NFS Class

Properties   Methods   Events   Config Settings   Errors  

This class is used to create a Network File System (NFS) server based on NFS version 4.1.

Syntax

class cbfsconnect.NFS

Remarks

This class provides a simple way to create a Network File System (NFS) server, enabling NFS clients the ability to access and share files seamlessly across a network.

Getting Started

To begin, call start_listening to start listening for incoming connections. The class will listen on the interface defined by local_host and local_port. For example:

Component.LocalHost = "localhost"; Component.LocalPort = 2049; // default Component.StartListening(); while (Component.Listening) { Component.DoEvents(); }

stop_listening may be called to stop listening for incoming connections. shutdown may be called to stop listening for incoming connections and disconnect all existing connections.

Handling Connections

Once listening, the class can accept (or reject) incoming connections. Incoming connection details are first available through the on_connection_request event. Here, the connection's originating address and port can be queried. By default, the class will only accept connections originating from the local host, but this behavior can be overridden within this event (see note below for clarification).

Once a connection is complete, the on_connected event will fire. Note that this event will fire if a connection succeeds or fails. If successful, the event will fire with a StatusCode of 0. A non-zero value indicates the connection was unsuccessful, and the Description parameter will contain relevant details.

After a successful connection, relevant connection-specific details will be available within the connections collection. Each connection will be assigned a unique ConnectionId which may be used to access these details.

To manually disconnect a connected client call the disconnect method and pass the ConnectionId. After a connection has disconnected, the on_disconnected event will fire. In the case a connection ends and an error is encountered, the StatusCode and Description parameters will contain relevant details regarding the error. Once disconnected, the connection will be removed from the connections collection.

Note: The class is designed for use on single-user machines only. For use in other contexts, additional security should be handled by the user. As a result, the class will only accept incoming connections originating from the the local host by default, as indicated by the AllowedClients config (127.0.0.1). This behavior may be overridden by modifying the AllowedClients config, or manually accepting a connection in on_connection_request.

Handling Events

File and folder operations are serviced through the events listed below. In addition to the connection-related events discussed in the previous section, the following events may fire while the class is listening:

Many of the listed events expose a Result parameter, which communicates the operation's success (or failure) to the class and connection. This parameter is always 0 (NFS4_OK) when relevant events fire. If the event, or operation, cannot be handled successfully, this parameter should be set to a non-zero value. Possible Result codes and their descriptions are defined in RFC 7530 section 13.

For more information on how to handle each of these events, please refer to the event's documentation.

Property List

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

Method List

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

Event List

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

Config Settings

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

nfs_connection_count Property

The number of records in the NFSConnection arrays.

Syntax

def get_nfs_connection_count() -> int: ...

nfs_connection_count = property(get_nfs_connection_count, None)

Default Value

0

Remarks

This property controls the size of the following arrays:

• nfs_connection_aux_gi_ds
• nfs_connection_connected
• nfs_connection_current_file
• nfs_connection_gid
• nfs_connection_remote_host
• nfs_connection_remote_port
• nfs_connection_uid

The array indices start at 0 and end at nfs_connection_count - 1.

This property is read-only.

nfs_connection_aux_gi_ds Property

This property contains a comma-separated list of Auxiliary GIDs (or groups the client is a part of) associated with the connection making a request.

Syntax

def get_nfs_connection_aux_gi_ds(connection_id: int) -> str: ...

Default Value

""

Remarks

This property contains a comma-separated list of Auxiliary GIDs (or groups the client is a part of) associated with the connection making a request. This property is only meaningful within the classes events.

For example, if a user with a nfs_connection_gid of 1000 makes a request, this property may be: 4,24,27,30,46,110,1000

Note that this value may change for a given connection assuming multiple users have access to the mounted folder on the client machine. This property will reflect the Auxiliary GIDs associated with the current user making the request.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the nfs_connection_count property.

This property is read-only.

nfs_connection_connected Property

This property shows the status of a particular connection (connected/disconnected).

Syntax

def get_nfs_connection_connected(connection_id: int) -> bool: ...

Default Value

FALSE

Remarks

This property shows the status of a particular connection (connected/disconnected).

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the nfs_connection_count property.

This property is read-only.

nfs_connection_current_file Property

This property represents the current file opened by the connection.

Syntax

def get_nfs_connection_current_file(connection_id: int) -> str: ...

Default Value

""

Remarks

This property represents the current file opened by the connection. An empty string indicates the connection has no file opened.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the nfs_connection_count property.

This property is read-only.

nfs_connection_gid Property

This property represents the current group identifier (GID) of the connection making a request.

Syntax

def get_nfs_connection_gid(connection_id: int) -> int: ...

Default Value

0

Remarks

This property represents the current group identifier (GID) of the connection making a request. This property is only meaningful within the classes events.

Note that this value may change for a given connection. Assuming multiple users have access to the mounted folder on the client machine, this property will reflect the GID of the current user making the request.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the nfs_connection_count property.

This property is read-only.

nfs_connection_remote_host Property

This property indicates the IP address of the remote host through which the connection is coming.

Syntax

def get_nfs_connection_remote_host(connection_id: int) -> str: ...

Default Value

""

Remarks

This property indicates the IP address of the remote host through which the connection is coming.

The connection must be valid or an error will be fired.

If the class is configured to use a SOCKS firewall, the value assigned to this property may be preceded with an "*". If this is the case, the host name is passed to the firewall unresolved and the firewall performs the DNS resolution.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the nfs_connection_count property.

This property is read-only.

nfs_connection_remote_port Property

This property indicates the TCP port on the remote host through which the connection is coming.

Syntax

def get_nfs_connection_remote_port(connection_id: int) -> int: ...

Default Value

0

Remarks

This property indicates the TCP port on the remote host through which the connection is coming.

The connection must be valid or an error will be fired.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the nfs_connection_count property.

This property is read-only.

nfs_connection_uid Property

This property represents the current user identifier (UID) of the connection making a request.

Syntax

def get_nfs_connection_uid(connection_id: int) -> int: ...

Default Value

0

Remarks

This property represents the current user identifier (UID) of the connection making a request. This property is only meaningful within the classes events.

Note that this value may change for a given connection. Assuming multiple users have access to the mounted folder on the client machine, this property will reflect the UID of the current user making the request.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the nfs_connection_count property.

This property is read-only.

listening Property

This property indicates whether the class is listening for incoming connections.

Syntax

def get_listening() -> bool: ...

listening = property(get_listening, None)

Default Value

FALSE

Remarks

This property indicates whether the class is listening for incoming connections on the interface identified by local_host and local_port.

Upon the successful return of start_listening or stop_listening, this property will be adjusted accordingly.

This property is read-only.

local_host Property

The name of the local host or user-assigned IP interface through which connections are initiated or accepted.

Syntax

def get_local_host() -> str: ...
def set_local_host(value: str) -> None: ...

local_host = property(get_local_host, set_local_host)

Default Value

""

Remarks

This property contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multihomed hosts (machines with more than one IP interface) setting LocalHost to the IP address of an interface will make the class initiate connections (or accept in the case of server classs) only through that interface. It is recommended to provide an IP address rather than a hostname when setting this property to ensure the desired interface is used.

If the class is connected, the local_host property shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multihomed hosts (machines with more than one IP interface).

Note: local_host is not persistent. You must always set it in code, and never in the property window.

local_port Property

The TCP port in the local host where the class listens.

