CBFS Component

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The CBFS component gives applications the ability to create a virtual filesystem.

Syntax

callback.CBFSConnect.Cbfs

Remarks

The CBFS component is used to create a virtual filesystem whose contents are stored and exposed in an application-defined manner. The CBFS component's unique and powerful event-based design gives applications the flexibility needed to support a wide range of use cases, ranging from something as simple as translating filesystem calls to files and directories on another storage medium, to something as complex as generating the entire contents of the virtual filesystem on the fly based on some application-specific data source.

Getting Started

Each CBFS component instance controls a single virtual filesystem, and therefore a single virtual drive. Applications can use multiple instances of the CBFS component if their use case requires the creation of multiple virtual drives; the component's Tag property can be used to distinguish between instances during event handlers.

Here's how to get up and running:

1. If the system driver has not been installed yet, call the Install method to do so. This needs to be done only once.
   • In production, the system driver can be installed (or updated) ahead of time by 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 CBFS component. This must be done each time the application starts (if the application is using multiple CBFS component instances, only the first instance created should be used to call Initialize).
3. Ensure that all of the necessary event handlers have been implemented. Some event handlers, such as OpenFile, ReadFile, GetFileInfo, and EnumerateDirectory are mandatory and must be implemented by all applications (this is not an exhaustive list). Others are optional, and only need to be implemented when certain features are enabled. Please refer to the event's documentation for more information.
4. Create a virtual drive by calling the CreateStorage method.
5. Call the MountMedia method to "insert storage media" into the virtual drive. (This "media" can be changed at any time later using the UnmountMedia and MountMedia methods.)
6. Create one or more Mounting Points for the virtual drive using the AddMountingPoint method. A mounting point can be a drive letter, a UNC path, or a directory on an existing NTFS-formatted drive.
7. Later, the application can unmount the "media" from the virtual drive using the UnmountMedia method. At this point, the application could call the MountMedia method again to "insert different storage media".
8. To delete the virtual drive entirely, call the DeleteStorage method.
9. To uninstall the system driver, call the Uninstall method. This should not be done as part of the driver upgrade process.
   • In production, the system 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

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

Method List

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

Event List

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

Config Settings

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

AccessDeniedProcesses Property (CBFS Component)

Collection of access rules that define which processes may not access the virtual drive.

Syntax

• C#
• VB.NET

public ProcessAccessRuleList AccessDeniedProcesses { get; }

Public ReadOnly Property AccessDeniedProcesses As ProcessAccessRuleList

Remarks

This property holds a collection of ProcessAccessRule objects representing rules that deny processes certain kinds of access to the virtual drive.

Please refer to the AddDeniedProcess and RemoveDeniedProcess methods for more information.

Note: The methods and properties related to process access lists are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of process access information occurs in a thread-safe manner.

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

AccessGrantedProcesses Property (CBFS Component)

Collection of access rules that define which processes may access the virtual drive.

Syntax

• C#
• VB.NET

public ProcessAccessRuleList AccessGrantedProcesses { get; }

Public ReadOnly Property AccessGrantedProcesses As ProcessAccessRuleList

Remarks

This property holds a collection of ProcessAccessRule objects representing rules that grant processes certain kinds of access to the virtual drive.

Please refer to the AddGrantedProcess and RemoveGrantedProcess methods for more information.

Note: The methods and properties related to process access lists are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of process access information occurs in a thread-safe manner.

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

Active Property (CBFS Component)

This property specifies whether the component is active and handling OS requests.

Syntax

• C#
• VB.NET

public bool Active { get; }

Public ReadOnly Property Active As Boolean

Default Value

False

Remarks

This property reflects whether the component is currently active and handling OS requests.

The property will be true once both CreateStorage and MountMedia have been called.

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

FileCache Property (CBFS Component)

This property specifies which file data cache implementation to use.

Syntax

• C#
• VB.NET

public CbfsFileCaches FileCache { get; set; }

enum CbfsFileCaches {
  fcNone,
  fcSystem,
  fcInternalKernelMode,
  fcInternalUserMode
}

Public Property FileCache As CbfsFileCaches

Enum CbfsFileCaches
  fcNone
  fcSystem
  fcInternalKernelMode
  fcInternalUserMode
End Enum

Default Value

1

Remarks

This property specifies which file data cache implementation a virtual drive should use, if any. Possible values are as follows:

• fcNone (0): Do not use file data caching.
• fcSystem (1, default): Delegate file data caching to the Windows file management system cache (recommended).
• fcInternalKernelMode (2): Use the CBFS kernel mode file data cache implementation.
• fcInternalUserMode (3): Use the CBFS user mode file data cache implementation.

When set to fcInternalUserMode (3), the UserModeFileCacheSize configuration setting can be used to control the cache size.

Please refer to the Caching topic for detailed information on each of the cache implementations.

Note: This property cannot be changed within events.

FileSystemName Property (CBFS Component)

The name of the virtual filesystem.

Syntax

• C#
• VB.NET

public string FileSystemName { get; set; }

Public Property FileSystemName As String

Default Value

"FAT32"

Remarks

This property specifies the name of the virtual filesystem. Windows, and some other applications, use this name to identify the filesystem.

In general, the filesystem name can be any reasonable string up to 10 characters in length. However, some versions of Windows and some third-party programs may behave differently when they encounter an unknown filesystem name (i.e., anything other than FAT, FAT32, exFAT, NTFS, etc.). Applications should keep this restriction in mind when choosing a filesystem name.

This property is set to FAT32 by default, which may cause some applications to fail when attempting to copy large (>4GB) files to and from the virtual drive. It is recommended that applications set this property to exFAT if such issues occur.

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

FireAllOpenCloseEvents Property (CBFS Component)

This property specifies whether to fire events for all file open/close operations, or just the first and last.

Syntax

• C#
• VB.NET

public bool FireAllOpenCloseEvents { get; set; }

Public Property FireAllOpenCloseEvents As Boolean

Default Value

False

Remarks

This property specifies when the component should fire the CreateFile/OpenFile and CleanupFile/CloseFile events.

When this property is disabled (default), the component will not fire CreateFile/OpenFile for a file if another handle is already open for it. Similarly, the CleanupFile/CloseFile events will not be fired unless the handle being closed is the last handle open for the file in question. This behavior results in better overall performance because the number of event firings is minimized, but there are some drawbacks as well:

• If the file is opened only for reading initially, and then another process opens it for writing, the application will not be notified about the new mode, and may not be prepared to respond to the "unexpected" WriteFile events that will arrive should the second process start writing to the file. (Such an application may be able to mitigate this issue by always opening the file data from the backend store in read-write mode.)
• The HandleInfo parameter of various events has no effect; they carry handle-specific information that is not accessible to the application if this property is disabled.

When this property is enabled, the component fires the CreateFile/OpenFile and CleanupFile/CloseFile events every time a file handle is opened or closed.

This table shows when events will fire based on how this property is set:

Note: This property cannot be changed after a virtual drive is created, and it cannot be changed within events.

HandleAllFsctls Property (CBFS Component)

This property specifies whether or not to fire the Fsctl event for all FSCTL_* requests.

Syntax

• C#
• VB.NET

public bool HandleAllFsctls { get; set; }

Public Property HandleAllFsctls As Boolean

Default Value

False

Remarks

This property specifies when the component should fire the Fsctl event. When disabled (default), the Fsctl event will fire only for FSCTLs whose function codes are in the 2400-4096 range (these codes are reserved by CBFS Connect for application use). When enabled, this Fsctl will fire for every FSCTL, except those processed by CBFS Connect itself.

Note: This property cannot be changed after a virtual drive is created, and it cannot be changed within events.

MaxFileNameLength Property (CBFS Component)

This property includes the maximum filename length supported by the virtual filesystem.

Syntax

• C#
• VB.NET

public int MaxFileNameLength { get; set; }

Public Property MaxFileNameLength As Integer

Default Value

260

Remarks

This property specifies the virtual filesystem's maximum supported filename length, measured in characters. Setting this property to a value less than its default of 260 characters, which corresponds to Windows' MAX_PATH constant, is not recommended.

Note: This property cannot be changed after a virtual drive is created, and it cannot be changed within events.

MaxFilePathLength Property (CBFS Component)

This property includes the maximum file path length supported by the virtual filesystem.

Syntax

• C#
• VB.NET

public int MaxFilePathLength { get; set; }

Public Property MaxFilePathLength As Integer

Default Value

32767

Remarks

This property specifies the virtual filesystem's maximum supported file path length, measured in characters; where file path means "a string containing all directory names plus the name of the file itself". Setting this property to a value of less than 260 characters, which corresponds to Windows' MAX_PATH constant, is not recommended.

Note: This property cannot be changed after a virtual drive is created, and it cannot be changed within events.

MaxFileSize Property (CBFS Component)

This property includes the maximum file size supported by the virtual filesystem.

Syntax

• C#
• VB.NET

public long MaxFileSize { get; set; }

Public Property MaxFileSize As Long

Default Value

0

Remarks

This property specifies the maximum file size, in bytes, supported by the virtual filesystem. The default value of 0 means "no limit".

Note: This property cannot be changed within events.

MetadataCacheEnabled Property (CBFS Component)

This property specifies whether or not the metadata cache should be used.

Syntax

• C#
• VB.NET

public bool MetadataCacheEnabled { get; set; }

Public Property MetadataCacheEnabled As Boolean

Default Value

True

Remarks

This property controls whether the file metadata cache is enabled for a virtual drive. The size of the file metadata cache can be controlled using the MetadataCacheSize property.

When enabled, the component caches file information obtained via EnumerateDirectory and GetFileInfo events and uses the cached metadata to serve operating system requests, thus reducing how often the GetFileInfo events fire.

While a file or directory is open, its metadata is kept available in a special record called a File Control Block, regardless of whether or not the metadata cache is enabled.

For closed files and directories, the metadata is kept in the cache for the time, defined by the UnusedMetadataLifetime configuration setting.

Please refer to the Caching topic for more information.

Note: This property cannot be changed within events.

MetadataCacheSize Property (CBFS Component)

This property includes the size of the metadata cache.

Syntax

• C#
• VB.NET

public int MetadataCacheSize { get; set; }

Public Property MetadataCacheSize As Integer

Default Value

2048

Remarks

This property specifies the size of the file metadata cache as a number of entries. The value must be a positive number. The maximum valid value is 65536.

Please refer to the MetadataCacheEnabled property, as well as the Caching topic, for more information.

Note: This property cannot be changed within events.

MountingPoints Property (CBFS Component)

Collection of mounting points for the virtual drive.

Syntax

• C#
• VB.NET

public MountingPointList MountingPoints { get; }

Public ReadOnly Property MountingPoints As MountingPointList

Remarks

This property holds a collection of MountingPoint objects, each of which represents an available mounting point for the virtual drive.

Please refer to the AddMountingPoint and RemoveMountingPoint methods for more information.

Note: The methods and properties related to mounting points are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of mounting points occurs in a thread-safe manner.

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

NonExistentFilesCacheEnabled Property (CBFS Component)

This property specifies whether or not the nonexistent files cache should be used.

Syntax

• C#
• VB.NET

public bool NonExistentFilesCacheEnabled { get; set; }

Public Property NonExistentFilesCacheEnabled As Boolean

Default Value

True

Remarks

This property controls whether the nonexistent files cache is enabled for a virtual drive. The size of the nonexistent files cache can be controlled using the NonExistentFilesCacheSize property.

When enabled, the component will cache any GetFileInfo responses that indicate that the requested file does not exist. If another request is later made for the same file, the component will use this information to automatically report a file not found error rather than firing the GetFileInfo event again.

Please refer to the Caching topic for more information.

Note: This property cannot be changed within events.

NonExistentFilesCacheSize Property (CBFS Component)

This property includes the size of the nonexistent files cache.

Syntax

• C#
• VB.NET

public int NonExistentFilesCacheSize { get; set; }

Public Property NonExistentFilesCacheSize As Integer

Default Value

2048

Remarks

This property specifies the maximum size of the nonexistent files cache as a number of entries. The value must be a positive number. The maximum valid value is 65536.

Please refer to the NonExistentFilesCacheEnabled property, as well as the Caching topic, for more information.

Note: This property cannot be changed within events.

OpenFiles Property (CBFS Component)

Collection of information about the objects in the virtual drive that are currently open.

Syntax

• C#
• VB.NET

public OpenFileList OpenFiles { get; }

Public ReadOnly Property OpenFiles As OpenFileList

Remarks

This property holds a collection of OpenFile objects representing filesystem objects (files, directories, etc.) from the virtual drive that are currently open. The collection is populated anytime CreateOpenedFilesSnapshot is called, and cleared when CloseOpenedFilesSnapshot is called; please refer to those methods for more information.

Note: The methods and properties related to open files snapshots are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that creation, use, and cleanup of open files snapshots occurs in a thread-safe manner.

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

OpenHandlesCount Property (CBFS Component)

This property includes the number of handles to filesystem objects in the virtual drive that are currently open.

Syntax

• C#
• VB.NET

public int OpenHandlesCount { get; }

Public ReadOnly Property OpenHandlesCount As Integer

Default Value

0

Remarks

This property reflects the number of handles to filesystem objects (e.g., files, directories) in the virtual drive that are currently open. It is populated when CreateOpenedFilesSnapshot is called, and cleared when CloseOpenedFilesSnapshot is called; please refer to those methods for more information.

This property's value may differ from that of the OpenObjectsCount property, and from the number of items in the OpenFiles collection property. This occurs because each object can be opened several times, and because the OS may keep files open even after all handles to them have been closed.

Note: The methods and properties related to open files snapshots are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that creation, use, and cleanup of open files snapshots occurs in a thread-safe manner.

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

OpenObjectsCount Property (CBFS Component)

This property includes the number of filesystem objects in the virtual drive that are currently open.

Syntax

• C#
• VB.NET

public int OpenObjectsCount { get; }

Public ReadOnly Property OpenObjectsCount As Integer

Default Value

0

Remarks

This property reflects the number of filesystem objects (e.g., files, directories) in the virtual drive that are currently open. It is populated when CreateOpenedFilesSnapshot is called and cleared when CloseOpenedFilesSnapshot is called; please refer to those methods for more information.

