or altered during this event.

Please refer to the Reparse Points topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

WorkerThreadCreation Event (CBFilter Class)

Fires just after a new worker thread is created.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void workerThreadCreation(CBFilterWorkerThreadCreationEvent e) {}
  ...
}

public class CBFilterWorkerThreadCreationEvent {
  public int resultCode; //read-write
}

Remarks

This event fires just after a worker thread is created, in the context of that worker thread.

This event is optional; it is provided to give applications a chance to perform additional processing when a new worker thread is created, such as allocating per-thread objects.

The class maintains a pool of worker threads and uses them to fire events; please refer to the Threading and Concurrency topic for more information.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource is not available or security checks failed), set it to a nonzero value to report an appropriate error. Please see the Error Handling topic for more information.

This event is fired synchronously; please refer to the Event Types topic for more information.

WorkerThreadTermination Event (CBFilter Class)

Fires just before a worker thread is terminated.

Syntax

public class DefaultCBFilterEventListener implements CBFilterEventListener {
  ...
  public void workerThreadTermination(CBFilterWorkerThreadTerminationEvent e) {}
  ...
}

public class CBFilterWorkerThreadTerminationEvent {
}

Remarks

This event fires just before a worker thread is terminated, in the context of that worker thread.

This event is optional; it is provided to give applications a chance to perform additional processing before a worker thread is terminated, such as deallocating per-thread objects.

The class maintains a pool of worker threads and uses them to fire events; please refer to the Threading and Concurrency topic for more information.

Any errors that occur during this event are ignored.

This event is fired synchronously; please refer to the Event Types topic for more information.

FileDefaultRule Type

This type represents a filesystem default rule.

Remarks

This type represents a filesystem default rule. Please refer to the Default Rules topic for more information.

Fields

FileFilterRule Type

This type represents a filesystem filter rule.

Remarks

This type represents a filesystem filter rule, which may be a standard filter rule, an access rule, or a combination of both. Please refer to the File and Registry Filter Rules and Access Rules topics for more information.

Fields

FilePassthroughRule Type

This type represents a filesystem passthrough rule.

Remarks

This type represents a filesystem passthrough rule. Please refer to the Passthrough Rules topic for more information.

Fields

FileReparseRule Type

This type represents a filesystem reparse rule.

Remarks

This type represents a filesystem reparse rule. Please refer to the Reparse Rules topic for more information.

Fields

VirtualFile Type

This type represents a virtual file .

Remarks

This type represents a virtual file , managed by by CBFilter class . The file can be added to the list using the AddVirtualFile method.

Fields

CBFSFilterStream Type

Syntax

cbfsfilter.CBFSFilterStream

Remarks

The CBFSFilterStream type is returned by some of the CBFilter class's methods. All stream types in CBFS Filter share a common API, documented below.

This type provides a custom streaming API with full read, write, and seek functionality; and implements Closable in order to be compatible with the try-with-resources pattern. To interact with a stream via conventional Java streaming APIs, use the GetInputStream and GetOutputStream methods to obtain an InputStream or OutputStream object.

Properties
Length	Gets or sets the length of the stream, in bytes. public long getLength(); public void setLength(long value);
Position	Gets or sets the current position within the stream. public long getPosition(); public void setPosition(long value);
Methods
Close	Closes the stream, releasing all resources currently allocated for it. public void close(); Closing a CBFSFilterStream instance also closes all Java stream objects that have been created using its GetInputStream and GetOutputStream methods.
Flush	Forces all data held by the stream's buffers to be written out to storage. public void flush();
GetInputStream	Creates a standard Java InputStream tied to the current CBFSFilterStream instance. public InputStream getInputStream(); When an InputStream obtained from this method is closed, the CBFSFilterStream instance that created it is also closed (which, as Close describes, causes all other Java stream objects tied to that CBFSFilterStream instance to be closed as well).
GetOutputStream	Creates a standard Java OutputStream tied to the current CBFSFilterStream instance. public OutputStream getOutputStream(); When an OutputStream obtained from this method is closed, the CBFSFilterStream instance that created it is also closed (which, as Close describes, causes all other Java stream objects tied to that CBFSFilterStream instance to be closed as well).
Read	Reads a sequence of bytes from the stream and advances the current position within the stream by the number of bytes read. public byte[] read(int count); Count specifies the number of bytes that should be read from the stream. Returns a byte array containing the data read from the stream. The length of the returned byte array may be less than Count if that many bytes are not currently available, or may be 0 if the end of the stream has been reached.
Seek	Sets the current position within the stream based on a particular point of origin. public long seek(long offset, CBFSFilterStream.SeekOrigin origin); public enum SeekOrigin { FROM_BEGIN(0), FROM_CURRENT(1), FROM_END(2); } Offset specifies the offset in the stream to seek to, relative to Origin. SeekOrigin is an enum declared within the CBFSFilterStream class as shown above. Returns the new position within the stream.
Write	Writes a sequence of bytes to the stream and advances the current position within the stream by the number of bytes written. public int write(byte[] data); Data specifies the data to write to the stream. Returns the total number of bytes written to the stream.

Config Settings (CBFilter Class)

The class accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

CBFilter Config Settings

Base Config Settings

Trappable Errors (CBFilter Class)

The class uses Windows error codes during operations as necessary. Please refer to the Error Handling topic for more information.

Special Use Errors