Syntax

def get_local_port() -> int: ...
def set_local_port(value: int) -> None: ...

local_port = property(get_local_port, set_local_port)

Default Value

2049

Remarks

The local_port property must be set before the server starts listening. By default, this value is 2049. If its value is 0, then the TCP/IP subsystem picks a port number at random. The port number can be found by checking the value of the local_port property after successfully calling start_listening.

The service port is not shared among servers (i.e. there can be only one server 'listening' on a particular port at one time).

config Method

Sets or retrieves a configuration setting.

Syntax

def config(configuration_string: str) -> str: ...

Remarks

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

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

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

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

disconnect Method

This method disconnects the specified client.

Syntax

def disconnect(connection_id: int) -> None: ...

Remarks

Calling this method will disconnect the client specified by the ConnectionId parameter.

do_events Method

This method processes events from the internal message queue.

Syntax

def do_events() -> None: ...

Remarks

The method checks for events to process, such as incoming data, and fires corresponding events as necessary. If there are no events to process, the method waits for a time specified by the SelectWaitMillis configuration setting before returning.

Windows: By default, the server socket uses Windows messages, and do_events dispatches Windows messages internally. It is not necessary to call do_events from Windows GUI applications as these applications have an internal message dispatch loop. When called, this method must be called in the same thread or task in which the start_listening and stop_listening methods are called.

To avoid using Windows messages and a dispatch loop, set UseWindowsMessages to False. The application still needs to call this do_events method to let the class handle socket updates, but when Windows messages are not used, do_events and stop_listening may be called from a separate thread or task.

Linux: The method may be called from any worker thread, and events will fire in this thread.

macOS: In GUI applications, it is not necessary to call this method as the class registers itself in the main message loop. In other applications, the method may be called from any worker thread, and events will fire in this thread.

fill_dir Method

This method fills the buffer with information about a directory entry.

Syntax

def fill_dir(connection_id: int, name: str, file_id: int, cookie: int, mode: int, user: str, group: str, link_count: int, size: int, a_time: datetime.datetime, m_time: datetime.datetime, c_time: datetime.datetime) -> int: ...

Remarks

This method fills the buffer with information about a directory entry. The Path parameter identifies the location and name of this object. The Name parameter identifies only the name of this object.

This method must be called when the class needs to send information regarding a directory entry to a client, specified by ConnectionId.

Information regarding a directory entry is required when the on_read_dir event fires. Please see the event description for additional information and sample implementation.

The FileId parameter assigns a unique identifier to the file within the filesystem. If set to 0, the class generates an Id based on the checksum value of the Path. Therefore, if set to 0, the generated Id is guaranteed to be unique for a specific Path, and persist across server restarts assuming equivalent paths.

The Cookie parameter should be set to a value unique to the specific directory entry that can later be used to identify the last returned entry within the listing. As some background, when on_read_dir fires, the client is attempting to read all entries within a directory. To start reading from the beginning of a directory, the client will specify a cookie value of 0.

The application is then responsible for calling fill_dir for each existing directory entry. In some cases, the directory may contain a large number of entries. This can become problematic as a client will specify a maximum byte limit on the amount of returned data, meaning the application may not be able to return all directory entries in one response.

To ensure the limit is respected, fill_dir will return a non-zero value if this limit is reached. After on_read_dir returns, the client will follow up with a subsequent request specifying the last cookie value received (the cookie provided in the last successful call to fill_dir). This value should be used as a "bookmark", representing a point the application can continue listing directory entries from in subsequent requests.

Note: Cookie values of 0, 1, and 2 should never be specified within this method. These values are considered to be reserved in certain environments.

The Mode parameter is used to specify the mode of the object, indicating its associated file type and permission bits. This parameter should be set to a combination of the following bit flags, as defined in the UNIX standard sys/stat.h header:

File Type

File Mode Bits

The User parameter is used to provide the NFSv4.0 owner attribute, which is a string name of the owner of this filesystem object. Mode flags S_IRUSR, S_IWUSR, and S_IXUSR apply to the principal identified via the User parameter.

The Group parameter is used to provide the NFSv4.0 owner_group attribute, which is a string name of the group ownership of this filesystem object. Mode flags S_IRGRP, S_IWGRP, and S_IXGRP apply to the principals identified via the Group parameter.

Mode flags S_IROTH, S_IWOTH, and S_IXOTH apply to any principal that does that match the User and does not have a group matching the Group.

The LinkCount parameter is used to provide the NFSv4.0 numlinks attribute, which represents the number of hard links associated with this filesystem object.

The Size parameter is used to provide the NFSv4.0 size attribute, which represents the size of the filesystem object in bytes.

The ATime parameter is used to provide the NFSv4.0 time_access attribute, which represents the time of last access to the object by a on_read operation sent to the server.

The MTime parameter is used to provide the NFSv4.0 time_modify attribute, which represents the time of the last modification to the object.

The CTime parameter is used to provide the NFSv4.0 time_create attribute, which represents the time the object was created (unrelated to the UNIX file attribute "ctime").

shutdown Method

This method shuts down the server.

Syntax

def shutdown() -> None: ...

Remarks

This method shuts down the server. Calling this method is equivalent to calling stop_listening and then breaking every client connection by calling disconnect.

start_listening Method

This method starts listening for incoming connections.

Syntax

def start_listening() -> None: ...

Remarks

This method starts listening for incoming connections on the port specified by local_port. Once listening, events will fire as new clients connect and data are transferred.

To stop listening for new connections, call stop_listening. To stop listening for new connections and to disconnect all existing clients, call shutdown.

To process incoming client data, call the do_events method. It may need to be called from the same thread or task, in which start_listening is called. Please refer to the do_events topic for details.

stop_listening Method

This method stops listening for new connections.

Syntax

def stop_listening() -> None: ...

Remarks

This method stops listening for new connections. After being called, any new connection attempts will be rejected. Calling this method does not disconnect existing connections.

To stop listening and disconnect all existing clients, call shutdown instead.

on_access Event

This event fires when a client verifies their access permissions for an object.

Syntax

class NFSAccessEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def access() -> int: ...
  @access.setter
  def access(value) -> None: ...

  @property
  def supported() -> int: ...
  @supported.setter
  def supported(value) -> None: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_access() -> Callable[[NFSAccessEventParams], None]: ...
@on_access.setter
def on_access(event_hook: Callable[[NFSAccessEventParams], None]) -> None: ...

Remarks

This event fires when a client verifies their access permissions for an object, identified by the Path parameter.

The ConnectionId parameter indicates the client requesting the file access permissions.

The Access parameter contains an encoded bitmask of access rights that the application should check. This parameter can be a combination of the following flags (or access permissions):

To handle this event appropriately, the application should set the Supported parameter to the access rights which the server can verify reliably. The application should then set the Access parameter to the access rights available to this client for the specified object.

Note that the Supported parameter should only contain as many values as were originally present in the provided Access parameter. For example, if the client is only checking the ACCESS4_READ permission, the application should only set the ACCESS4_READ permission in Supported, assuming it can reliably verify this permission.

Assuming Result is set to NFS4_OK, this operation only serves as an advisement to the client. The return of a certain access permission does not imply such access for this object will be permitted in the future, as the application can revoke or change access rights at any time.

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_chmod Event

This event fires when a client attempts to modify the permission bits of an object.

Syntax

class NFSChmodEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def file_context() -> int: ...

  @property
  def mode() -> int: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_chmod() -> Callable[[NFSChmodEventParams], None]: ...
@on_chmod.setter
def on_chmod(event_hook: Callable[[NFSChmodEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to modify the permission bits of an object, identified by the FileContext and/or Path parameters.