This property's value may differ from that of the OpenHandlesCount property, and from the number of items in the OpenFiles collection property. This occurs because each object can be opened several times, and because the OS may keep files open even after all handles to them have been closed.

Note: The methods and properties related to open files snapshots are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that creation, use, and cleanup of open files snapshots occurs in a thread-safe manner.

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

ProcessRestrictionsEnabled Property (CBFS Component)

Whether process access restrictions are enabled.

Syntax

• C#
• VB.NET

public bool ProcessRestrictionsEnabled { get; set; }

Public Property ProcessRestrictionsEnabled As Boolean

Default Value

False

Remarks

This property controls whether the component should enforce per-process access restrictions; by default, it is disabled. When enabled, the AddGrantedProcess and AddDeniedProcess methods can be used to add process-specific access rules for the component to enforce across the entire virtual drive.

When an application enables this propery, it should use the AddGrantedProcess method to add at least one pocess as allowed; otherwise, the data will be inaccessible.

The current process access rules are reflected by the AccessGrantedProcesses and AccessDeniedProcesses collection properties.

Note: The methods and properties related to process access lists are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of process access information occurs in a thread-safe manner.

SerializeAccess Property (CBFS Component)

This property specifies whether nonintersecting operations against the same file should execute serially or in parallel.

Syntax

• C#
• VB.NET

public bool SerializeAccess { get; set; }

Public Property SerializeAccess As Boolean

Default Value

True

Remarks

This property specifies whether the component should force nonintersecting operations against a single file or directory to execute serially (default), or allow them to execute in parallel.

Parallel processing can speed up operations, to a certain extent. When this property is disabled, and two or more requests (which do not change filesystem information) are made against the same file or directory, those requests are surfaced in parallel through the appropriate events (assuming that enough worker threads are available to service them at the time). By default, this property is enabled, and such requests are serialized. Please refer to the Threading and Concurrency topic for more information.

Note: For parallel processing to work, the SerializeEvents property must be disabled, and the MinWorkerThreadCount and MaxWorkerThreadCount configuration settings must be set such that parallel processing can actually occur.

Note: This property cannot be changed after a virtual drive is created, and it cannot be changed within events.

SerializeEvents Property (CBFS Component)

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

Syntax

• C#
• VB.NET

public CbfsSerializeEvents SerializeEvents { get; set; }

enum CbfsSerializeEvents {
  seOnMultipleThreads,
  seOnOneWorkerThread
}

Public Property SerializeEvents As CbfsSerializeEvents

Enum CbfsSerializeEvents
  seOnMultipleThreads
  seOnOneWorkerThread
End Enum

Default Value

0

Remarks

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

Please note that, in general, the component will always fire events related to a single file sequentially (though not necessarily on the same worker thread all the time), regardless of how this property is set. The one exception is that, if this property is set to seOnMultipleThreads, the SerializeAccess property can be enabled to allow multiple read requests made against a single file to execute concurrently. 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.

StorageCharacteristics Property (CBFS Component)

The characteristic flags to create the virtual drive with (Windows only).

Syntax

• C#
• VB.NET

public int StorageCharacteristics { get; set; }

Public Property StorageCharacteristics As Integer

Default Value

16

Remarks

The system, as well as other applications, use these flags to optimize their use of the virtual drive. This property should be set by OR'ing together zero or more of the following flags:

Note: This property cannot be changed after a virtual drive is created, and it cannot be changed within events.

StorageGUID Property (CBFS Component)

The GUID to create the virtual drive with.

Syntax

• C#
• VB.NET

public string StorageGUID { get; set; }

Public Property StorageGUID As String

Default Value

""

Remarks

This property is used to specify a GUID for the virtual drive, and must be set to GUID-formatted string (e.g., {676D0357-A23A-49c3-B433-65AAD72DD282}). Otherwise, this property may be left empty; in the latter case, the driver will generate a unique value when a drive is mounted.

Some software uses a drive's GUID for the purpose of setting and maintaining certain configuration parameters. Therefore, applications are expected to use the same GUID when repeatedly creating a virtual drive that represents the same data.

In multiuser environments (Terminal Server, Citrix and similar software) where the application may be run concurrently by different users, using the same GUID for all users will cause a name conflict. To avoid it, mix the constant GUID value with the user-unique information such as the hash of the username or SID. This way, each user will use a constant but distinct GUID for their virtual drive.

Note: This property cannot be changed after a virtual drive is created, and it cannot be changed within events.

StoragePresent Property (CBFS Component)

This property specifies whether a virtual drive has been created.

Syntax

• C#
• VB.NET

public bool StoragePresent { get; }

Public ReadOnly Property StoragePresent As Boolean

Default Value

False

Remarks

This property reflects whether a virtual drive has been created; it is automatically updated by the component whenever the virtual drive's presence changes (e.g., due to calls to CreateStorage, DeleteStorage).

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

StorageType Property (CBFS Component)

The type of virtual drive to create (Windows only).

Syntax

• C#
• VB.NET

public int StorageType { get; set; }

Public Property StorageType As Integer

Default Value

0

Remarks

This property specifies what type of virtual drive should be created. Windows Explorer uses this information to display the appropriate icon and apply the appropriate security settings for the virtual drive. Other applications may also make use of this information in various ways.

Possible values are:

Note: This property cannot be changed after a virtual drive is created, and it cannot be changed within events.

Plug-and-play Virtual Drives

Virtual drives created as plug-and-play (STGT_DISK_PNP) require that a "physical device" be visible in the Disk Manager snap-in of the Microsoft Management Console (mmc.exe). This can be accomplished by calling the AddMountingPoint method and including the STGMP_MOUNT_MANAGER flag in the value passed for its Flags parameter.

In addition to supporting the STGC_REMOVABLE_MEDIA StorageCharacteristics flag, which specifies whether a virtual drive's media is removable or non-removable, plug-and-play virtual drives also support the STGC_ALLOW_EJECTION flag, which specifies whether a virtual drive itself is removable or non-removable.

SupportChangeTimeAttribute Property (CBFS Component)

This property specifies whether the virtual filesystem supports the ChangeTime file attribute.

Syntax

• C#
• VB.NET

public bool SupportChangeTimeAttribute { get; set; }

Public Property SupportChangeTimeAttribute As Boolean

Default Value

False

Remarks

This property specifies whether the virtual filesystem should indicate to the system that it supports the ChangeTime file attribute, which tracks the last time a file's metadata (e.g., permissions) or content was changed. The ChangeTime attribute is optional, and applications can choose not to handle it in events by simply leaving the value of the corresponding parameter unchanged.

Note: If the application is identifying its virtual filesystem (via FileSystemName) as NTFS, and this property is disabled, the component will still handle the ChangeTime attribute implicitly by setting it equal to LastWriteTime.

Note: This property cannot be changed after a virtual drive is created, and it cannot be changed within events.

SupportCompressedAttribute Property (CBFS Component)

This property specifies whether the virtual filesystem supports the Compressed file attribute.

Syntax

• C#
• VB.NET

public bool SupportCompressedAttribute { get; set; }

Public Property SupportCompressedAttribute As Boolean

Default Value

False

Remarks

When enabled, this property tells the driver to report support of compression to the operating system. When such a support is reported, processes may read or change the Compressed attribute of a file. An implementation of a virtual filesystem should provide the Compressed status through the file attributes in the GetFileInfo and EnumerateDirectory events. The attribute may be changed by the system, and such a change is communicated to the implementation by the Attributes parameter in the SetFileAttributes event.

Note: This property cannot be changed after a virtual drive is created, and it cannot be changed within events.

SupportLastAccessTimeAttribute Property (CBFS Component)

This property specifies whether the virtual filesystem supports the LastAccessTime file attribute.

Syntax

• C#
• VB.NET

public bool SupportLastAccessTimeAttribute { get; set; }

Public Property SupportLastAccessTimeAttribute As Boolean

Default Value

True

Remarks

This property specifies whether the virtual filesystem should indicate to the system that it supports the LastAccessTime file attribute, which tracks the last time a file's contents were accessed.

When this property is enabled (default), a file's LastAccessTime attribute gets updated whenever the file is closed (unless fewer than 60 seconds have elapsed since the previous LastAccessTime). When this property is disabled, a file's LastAccessTime is still tracked and passed along with its LastWriteTime when the latter is changed, but it is not updated separately when the file is closed.

Note: This property cannot be changed after a virtual drive is created, and it cannot be changed within events.

SupportODXReadWrite Property (CBFS Component)

This property specifies whether the virtual filesystem supports ODX (Offloaded Data Transfer) operations.

Syntax

• C#
• VB.NET

public bool SupportODXReadWrite { get; set; }

Public Property SupportODXReadWrite As Boolean

Default Value

False

Remarks

This property specifies whether the virtual filesystem should indicate to the system that it supports ODX (Offloaded Data Transfer) operations. Please refer to Microsoft's Offloaded Data Transfer article for more information.

If this property is enabled, the application must properly handle the OffloadReadFile and OffloadWriteFile events, which will fire anytime the OS sends an offload read or offload write request to the virtual filesystem.

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

Tag Property (CBFS Component)

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

Syntax

• C#
• VB.NET

public long Tag { get; set; }

Public Property Tag As Long

Default Value

0

Remarks

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

UseAlternateDataStreams Property (CBFS Component)

This property specifies whether or not the virtual filesystem supports alternate data streams.

Syntax

• C#
• VB.NET

public bool UseAlternateDataStreams { get; set; }

Public Property UseAlternateDataStreams As Boolean

Default Value

False

Remarks

This property specifies whether or not the virtual filesystem should indicate to the system that it supports alternate data streams (ADS, otherwise known as "named streams"). Alternate data streams can be present in both files and directories.

If this property is enabled, the application must properly handle the EnumerateNamedStreams and CloseNamedStreamsEnumeration events for alternate data streams to function correctly. Additionally, the application's GetFileInfo and EnumerateDirectory event handlers must take into account requests made by the OS to work with the alternate data streams.

Note: Alternate data streams are an expected feature of the NTFS filesystem; if the application is identifying its virtual filesystem (via FileSystemName) as NTFS, supporting alternate data streams is recommended.

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

UseCaseSensitiveFileNames Property (CBFS Component)

This property specifies whether the virtual filesystem is case-sensitive or just case-preserving.

Syntax

• C#
• VB.NET

public bool UseCaseSensitiveFileNames { get; set; }

Public Property UseCaseSensitiveFileNames As Boolean

Default Value

False

Remarks

This property specifies whether the virtual filesystem should indicate to the system that it is case-sensitive (true) or just case-preserving (false; default).

Traditionally, Windows uses a case-insensitive filesystem architecture. The NTFS filesystem has a case-sensitive mode, however, to support a POSIX subsystem; enabling this property will make the component behave in a manner similar to NTFS with regards to case-sensitivity by doing the following:

• Informing Windows that it supports preserving filename casing (which the application must actually do in its code).
• Working in a case-sensitive manner when managing caches.
• Firing the GetFileInfo event to obtain a real filename if a mixed-case name is encountered.

In addition to enabling this property, a flag must be set in the registry for case-sensitive filename support to work. Specifically, in the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\kernel registry key, the DWORD ObCaseInsensitive must be set to 0.

Note: The component always attempts to work with case-sensitive filenames, regardless of how this property is set. When a file is being opened, the CBFS Connect driver looks for the name of the file in the metadata cache, if an exact match is not found, the GetFileInfo event is fired to allow the application to supply a corrected filename through the RealFileName parameter. If the application chooses not to do so, the case-insensitive name will be used.

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

UseDirectoryEmptyCheck Property (CBFS Component)

This property specifies whether the IsDirectoryEmpty event should be used.

Syntax

• C#
• VB.NET

public bool UseDirectoryEmptyCheck { get; set; }

Public Property UseDirectoryEmptyCheck As Boolean

Default Value

True

Remarks

This property specifies whether the component should fire the IsDirectoryEmpty event when the OS needs to check whether a directory is empty. Such checks typically are performed just before the OS requests that a directory be deleted.

If this property is enabled (default), the application must properly handle the IsDirectoryEmpty event.

Note: Use of the IsDirectoryEmpty event is efficient only if the virtual filesystem has a fast way to check whether directories contain any entries (e.g., files, subdirectories, links). If such a check would require enumerating child entries, it is more efficient for the application to disable this property and perform the check directly within the CanFileBeDeleted event instead.

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

UseDiskQuotas Property (CBFS Component)

This property specifies whether the virtual filesystem supports disk quotas.

Syntax

• C#
• VB.NET

public bool UseDiskQuotas { get; set; }

Public Property UseDiskQuotas As Boolean

Default Value

False

Remarks

This property specifies whether the virtual filesystem should indicate to the system that it supports disk quota management.

If this property is enabled, the application must properly handle the QueryQuotas, SetQuotas, GetDefaultQuotaInfo, and SetDefaultQuotaInfo events for quota management to function correctly. The GetFileNameByFileId event must be handled as well.

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

UseFileIds Property (CBFS Component)

This property specifies whether the virtual filesystem supports file Ids.

Syntax

• C#
• VB.NET

public bool UseFileIds { get; set; }

Public Property UseFileIds As Boolean

Default Value

True

Remarks

This property specifies whether the virtual filesystem should indicate to the system that it supports File IDs.

If this property is enabled, the application must properly handle the GetFileInfo and EnumerateDirectory events and return proper file Ids for files and directories. The GetFileNameByFileId event must be handled as well.

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

UseHardLinks Property (CBFS Component)

This property specifies whether the virtual filesystem supports hard links.

Syntax

• C#
• VB.NET

public bool UseHardLinks { get; set; }

Public Property UseHardLinks As Boolean

Default Value

False

Remarks

This property specifies whether the virtual filesystem should indicate to the system that it supports hard links to files.

If this property is enabled, the application must properly handle the CreateHardLink, EnumerateHardLinks, and CloseHardLinksEnumeration events for hard links to function correctly. The GetFileNameByFileId event must be handled as well, and the GetFileInfo must always be sure to return the number of hard links a file has by setting the HardLinkCount event parameter appropriately.

Note: Hard links are an expected feature of the NTFS filesystem; if the application is identifying its virtual filesystem (via FileSystemName) as NTFS, supporting hard links is recommended.

