FltNotifyFilterChangeDirectory function (fltkernel.h)

Article
10/21/2021

The FltNotifyFilterChangeDirectory routine creates a notify structure for an IRP_MN_NOTIFY_CHANGE_DIRECTORY operation and adds it to the specified notify list.

Syntax

VOID FLTAPI FltNotifyFilterChangeDirectory(
  [in, out]      PNOTIFY_SYNC               NotifySync,
  [in, out]      PLIST_ENTRY                NotifyList,
  [in]           PVOID                      FsContext,
  [in]           PSTRING                    FullDirectoryName,
  [in]           BOOLEAN                    WatchTree,
  [in]           BOOLEAN                    IgnoreBuffer,
  [in]           ULONG                      CompletionFilter,
  [in]           PFLT_CALLBACK_DATA         NotifyCallbackData,
  [in, optional] PCHECK_FOR_TRAVERSE_ACCESS TraverseCallback,
  [in, optional] PSECURITY_SUBJECT_CONTEXT  SubjectContext,
  [in, optional] PFILTER_REPORT_CHANGE      FilterCallback
);

Parameters

[in, out] NotifySync

Pointer to an opaque synchronization object for the change directory notify list that the NotifyList parameter points to.

[in, out] NotifyList

Pointer to the head of the change directory notify list for the current volume. Each element in the list is an opaque notify structure.

[in] FsContext

Pointer to a unique value assigned by the caller to identify the notify structure to be created. If a callback routine is supplied in the TraverseCallback parameter, FsContext is passed as the NotifyContext parameter to that routine.

[in] FullDirectoryName

Pointer to an ANSI or Unicode string that contains the full name for the directory associated with this notify structure.

[in] WatchTree

Set to TRUE if all subdirectories of the directory that is specified by the FullDirectoryName parameter should also be watched. Set to FALSE if only the directory itself is to be watched.

[in] IgnoreBuffer

Set to TRUE to ignore any user buffers and force the directory to be reenumerated. This action speeds the operation.

[in] CompletionFilter

Bitmask of flags that specify the types of changes to files or directories that should cause the callback data structures in the notify list to be completed. The possible flag values are described in the following table.

Flag	Meaning
FILE_NOTIFY_CHANGE_FILE_NAME	A file has been added, deleted, or renamed in this directory.
FILE_NOTIFY_CHANGE_DIR_NAME	A subdirectory has been created, removed, or renamed.
FILE_NOTIFY_CHANGE_NAME	This directory's name has changed.
FILE_NOTIFY_CHANGE_ATTRIBUTES	The value of an attribute of this file, such as last access time, has changed.
FILE_NOTIFY_CHANGE_SIZE	This file's size has changed.
FILE_NOTIFY_CHANGE_LAST_WRITE	This file's last modification time has changed.
FILE_NOTIFY_CHANGE_LAST_ACCESS	This file's last access time has changed.
FILE_NOTIFY_CHANGE_CREATION	This file's creation time has changed.
FILE_NOTIFY_CHANGE_EA	This file's extended attributes have been modified.
FILE_NOTIFY_CHANGE_SECURITY	This file's security information has changed.
FILE_NOTIFY_CHANGE_STREAM_NAME	A file stream has been added, deleted, or renamed in this directory.
FILE_NOTIFY_CHANGE_STREAM_SIZE	This file stream's size has changed.
FILE_NOTIFY_CHANGE_STREAM_WRITE	This file stream's data has changed.

[in] NotifyCallbackData

Pointer to the callback data structure for the operation to be added to the notify list. This parameter is required and cannot be NULL.

[in, optional] TraverseCallback

Optional pointer to a callback routine to be invoked when a change occurs in a subdirectory that is being watched in a directory tree. This pointer lets the file system check whether the watcher has traverse access to that directory. Such a caller-supplied routine is declared as follows:

NTSTATUS
(*PCHECK_FOR_TRAVERSE_ACCESS) (
    IN PVOID NotifyContext,                     // FsContext
    IN PVOID TargetContext,                     // Context pointer
    IN PSECURITY_SUBJECT_CONTEXT SubjectContext // SubjectContext
    );

For more information about the TargetContext parameter, see the TargetContext parameter of the FsRtlNotifyFullReportChange routine.

[in, optional] SubjectContext

Pointer to a context structure to be passed to TraverseCallback. FltNotifyFilterChangeDirectory releases the context and frees the structure after using it. If a TraverseCallback routine is supplied, SubjectContext is passed as the SubjectContext parameter to that routine.

[in, optional] FilterCallback

Optional pointer to a callback routine to be invoked when a change occurs to the directory. If this callback routine returns TRUE, FsRtlNotifyFilterReportChange completes the pending IRP_MN_NOTIFY_CHANGE_DIRECTORY operations in the notify list; otherwise, it does not. Such a caller-supplied routine is declared as follows:

BOOLEAN
(*PFILTER_REPORT_CHANGE) (
    IN PVOID NotifyContext,                     // FsContext
    IN PVOID FilterContext                      // Context pointer
    );

Return value

None

Remarks

A minifilter driver can call FltNotifyFilterChangeDirectory from the preoperation callback routine (PFLT_PRE_OPERATION_CALLBACK) that it registered to process notify change directory operations. These operations have a major function code of IRP_MJ_DIRECTORY_CONTROL and a minor function code of IRP_MN_NOTIFY_CHANGE_DIRECTORY.

The minifilter driver calls FltNotifyFilterChangeDirectory to create a notify structure to hold the callback data structure for the operation and add the notify structure to the notify list for the current volume.

FltNotifyFilterChangeDirectory does the following:

Checks whether the operation's file object has been cleaned up. If so, FltNotifyFilterChangeDirectory completes the operation with status STATUS_NOTIFY_CLEANUP and does not add it to the notify list.
If the operation's file object has not been cleaned up, FltNotifyFilterChangeDirectory checks whether the notify list already contains a notify structure for the given FsContext value. If such a notify structure is found, and there are pending changes to report, FltNotifyFilterChangeDirectory completes the callback data structure pointed to by the NotifyCallbackData parameter. If a notify structure is found, but there are no pending changes to report, FltNotifyFilterChangeDirectory adds the operation to the notify structure. If no such notify structure is found, FltNotifyFilterChangeDirectory creates a notify structure for the operation and inserts it into the list.

When a change occurs to the directory, the file system calls FsRtlNotifyFilterReportChange to complete the pending IRP_MN_NOTIFY_CHANGE_DIRECTORY operations in the notify list.

Requirements

Requirement	Value
Target Platform	Universal
Header	fltkernel.h (include Fltkernel.h)
Library	FltMgr.lib
DLL	Fltmgr.sys
IRQL	<= APC_LEVEL