The ConnectionId parameter indicates the client attempting to set this attribute.

The Mode parameter specifies the new permission bits the client wishes to set for this object. The client may specify a combination of the following permission bits, as defined in the UNIX standard sys/stat.h header:

Example: Modifying the permission bits and preserving stored file type nfs.OnChmod += (o, e) => { string path = "C:\\NFSRootDir" + e.Path; int currentFileMode = GetFileMode(path); // Arbitrary function to retrieve stored mode int currentType = currentFileMode & 0xF000; // 0xF000 == S_IFMT // Client cannot change type bits, only permission bits SetFileMode(e.Path, currentType | e.Mode); }; The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_chown Event

This event fires when a client attempts to modify an object's owner attribute, group attribute, or both.

Syntax

class NFSChownEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def file_context() -> int: ...

  @property
  def user() -> str: ...

  @property
  def group() -> str: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_chown() -> Callable[[NFSChownEventParams], None]: ...
@on_chown.setter
def on_chown(event_hook: Callable[[NFSChownEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to modify an object's owner attribute, group attribute, or both. The object is identified by the FileContext and/or Path parameters.

The ConnectionId parameter indicates the client attempting to set these attributes.

The User parameter indicates the desired value the client wishes to set the NFSv4.0 owner attribute to. The owner attribute specifies the owner of a file.

The Group parameter indicates the desired value the client wishes to set the NFSv4.0 owner_group attribute to. The owner_group attribute specifies the group ownership of a file.

Note that if the User or Group parameter is equal to an empty string, the client does not wish to modify the associated attribute and the parameter should be ignored.

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_close Event

This event fires when a client requests the closure of a previously opened file.

Syntax

class NFSCloseEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def file_context() -> int: ...
  @file_context.setter
  def file_context(value) -> None: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_close() -> Callable[[NFSCloseEventParams], None]: ...
@on_close.setter
def on_close(event_hook: Callable[[NFSCloseEventParams], None]) -> None: ...

Remarks

This event fires when a client requests the closure of a previously opened file, identified by the Path and/or FileContext parameters.

The ConnectionId parameter indicates the client performing this operation.

To handle this event properly, the application should release the share reservations for this specific file created during a previous on_open operation. This operation is only applicable to the on_open operation performed by a given client for the specified file and does not apply to any on_open operations performed by other clients for the same file.

Note that clients should release any byte-range locks currently held for this file before this operation. However, applications should not assume this. In the event any relevant locks exist, the application may release all locks and return NFS4_OK. Alternatively, if the application chooses not to release the locks, it must respond with NFS4ERR_LOCKS_HELD, offloading the task to the client.

Assuming the operation was successful, applications should free the associated FileContext and set this parameter to IntPtr.Zero, if applicable.

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_commit Event

This event fires when a client attempts to flush any uncommitted file data from a previous Write operation to stable storage.

Syntax

class NFSCommitEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def file_context() -> int: ...

  @property
  def offset() -> int: ...

  @property
  def count() -> int: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_commit() -> Callable[[NFSCommitEventParams], None]: ...
@on_commit.setter
def on_commit(event_hook: Callable[[NFSCommitEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to flush any uncommitted file data from a previous on_write operation to stable storage. The file is identified by the FileContext and/or Path parameters.

The ConnectionId parameter indicates the client performing this operation.

The data to flush to stable storage is the data that was cached in a previous on_write operation. This operation will only occur when the previous on_write operation returns a commitment level of UNSTABLE4 or DATA_SYNC4 to the client. If FILE_SYNC4 was returned previously and all data was written to stable storage, this event will not fire.

Note that the application may cache multiple on_write operations. If the Offset and Count parameters are equal to zero, this indicates that the application should flush all cached data, buffered with each previous on_write operation, for this file to stable storage.

It is also possible that Offset and Count are non-zero. In this case, the application should flush only the specified cached data, buffered with a specific on_write operation.

If the data has already been written to stable storage, and no cached data exists for this value (depending on Offset and Count), the operation should succeed.

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_connected Event

This event fires immediately after a connection completes (or fails).

Syntax

class NFSConnectedEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def status_code() -> int: ...

  @property
  def description() -> str: ...

# In class NFS:
@property
def on_connected() -> Callable[[NFSConnectedEventParams], None]: ...
@on_connected.setter
def on_connected(event_hook: Callable[[NFSConnectedEventParams], None]) -> None: ...

Remarks

If the connection is made normally, StatusCode is 0, and Description is "OK".

If the connection fails, StatusCode has the error code returned by the system. Description contains a description of this code. The value of StatusCode is equal to the value of the system error.

Please refer to the Error Codes section for more information.

on_connection_request Event

This event fires when a connection request comes from a remote host.

Syntax

class NFSConnectionRequestEventParams(object):
  @property
  def address() -> str: ...

  @property
  def port() -> int: ...

  @property
  def accept() -> bool: ...
  @accept.setter
  def accept(value) -> None: ...

# In class NFS:
@property
def on_connection_request() -> Callable[[NFSConnectionRequestEventParams], None]: ...
@on_connection_request.setter
def on_connection_request(event_hook: Callable[[NFSConnectionRequestEventParams], None]) -> None: ...

Remarks

This event indicates an incoming connection. The connection is accepted by default. Address and Port will contain information about the remote host requesting the inbound connection. If you want to refuse it, you can set the Accept parameter to False.

on_create_link Event

This event fires when a client attempts to create a symbolic link or hard link.

Syntax

class NFSCreateLinkEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def name() -> str: ...

  @property
  def link_target() -> bytes: ...

  @property
  def link_type() -> int: ...

  @property
  def file_context() -> int: ...
  @file_context.setter
  def file_context(value) -> None: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_create_link() -> Callable[[NFSCreateLinkEventParams], None]: ...
@on_create_link.setter
def on_create_link(event_hook: Callable[[NFSCreateLinkEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to create a symbolic link or hard link.

The Path parameter identifies the location and name of this link. The Name parameter identifies only the name of this link. If an object exists with the same path and name, the operation should fail and Result should be set to NFS4ERR_EXIST.

The ConnectionId parameter indicates the client attempting to create the link.

The LinkType parameter indicates the type of link the client is attempting to create. The following values are applicable:

Please see below for additional details on how the application should handle this event for each type of link.

Symbolic Links

If LinkType is equal to 0, the client is attempting to create a symbolic link. An object should be created at the specified Path that, in future operations, can be identified as a symbolic link and can be used to return the content of the symbolic link.

The LinkTarget parameter provides the content of the symbolic link, as sent by the client. Note that the content should be treated as opaque by the server, i.e., the server does not need to interpret the data. It is possible that a client will provide a pathname that is not meaningful to the application. Therefore, it is the client's responsibility to interpret the content of the symbolic link. Although UTF-8 encoding is often used, it is not a requirement. In that regard, the content of a symbolic link is like the content of a regular file.

In many cases, the LinkTarget will be a UTF-8 string, though as mentioned, this is not a requirement. Applications should ensure that the exact contents of the LinkTarget are returned to the client in on_read_link.

Hard Links

If LinkType is equal to 1, the client is attempting to create a hard link.

In the case of a hard link, the LinkTarget indicates an existing file that the new object, identified by Path, will point to. Unlike with symbolic links, the LinkTarget parameter is guaranteed to be a UTF-8 string, and will contain the exact file path the hard link should target.