Please refer to the Hard Links topic for more information.

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

UseObjectIds Property (CBFS Component)

This property specifies whether the virtual filesystem supports a volume object Id.

Syntax

• C#
• VB.NET

public bool UseObjectIds { get; set; }

Public Property UseObjectIds As Boolean

Default Value

True

Remarks

This property specifies whether the virtual filesystem should indicate to the system that it supports a volume object Id.

If this property is true, the application must properly handle the GetVolumeObjectId and SetVolumeObjectId events. Set this property to false to tell the OS that the volume object Id is not supported.

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

UseReparsePoints Property (CBFS Component)

This property specifies whether the virtual filesystem supports reparse points.

Syntax

• C#
• VB.NET

public bool UseReparsePoints { get; set; }

Public Property UseReparsePoints As Boolean

Default Value

False

Remarks

This property specifies whether the virtual filesystem should indicate to the system that it supports reparse points.

If this property is enabled, the application must properly handle the SetReparsePoint, GetReparsePoint, and DeleteReparsePoint events for reparse points to function correctly.

Note: Reparse points are an expected feature of the NTFS filesystem; if the application is identifying its virtual filesystem (via FileSystemName) as NTFS, supporting reparse points is recommended. Reparse point support is also expected by the NFS sharing components of the OS.

Please refer to the Reparse Points topic for more information.

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

UseShortFileNames Property (CBFS Component)

This property specifies whether the virtual filesystem supports short (8.3) filenames.

Syntax

• C#
• VB.NET

public bool UseShortFileNames { get; set; }

Public Property UseShortFileNames As Boolean

Default Value

False

Remarks

This property specifies whether the virtual filesystem should indicate to the system that it supports short filenames (also known as 8.3 filenames). Short filename support may be necessary for some older third-party applications to be able to access the virtual filesystem's files.

If this property is enabled, the application must be sure to return short filenames when handling the EnumerateDirectory and GetFileInfo events; and must be able to handle any event firing with a short filename rather than a normal one.

Please refer to the Short File Names topic for more information.

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

UseWindowsSecurity Property (CBFS Component)

This property specifies whether the virtual filesystem supports Windows' ACL-based security mechanisms.

Syntax

• C#
• VB.NET

public bool UseWindowsSecurity { get; set; }

Public Property UseWindowsSecurity As Boolean

Default Value

False

Remarks

This property specifies whether the virtual filesystem should indicate to the system that it supports Windows' standard security mechanisms, which are based on ACLs (access control lists).

If this property is enabled, the application must properly handle the GetFileSecurity and SetFileSecurity events for Windows' security mechanisms to function properly.

Note: Windows' security attributes are an expected feature of the NTFS filesystem; if the application is identifying its virtual filesystem (via FileSystemName) as NTFS, supporting Windows' security attributes is recommended.

Please refer to the Security Checks topic for more information.

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

AddDeniedProcess Method (CBFS Component)

Adds a rule that prevents a process from accessing the virtual drive.

Syntax

• C#
• VB.NET

public void AddDeniedProcess(string processFileName, int processId, bool childProcesses, int desiredAccess);

Public Sub AddDeniedProcess(ByVal ProcessFileName As String, ByVal ProcessId As Integer, ByVal ChildProcesses As Boolean, ByVal DesiredAccess As Integer)

Remarks

When the ProcessRestrictionsEnabled property is enabled, this method can be used to add an access rule that denies the process specified by ProcessFileName or ProcessId the access right specified by DesiredAccess.

Processes that are already running can be specified by passing their process Id (PID) for the ProcessId parameter (in which case ProcessFileName should be empty). Processes that have not yet started can be specified by passing the full filename of the process's executable file for ProcessFileName (in which case ProcessId should be set to 0). If ProcessName is empty, and ProcessId is -1, the new rule will apply to all processes. When adding a PID-based rule, you need to be aware of the PID Reuse behavior of Windows.

ChildProcesses controls whether the rule also applies to children of the target process.

DesiredAccess specifies the access right to deny; valid values are:

To remove the process access rule later, pass the same ProcessFileName and ProcessId values to the RemoveDeniedProcess method.

Note: This method can be called only when Active is true, and it cannot be called within events.

The methods and properties related to process access lists are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of process access information occurs in a thread-safe manner.

AddGrantedProcess Method (CBFS Component)

Adds a rule that allows a process to access the virtual drive.

Syntax

• C#
• VB.NET

public void AddGrantedProcess(string processFileName, int processId, bool childProcesses, int desiredAccess);

Public Sub AddGrantedProcess(ByVal ProcessFileName As String, ByVal ProcessId As Integer, ByVal ChildProcesses As Boolean, ByVal DesiredAccess As Integer)

Remarks

When the ProcessRestrictionsEnabled property is enabled, this method can be used to add an access rule that grants the process specified by ProcessFileName or ProcessId the access right specified by DesiredAccess.

Processes that are already running can be specified by passing their process Id (PID) for the ProcessId parameter (in which case ProcessFileName should be empty). Processes that have not yet started can be specified by passing the full filename of the process's executable file for ProcessFileName (in which case ProcessId should be set to 0). If ProcessName is empty, and ProcessId is -1, the new rule will apply to all processes. When adding a PID-based rule, you need to be aware of the PID Reuse behavior of Windows.

ChildProcesses controls whether the rule also applies to children of the target process.

DesiredAccess specifies the access right to grant; valid values are:

To remove the process access rule later, pass the same ProcessFileName and ProcessId values to the RemoveGrantedProcess method.

Note: This method can be called only when Active is true, and it cannot be called within events.

The methods and properties related to process access lists are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of process access information occurs in a thread-safe manner.

AddMountingPoint Method (CBFS Component)

Adds a mounting point for the virtual drive.

Syntax

• C#
• VB.NET

public void AddMountingPoint(string mountingPoint, int flags, long authenticationId);

Public Sub AddMountingPoint(ByVal MountingPoint As String, ByVal Flags As Integer, ByVal AuthenticationId As Long)

Remarks

This method adds a new mounting point for the virtual drive (which must have already been created using CreateStorage). Virtual drives may have as many mounting points as desired.

Typically, mounting points may be added before or after MountMedia is called. However, for plug-and-play virtual drives with non-removable media (see StorageType), AddMountingPoint must not be called until after the MountMedia method has been called successfully, otherwise an error will occur.

MountingPoint should be set to the name/path of the mounting point. The format of this value varies based what type of mounting point the application wishes to create; please refer to the Mounting Points topic for more information.

The Flags parameter is used to specify properties for the mounting point, and should be set by OR'ing together zero or more of the following flags:

If the STGMP_LOCAL flag is set, the AuthenticationId parameter should be set to the Authentication ID of the user session the mounting point should visible in; or to 0 to make the mounting point visible in the current user session. If the aforementioned flag is not set and AuthenticationId is 0, the mounting point will be global (i.e., visible in all user sessions). When AuthenticationId is set to a non-zero value, STGMP_LOCAL is implied. Please refer to the Mounting Points topic for more information.

To create a virtual drive in a container from the host, set the container's Id via the DockerContainerId configuration setting prior to calling AddMountingPoint. Note: not all mounting point types are supported when a mounting point is created in a container. Please refer to the Docker Containers for more information.

Note: This method cannot be called within events.

The methods and properties related to mounting points are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of mounting points occurs in a thread-safe manner.

Virtual Drives, Media, and Mounting Points

In the FUSE component, a mount point is specified as a parameter of the Mount method. Mounting includes both creation of a drive (virtual device) and mounting a media into this device.

The information below applies to the CBFS component.

When applications call the CreateStorage method, a virtual drive is created. Virtual drives are created without any "media" in them (like a CD drive without a CD inserted), and without any mounting points (drive letters, UNC paths, etc.).

After creating a virtual drive, applications should call MountMedia to "insert" virtual storage media into the virtual drive. This call will cause the component's events to start firing; applications must handle these events correctly, or the MountMedia call will fail.

Once media has been mounted in the virtual drive, applications should use the AddMountingPoint method to add one or more mounting points for the virtual drive. These mounting points make the virtual drive, visible to the system and other applications, allowing them to start accessing the contents of the CBFS-based virtual filesystem.

Note that applications can technically call AddMountingPoint before MountMedia (except for plug-and-play virtual drives with non-removable media; see StorageType), but any attempts to access a virtual drive with no media mounted will result in a "no media" error.

CloseOpenedFilesSnapshot Method (CBFS Component)

Closes the previously-created opened files snapshot.

Syntax

• C#
• VB.NET

public void CloseOpenedFilesSnapshot();

Public Sub CloseOpenedFilesSnapshot()

Remarks

This method closes the opened files snapshot previously created by CreateOpenedFilesSnapshot, 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 open files snapshots are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that creation, use, and cleanup of open files snapshots occurs in a thread-safe manner.

Config Method (CBFS Component)

Sets or retrieves a configuration setting.

Syntax

• C#
• VB.NET

public string Config(string configurationString);

Public Function Config(ByVal ConfigurationString As String) As String

Remarks

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

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, 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.

CreateOpenedFilesSnapshot Method (CBFS Component)

Creates a snapshot of information about files that are currently open.

Syntax

• C#
• VB.NET

public void CreateOpenedFilesSnapshot();

Public Sub CreateOpenedFilesSnapshot()

Remarks

This method creates a snapshot of information about all files and directories in the virtual filesystem that are currently open. This information is then used to populate the OpenFiles collection property, as well as the OpenHandlesCount and OpenObjectsCount properties.

Note that there will always be at least one item in the OpenFiles collection property since the virtual volume itself is always inherently open.

When the application is finished working with the opened files snapshot, it must close it by calling the CloseOpenedFilesSnapshot method in order to release the associated memory. If this method is called again before an existing snapshot is closed, the component will attempt to close it before creating a new one.

Note: This method can be called only when Active is true, and it cannot be called within events.

The methods and properties related to open files snapshots are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that creation, use, and cleanup of open files snapshots occurs in a thread-safe manner.

CreateStorage Method (CBFS Component)

This method creates the virtual drive.

Syntax

• C#
• VB.NET

public void CreateStorage();

Public Sub CreateStorage()

Remarks

This method creates the virtual drive (without mounting points) based on the following properties and configuration settings, which cannot be changed once the virtual storage has been created:

• StorageType
• StorageCharacteristics
• StorageGUID (if applicable)
• SectorSize

Note: Many other properties, although not directly used by this method, nonetheless cannot be changed once a virtual drive is created. Such restrictions are noted where applicable.

After the virtual drive is created, use the MountMedia method to "insert storage media" into the virtual drive, and use the AddMountingPoint method to create one or more mounting points for it.

The Initialize method must have been called by some component instance in the application before calling this method.

Note: This method cannot be called within events.

Virtual Drives, Media, and Mounting Points

In the FUSE component, a mount point is specified as a parameter of the Mount method. Mounting includes both creation of a drive (virtual device) and mounting a media into this device.

The information below applies to the CBFS component.

When applications call the CreateStorage method, a virtual drive is created. Virtual drives are created without any "media" in them (like a CD drive without a CD inserted), and without any mounting points (drive letters, UNC paths, etc.).

After creating a virtual drive, applications should call MountMedia to "insert" virtual storage media into the virtual drive. This call will cause the component's events to start firing; applications must handle these events correctly, or the MountMedia call will fail.

Once media has been mounted in the virtual drive, applications should use the AddMountingPoint method to add one or more mounting points for the virtual drive. These mounting points make the virtual drive, visible to the system and other applications, allowing them to start accessing the contents of the CBFS-based virtual filesystem.

Note that applications can technically call AddMountingPoint before MountMedia (except for plug-and-play virtual drives with non-removable media; see StorageType), but any attempts to access a virtual drive with no media mounted will result in a "no media" error.

DeleteStorage Method (CBFS Component)

This method deletes the virtual drive.

Syntax

• C#
• VB.NET

public void DeleteStorage(bool forceUnmount);

Public Sub DeleteStorage(ByVal ForceUnmount As Boolean)

Remarks

This method attempts to delete the virtual drive. The ForceUnmount parameter controls how this method behaves if any mounting points currently exist for the virtual drive.

If ForceUnmount is true, any existing mounting points are forcibly removed (and any open handles are closed along the way). If ForceUnmount is false and any mounting points exist for it, this method throws an exception.

Note: This method cannot be called within events.

DisableRouteCache Method (CBFS Component)

This method disables the automatic routing of requests to local files.

Syntax

• C#
• VB.NET

public void DisableRouteCache(bool invalidateRoutedFiles);

Public Sub DisableRouteCache(ByVal InvalidateRoutedFiles As Boolean)

Remarks

This method disables the automatic routing of requests to files in the directory specified by a previous call to EnableRouteCache. Please refer to that method for more information about said request routing.

The InvalidateRoutedFiles parameter controls what happens to any handles currently open for files in the aforementioned directory: passing true will allow them to continue being used, whereas passing false will invalidate them immediately.

Note: This method cannot be called within events.

DispatchEvents Method (CBFS Component)

Reserved, do not use.

Syntax

• C#
• VB.NET

public void DispatchEvents();

Public Sub DispatchEvents()

Remarks

Reserved, do not use.

EnableRouteCache Method (CBFS Component)

This method enables the automatic routing of requests to local files.

Syntax

• C#
• VB.NET

public void EnableRouteCache(string location, int flags);

Public Sub EnableRouteCache(ByVal Location As String, ByVal Flags As Integer)

Remarks

This method enables the automatic routing of requests to files that exist in the directory specified by Location. The Flags parameter is used to specify which kinds of requests should not be routed automatically (see below).

When automatic request routing is enabled, and a file in the virtual drive is opened, the component will immediately check the cache directory to see if a file with the same path and name exists. If such a file is found, all operations will be performed on it directly and the corresponding events will not fire (except for the operations excluded from routing by the specified Flags).

When attempting to find a matching file, the component assumes that the contents of the specified cache directory mirror that of the virtual drive. That is, the cache directory corresponds to the root of the virtual drive, and the files and directory structure are the same in each. If the component fails to find a matching file (or if the operation in question is excluded from routing), then the applicable events fire as usual.