To handle this appropriately, the application should create an object at the specified Path that points to the data associated with the LinkTarget. Changes to any property of the LinkTarget are reflected in all linked files.

Depending on the underlying filesystem, "." and ".." are illegal values for a new object name. In this case, Result should be set to NFS4ERR_BADNAME and the operation should fail.

Additionally, if the new object name has a length of 0, or does not obey the UTF-8 definition, Result should be set to NFS4ERR_INVAL.

Please see below for an example handling both symbolic and hard links.

nfs.OnCreateLink += (o, e) => { string linkname = GetRealPath(root, e.Path); if (File.Exists(linkname)) { e.Result = NFS4ERR_EXIST; return; } // Symbolic link if (e.LinkType == 0) { try { // CreateSymbolicLink function from kernel32.dll CreateSymbolicLink(linkname, e.LinkTarget, 0); } catch (Exception ex) { e.Result = NFS4ERR_IO; } return; } string target = GetRealPath(root, e.LinkTarget); // Hard link if (e.LinkType == 1) { try { // CreateHardLink function from kernel32.dll CreateHardLink(linkname, target, IntPtr.Zero); } catch (Exception ex) { e.Result = NFS4ERR_IO; } } };

on_disconnected Event

This event fires when a connection is closed.

Syntax

class NFSDisconnectedEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def status_code() -> int: ...

  @property
  def description() -> str: ...

# In class NFS:
@property
def on_disconnected() -> Callable[[NFSDisconnectedEventParams], None]: ...
@on_disconnected.setter
def on_disconnected(event_hook: Callable[[NFSDisconnectedEventParams], None]) -> None: ...

Remarks

If the connection is broken normally, StatusCode is 0, and Description is "OK".

If the connection is broken for any other reason, StatusCode has the error code returned by the system. Description contains a description of this code. The value of StatusCode is equal to the value of the system error.

Please refer to the Error Codes section for more information.

on_error Event

This event fires information about errors during data delivery.

Syntax

class NFSErrorEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def error_code() -> int: ...

  @property
  def description() -> str: ...

# In class NFS:
@property
def on_error() -> Callable[[NFSErrorEventParams], None]: ...
@on_error.setter
def on_error(event_hook: Callable[[NFSErrorEventParams], None]) -> None: ...

Remarks

The on_error event is fired in case of exceptional conditions during message processing. Normally, the class raises an exception.

ErrorCode contains an error code and Description contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

ConnectionId indicates the connection for which the error is applicable.

on_get_attr Event

This event fires when a client requests attributes for an object (such as the owner, group, or mode attributes).

Syntax

class NFSGetAttrEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def file_context() -> int: ...

  @property
  def file_id() -> int: ...
  @file_id.setter
  def file_id(value) -> None: ...

  @property
  def mode() -> int: ...
  @mode.setter
  def mode(value) -> None: ...

  @property
  def user() -> str: ...
  @user.setter
  def user(value) -> None: ...

  @property
  def group() -> str: ...
  @group.setter
  def group(value) -> None: ...

  @property
  def link_count() -> int: ...
  @link_count.setter
  def link_count(value) -> None: ...

  @property
  def size() -> int: ...
  @size.setter
  def size(value) -> None: ...

  @property
  def a_time() -> datetime.datetime: ...
  @a_time.setter
  def a_time(value) -> None: ...

  @property
  def m_time() -> datetime.datetime: ...
  @m_time.setter
  def m_time(value) -> None: ...

  @property
  def c_time() -> datetime.datetime: ...
  @c_time.setter
  def c_time(value) -> None: ...

  @property
  def nfs_handle() -> str: ...
  @nfs_handle.setter
  def nfs_handle(value) -> None: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_get_attr() -> Callable[[NFSGetAttrEventParams], None]: ...
@on_get_attr.setter
def on_get_attr(event_hook: Callable[[NFSGetAttrEventParams], None]) -> None: ...

Remarks

This event fires when a client requests attributes for an object (such as the owner, group, or mode attributes), identified by the FileContext, NFSHandle, and/or Path parameters.

The NFSHandle parameter is the hex-encoded value of the internal file handle representation. By default, this parameter is calculated as the PPMD-compressed value of the Path. Assuming this format is used, the class will be able to decompress this handle and obtain the Path, if necessary for future operations.

This functionality is particularly useful in the event the server restarts. Assuming a client maintains their mount, the client may continue to utilize their cached file handles. Because the server was restarted, the class would typically be unable to recognize the received handle, and report the handle as stale. However, assuming the defualt format is used, the class will be able to decompress the file handle, retrieve the Path, and check the object's existence by firing on_lookup.

Note that at the protocol-level, file handles must be no more than 128 bytes (NFS4_FHSIZE). It is possible that the PPMD-compressed value of the Path is greater than 128 bytes, though this is unlikely, as the Path would need to be very large. In this case, the NFSHandle will instead be calculated as the SHA256 hash of the Path, which may result in stale file handles in the event of a server restart.

The ConnectionId parameter indicates the client requesting information about the filesystem object.

To handle this event properly, applications should set the below parameters to relevant attributes of the filesystem object.

The FileId parameter assigns a unique identifier to the file within the filesystem. If specified as 0 (default), the class generates an Id based on the checksum value of the Path. Therefore, if this parameter is set to 0 or remains unmodified, the generated Id is guaranteed to be unique for a specific Path, and persist across server restarts assuming equivalent paths.

The Mode parameter is used to specify the mode of the object, indicating its associated file type and permission bits. This parameter should be set to a combination of the following flags, as defined in the UNIX standard sys/stat.h header:

File Type

File Mode Bits

The User parameter is used to set the NFSv4.0 owner attribute, which is a string name of the owner of this filesystem object. Mode flags S_IRUSR, S_IWUSR, and S_IXUSR apply to the principal identified via the User parameter.

The Group parameter is used to set the NFSv4.0 owner_group attribute, which is a string name of the group ownership of this filesystem object. Mode flags S_IRGRP, S_IWGRP, and S_IXGRP apply to the principals identified via the Group parameter.

Mode flags S_IROTH, S_IWOTH, and S_IXOTH apply to any principal that does not match the User and does not have a group matching the Group.

The LinkCount parameter is used to set the NFSv4.0 numlinks attribute, which represents the number of hard links associated with this filesystem object.

The Size parameter is used to set the NFSv4.0 size attribute, which represents the size of the filesystem object in bytes.

The ATime parameter is used to set the NFSv4.0 time_access attribute, which represents the time of last access to the object by a on_read operation sent to the server.

The MTime parameter is used to set the NFSv4.0 time_modify attribute, which represents the time of the last modification to the object.

The CTime parameter is used to set the NFSv4.0 time_create attribute, which represents the time the object was created (unrelated to the UNIX file attribute "ctime").

Example: Retrieving file or directory attributes nfs.OnGetAttr += (o, e) => { string path = "C:\\NFSRootDir" + e.Path; if (!File.Exists(path) && !Directory.Exists(path)) { e.Result = NFS4ERR_NOENT; return; } e.User = OWNER; e.Group = OWNER_GROUP; e.LinkCount = 1; if (Directory.Exists(path)) { int fileMode = S_IFDIR | S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH; // Indicates file type (S_IFDIR) and permissions (755) e.Mode = fileMode; e.Size = 4096; e.ATime = Directory.GetLastAccessTime(real); e.CTime = Directory.GetCreationTime(real); e.MTime = Directory.GetLastWriteTime(real); } else { int fileMode = S_IFREG | S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH; // Indicates file type (S_IFREG) and permissions (644) e.Mode = fileMode; e.Size = new FileInfo(path).Length; e.ATime = File.GetLastAccessTime(path); e.MTime = File.GetLastWriteTime(path); e.CTime = File.GetCreationTime(path); } }; The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_lock Event

This event fires when a client attempts to create or test a byte-range lock for a file.

Syntax

class NFSLockEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def file_context() -> int: ...

  @property
  def lock_type() -> int: ...

  @property
  def lock_offset() -> int: ...
  @lock_offset.setter
  def lock_offset(value) -> None: ...

  @property
  def lock_len() -> int: ...
  @lock_len.setter
  def lock_len(value) -> None: ...

  @property
  def test() -> bool: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_lock() -> Callable[[NFSLockEventParams], None]: ...
@on_lock.setter
def on_lock(event_hook: Callable[[NFSLockEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to create or test a byte-range lock for a file, indicated by the FileContext or Path parameters.

The ConnectionId parameter indicates the client requesting the lock.

The LockOffset parameter specifies the position (or byte) within the file where the lock should begin. The LockLen parameter specifies the number of bytes that should be locked after the specified offset, indicating a range of bytes to lock. If the LockLen parameter is 0, the application should return NFS4ERR_INVAL. If the LockLen parameter is -1, this indicates the client wishes to lock all bytes from the specified LockOffset to the end of the file.

The LockType parameter specifies the type of lock to be created or tested on the file (read or write, blocking or non-blocking). This parameter may be equal to one of the following values:

Note a blocking lock type indicates the client wishes to 'wait' for the mentioned lock if a conflicting lock exists. Please see below for more information regarding blocking locks.

To handle this event properly, applications should determine whether the client wishes to create or test the lock by examining the Test parameter.

Testing a Lock

If the Test parameter is True, the client only intends to test the lock. In this case, no lock should be created. First, the application should determine whether a conflicting lock exists for this file based on the semantics of the server-exported file system. The test for a conflicting lock should exclude any locks held by the client making this request, identified by ConnectionId. If a conflicting lock exists, the application should set the LockOffset and LockLen parameters to that of the conflicting lock and return NFS4ERR_DENIED.

If the application chooses not to exclude these locks, and the client making this request owns the conflicting lock, NFS4ERR_LOCK_RANGE may be returned if any overlap exists between the conflicting lock and the range specified by LockOffset and LockLen.

Additionally, when Test is True, the lock types READ_LT and READW_LT should be interpreted in the same way, without regard to blocking or non-blocking behavior. This is also true for READW_LT and WRITEW_LT.

If no conflicting lock exists, no lock should be created and the operation should succeed.

Creating a Lock

If the Test parameter is False, the client wishes to create the lock. First, the application should determine whether a conflicting lock exists for this file based on the semantics of the server-exported file system. If the client making this request is the owner of the conflicting lock, NFS4ERR_LOCK_RANGE may be returned under the same conditions as described when testing a lock. Otherwise, the application should set the LockOffset and LockLen parameters to that of the conflicting lock and return NFS4ERR_DENIED. If the conflicting lock's offset and length cannot be determined by the application, the corresponding parameters should remain unchanged and NFS4ERR_DENIED should be returned.

If no conflicting lock exists, the application should create the lock and the operation should succeed.

Upgrading and Downgrading Locks

If a client has an existing write lock, they may request an atomic downgrade of the lock to a read lock. This is done by sending a LOCK request with the same LockOffset and LockLen, but specifying the LockType as READ_LT.

If a client has an existing read lock, they may request an atomic upgrade of the lock to a write lock. This is done by sending a LOCK request with the same LockOffset and LockLen, but specifying the LockType as WRITE_LT or WRITEW_LT. If a conflicting lock exists, the application should set the LockOffset and LockLen parameters to that of the conflicting lock and return NFS4ERR_DENIED. Additionally, if the LockType is specified as WRITEW_LT, the application should return NFS4ERR_DEADLOCK if a deadlock condition is detected.

In either case, if the application does not support upgrading or downgrading a lock, NFS4ERR_LOCK_NOTSUPP should be returned.

Blocking Locks

To ensure fairness and to support blocking locks, applications may maintain an ordered list of clients waiting to obtain a conflicting lock. Note this is only applicable to blocking locks. If implemented, it's important to note that clients will poll for the lock, following up with the identical lock request until accepted. Once a conflicting lock is released, the application may wait a fixed time (lease period) to grant the lock to the first waiting client. Since clients will poll for previously denied locks, this period ensures the client still wants the lock. If the application does not receive the re-request within this period, the application should assume the client no longer wants the lock, and the client should be removed from the ordered list. This process repeats with the next waiting client, and so on.

If implementing an ordered list, it may be the case that a waiting client sends the same lock request with a non-blocking lock type specified. If this occurs and the non-blocking request is denied, it can be assumed the client will no longer poll for this lock. The client may then be removed from the ordered list.

If the application determines a file locking deadlock condition would exist after a specific lock request, Result should be set to NFS4ERR_DEADLOCK.

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_log Event

This event fires once for each log message.

Syntax

class NFSLogEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def log_level() -> int: ...

  @property
  def message() -> str: ...

  @property
  def log_type() -> str: ...

# In class NFS:
@property
def on_log() -> Callable[[NFSLogEventParams], None]: ...
@on_log.setter
def on_log(event_hook: Callable[[NFSLogEventParams], None]) -> None: ...

Remarks

This event fires once for each log message generated by the class. The verbosity is controlled by the LogLevel configuration.

LogLevel indicates the detail level of the message. Possible values are:

Message is the log message.

LogType identifies the type of log entry. Possible values are as follows:

• NFS

ConnectionId identifies the connection to which the log message applies.

on_lookup Event

This event fires when the class needs to determine the existence of an object in the current directory.

Syntax

class NFSLookupEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def name() -> str: ...

  @property
  def path() -> str: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_lookup() -> Callable[[NFSLookupEventParams], None]: ...
@on_lookup.setter
def on_lookup(event_hook: Callable[[NFSLookupEventParams], None]) -> None: ...

Remarks

This event fires when the class needs to determine the existence of an object in the current directory. The Path parameter identifies the location and name of this object. The Name parameter identifies only the name of this object.

The ConnectionId parameter indicates the client this information is required for.

The existence of a filesystem object can be requested in either of the following cases:

• When a client is attempting to open and/or create a regular file. In this case, on_open will fire shortly after this event returns.
• When a client is performing a LOOKUP operation on a filesystem object.
• When a client sends an unknown file handle value. In this case, the class will attempt to decompress the handle to obtain the relevant Path, and will check the existence of the object. See on_get_attr for additional details.

To handle this event properly, the application should check whether this object exists within the specified directory. If the object does not exist, the Result parameter should be set to NFS4ERR_NOENT. Otherwise, NFS4_OK indicates the object exists.

Example: Check if object exists nfs.OnLookup += (o, e) => { string path = e.Path; // Varies depending on underlying filesystem implementation if (File.Exists(path)) { return; } if (Directory.Exists(path)) { return; } // Object does not exist e.Result = NFS4ERR_NOENT; };

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_mk_dir Event

This event fires when a client attempts to create a new directory.

Syntax

class NFSMkDirEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_mk_dir() -> Callable[[NFSMkDirEventParams], None]: ...
@on_mk_dir.setter
def on_mk_dir(event_hook: Callable[[NFSMkDirEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to create a new directory, identified by the Path parameter.