The Flags value should be created by ORing together zero or more of the following flags:

Note: This method cannot be called within events.

FileMatchesMask Method (CBFS Component)

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

Syntax

• C#
• VB.NET

public bool FileMatchesMask(string mask, string fileName, bool caseSensitive);

Public Function FileMatchesMask(ByVal Mask As String, ByVal FileName As String, ByVal CaseSensitive As Boolean) As Boolean

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 (CBFS Component)

Retrieves the status of the system driver.

Syntax

• C#
• VB.NET

public int GetDriverStatus(string productGUID, int module);

Public Function GetDriverStatus(ByVal ProductGUID As String, ByVal Module As Integer) As Integer

Remarks

This method retrieves the status of the system driver module specified by Module. 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 between driver installations performed by different applications. Such information is necessary to guard against unexpected situations such as, e.g., the driver being uninstalled by one application despite other applications still needing it.

The GUID must be specified in so-called "Registry Format" (e.g., "{1FAD0EF2-9A03-4B87-B4BC-645B7035ED90}") with curly braces included.

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
• GetModuleVersion
• RegisterIcon
• UnregisterIcon
• Initialize

The Module parameter specifies which driver module to query the status of. Possible values are:

This method is available in both the component 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 (CBFS Component)

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

Syntax

• C#
• VB.NET

public string GetEventFilename();

Public Function GetEventFilename() As String

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 filename, this method returns an empty string.

GetHandleCreatorProcessId Method (CBFS Component)

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

Syntax

• C#
• VB.NET

public int GetHandleCreatorProcessId(long handleInfo);

Public Function GetHandleCreatorProcessId(ByVal HandleInfo As Long) As Integer

Remarks

This method can be called within certain events to retrieve the Id of the process (PID) that opened the file handle specified by HandleInfo. The value to pass for HandleInfo should be obtained directly from the event. 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 virtual 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 that expose a HandleInfo parameter, and must be called in the same thread that the event was originally fired on.

GetHandleCreatorProcessName Method (CBFS Component)

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

Syntax

• C#
• VB.NET

public string GetHandleCreatorProcessName(long handleInfo);

Public Function GetHandleCreatorProcessName(ByVal HandleInfo As Long) As String

Remarks

This method can be called within certain events to retrieve the name of the process that opened the file handle specified by HandleInfo. The value to pass for HandleInfo should be obtained directly from the event. If the query fails, this method returns an empty string.

Applications cannot use this method to retrieve information about remote processes accessing virtual 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 that expose a HandleInfo parameter, and must be called in the same thread that the event was originally fired on.

GetHandleCreatorThreadId Method (CBFS Component)

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

Syntax

• C#
• VB.NET

public int GetHandleCreatorThreadId(long handleInfo);

Public Function GetHandleCreatorThreadId(ByVal HandleInfo As Long) As Integer

Remarks

This method can be called within certain events to retrieve the Id of the thread that opened the file handle specified by HandleInfo. The value to pass for HandleInfo should be obtained directly from the event. 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 events that expose a HandleInfo parameter, and must be called in the same thread that the event was originally fired on.

GetHandleCreatorToken Method (CBFS Component)

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

Syntax

• C#
• VB.NET

public long GetHandleCreatorToken(long handleInfo);

Public Function GetHandleCreatorToken(ByVal HandleInfo As Long) As Long

Remarks

This method can be called within certain events to retrieve the security token associated with the process that opened the file handle specified by HandleInfo. The value to pass for HandleInfo should be obtained directly from the event. 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. This is particularly useful for implementing custom security checks; please refer to the Security Checks topic for more information.

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

Network Access Notes

For virtual drives shared on the network, applications 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 Helper DLL (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 that expose a HandleInfo parameter, and must be called in the same thread that the event was originally fired on.

GetModuleVersion Method (CBFS Component)

Retrieves the version of a given product module.

Syntax

• C#
• VB.NET

public long GetModuleVersion(string productGUID, int module);

Public Function GetModuleVersion(ByVal ProductGUID As String, ByVal Module As Integer) As Long

Remarks

This method retrieves the version of the product module specified by Module. 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 specified module is not installed, this method returns 0.

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

The GUID must be specified in so-called "Registry Format" (e.g., "{1FAD0EF2-9A03-4B87-B4BC-645B7035ED90}") with curly braces included.

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
• GetModuleVersion
• RegisterIcon
• UnregisterIcon
• Initialize

The Module parameter specifies which driver module to query the status of. Possible values are:

This method is available in both the component 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.

GetOriginatorProcessId Method (CBFS Component)

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

Syntax

• C#
• VB.NET

public int GetOriginatorProcessId();

Public Function GetOriginatorProcessId() As Integer

Remarks

This method can be called within certain events 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 virtual 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 , such as ReadFile and WriteFile, 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.

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.

GetOriginatorProcessName Method (CBFS Component)

Retrieves the name of the process that initiated the operation.

Syntax

• C#
• VB.NET

public string GetOriginatorProcessName();

Public Function GetOriginatorProcessName() As String

Remarks

This method can be called within certain events 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 virtual 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 , such as ReadFile and WriteFile, 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.

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.

GetOriginatorThreadId Method (CBFS Component)

Retrieves the Id of the thread that initiated the operation (Windows only).

Syntax

• C#
• VB.NET

public int GetOriginatorThreadId();

Public Function GetOriginatorThreadId() As Integer

Remarks

This method can be called within certain events 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 , such as ReadFile and WriteFile, 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.

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.

GetOriginatorToken Method (CBFS Component)

Retrieves the security token associated with the process that initiated the operation (Windows only).

Syntax

• C#
• VB.NET

public long GetOriginatorToken();

Public Function GetOriginatorToken() As Long

Remarks

This method can be called within certain events to retrieve the security token associated with the process that initiated the operation. 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. This is particularly useful for implementing custom security checks; please refer to the Security Checks topic for more information.

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

Network Access Notes

For virtual drives shared on the network, applications 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 Helper DLL (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 , such as ReadFile and WriteFile, 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.

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.

Initialize Method (CBFS Component)

This method initializes the component.

Syntax

• C#
• VB.NET

public void Initialize(string productGUID);

Public Sub Initialize(ByVal ProductGUID As String)

Remarks

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

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

The GUID must be specified in so-called "Registry Format" (e.g., "{1FAD0EF2-9A03-4B87-B4BC-645B7035ED90}") with curly braces included.

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
• GetModuleVersion
• RegisterIcon
• UnregisterIcon
• 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 component can be used.

Install Method (CBFS Component)

Installs (or upgrades) the product's system drivers and/or the helper DLL (Windows only).

Syntax

• C#
• VB.NET

public int Install(string cabFileName, string productGUID, string pathToInstall, int modulesToInstall, int flags);

Public Function Install(ByVal CabFileName As String, ByVal ProductGUID As String, ByVal PathToInstall As String, ByVal ModulesToInstall As Integer, ByVal Flags As Integer) As Integer

Remarks

This method is used to install or upgrade the product's various modules (i.e., the system drivers and the Helper DLL). The ModulesToInstall parameter selects which modules should be installed. If the system must be rebooted to complete the installation process, this method will return a non-zero value indicating which module(s) requested the reboot (out of those initially selected).

Important: To upgrade the product's modules, use only the Install method. Previously installed versions of the modules 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 .cab file containing the product modules. Important: This .cab file must remain on the target system (or be available in some other way) after installation, as it is required for uninstalling the modules from the system.

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

The GUID must be specified in so-called "Registry Format" (e.g., "{1FAD0EF2-9A03-4B87-B4BC-645B7035ED90}") with curly braces included.

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
• GetModuleVersion
• RegisterIcon
• UnregisterIcon
• Initialize

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

ModulesToInstall should contain one or more of the following flags, OR'd together:

Flags specifies various installation options, and should contain zero or more of the following flags, OR'd together:

This method is available in both the component 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.

IsCBFSVolume Method (CBFS Component)

This method checks whether the specified volume is powered by CBFS.

Syntax

• C#
• VB.NET

public bool IsCBFSVolume(string volumePath);

Public Function IsCBFSVolume(ByVal VolumePath As String) As Boolean

Remarks

This method checks to see whether the volume specified by VolumePath is powered by CBFS; if it is, this method returns true.

Valid formats for VolumePath include the following:

• Drive letters, like X:.
• Volume GUIDs, like Volume{676D0357-A23A-49C3-B433-65AAD72DD282}.

IsIconRegistered Method (CBFS Component)

Checks whether the specified icon is registered (Windows only).

Syntax

• C#
• VB.NET

public bool IsIconRegistered(string iconId);

Public Function IsIconRegistered(ByVal IconId As String) As Boolean

Remarks

This method checks whether an icon with the specified IconId has been registered. If such an icon has been registered, this method returns true; otherwise it returns false.

Icons can be registered using the RegisterIcon method. Please refer to that method's documentation, as well as the Custom Drive Icons topic, for more information.

The Helper DLL must be installed in order for this method to function correctly. Applications can check to see whether the Helper DLL is installed using the GetModuleVersion method, and install it using the Install method if necessary.

MountMedia Method (CBFS Component)

This method mounts media in the virtual drive, making it accessible for reading and writing.

Syntax

• C#
• VB.NET

public void MountMedia(int timeout);

Public Sub MountMedia(ByVal Timeout As Integer)

Remarks

After using CreateStorage to create a virtual drive, applications should call this method to "insert storage media" into it. For plug-and-play virtual drives with nonremovable media (see StorageType), this method must be called before AddMountingPoint is called. For all other virtual drives, AddMountingPoint can be called before or after calling this method.

Timeout specifies how many milliseconds the driver will wait for events to execute before canceling 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. (Passing a nonzero value less than 3000 will cause this method to fail with an ERROR_IMPLEMENTATION_LIMIT (1292, 0x50C) error code.)

When event timeouts are in effect, event handlers can call ResetTimeout to reset the timer if they require additional time to complete an operation.

Note: A number of properties cannot be changed once media is mounted. Such restrictions are noted in properties' documentation as applicable.

If this method encounters any issues during its execution, it throws an exception, and additional information is logged to the Windows system log as described in the Error Reporting and Handling topic.

Note: This method can be called only after creating a virtual drive, and it cannot be called within events.

Virtual Drives, Media, and Mounting Points

In the FUSE component, a mount point is specified as a parameter of the Mount method. Mounting includes both creation of a drive (virtual device) and mounting a media into this device.

The information below applies to the CBFS component.

When applications call the CreateStorage method, a virtual drive is created. Virtual drives are created without any "media" in them (like a CD drive without a CD inserted), and without any mounting points (drive letters, UNC paths, etc.).

After creating a virtual drive, applications should call MountMedia to "insert" virtual storage media into the virtual drive. This call will cause the component's events to start firing; applications must handle these events correctly, or the MountMedia call will fail.

Once media has been mounted in the virtual drive, applications should use the AddMountingPoint method to add one or more mounting points for the virtual drive. These mounting points make the virtual drive, visible to the system and other applications, allowing them to start accessing the contents of the CBFS-based virtual filesystem.

Note that applications can technically call AddMountingPoint before MountMedia (except for plug-and-play virtual drives with non-removable media; see StorageType), but any attempts to access a virtual drive with no media mounted will result in a "no media" error.

NotifyDirectoryChange Method (CBFS Component)

This method notifies the OS that a file or directory has changed.

Syntax

• C#
• VB.NET

public bool NotifyDirectoryChange(string fileName, int action, string newFileName, bool wait);

Public Function NotifyDirectoryChange(ByVal FileName As String, ByVal Action As Integer, ByVal NewFileName As String, ByVal Wait As Boolean) As Boolean

Remarks

If a file or directory is modified by some means external to the virtual filesystem, this method should be called to notify the OS. Doing so prompts the OS to make any requests necessary to obtain the most up-to-date information, which in turn fires the relevant component events. This method returns either true or false to indicate whether it executed successfully.

Applications must be careful to call this method only when some changes have occurred that the OS has no possibility of detecting on its own. Said another way, applications should not call this method to notify the OS of changes made by invoking filesystem APIs on files or directories in the virtual filesystem; such changes are inherently visible to OS.

For further clarity, the following examples describe scenarios in which NotifyDirectoryChange should and should not be called:

• DO call NotifyDirectoryChange if, for example, the application is in charge of mapping the contents of some database to its virtual filesystem, and an external process changes the database's contents directly. The OS only knows about the filesystem, it does not know or care about the database contents; thus, the application must notify it that "something has changed".
• DO NOT call NotifyDirectoryChange if, for example, the application has created a virtual drive Z:, and either it or some other process makes a filesystem call against the virtual drive's contents; for example, DeleteFile("Z:\SomeFile.txt"). The OS detects such a change automatically because it was made through the filesystem APIs.

FileName specifies the path to the file or directory (in the virtual drive) that has changed. This path must not include a mounting point name.

Several files or directories may be referenced in this parameter at once. To specify the exact names, join the paths with CRLF (characters with codes #13 and #10) and pass the final string to FileName. The paths may reference files and directories in different parent directories.

An application also may specify the path with a mask. When passing a mask, only the filename portion of the mask may contain wildcard characters (* and ?). Such mask will denote multiple entries in a single directory. The component will fire the EnumerateDirectory event with the specified mask to collect the names of files and subdirectories, next they will be reported as changed.

Note: When the EnumerateDirectory event is fired, its HandleInfo, DirectoryContext, and HandleContext parameters will be empty because no system-initiated enumeration takes place and the directory is not opened.

Action specifies the type of change so that the OS knows what kind of information it needs to request. Possible values are as follows:

NewFileName specifies the new path/name of the file or directory (in the virtual drive) if the rename operation was performed. In other cases, the value is ignored.

Wait specifies whether this method should wait until the OS has finished making all of the requests necessary to handle the notification sent by this method. Passing true will cause this method to block until all requests are complete. Passing false will cause it to send the notification to the OS and return immediately, letting the OS make the necessary requests in the background. In the latter case, this method returns false.

Note: This method can be called only when Active is true. It may be called both within and outside of events; when called within an event, the Wait parameter is ignored and is assumed to be set to false.

If this method encounters any issues during its execution, it throws an exception.