The ConnectionId parameter indicates the client attempting to create a directory.

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_open Event

This event fires when a client attempts to create or open a file.

Syntax

class NFSOpenEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def share_access() -> int: ...

  @property
  def share_deny() -> int: ...

  @property
  def create_mode() -> int: ...

  @property
  def open_type() -> int: ...

  @property
  def file_context() -> int: ...
  @file_context.setter
  def file_context(value) -> None: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_open() -> Callable[[NFSOpenEventParams], None]: ...
@on_open.setter
def on_open(event_hook: Callable[[NFSOpenEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to create or open a file. This event is not applicable to directories (please see on_mk_dir, on_read_dir, and on_rm_dir for further details).

The client where the request originates from is specified via ConnectionId.

The Path parameter contains the path to the file to open, along with the file name. Unless the file is already open, the FileContext parameter will initially be IntPtr.Zero. The application may use the FileContext parameter to store a file handle or other information related to the open file.

To appropriately handle this event, the application should perform any actions needed to create or open the requested file as indicated by the OpenType and CreateMode parameters, with the desired share reservations as specified by the ShareAccess and ShareDeny parameters. Please see the parameter descriptions below for additional information.

The OpenType parameter specifies how the client would like to open the file. This parameter may be equal to one of the following values:

The CreateMode parameter indicates the file creation method specified by the client. This parameter is only relevant when OpenType is equal to rsOPEN4CREATE;, and may be equal to one of the following values:

Note GUARDED4 only indicates that if the file already exists, the OPEN operation will fail. It does not imply exclusive creation, which would ensure only one client can create or open a file with a specific name at once. If the mentioned exclusive creation semantics cannot be supported by the file system, the OPEN operation should fail and NFS4ERR_NOTSUPP should be returned.

The ShareAccess parameter specifies the client's desired share access utilized when opening a file. This value may be equal to one of the following access flags:

In the case that there is an existing share reservation that conflicts with the request, NFS4ERR_SHARE_DENIED should be returned. If the underlying file system is only accessible in a read-only mode, and OPEN4_SHARE_ACCESS_WRITE or OPEN4_SHARE_ACCESS_BOTH are requested, NFS4ERR_ROFS should be returned to indicate a read-only file system.

The ShareDeny parameter defines the client's desired restrictions on share access for other clients when this file is open. This value may be equal to one of the following deny flags:

Note that if OPEN4_SHARE_DENY_WRITE or OPEN4_SHARE_DENY_BOTH are specified and on_unlink is fired while the object is still open, the application should not delete the file. If OPEN4_SHARE_DENY_NONE or OPEN4_SHARE_DENY_READ are specified and on_unlink is fired while the object is still open, the application should delete the file.

Example: Opening or creating a file with share reservations

nfs.OnOpen += (o, e) => { string path = "C:\\NFSRootDir" + e.Path; FileStream fs = null; FileAccess shareAccess = (FileAccess)e.ShareAccess; // ShareAccess correlates directly with FileAccess FileShare shareDeny = 0; // ShareDeny does not correlate directly with FileShare, so let's translate ShareDeny to FileShare switch (e.ShareDeny) { case OPEN4_SHARE_DENY_BOTH: { shareDeny = FileShare.None; // Allow no access by other clients break; } case OPEN4_SHARE_DENY_WRITE: { shareDeny = FileShare.Read; // Allow read access by other clients break; } case OPEN4_SHARE_DENY_READ: { shareDeny = FileShare.Write | FileShare.Delete; // Allow write access and deletion by other clients break; } default: { // Default OPEN4_SHARE_DENY_NONE shareDeny = FileShare.ReadWrite | FileShare.Delete; // Allow read and write access and deletion by other clients break; } } FileMode createMode = FileMode.Open; if (e.OpenType == OPEN4_NOCREATE) { // The client wishes to open the file without creating it. If it doesn't exist, return NFS4ERR_NOENT, otherwise open with FileMode.Open. if (!File.Exists(e.Path)) { e.Result = NFS4ERR_NOENT; return; } } else { // The client wishes to create a file, with the specified CreateMode switch (e.CreateMode) { case UNCHECKED4: { createMode = FileMode.Create; // If a duplicate exists, no error is returned break; } default: { // Implies e.CreateMode == GUARDED4 || EXCLUSIVE4. If a duplicate exists, NFS4ERR_EXIST is returned if (File.Exists(path)) { e.Result = NFS4ERR_EXIST; return; } // Otherwise, proceed with creating the file. createMode = FileMode.CreateNew; break; } } } fs = File.Open(path, createMode, shareAccess, shareDeny); e.FileContext = (IntPtr)GCHandle.Alloc(fs); };

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_read Event

This event fires when a client attempts to read any part of a file.

Syntax

class NFSReadEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def file_context() -> int: ...

  @property
  def buffer() -> c_void_p: ...

  @property
  def count() -> int: ...
  @count.setter
  def count(value) -> None: ...

  @property
  def offset() -> int: ...

  @property
  def eof() -> bool: ...
  @eof.setter
  def eof(value) -> None: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_read() -> Callable[[NFSReadEventParams], None]: ...
@on_read.setter
def on_read(event_hook: Callable[[NFSReadEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to read any part of a file, identified by the FileContext and/or Path parameters. Note this operation is subject to access permissions checking performed by the application.

The ConnectionId parameter indicates the client this information is required for.

To handle this event properly, applications should read up to Count bytes of data from the specified file into the byte array provided by Buffer. Reading must begin at the specified Offset in the file, and applications must not copy more than Count bytes into the buffer. Note the server may read less data than requested by the client, though this should only be done under particular circumstances, and will ultimately result in the client sending another read operation (unless EOF was reached) to finish reading the file data.

After the appropriate amount of data is read, the application must set the Count parameter to the number of bytes written to the buffer. The application should also update the last accessed time of the file upon a successful read.

If the EOF is reached (e.g., the offset and count are equal to or greater than the size of the file), the Eof parameter should be set to True.

If Count is specified by the client as 0, this value should remain unchanged and the operation should succeed subject to permissions checking. No data should be returned (Buffer should be empty), and the operation should return success.

If Offset is greater than or equal to the size of the file, Count should be set to 0, Eof should be set to True, and the operation should succeed.

If mandatory byte-range locking is in effect, and the current file has a write lock held by another client that conflicts with the data to be read, the operation should fail and Result should be set to NFS4ERR_LOCKED.

Example: Reading data from a file nfs.OnRead += (o, e) => { if (e.Count == 0) { return; } try { IntPtr p = e.FileContext; GCHandle h = (GCHandle)p; FileStream fs = h.Target as FileStream; if (e.Offset >= fs.Length) { e.Count = 0; e.Eof = true; return; } fs.Position = e.Offset; int count = fs.Read(e.BufferB, 0, e.Count); // If EOF was reached, notify the client if (fs.Position == fs.Length) { e.Eof = true; } else { e.Eof = false; } // Return number of bytes read e.Count = c; } catch (Exception ex) { e.Result = NFS4ERR_IO; } };

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_read_dir Event

This event fires when a client attempts to list the contents of a directory.

Syntax

class NFSReadDirEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def file_context() -> int: ...
  @file_context.setter
  def file_context(value) -> None: ...

  @property
  def path() -> str: ...