RegisterIcon Method (CBFS Component)

Registers an icon that can be displayed as an overlay on the virtual drive in Windows Explorer (Windows only).

Syntax

• C#
• VB.NET

public bool RegisterIcon(string iconPath, string productGUID, string iconId);

Public Function RegisterIcon(ByVal IconPath As String, ByVal ProductGUID As String, ByVal IconId As String) As Boolean

Remarks

This method registers an icon in the file specified by IconPath so that it can later be used to display an overlay on the virtual drive in Windows Explorer. If the system must be rebooted before the icon can be used, this method returns true, otherwise it returns false.

Please note that this method only registers overlay icons; Applications should call the SetIcon and ResetIcon methods to select an icon for display. Please refer to the Custom Drive Icons topic for more information.

IconPath must be the full path and file name of the .ico file whose icon should be registered. The file must exist and remain available in order for the icon to be used until the icon is unregistered using UnregisterIcon.

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

The GUID must be specified in so-called "Registry Format" (e.g., "{1FAD0EF2-9A03-4B87-B4BC-645B7035ED90}") with curly braces included.

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
• GetModuleVersion
• RegisterIcon
• UnregisterIcon
• Initialize

IconId specifies an identifier that can later be passed to the SetIcon and UnregisterIcon methods. Each registered icon should have a unique IconId value; if a value is passed that is already in use, the existing icon will be removed (by calling UnregisterIcon internally) before the new one is registered.

This method is available in both the component API and the Installer DLL included with the product; please refer to the Driver Installation topic for more information about the latter. The Helper DLL must be installed in order for this method to function correctly. Applications can check to see whether the Helper DLL is installed using the GetModuleVersion method, and install it using the Install method if necessary.

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.

ReleaseUnusedFiles Method (CBFS Component)

This method instructs the OS to release any files kept open by the cache manager.

Syntax

• C#
• VB.NET

public bool ReleaseUnusedFiles();

Public Function ReleaseUnusedFiles() As Boolean

Remarks

This method instructs the OS to release any files that the system cache manager has kept open, and returns either true or false to indicate whether the files were released successfully. Having the OS release open files can be useful in situations in which operations need to be performed while the filesystem is not in use.

Note: The OS may open additional files during the execution of this method. To guard against this, it is recommended that application use a critical section (or other synchronization object) when calling this method, and use the same one in the OpenFile event handler. Such an approach ensures that the cache manager has no files open after calling this method.

Note: This method can be called only when Active is true. It may be called both within and outside of events; when called within an event, it is executed asynchronously on another thread (causing the call to return immediately, and an ERROR_IO_PENDING result code to be reported to the OS).

RemoveDeniedProcess Method (CBFS Component)

Removes a rule that prevents a process from accessing the virtual drive.

Syntax

• C#
• VB.NET

public void RemoveDeniedProcess(string processFileName, int processId);

Public Sub RemoveDeniedProcess(ByVal ProcessFileName As String, ByVal ProcessId As Integer)

Remarks

When the ProcessRestrictionsEnabled property is enabled, this method can be used to remove an access rule previously added with the AddDeniedProcess method.

Pass the same values for ProcessFileName and ProcessId as were used to add the rule when AddDeniedProcess was called previously. Please refer to that method's documentation for more information.

Note: This method can be called only when Active is true, and it cannot be called within events.

The methods and properties related to process access lists are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of process access information occurs in a thread-safe manner.

RemoveGrantedProcess Method (CBFS Component)

Removes a rule that allows a process to access the virtual drive.

Syntax

• C#
• VB.NET

public void RemoveGrantedProcess(string processFileName, int processId);

Public Sub RemoveGrantedProcess(ByVal ProcessFileName As String, ByVal ProcessId As Integer)

Remarks

When the ProcessRestrictionsEnabled property is enabled, this method can be used to remove an access rule previously added with the AddGrantedProcess method.

Pass the same values for ProcessFileName and ProcessId as were used to add the rule when AddGrantedProcess was called previously. Please refer to that method's documentation for more information.

Note: This method can be called only when Active is true, and it cannot be called within events.

The methods and properties related to process access lists are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of process access information occurs in a thread-safe manner.

RemoveMountingPoint Method (CBFS Component)

Removes a mounting point for the virtual drive.

Syntax

• C#
• VB.NET

public void RemoveMountingPoint(int index, string mountingPoint, int flags, long authenticationId);

Public Sub RemoveMountingPoint(ByVal Index As Integer, ByVal MountingPoint As String, ByVal Flags As Integer, ByVal AuthenticationId As Long)

Remarks

This method removes a previously-created mounting point for the virtual drive.

Index must be set to the index of an item in the MountingPoints collection property, or to -1 to remove an item based on the other method parameters.

If Index is -1, then the same values must be passed for MountingPoint, Flags, AuthenticationId as were used to add the mounting point when AddMountingPoint was called previously. Please refer to that method's documentation for more information. (If Index is not -1, these parameters are ignored.)

The sgSTGMPDRIVELETTERNOTIFYASYNC; flag may be passed in Flags to send notifications about removal of the mounting point asynchronously. Do not use this flag if the process quits right after a call to this method because asynchronous delivery involves a secondary thread, which will be terminated when the process quits.

To remove a virtual drive, created in a container from the host, set the container's Id via the DockerContainerId configuration setting prior to calling RemoveMountingPoint.

Note: This method cannot be called within events.

The methods and properties related to mounting points are not intended to be used from multiple threads at once. Applications that wish to use said methods and properties from multiple threads are responsible for employing proper thread synchronization techniques to ensure that manipulation and enumeration of mounting points occurs in a thread-safe manner.

ResetIcon Method (CBFS Component)

Resets the virtual drive's icon back to default by deselecting the active overlay icon (Windows only).

Syntax

• C#
• VB.NET

public void ResetIcon();

Public Sub ResetIcon()

Remarks

This method deselects the overlay icon currently in use, thus resetting the virtual drive's icon back to its default state (i.e., displayed without any overlay icons).

Please refer to the SetIcon method, as well as the Custom Drive Icons topic, for more information.

The Helper DLL must be installed in order for this method to function correctly. Applications can check to see whether the Helper DLL is installed using the GetModuleVersion method, and install it using the Install method if necessary.

Note: This method can be called only after creating a virtual drive, and it cannot be called within events.

ResetTimeout Method (CBFS Component)

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

Syntax

• C#
• VB.NET

public bool ResetTimeout(int timeout);

Public Function ResetTimeout(ByVal Timeout As Integer) As Boolean

Remarks

When event timeouts are being enforced, this method can be called within an event handler to inform the component 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 cancel the underlying OS request. 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 property is set to false), 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.

RouteToFile Method (CBFS Component)

This method instructs the component to route future requests directly to a given file.

Syntax

• C#
• VB.NET

public bool RouteToFile(long fileInfo, string fileName, int flags);

Public Function RouteToFile(ByVal FileInfo As Long, ByVal FileName As String, ByVal Flags As Integer) As Boolean

Remarks

This method can be called from within the CreateFile or OpenFile event to instruct the component to route any future requests against the file specified by FileInfo directly to the file at the path specified by FileName instead of firing the corresponding events. The Flags parameter is used to specify which kinds of requests should not be routed automatically (see below).

Pass the value obtained from the CreateFile or OpenFile event's FileInfo parameter for this method's FileInfo parameter.

This method returns either true or false to indicate whether routing was set up successfully. If, after this method is called successfully, the application later wishes for routing to cease, it may do one of the following:

• Call the NotifyDirectoryChange method, passing CBFS_NOTIFY_FLAG_METADATA_MODIFIED for its Action parameter, and the same FileName value as received in the original CreateFile or OpenFile event.
• Disable the metadata cache entirely using the MetadataCacheEnabled property.

The Flags value should be created by ORing together zero or more of the following flags:

Note: This method can be called only within the CreateFile and OpenFile event handlers.

SetIcon Method (CBFS Component)

Selects a registered overlay icon for display on the virtual drive in Windows Explorer (Windows only).

Syntax

• C#
• VB.NET

public void SetIcon(string iconId);

Public Sub SetIcon(ByVal IconId As String)

Remarks

This method selects the overlay icon specified by IconId for display, causing it to be shown on the virtual drive in Windows Explorer. The desired icon must have already been registered using the RegisterIcon method, and the value passed for IconId must match the one passed RegisterIcon at that time.

To switch to a different overlay icon later, call this method again with a different IconId. To reset the virtual drive's icon back to its default state (i.e., displayed without any overlay icons), call the ResetIcon method. Please refer to the Custom Drive Icons topic for more information.

The Helper DLL must be installed in order for this method to function correctly. Applications can check to see whether the Helper DLL is installed using the GetModuleVersion method, and install it using the Install method if necessary.

Note: This method can be called only after creating a virtual drive, and it cannot be called within events. Also, note that the effects of this method only last until the virtual drive is destroyed; applications that always want to have some overlay icon displayed must call this method each time the virtual drive is created.

ShutdownSystem Method (CBFS Component)

Shuts down or reboots the operating system.

Syntax

• C#
• VB.NET

public bool ShutdownSystem(string shutdownPrompt, int timeout, bool forceCloseApps, bool reboot);

Public Function ShutdownSystem(ByVal ShutdownPrompt As String, ByVal Timeout As Integer, ByVal ForceCloseApps As Boolean, ByVal Reboot As Boolean) As Boolean

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 component 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.

Uninstall Method (CBFS Component)

Uninstalls the product's system drivers and/or helper DLL (Windows only).

Syntax

• C#
• VB.NET

public int Uninstall(string cabFileName, string productGUID, string installedPath, int flags);

Public Function Uninstall(ByVal CabFileName As String, ByVal ProductGUID As String, ByVal InstalledPath As String, ByVal Flags As Integer) As Integer

Remarks

This method is used to uninstall the product's various modules (i.e., the system drivers and Helper DLL). If the system must be rebooted to complete the uninstallation process, this method will return a non-zero value indicating which module(s) requested the reboot (see Install for possible values).

Important: To upgrade the product's modules, use only the Install method. Previously installed versions of the modules 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 product's modules should be uninstalled, and should be set by OR'ing together one or more of the following values:

This method is available in both the component 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.

UnmountMedia Method (CBFS Component)

This method unmounts media from the virtual drive.

Syntax

• C#
• VB.NET

public void UnmountMedia(bool forceUnmount);

Public Sub UnmountMedia(ByVal ForceUnmount As Boolean)

Remarks

This method unmounts the virtual storage media from the virtual drive. The virtual drive, as well as any existing mounting points, remain present.

If ForceUnmount is true, all open files are forcefully closed. If ForceUnmount is false and open files or directories are detected, this method throws an exception.

This method must not be called for plug-and-play virtual drives with nonremovable media (see StorageType); attempting to do so will cause the call will fail with an "access denied" error.

Note: This method can be called only after creating a virtual drive, and it cannot be called within events.

UnregisterIcon Method (CBFS Component)

Unregisters an existing overlay icon (Windows only).

Syntax

• C#
• VB.NET

public bool UnregisterIcon(string productGUID, string iconId);

Public Function UnregisterIcon(ByVal ProductGUID As String, ByVal IconId As String) As Boolean

Remarks

This method unregisters the overlay icon identified by IconId. If the system must be rebooted to completely remove the icon, this method returns true, otherwise it returns false.

The same values must be passed for the ProductGUID and IconId parameters as were passed when RegisterIcon was called; please refer to its documentation, as well as the Custom Drive Icons topic, for more information.

This method is available in both the component API and the Installer DLL included with the product; please refer to the Driver Installation topic for more information about the latter. The Helper DLL must be installed in order for this method to function correctly. Applications can check to see whether the Helper DLL is installed using the GetModuleVersion method, and install it using the Install method if necessary.

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.

CanFileBeDeleted Event (CBFS Component)

This event fires when the driver needs to know whether a file or directory can be deleted.

Syntax

• C#
• VB.NET

public event OnCanFileBeDeletedHandler OnCanFileBeDeleted;

public delegate void OnCanFileBeDeletedHandler(object sender, CbfsCanFileBeDeletedEventArgs e);

public class CbfsCanFileBeDeletedEventArgs : EventArgs {
  public string FileName { get; }
  public long HandleInfo { get; }
  public IntPtr FileContext { get; set; }
  public IntPtr HandleContext { get; set; }
  public bool CanBeDeleted { get; set; }
  public int ResultCode { get; set; }
}

Public Event OnCanFileBeDeleted As OnCanFileBeDeletedHandler

Public Delegate Sub OnCanFileBeDeletedHandler(sender As Object, e As CbfsCanFileBeDeletedEventArgs)

Public Class CbfsCanFileBeDeletedEventArgs Inherits EventArgs
  Public ReadOnly Property FileName As String
  Public ReadOnly Property HandleInfo As Long
  Public Property FileContext As IntPtr
  Public Property HandleContext As IntPtr
  Public Property CanBeDeleted As Boolean
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the driver needs to know whether the file or directory specified by FileName can be deleted.

To handle this event properly, applications must set the CanBeDeleted parameter appropriately.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

Note: The firing of this event does not necessarily mean the specified file or directory will be deleted if CanBeDeleted is set to true. It means only that the OS needs to know whether or not it can be deleted.

The HandleInfo parameter carries a handle to an object with information about the file handle. While within the event handler, it can be used to call any of the following methods: GetHandleCreatorProcessId, GetHandleCreatorProcessName, GetHandleCreatorThreadId, or GetHandleCreatorToken.

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 Reporting and Handling topic for more information.

CleanupFile Event (CBFS Component)

This event fires when the OS needs to clean up a file.

Syntax

• C#
• VB.NET

public event OnCleanupFileHandler OnCleanupFile;

public delegate void OnCleanupFileHandler(object sender, CbfsCleanupFileEventArgs e);

public class CbfsCleanupFileEventArgs : EventArgs {
  public string FileName { get; }
  public long HandleInfo { get; }
  public IntPtr FileContext { get; set; }
  public IntPtr HandleContext { get; set; }
  public int ResultCode { get; set; }
}

Public Event OnCleanupFile As OnCleanupFileHandler

Public Delegate Sub OnCleanupFileHandler(sender As Object, e As CbfsCleanupFileEventArgs)

Public Class CbfsCleanupFileEventArgs Inherits EventArgs
  Public ReadOnly Property FileName As String
  Public ReadOnly Property HandleInfo As Long
  Public Property FileContext As IntPtr
  Public Property HandleContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the OS needs to close a handle to the currently open file specified by FileName. This event differs from CloseFile in that CleanupFile fires immediately when an open handle to the specified file is closed by a process, whereas CloseFile may be fired much later when the OS itself decides that the file can be formally closed. Similar to CloseFile, however, this event will fire only for the last handle to a file if the FireAllOpenCloseEvents property is disabled.