  @property
  def cookie() -> int: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_read_dir() -> Callable[[NFSReadDirEventParams], None]: ...
@on_read_dir.setter
def on_read_dir(event_hook: Callable[[NFSReadDirEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to list the contents of a directory, identified by the Path parameter. Similar to on_open, the application may use the FileContext parameter to store a handle or other information related to the directory.

The FileContext parameter is initially IntPtr.Zero when a directory listing begins, as indicated by a Cookie value of 0. In this case, the application may assign this parameter for future reference, as the directory listing operation could span multiple on_read_dir events. See below for more information regarding this case. Note that if all directory entries have been listed, the FileContext should be freed and set to IntPtr.Zero before on_read_dir returns.

The ConnectionId parameter indicates the client requesting the directory information.

The Cookie parameter represents where the application should start reading entries from within the directory. A cookie value of 0 is used by the client to start reading at the beginning of the directory. Please see fill_dir and below for more details regarding non-zero cookie values.

To handle this event properly, the application must call the fill_dir method for each existing entry within the associated directory. Doing so will buffer the relevant directory entry information to be sent to the client upon the return of this event.

Note when listing a directory, the client will specify a limit on the amount of data (or number of entries) to return in a single response. To handle this, the application should analyze the returned value of each call to fill_dir within this event to ensure the limit is not exceeded. A non-zero return value indicates that the most recent call to fill_dir would have caused the application to send more data than the limit specified by the client. In this case, the event should return immediately with a Result of NFS4_OK.

Afterwards, the client will send subsequent requests to continue retrieving entries. In these requests, the Cookie parameter will be equal to the cookie value the application specified in the last successful entry provided by fill_dir. Note that the cookie value provided in fill_dir and the Cookie parameter specified by the client are only meaningful to the server. The cookie values should be interpreted and utilized as a "bookmark" of the directory entry, indicating a point for continuing the directory listing.

Note if a single directory entry is unable to be returned by the application within this operation, the event should return immediately with a Result of NFS4ERR_TOOSMALL. Please see fill_dir for further details. Additionally, please see below for a simple implementation of on_read_dir.

Example: Starting or continuing a directory listing

int baseCookie = 0x12345678; nfs.OnReadDir += (o, e) => { int dirOffset = 0; // Initial directory offset // Arbitrary base cookie to start at for listing directory entries. // On calls to FillDir, this value will be incremented, so subsequent READDIR operations can resume from a specified cookie. long cookie = baseCookie; // If e.Cookie == 0, we start listing from the beginning of the directory. // Otherwise, we start listing from the offset indicated by this parameter. if (e.Cookie != 0) { offset = e.Cookie - baseCookie + 1; cookie = e.Cookie + 1; } string path = "C:\\NFSRootDir" + e.Path; var entries = Directory.GetFileSystemEntries(path, "*", SearchOption.TopDirectoryOnly); // Iterate through all directory entries. // dirOffset indicates the next entry to be listed given the client's provided Cookie. for (int i = dirOffset; i < entries.Length; i++) { string name = Path.GetFileName(entries[i]); bool isDir = Directory.Exists(entries[i]); int result = 0; if (isDir) { int fileMode = S_IFDIR | S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH; // Indicates file type (S_IFDIR) and permissions (755) result = nfs.FillDir(e.ConnectionId, name, cookie++, fileMode, "OWNER", "OWNER_GROUP", 1, 4096, new DirectoryInfo(path).LastAccessTime, new DirectoryInfo(path).LastWriteTime, new DirectoryInfo(path).CreationTime); } else { int fileMode = S_IFREG | S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH; // Indicates file type (S_IFREG) and permissions (644). result = nfs.FillDir(e.ConnectionId, name, cookie++, fileMode, "OWNER", "OWNER_GROUP", 1, FileInfo(path).Length, new FileInfo(path).LastAccessTime, new FileInfo(path).LastWriteTime, new FileInfo(path).CreationTime); } // Return if FillDir returned non-zero value (client's entry limit has been reached) if (result != 0) { // No entries were returned, set Result in this case to alert client if (i == dirOffset) { e.Result = NFS4ERR_TOOSMALL; } return; } } };

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_read_link Event

This event fires when a client attempts to read data associated with a symbolic link.

Syntax

class NFSReadLinkEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def file_context() -> int: ...

  @property
  def buffer() -> c_void_p: ...

  @property
  def count() -> int: ...
  @count.setter
  def count(value) -> None: ...

  @property
  def offset() -> int: ...

  @property
  def eof() -> bool: ...
  @eof.setter
  def eof(value) -> None: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_read_link() -> Callable[[NFSReadLinkEventParams], None]: ...
@on_read_link.setter
def on_read_link(event_hook: Callable[[NFSReadLinkEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to read data associated with a symbolic link, identified by the Path or FileContext parameters.

The ConnectionId parameter indicates the client attempting to read the symbolic link.

To appropriately handle this event, the application should attempt to retrieve up to Count bytes of data associated with the symbolic link, i.e., the link's target. This data should be read into the byte array provided by the Buffer parameter starting at the specified Offset. Afterwards, Count should be set to the number of bytes read into the buffer. Additionally, if all bytes were read into the buffer, Eof should be set to True.

If Eof is set to False, this indicates to the class that additional data associated with the symbolic link has not been read. In this case, this event will fire again, allowing the application to continue reading the data associated with the symbolic link from the indicated Offset.

Please see below for an example.

nfs.OnReadLink += (o, e) => { try { string real = GetRealPath(root, e.Path); // NET 6 FileSystemInfo class contains a LinkTarget property FileSystemInfo fileInfo = new FileInfo(real); byte[] data = System.Text.Encoding.UTF8.GetBytes(fileInfo.LinkTarget); int bytesToRead = data.Length - (int)e.Offset; e.Eof = true; if (bytesToRead > e.Count) { bytesToRead = e.Count; // 1024 bytes, size of e.BufferB e.Eof = false; // ReadLink will fire again to finish copying link content } System.Array.Copy(data, e.Offset, e.BufferB, 0, bytesToRead); e.Count = bytesToRead; } catch (Exception ex) { e.Result = NFS4ERR_IO; } }

on_rename Event

This event fires when a client attempts to rename or move an object.

Syntax

class NFSRenameEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def old_path() -> str: ...

  @property
  def new_path() -> str: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_rename() -> Callable[[NFSRenameEventParams], None]: ...
@on_rename.setter
def on_rename(event_hook: Callable[[NFSRenameEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to rename or move an object from OldPath to NewPath.

If OldPath and NewPath refer to the same object, the application should perform no action and return success immediately.

The ConnectionId parameter indicates the client attempting to rename the file or directory.

If an entry already exists with the name NewPath, the source object must be compatible with the target. To clarify, to be compatible, either both objects must be non-directories, or both objects must be directories. If both objects are directories, the target must be empty.

Assuming the objects are compatible, the existing target is removed before the rename (or move) occurs.

If the objects are incompatible, or if the target is a directory but not empty, the application must set Result to NFS4ERR_EXIST.

Example: Renaming a file or directory nfs.OnRename += (o, e) => { string oldPath = "C:\\NFSRootDir" + e.OldPath; string newPath = "C:\\NFSRootDir" + e.NewPath; // Check if oldPath and newPath refer to the exact same file. If so, return successfully. if (oldPath.Equals(newPath)) { return; } // Check whether oldPath is a file or directory if (Directory.Exists(oldPath)) { // oldPath is a directory. Check for incompatible rename operation. if (File.Exists(newPath)) { // Incompatible, Directory -> File e.Result = NFS4ERR_EXIST; return; } // Check if target directory exists. If so, check the number of files in this directory. int fileCount = 0; if (Directory.Exists(newPath)) { fileCount = Directory.GetFiles(newPath, "*", SearchOption.TopDirectoryOnly).Length; } // If files exist in the target directory, return error. if (fileCount == 0) { Directory.Move(oldPath, newPath); } else { e.Result = NFS4ERR_EXIST; } } else { // oldPath is a file. Check for incompatible rename operation. if (Directory.Exists(newPath)) { // Incompatible, File -> Directory e.Result = NFS4ERR_EXIST; return; } if (File.Exists(newPath)) { File.Delete(newPath); } File.Move(oldPath, newPath); } };

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_rm_dir Event

This event fires when a client attempts to remove a directory.

Syntax

class NFSRmDirEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_rm_dir() -> Callable[[NFSRmDirEventParams], None]: ...
@on_rm_dir.setter
def on_rm_dir(event_hook: Callable[[NFSRmDirEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to remove a directory, identified by the Path parameter.

The ConnectionId parameter indicates the client attempting to delete the directory.

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_truncate Event

This event fires when a client attempts to modify a file's size attribute.

Syntax

class NFSTruncateEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def file_context() -> int: ...

  @property
  def size() -> int: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_truncate() -> Callable[[NFSTruncateEventParams], None]: ...
@on_truncate.setter
def on_truncate(event_hook: Callable[[NFSTruncateEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to modify a file's size attribute, identified by the FileContext and/or Path parameters.

The ConnectionId parameter indicates the client attempting to truncate the file.

The Size parameter indicates the desired value the client wishes to set the NFSv4.0 size attribute to.

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_unlink Event

This event fires when a client attempts to unlink (or delete) a file.

Syntax

class NFSUnlinkEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_unlink() -> Callable[[NFSUnlinkEventParams], None]: ...
@on_unlink.setter
def on_unlink(event_hook: Callable[[NFSUnlinkEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to unlink (or delete) a file, identified by the Path parameter.

The ConnectionId parameter indicates the client attempting to delete the file.

Note the file may still be open when this event fires. In this case, the application should not delete the file if the file was opened with OPEN4_SHARE_DENY_WRITE or OPEN4_SHARE_DENY_BOTH (see on_open for additional details). If the file was opened with OPEN4_SHARE_DENY_NONE or OPEN4_SHARE_DENY_READ, the application should delete the file.

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_unlock Event

This event fires when a client attempts to release a lock.

Syntax

class NFSUnlockEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def file_context() -> int: ...

  @property
  def lock_type() -> int: ...

  @property
  def lock_offset() -> int: ...

  @property
  def lock_len() -> int: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_unlock() -> Callable[[NFSUnlockEventParams], None]: ...
@on_unlock.setter
def on_unlock(event_hook: Callable[[NFSUnlockEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to release a lock, indicated by the FileContext and/or Path parameters.

The ConnectionId parameter indicates the client requesting to release the lock.

The LockOffset parameter specifies the position (or byte) within the file where the unlock should begin at. The LockLen parameter specifies the number of bytes that should be unlocked after the specified offset, effectively creating a range of bytes to unlock. If the LockLen parameter is 0, the application should return NFS4ERR_INVAL. If the LockLen parameter is -1, this indicates the client wishes to lock all bytes from the specified LockOffset to the end of the file.

The LockType parameter indicates the type of lock used on the file (read or write, blocking or non-blocking). Please see on_lock for possible values. This parameter should not affect the success or failure of this operation.

If the LockOffset and LockLen parameters do not correspond exactly to a lock held by the client, NFS4ERR_LOCK_RANGE may be returned.

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_u_time Event

This event fires when a client attempts to change a file's last access time, last modification time, or both.

Syntax

class NFSUTimeEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def file_context() -> int: ...

  @property
  def a_time() -> datetime.datetime: ...

  @property
  def m_time() -> datetime.datetime: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_u_time() -> Callable[[NFSUTimeEventParams], None]: ...
@on_u_time.setter
def on_u_time(event_hook: Callable[[NFSUTimeEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to change a file's access time, modification time, or both.

The ConnectionId parameter indicates the client attempting to modify these values.

The ATime parameter indicates the desired value the client wishes to set the NFSv4.0 time_access attribute to.

The MTime parameter indicates the desired value the client wishes to set the NFSv4.0 time_modify attribute to.

Note that if the ATime or MTime parameter is equal to the smallest possible time allowed for the given parameter type, the client does not wish to modify the associated attribute and the parameter should be ignored.

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

on_write Event

This event fires when a client attempts to write data to a file.

Syntax

class NFSWriteEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def path() -> str: ...

  @property
  def file_context() -> int: ...

  @property
  def offset() -> int: ...

  @property
  def buffer() -> bytes: ...

  @property
  def count() -> int: ...
  @count.setter
  def count(value) -> None: ...

  @property
  def stable() -> int: ...
  @stable.setter
  def stable(value) -> None: ...

  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class NFS:
@property
def on_write() -> Callable[[NFSWriteEventParams], None]: ...
@on_write.setter
def on_write(event_hook: Callable[[NFSWriteEventParams], None]) -> None: ...

Remarks

This event fires when a client attempts to write data to a file, identified by the FileContext and/or Path parameters. Note this operation is subject to access permissions checking performed by the application.

The ConnectionId parameter indicates the client writing to a file.

To handle this event properly, applications should write Count bytes of data from the byte array specified by Buffer to the relevant file. Writing must begin at the indicated Offset in the file. Note the server may write less data than requested by the client.

After the appropriate amount of data is written, the application must set the Count parameter to the number of bytes written to the relevant file.

If Count is specified by the client as 0, this value should remain unchanged and the operation should succeed (subject to permissions checking). In this case, the application should also ensure the modified time of the file is not changed.

The Stable parameter is specified by the client to indicate how the write operation should be performed, or how the data should be committed by the application. This parameter may be equal to one of the following values as specified by the connection:

The application must also specify the level of commitment fulfilled and can do so by modifying the Stable parameter to one of the above values. Note that the level of commitment must at least be as strong as the value specified in Stable (with FILE_SYNC4 being the strongest and UNSTABLE4 being the weakest). A returned level of commitment less than the provided value of Stable constitutes a protocol violation.

Assuming UNSTABLE4 or DATA_SYNC4 are returned by the application, it can be expected that the client will follow up to ensure the data and metadata are written to stable storage. In this case, on_commit will fire.

If mandatory byte-range locking is in effect, and the current file has a read or write lock held by another client that conflicts with the data to be written, the operation should fail and Result should be set to NFS4ERR_LOCKED.

Example: Writing data to a file nfs.OnWrite += (o, e) => { if (e.Count == 0) { return; } try { IntPtr p = e.FileContext; GCHandle h = (GCHandle)p; FileStream fs = h.Target as FileStream; fs.Position = e.Offset; fs.Write(e.BufferB, 0, e.Count); fs.Flush(); // All data was written to disk, indicate this via Stable. e.Stable = FILE_SYNC4; } catch (Exception ex) { e.Result = NFS4ERR_IO; } };

The Result parameter will always be 0 (NFS4_OK) when this event fires. If the event cannot be handled successfully, set it to a nonzero value to report an appropriate error. Possible Result codes and their descriptions are listed in the NFS Result Codes section. Additional information regarding these result codes may be found in RFC 7530 Section 13.

NFS Config Settings

The class accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the config method.

NFS Config Settings

Base Config Settings

NFS Errors

NFS Errors