Other events may fire for the file handle in the time between when this event fires and when the CloseFile event fires. For example, system components such as the memory manager or cache manager may cause the ReadFile and WriteFile events to fire.

This event is optional; it is provided to give applications a chance to, for example, free up resources associated with a file before it's formally closed.

When the FireAllOpenCloseEvents is set to false, this event is fired each time the file is closed by the application. When the file is opened and closed by some process multiple times consequently, the event handler can end up being called multiple times seemingly without a match with the OpenFile and CloseFile . However, such behavior is correct. The exact order of Open/Cleanup/Close events cannot be guaranteed because of the way Windows closes files.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

The HandleInfo parameter carries a handle to an object with information about the file handle. While within the event handler, it can be used to call any of the following methods: GetHandleCreatorProcessId, GetHandleCreatorProcessName, GetHandleCreatorThreadId, or GetHandleCreatorToken.

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 Reporting and Handling topic for more information.

CloseDirectoryEnumeration Event (CBFS Component)

This event fires when the OS is finished enumerating a directory's contents.

Syntax

• C#
• VB.NET

public event OnCloseDirectoryEnumerationHandler OnCloseDirectoryEnumeration;

public delegate void OnCloseDirectoryEnumerationHandler(object sender, CbfsCloseDirectoryEnumerationEventArgs e);

public class CbfsCloseDirectoryEnumerationEventArgs : EventArgs {
  public string DirectoryName { get; }
  public IntPtr DirectoryContext { get; set; }
  public IntPtr EnumerationContext { get; }
  public int ResultCode { get; set; }
}

Public Event OnCloseDirectoryEnumeration As OnCloseDirectoryEnumerationHandler

Public Delegate Sub OnCloseDirectoryEnumerationHandler(sender As Object, e As CbfsCloseDirectoryEnumerationEventArgs)

Public Class CbfsCloseDirectoryEnumerationEventArgs Inherits EventArgs
  Public ReadOnly Property DirectoryName As String
  Public Property DirectoryContext As IntPtr
  Public ReadOnly Property EnumerationContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the OS is finished enumerating the contents of the directory specified by DirectoryName.

To handle this event properly, applications must release any resources that were allocated for/by the directory enumeration in earlier EnumerateDirectory events.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

The DirectoryContext and EnumerationContext parameters are placeholders for application-defined data associated with the directory and enumeration, respectively. Please refer to the Contexts topic for more information about them.

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 Reporting and Handling topic for more information.

CloseFile Event (CBFS Component)

This event fires when the OS needs to close a file.

Syntax

• C#
• VB.NET

public event OnCloseFileHandler OnCloseFile;

public delegate void OnCloseFileHandler(object sender, CbfsCloseFileEventArgs e);

public class CbfsCloseFileEventArgs : EventArgs {
  public string FileName { get; }
  public bool PendingDeletion { get; }
  public long HandleInfo { get; }
  public IntPtr FileContext { get; set; }
  public IntPtr HandleContext { get; set; }
  public int ResultCode { get; set; }
}

Public Event OnCloseFile As OnCloseFileHandler

Public Delegate Sub OnCloseFileHandler(sender As Object, e As CbfsCloseFileEventArgs)

Public Class CbfsCloseFileEventArgs Inherits EventArgs
  Public ReadOnly Property FileName As String
  Public ReadOnly Property PendingDeletion As Boolean
  Public ReadOnly Property HandleInfo As Long
  Public Property FileContext As IntPtr
  Public Property HandleContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the OS needs to close the file specified by FileName. If the FireAllOpenCloseEvents property is disabled, this event will fire only after the last handle to the specified file is closed.

To handle this event properly, applications can (if necessary/applicable) check to see if any other handles are open for the file, and if not, close whatever backend resources are currently open for it.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

The PendingDeletion parameter indicates whether the file should be deleted; if it's true, the DeleteFile event will fire immediately after this event. The application may delete the file from either event handler.

If an application uses some object to store user context, uses FileContext to store the reference to this object, and deletes an object referenced in FileContext, the pointer stored in FileContext becomes invalid. In this scenario, if the PendingDeletion parameter is true, the DeleteFile event will fire with the invalid value in its FileContext parameter. The solution to this issue is to inspect the value of the DeleteFile parameter and if it is true, postpone deletion of the object referenced in FileContext until the DeleteFile event. Alternatively, an event handler may set FileContext to an empty value, in which case, a DeleteFile event handler will receive that empty value as a file context.

The HandleInfo parameter carries a handle to an object with information about the file handle. While within the event handler, it can be used to call any of the following methods: GetHandleCreatorProcessId, GetHandleCreatorProcessName, GetHandleCreatorThreadId, or GetHandleCreatorToken.

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 Reporting and Handling topic for more information.

Note: The OS sends a file close request asynchronously, which is later than a process closes its handle(s) to the opened file. Because of this, the result code returned by the event handler does not get back to the process that closed the file handle.

CloseHardLinksEnumeration Event (CBFS Component)

This event fires when the OS is finished enumerating a file's hard links.

Syntax

• C#
• VB.NET

public event OnCloseHardLinksEnumerationHandler OnCloseHardLinksEnumeration;

public delegate void OnCloseHardLinksEnumerationHandler(object sender, CbfsCloseHardLinksEnumerationEventArgs e);

public class CbfsCloseHardLinksEnumerationEventArgs : EventArgs {
  public string FileName { get; }
  public long HandleInfo { get; }
  public IntPtr FileContext { get; set; }
  public IntPtr HandleContext { get; set; }
  public IntPtr EnumerationContext { get; }
  public int ResultCode { get; set; }
}

Public Event OnCloseHardLinksEnumeration As OnCloseHardLinksEnumerationHandler

Public Delegate Sub OnCloseHardLinksEnumerationHandler(sender As Object, e As CbfsCloseHardLinksEnumerationEventArgs)

Public Class CbfsCloseHardLinksEnumerationEventArgs Inherits EventArgs
  Public ReadOnly Property FileName As String
  Public ReadOnly Property HandleInfo As Long
  Public Property FileContext As IntPtr
  Public Property HandleContext As IntPtr
  Public ReadOnly Property EnumerationContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the OS is finished enumerating the hard links of the file specified by FileName.

This event needs to be handled only if the UseHardLinks property is enabled. To handle this event properly, applications must release any resources that were allocated for/by the hard link enumeration in earlier EnumerateHardLinks events.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

The HandleInfo parameter carries a handle to an object with information about the file handle. While within the event handler, it can be used to call any of the following methods: GetHandleCreatorProcessId, GetHandleCreatorProcessName, GetHandleCreatorThreadId, or GetHandleCreatorToken.

The FileContext, HandleContext, and EnumerationContext parameters are placeholders for application-defined data associated with the file, specific handle, and enumeration, 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 Reporting and Handling topic for more information.

CloseNamedStreamsEnumeration Event (CBFS Component)

This event fires when the OS is finished enumerating a file's named streams.

Syntax

• C#
• VB.NET

public event OnCloseNamedStreamsEnumerationHandler OnCloseNamedStreamsEnumeration;

public delegate void OnCloseNamedStreamsEnumerationHandler(object sender, CbfsCloseNamedStreamsEnumerationEventArgs e);

public class CbfsCloseNamedStreamsEnumerationEventArgs : EventArgs {
  public string FileName { get; }
  public long HandleInfo { get; }
  public IntPtr FileContext { get; set; }
  public IntPtr HandleContext { get; set; }
  public IntPtr EnumerationContext { get; }
  public int ResultCode { get; set; }
}

Public Event OnCloseNamedStreamsEnumeration As OnCloseNamedStreamsEnumerationHandler

Public Delegate Sub OnCloseNamedStreamsEnumerationHandler(sender As Object, e As CbfsCloseNamedStreamsEnumerationEventArgs)

Public Class CbfsCloseNamedStreamsEnumerationEventArgs Inherits EventArgs
  Public ReadOnly Property FileName As String
  Public ReadOnly Property HandleInfo As Long
  Public Property FileContext As IntPtr
  Public Property HandleContext As IntPtr
  Public ReadOnly Property EnumerationContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the OS is finished enumerating the named streams of the file specified by FileName.

This event needs to be handled only if the UseAlternateDataStreams property is enabled. To handle this event properly, applications must release any resources that were allocated for/by the named stream enumeration in earlier EnumerateNamedStreams events.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

The HandleInfo parameter carries a handle to an object with information about the file handle. While within the event handler, it can be used to call any of the following methods: GetHandleCreatorProcessId, GetHandleCreatorProcessName, GetHandleCreatorThreadId, or GetHandleCreatorToken.

The FileContext, HandleContext, and EnumerationContext parameters are placeholders for application-defined data associated with the file, specific handle, and enumeration, 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 Reporting and Handling topic for more information.

CloseQuotasEnumeration Event (CBFS Component)

This event fires when the OS is finished reading or updating quota information.

Syntax

• C#
• VB.NET

public event OnCloseQuotasEnumerationHandler OnCloseQuotasEnumeration;

public delegate void OnCloseQuotasEnumerationHandler(object sender, CbfsCloseQuotasEnumerationEventArgs e);

public class CbfsCloseQuotasEnumerationEventArgs : EventArgs {
  public IntPtr EnumerationContext { get; }
  public int ResultCode { get; set; }
}

Public Event OnCloseQuotasEnumeration As OnCloseQuotasEnumerationHandler

Public Delegate Sub OnCloseQuotasEnumerationHandler(sender As Object, e As CbfsCloseQuotasEnumerationEventArgs)

Public Class CbfsCloseQuotasEnumerationEventArgs Inherits EventArgs
  Public ReadOnly Property EnumerationContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the OS is finished reading or updating quota information.

This event only needs to be handled if the UseDiskQuotas property is enabled. To handle this event properly, applications must release any resources that were allocated for/by the quota enumeration in earlier QueryQuotas or SetQuotas events.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

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 Reporting and Handling topic for more information.

CreateFile Event (CBFS Component)

This event fires when the OS wants to create a file or directory.

Syntax

• C#
• VB.NET

public event OnCreateFileHandler OnCreateFile;

public delegate void OnCreateFileHandler(object sender, CbfsCreateFileEventArgs e);

public class CbfsCreateFileEventArgs : EventArgs {
  public string FileName { get; }
  public int DesiredAccess { get; }
  public int Attributes { get; }
  public int ShareMode { get; }
  public int NTCreateDisposition { get; }
  public int NTDesiredAccess { get; }
  public long FileInfo { get; }
  public long HandleInfo { get; }
  public IntPtr FileContext { get; set; }
  public IntPtr HandleContext { get; set; }
  public int ResultCode { get; set; }
}

Public Event OnCreateFile As OnCreateFileHandler

Public Delegate Sub OnCreateFileHandler(sender As Object, e As CbfsCreateFileEventArgs)

Public Class CbfsCreateFileEventArgs Inherits EventArgs
  Public ReadOnly Property FileName As String
  Public ReadOnly Property DesiredAccess As Integer
  Public ReadOnly Property Attributes As Integer
  Public ReadOnly Property ShareMode As Integer
  Public ReadOnly Property NTCreateDisposition As Integer
  Public ReadOnly Property NTDesiredAccess As Integer
  Public ReadOnly Property FileInfo As Long
  Public ReadOnly Property HandleInfo As Long
  Public Property FileContext As IntPtr
  Public Property HandleContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the OS wants to create a file or directory named FileName using the creation options reflected in Attributes. If the FireAllOpenCloseEvents property is disabled, this event will fire only when the first handle to the specified file or directory is opened. 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;

If the UseAlternateDataStreams property is enabled, this event also fires any time the OS wants to create a named datastream in a file. Such requests are distinguished by the presence of a colon (:) in the FileName value; the text before the colon is the name of the file itself, and the text after the colon is the name of the stream to create.

To handle this event properly, applications should (at least) perform any actions needed to create and/or open the requested file, directory, or named stream in their backend storage. Applications are also responsible for validating the access rights of the process that initiated the request before performing the requested operation; please refer to the Security Checks topic for more information.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

If an existing local file corresponds to the virtual one specified by FileName, the application may call RouteToFile to have the component route future requests directly to that file. This event's FileInfo value must be passed to RouteToFile to request routing to be configured successfully.

In certain cases, a request to open an existing file may unexpectedly be surfaced through this event instead of through OpenFile. Normally, this will not happen, as the OS already knows which files exist (based on information obtained via GetFileInfo/EnumerateDirectory) before it sends the create or open request. If, however, a file is created externally, a rare condition may occur in which said file exists but is not known to the OS or the virtual filesystem yet. In such cases, the application must decide how to handle the unexpected CreateFile event; it can either truncate the existing file, or return the ERROR_ALREADY_EXISTS error code via ResultCode.

If an original call to CreateFile() or a similar Windows API function included security attributes, the SetFileSecurity event will immediately follow this CreateFile event, and the mentioned security attributes will be passed via SetFileSecurity.

The DesiredAccess parameter specifies the access mode desired by the process that initiated the request; it may contain one or more of the following access flags:

This value may differ from the one originally passed to the OS; the component alters it in the following cases:

• The DELETE flag is added if the requested CreateDisposition is FILE_SUPERSEDE.
• The FILE_WRITE_DATA, FILE_WRITE_EA, and FILE_WRITE_ATTRIBUTES flags are added if the requested CreateDisposition is FILE_OVERWRITE or FILE_OVERWRITE_IF.

Note: These values are in NT format; that is, as expected by the Windows API's ZwCreateFile function.

The Attributes parameter contains file attributes; it may contain one or more of the following attributes:

Attributes specifies both the attributes and create/open options for the new file. Some options, such as FILE_FLAG_SEQUENTIAL_SCAN, FILE_FLAG_WRITE_THROUGH, and FILE_FLAG_RANDOM_ACCESS, may be useful for applications that wish to fine-tune their performance. For example, such information could be used to decide whether it is necessary to locally cache some amount of data that is stored remotely.

The ShareMode parameter specifies the access sharing mode desired by the process that initiated the request; it may contain zero or more of the following share mode flags:

Please refer to the Windows API's ZwCreateFile function for detailed information about possible values for the DesiredAccess, Attributes, ShareMode, NTCreateDisposition, and NTDesiredAccess parameters.

The FileInfo parameter carries a handle to an object with information about the file. As mentioned earlier, this value should be used if the application chooses to call the RouteToFile method.

The HandleInfo parameter carries a handle to an object with information about the file handle. While within the event handler, it can be used to call any of the following methods: GetHandleCreatorProcessId, GetHandleCreatorProcessName, GetHandleCreatorThreadId, or GetHandleCreatorToken.

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 Reporting and Handling topic for more information.

CreateHardLink Event (CBFS Component)

This event fires when the OS wants to create a new hard link to an existing file.

Syntax

• C#
• VB.NET

public event OnCreateHardLinkHandler OnCreateHardLink;

public delegate void OnCreateHardLinkHandler(object sender, CbfsCreateHardLinkEventArgs e);

public class CbfsCreateHardLinkEventArgs : EventArgs {
  public string FileName { get; }
  public string LinkName { get; }
  public long HandleInfo { get; }
  public IntPtr FileContext { get; set; }
  public IntPtr HandleContext { get; set; }
  public int ResultCode { get; set; }
}

Public Event OnCreateHardLink As OnCreateHardLinkHandler

Public Delegate Sub OnCreateHardLinkHandler(sender As Object, e As CbfsCreateHardLinkEventArgs)

Public Class CbfsCreateHardLinkEventArgs Inherits EventArgs
  Public ReadOnly Property FileName As String
  Public ReadOnly Property LinkName As String
  Public ReadOnly Property HandleInfo As Long
  Public Property FileContext As IntPtr
  Public Property HandleContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the OS wants to create a new hard link that points to the existing file specified by FileName. The LinkName parameter specifies the absolute path (including filename) of the link to be created.

This event needs to be handled only if the UseHardLinks property is enabled. To handle this event properly, applications should perform any actions needed to create an additional hard link to the specified file in their backend storage.

Please refer to the Hard Links topic for more information.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

The HandleInfo parameter carries a handle to an object with information about the file handle. While within the event handler, it can be used to call any of the following methods: GetHandleCreatorProcessId, GetHandleCreatorProcessName, GetHandleCreatorThreadId, or GetHandleCreatorToken.

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 Reporting and Handling topic for more information.

DeleteFile Event (CBFS Component)

This event fires when the OS needs to delete a file or directory.

Syntax

• C#
• VB.NET

public event OnDeleteFileHandler OnDeleteFile;

public delegate void OnDeleteFileHandler(object sender, CbfsDeleteFileEventArgs e);

public class CbfsDeleteFileEventArgs : EventArgs {
  public string FileName { get; }
  public IntPtr FileContext { get; set; }
  public int ResultCode { get; set; }
}

Public Event OnDeleteFile As OnDeleteFileHandler

Public Delegate Sub OnDeleteFileHandler(sender As Object, e As CbfsDeleteFileEventArgs)

Public Class CbfsDeleteFileEventArgs Inherits EventArgs
  Public ReadOnly Property FileName As String
  Public Property FileContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the OS has decided to delete the file or directory specified by FileName.

To handle this event properly, applications must perform any actions needed to delete the specified file or directory from their backend storage. If the UseHardLinks property is enabled, a file's data should be deleted only when its last hard link has been deleted; please refer to the Hard Links topic for more information.

Note:

• A deletion cannot be canceled from this event; applications that wish to prevent a deletion must do so via the CanFileBeDeleted event.
• This event fires immediately after the last CloseFile event. If the application disposes of the FileContext in the CloseFile event handler, it will be invalid when this event fires. The CloseFile event includes a DeleteFile parameter that helps address this situation.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

The FileContext parameter is a placeholder for application-defined data associated with the file. 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 Reporting and Handling topic for more information.

DeleteReparsePoint Event (CBFS Component)

This event fires when the OS wants to delete a reparse point from a file or directory.

Syntax

• C#
• VB.NET

public event OnDeleteReparsePointHandler OnDeleteReparsePoint;

public delegate void OnDeleteReparsePointHandler(object sender, CbfsDeleteReparsePointEventArgs e);

public class CbfsDeleteReparsePointEventArgs : EventArgs {
  public string FileName { get; }
  public IntPtr ReparseBuffer { get; }
  public int ReparseBufferLength { get; }
  public long HandleInfo { get; }
  public IntPtr FileContext { get; set; }
  public IntPtr HandleContext { get; set; }
  public int ResultCode { get; set; }
}

Public Event OnDeleteReparsePoint As OnDeleteReparsePointHandler

Public Delegate Sub OnDeleteReparsePointHandler(sender As Object, e As CbfsDeleteReparsePointEventArgs)

Public Class CbfsDeleteReparsePointEventArgs Inherits EventArgs
  Public ReadOnly Property FileName As String
  Public ReadOnly Property ReparseBuffer As IntPtr
  Public ReadOnly Property ReparseBufferLength As Integer
  Public ReadOnly Property HandleInfo As Long
  Public Property FileContext As IntPtr
  Public Property HandleContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the OS wants to delete a reparse point from the file or directory specified by FileName.

This event needs to be handled only if the UseReparsePoints property is enabled.

Note: NFS sharing makes use of reparse points.

To handle this event properly, applications must delete the reparse point data (and tag) stored previously for the specified file or directory. Any other actions taken in an earlier SetReparsePoint event also should be reversed appropriately.

Note: The file or directory itself should not be deleted.

Please refer to the Reparse Points topic for more information.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

The existing reparse point data are provided in this event as a convenience for use-cases that wish to utilize it.

The HandleInfo parameter carries a handle to an object with information about the file handle. While within the event handler, it can be used to call any of the following methods: GetHandleCreatorProcessId, GetHandleCreatorProcessName, GetHandleCreatorThreadId, or GetHandleCreatorToken.

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.

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

Ejected Event (CBFS Component)

Fires when the media and virtual drive have been ejected (Windows only).

Syntax

• C#
• VB.NET

public event OnEjectedHandler OnEjected;

public delegate void OnEjectedHandler(object sender, CbfsEjectedEventArgs e);

public class CbfsEjectedEventArgs : EventArgs {
  public int ResultCode { get; set; }
}

Public Event OnEjected As OnEjectedHandler

Public Delegate Sub OnEjectedHandler(sender As Object, e As CbfsEjectedEventArgs)

Public Class CbfsEjectedEventArgs Inherits EventArgs
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when a user has ejected the media and virtual drive using the Eject command in Windows Explorer.

For ejection via the system notification area (tray) to work correctly, the StorageType property must be set to STGT_DISK_PNP, and the StorageCharacteristics property must include ejection-related flags.

This event is optional; it is provided to give applications a chance to, e.g., free up resources associated with the virtual drive. Since the virtual drive has already been destroyed by the time this event fires, applications must not call UnmountMedia or DeleteStorage (the latter is called automatically with its ForceUnmount parameter set to true) .

The ResultCode parameter will always be initially set to the result of a storage deletion operation. The expected value is 0. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource isn't available, security checks failed, etc.), set it to a non-zero value to report an appropriate error. Note that as ejection has already occured, this non-zero value will not have effect on the media's state. Please refer to the Error Reporting and Handling topic for more information.

EnumerateDirectory Event (CBFS Component)

This event fires when the OS wants to enumerate a directory's contents.

Syntax

• C#
• VB.NET

public event OnEnumerateDirectoryHandler OnEnumerateDirectory;

public delegate void OnEnumerateDirectoryHandler(object sender, CbfsEnumerateDirectoryEventArgs e);

public class CbfsEnumerateDirectoryEventArgs : EventArgs {
  public string DirectoryName { get; }
  public string Mask { get; }
  public bool CaseSensitive { get; }
  public bool Restart { get; }
  public int RequestedInfo { get; }
  public bool FileFound { get; set; }
  public string FileName { get; set; }
  public string ShortFileName { get; set; }
  public DateTime CreationTime { get; set; }
  public DateTime LastAccessTime { get; set; }
  public DateTime LastWriteTime { get; set; }
  public DateTime ChangeTime { get; set; }
  public long Size { get; set; }
  public long AllocationSize { get; set; }
  public long FileId { get; set; }
  public long Attributes { get; set; }
  public long ReparseTag { get; set; }
  public long HandleInfo { get; }
  public IntPtr DirectoryContext { get; set; }
  public IntPtr HandleContext { get; set; }
  public IntPtr EnumerationContext { get; set; }
  public int ResultCode { get; set; }
}

Public Event OnEnumerateDirectory As OnEnumerateDirectoryHandler

Public Delegate Sub OnEnumerateDirectoryHandler(sender As Object, e As CbfsEnumerateDirectoryEventArgs)

Public Class CbfsEnumerateDirectoryEventArgs Inherits EventArgs
  Public ReadOnly Property DirectoryName As String
  Public ReadOnly Property Mask As String
  Public ReadOnly Property CaseSensitive As Boolean
  Public ReadOnly Property Restart As Boolean
  Public ReadOnly Property RequestedInfo As Integer
  Public Property FileFound As Boolean
  Public Property FileName As String
  Public Property ShortFileName As String
  Public Property CreationTime As DateTime
  Public Property LastAccessTime As DateTime
  Public Property LastWriteTime As DateTime
  Public Property ChangeTime As DateTime
  Public Property Size As Long
  Public Property AllocationSize As Long
  Public Property FileId As Long
  Public Property Attributes As Long
  Public Property ReparseTag As Long
  Public ReadOnly Property HandleInfo As Long
  Public Property DirectoryContext As IntPtr
  Public Property HandleContext As IntPtr
  Public Property EnumerationContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the OS wants to enumerate the contents of the directory specified by DirectoryName (which will have been opened via OpenFile).

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

To handle this event properly, applications must return information about each directory entry (e.g., file, subdirectory, link) that matches the specified Mask.

For each matching entry found, set FileFound to true, inspect the RequestedInfo parameter for the types of information required, and supply the entry's information using the following parameters:

• FileName: Set to the name of the entry (not including its path).
  • The length of the returned name must not exceed the value of the MaxFileNameLength property.
• ShortFileName: If the UseShortFileNames property is enabled, set to the short (8.3) name of the entry.
  • The short name must adhere to the 8.3 name format; please refer to the Short File Names topic for more information.
• CreationTime, LastAccessTime, LastWriteTime, ChangeTime: Set to the entry's corresponding time values, specified in UTC. Any time values not applicable to the entry can be left unchanged, or set to January 1, 1601 00:00:00 UTC.
  • Leave LastAccessTime unchanged if the SupportLastAccessTimeAttribute property is disabled.
  • Leave ChangeTime unchanged if the SupportChangeTimeAttribute property is disabled.
• Size: For file entries, set to the size of the file, in bytes; for other entries, set to 0.
• AllocationSize: For file entries, set to the number of bytes allocated locally for the file; for other entries, set to 0. The allocation size is typically a multiple of the ClusterSize.
• FileId: Set to the unique Id of the file or directory represented by the entry. Please refer to the File IDs topic for more information.
• Attributes: Set to the file or directory attributes of the entry. If the SupportCompressedAttribute property is set to true, an event handler should properly set or clear the FILE_ATTRIBUTE_COMPRESSED in the Attributes parameter.
• ReparseTag: If the UseReparsePoints property is enabled, and the entry is a reparse point, set to the reparse point's tag.
  • Ensure that the FILE_ATTRIBUTE_REPARSE_POINT attribute is included in the value supplied for the Attributes parameter.
  • The tag should have been stored when the reparse point was created (i.e., during an earlier SetReparsePoint event).
  • Please refer to the Reparse Points topic for more information.

If there are no more matching entries present, set FileFound to false and leave the above parameters unchanged. When the OS is finished with the directory enumeration, the CloseDirectoryEnumeration event will fire.

RequestedInfo: This value specifies which kinds of information the component is interested in. Use this information as a hint to save some CPU ticks. Providing unrequested information will not cause a problem, but this information will be ignored, thus wasting the time used to obtain it. The value is a combination of the following flags:

The Mask parameter specifies the filename mask that should be used to filter the results. This value may contain any combination of valid filename characters and wildcards (the * and ? characters). Alternatively, it may be an exact filename (i.e., a value without any wildcards), as some applications query file information by specifying an exact filename in an enumeration. Note: When a request for directory enumeration passes Windows network redirector, it always uses the mask * regardless of what the original mask was.

The CaseSensitive parameter indicates whether entry names should be matched against the specified Mask in a case-sensitive manner. It will always be false if the UseCaseSensitiveFileNames property is disabled.

Note: This parameter is not currently used; the search is always case-insensitive.

The Restart parameter, if true, indicates that the enumeration should be restarted from the beginning of the directory. Any previously reported entries that still exist should be reported again.

The HandleInfo parameter carries a handle to an object with information about the file handle. While within the event handler, it can be used to call any of the following methods: GetHandleCreatorProcessId, GetHandleCreatorProcessName, GetHandleCreatorThreadId, or GetHandleCreatorToken.

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.

Note: If an application calls the NotifyDirectoryChange method and passes a mask instead of a filename, the component will fire this EnumerateDirectory event to collect the names of files and subdirectories, and in this case, the HandleInfo, DirectoryContext, and HandleContext parameters will be empty.

Note: To avoid unexpected delays and slowdown, enumeration does not refresh the metadata cache or nonexistent file cache. If your data may be altered on the backend side (i.e., not through the virtual disk), your application needs to track the changes and use NotifyDirectoryChange, as needed, which will update the mentioned caches. Alternatively, you may disable either or both of the caches.

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 Reporting and Handling topic for more information.

Note: For this event, returning ERROR_FILE_INVALID has no effect.

EnumerateHardLinks Event (CBFS Component)

This event fires when the OS needs to enumerate a file's hard links.

Syntax

• C#
• VB.NET

public event OnEnumerateHardLinksHandler OnEnumerateHardLinks;

public delegate void OnEnumerateHardLinksHandler(object sender, CbfsEnumerateHardLinksEventArgs e);

public class CbfsEnumerateHardLinksEventArgs : EventArgs {
  public string FileName { get; }
  public bool LinkFound { get; set; }
  public string LinkName { get; set; }
  public long ParentId { get; set; }
  public long HandleInfo { get; }
  public IntPtr FileContext { get; set; }
  public IntPtr HandleContext { get; set; }
  public IntPtr EnumerationContext { get; set; }
  public int ResultCode { get; set; }
}

Public Event OnEnumerateHardLinks As OnEnumerateHardLinksHandler

Public Delegate Sub OnEnumerateHardLinksHandler(sender As Object, e As CbfsEnumerateHardLinksEventArgs)

Public Class CbfsEnumerateHardLinksEventArgs Inherits EventArgs
  Public ReadOnly Property FileName As String
  Public Property LinkFound As Boolean
  Public Property LinkName As String
  Public Property ParentId As Long
  Public ReadOnly Property HandleInfo As Long
  Public Property FileContext As IntPtr
  Public Property HandleContext As IntPtr
  Public Property EnumerationContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the OS needs to enumerate the hard links of the file specified by FileName (which will have been opened via OpenFile).

This event needs to be handled only if the UseHardLinks property is enabled.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

To handle this event properly, applications must return information about each of the file's hard links.

Note: A file's "primary" name (i.e., the one contained in FileName) is itself one of the hard links that must be reported; please refer to the Hard Links topic for more information.

For each hard link, set LinkFound to true and supply the hard link's information using the following parameters:

• LinkName: Set to the name of the hard link (not including its path).
  • The length of the returned name must not exceed the value of the MaxFileNameLength property.
• ParentId: Set to the unique Id of the directory the hard link resides in (this Id should not change over time). Always use 0x7FFFFFFFFFFFFFFF if the hard link resides in the root directory (\).

If there are no more hard links present, set LinkFound to false and leave the above parameters unchanged. When the OS is finished with the hard links enumeration, the CloseHardLinksEnumeration event will fire.

The HandleInfo parameter carries a handle to an object with information about the file handle. While within the event handler, it can be used to call any of the following methods: GetHandleCreatorProcessId, GetHandleCreatorProcessName, GetHandleCreatorThreadId, or GetHandleCreatorToken.

The FileContext, HandleContext, and EnumerationContext parameters are placeholders for application-defined data associated with the file, specific handle, and enumeration, 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 Reporting and Handling topic for more information.

EnumerateNamedStreams Event (CBFS Component)

This event fires when the OS needs to enumerate a file's named streams.

Syntax

• C#
• VB.NET

public event OnEnumerateNamedStreamsHandler OnEnumerateNamedStreams;

public delegate void OnEnumerateNamedStreamsHandler(object sender, CbfsEnumerateNamedStreamsEventArgs e);

public class CbfsEnumerateNamedStreamsEventArgs : EventArgs {
  public string FileName { get; }
  public bool NamedStreamFound { get; set; }
  public string StreamName { get; set; }
  public long StreamSize { get; set; }
  public long StreamAllocationSize { get; set; }
  public long HandleInfo { get; }
  public IntPtr FileContext { get; set; }
  public IntPtr HandleContext { get; set; }
  public IntPtr EnumerationContext { get; set; }
  public int ResultCode { get; set; }
}

Public Event OnEnumerateNamedStreams As OnEnumerateNamedStreamsHandler

Public Delegate Sub OnEnumerateNamedStreamsHandler(sender As Object, e As CbfsEnumerateNamedStreamsEventArgs)

Public Class CbfsEnumerateNamedStreamsEventArgs Inherits EventArgs
  Public ReadOnly Property FileName As String
  Public Property NamedStreamFound As Boolean
  Public Property StreamName As String
  Public Property StreamSize As Long
  Public Property StreamAllocationSize As Long
  Public ReadOnly Property HandleInfo As Long
  Public Property FileContext As IntPtr
  Public Property HandleContext As IntPtr
  Public Property EnumerationContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the OS needs to enumerate the named streams of the file specified by FileName (which will have been opened via OpenFile).

This event needs to be handled only if the UseAlternateDataStreams property is enabled.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

To handle this event properly, applications must return information about each of the file's named streams. For each named stream, set StreamNameFound to true and supply the named stream's information using the following parameters:

• StreamName: Set to the name of the named stream, prefixed with : (e.g. :MyStreamName). For more information about stream naming conventions, refer to Microsoft's Naming Conventions for Streams information.
  • The length of the returned name must not exceed the value of the MaxFileNameLength property.
• StreamSize: Set the size, in bytes, of the named stream's data.
• StreamAllocationSize: Set to the number of bytes allocated locally for the named stream. This is typically a multiple of the ClusterSize.

If there are no more named streams present, set StreamNameFound to false and leave the above parameters unchanged. When the OS is finished with the named streams enumeration, the CloseNamedStreamsEnumeration event will fire.

The HandleInfo parameter carries a handle to an object with information about the file handle. While within the event handler, it can be used to call any of the following methods: GetHandleCreatorProcessId, GetHandleCreatorProcessName, GetHandleCreatorThreadId, or GetHandleCreatorToken.

The FileContext, HandleContext, and EnumerationContext parameters are placeholders for application-defined data associated with the file, specific handle, and enumeration, 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 Reporting and Handling topic for more information.

Error Event (CBFS Component)

This event fires if an unhandled error occurs during an event.

Syntax

• C#
• VB.NET

public event OnErrorHandler OnError;

public delegate void OnErrorHandler(object sender, CbfsErrorEventArgs e);

public class CbfsErrorEventArgs : EventArgs {
  public int ErrorCode { get; }
  public string Description { get; }
}

Public Event OnError As OnErrorHandler

Public Delegate Sub OnErrorHandler(sender As Object, e As CbfsErrorEventArgs)

Public Class CbfsErrorEventArgs Inherits EventArgs
  Public ReadOnly Property ErrorCode As Integer
  Public ReadOnly Property Description As String
End Class

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.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

FlushFile Event (CBFS Component)

This event fires when the OS needs to flush an open file's data out to storage.

Syntax

• C#
• VB.NET

public event OnFlushFileHandler OnFlushFile;

public delegate void OnFlushFileHandler(object sender, CbfsFlushFileEventArgs e);

public class CbfsFlushFileEventArgs : EventArgs {
  public string FileName { get; }
  public IntPtr FileContext { get; }
  public int ResultCode { get; set; }
}

Public Event OnFlushFile As OnFlushFileHandler

Public Delegate Sub OnFlushFileHandler(sender As Object, e As CbfsFlushFileEventArgs)

Public Class CbfsFlushFileEventArgs Inherits EventArgs
  Public ReadOnly Property FileName As String
  Public ReadOnly Property FileContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

This event fires any time the OS needs the virtual filesystem to flush data out to storage. If the FileName parameter is nonempty, then all data related to the specified file (i.e., contents and all metadata) should be flushed. If FileName is empty, everything related to the virtual drive should be flushed.

To handle this event properly, applications must flush the requested data, writing it out to their backend storage.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

The FileContext parameter is a placeholder for application-defined data associated with the file. Please refer to the Contexts topic for more information. (Not applicable if FileName is 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 Reporting and Handling topic for more information.

Fsctl Event (CBFS Component)

This event fires when the virtual filesystem receives a nonstandard request (filesystem control code).

Syntax

• C#
• VB.NET

public event OnFsctlHandler OnFsctl;

public delegate void OnFsctlHandler(object sender, CbfsFsctlEventArgs e);

public class CbfsFsctlEventArgs : EventArgs {
  public string FileName { get; }
  public int Code { get; }
  public IntPtr InputBuffer { get; }
  public int InputBufferLength { get; }
  public IntPtr OutputBuffer { get; }
  public int OutputBufferLength { get; }
  public int BytesReturned { get; set; }
  public IntPtr FileContext { get; set; }
  public int ResultCode { get; set; }
}

Public Event OnFsctl As OnFsctlHandler

Public Delegate Sub OnFsctlHandler(sender As Object, e As CbfsFsctlEventArgs)

Public Class CbfsFsctlEventArgs Inherits EventArgs
  Public ReadOnly Property FileName As String
  Public ReadOnly Property Code As Integer
  Public ReadOnly Property InputBuffer As IntPtr
  Public ReadOnly Property InputBufferLength As Integer
  Public ReadOnly Property OutputBuffer As IntPtr
  Public ReadOnly Property OutputBufferLength As Integer
  Public Property BytesReturned As Integer
  Public Property FileContext As IntPtr
  Public Property ResultCode As Integer
End Class

Remarks

An FSCTL is a system call for filesystem-specific I/O operations as well as for other operations that cannot be expressed through regular filesystem calls. Such calls carry a control code, and the effects of the call depend entirely on how a filesystem handles that control code. A control code is composed of, among other things, a function code and flags that describe how data are passed.

CBFS Connect reserves function codes 2400-4096 for applications' use, and normally fires this event only for control codes containing a function code from that range. If, however, the HandleAllFsctls property is enabled, the component will fire this event for all FSCTLs other than those processed by CBFS Connect itself.

This event is optional. Applications that choose to implement it are free to do so in any manner they desire based on the control code received.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

An application can send a custom FSCTL by defining a control code with the following macro and then using that control code to call the Windows API's DeviceIoControl function. #define CTL_CODE( DeviceType, Function, Method, Access ) \ ( ((DeviceType) << 16) | ((Access) << 14) | ((Function) << 2) | (Method) )

• DeviceType: Must always be FILE_DEVICE_FILE_SYSTEM (9).
• Function: Must be an integer in the range 2400-4096.
• Method ("TransferType"): Specifies how data are passed between the caller and the driver. Possible values are as follows:
  • METHOD_BUFFERED (0)
  • METHOD_IN_DIRECT (1)
  • METHOD_OUT_DIRECT (2)
  • METHOD_NEITHER (3)
  For small amounts of data (1-4096 bytes), it is best to use METHOD_BUFFERED (0); otherwise, use METHOD_NEITHER (3) or one of the other values.
• Access ("RequiredAccess"): Indicates the type(s) of access the caller must request when opening a handle to the target filesystem object (i.e., the handle passed for the hDevice parameter of the DeviceIoControl function). The system's I/O manager will block the request if the caller did not open the specified handle with the required access rights. Possible values are as follows:
  • FILE_ANY_ACCESS (0) (i.e., the caller can send the FSCTL regardless of access rights)
  • FILE_READ_ACCESS (1)
  • FILE_WRITE_ACCESS (2)
  The latter two options can be ORed together to require the caller to have both read and write access.

Please refer to Microsoft's Defining I/O Control Codes article for more information.

The FileName parameter identifies the file or directory targeted by the request. It may be empty if the request is targeting the virtual drive.

The Code parameter reflects the control code received. If the specified control code is unrecognized or unsupported (either in general, or for the filesystem object specified by FileName), return the ERROR_INVALID_FUNCTION error code via ResultCode.

The InputBuffer parameter points to the memory buffer containing the data required to perform the operation. The format of this data depends on the specified Code; it may be empty. The InputBufferLength parameter specifies the length, in bytes, of InputBuffer.

The OutputBuffer parameter points to the memory buffer that receives the data returned by the operation. The format of this data depends on the specified Code; it may be empty. The OutputBufferLength parameter specifies the capacity, in bytes, of OutputBuffer; applications should set the BytesReturned parameter to the number of bytes written to OutputBuffer.

If the application needs to return more than OutputBufferLength bytes of data, it should do one of the following:

1. If OutputBuffer is too small to hold all of the data, but can hold some entries, then the application should write as much data to it as possible, set BytesReturned appropriately, and return the ERROR_MORE_DATA error code via ResultCode.
2. If OutputBuffer is too small to hold any data, then the application should set BytesReturned to 0, 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 FileContext parameter is a placeholder for application-defined data associated with the file. Please refer to the Contexts topic for more information.

Initially, the Result parameter will be set to ERROR_INVALID_FUNCTION. If an event handler processes the request in a meaningful way (i.e., the requestor will receive an expected result), the event handler should set Result to 0 or another error code that should reach the requestor. Please refer to the Error Reporting and Handling topic for more information.

GetDefaultQuotaInfo Event (CBFS Component)

This event fires when the OS needs the virtual drive's default quota information.

Syntax

• C#
• VB.NET

public event OnGetDefaultQuotaInfoHandler OnGetDefaultQuotaInfo;

public delegate void OnGetDefaultQuotaInfoHandler(object sender, CbfsGetDefaultQuotaInfoEventArgs e);

public class CbfsGetDefaultQuotaInfoEventArgs : EventArgs {
  public long DefaultQuotaThreshold { get; set; }
  public long DefaultQuotaLimit { get; set; }
  public long FileSystemControlFlags { get; set; }
  public int ResultCode { get; set; }
}

Public Event OnGetDefaultQuotaInfo As OnGetDefaultQuotaInfoHandler

Public Delegate Sub OnGetDefaultQuotaInfoHandler(sender As Object, e As CbfsGetDefaultQuotaInfoEventArgs)

Public Class CbfsGetDefaultQuotaInfoEventArgs Inherits EventArgs
  Public Property DefaultQuotaThreshold As Long
  Public Property DefaultQuotaLimit As Long
  Public Property FileSystemControlFlags As Long
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the OS needs the default quota information, set during an earlier SetDefaultQuotaInfo event, for the virtual drive.

This event needs to be handled only if the UseDiskQuotas property is enabled. To handle this event properly, applications must return the virtual drive's default quota information by setting DefaultQuotaThreshold, DefaultQuotaLimit, and FileSystemControlFlags.

IMPORTANT: Not everything is possible or allowed in the event handlers. Please see the Event Handling topic for details.

Descriptions of the DefaultQuotaThreshold, DefaultQuotaLimit, and FileSystemControlFlags parameters can be found in the Windows API's FILE_FS_CONTROL_INFORMATION structure documentation.

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 Reporting and Handling topic for more information.