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        04、注册FsFilter回调例程：

        FsFilter通知回调例程在下层文件系统执行某些操作之前或之后调用。如果需要获取更多有关于FsFilter回调例程相关信息，可参见FsRtlRegisterFileSystemFilterCallbacks例程
        为了注册FsFilter的通知回调例程必须分配并初始化FS_FILTER_CALLBACKS结构体，然后向该结构体中促出FsFilter回调例 程，并将存储有Callbacks parameter到FsRtlRegisterFileSystemFilterCallbacks中。
        例如：FileSpy驱动范例按如下方式注册FsFilter回调。

fsFilterCallbacks.SizeOfFsFilterCallbacks = sizeof(FS_FILTER_CALLBACKS);
fsFilterCallbacks.PreAcquireForSectionSynchronization = SpyPreFsFilterOperation;
fsFilterCallbacks.PostAcquireForSectionSynchronization = SpyPostFsFilterOperation;
fsFilterCallbacks.PreReleaseForSectionSynchronization = SpyPreFsFilterOperation;
fsFilterCallbacks.PostReleaseForSectionSynchronization = SpyPostFsFilterOperation;
fsFilterCallbacks.PreAcquireForCcFlush = SpyPreFsFilterOperation;
fsFilterCallbacks.PostAcquireForCcFlush = SpyPostFsFilterOperation;
fsFilterCallbacks.PreReleaseForCcFlush = SpyPreFsFilterOperation;
fsFilterCallbacks.PostReleaseForCcFlush = SpyPostFsFilterOperation;
fsFilterCallbacks.PreAcquireForModifiedPageWriter = SpyPreFsFilterOperation;
fsFilterCallbacks.PostAcquireForModifiedPageWriter = SpyPostFsFilterOperation;
fsFilterCallbacks.PreReleaseForModifiedPageWriter = SpyPreFsFilterOperation;
fsFilterCallbacks.PostReleaseForModifiedPageWriter = SpyPostFsFilterOperation;

status = FsRtlRegisterFileSystemFilterCallbacks(DriverObject, &fsFilterCallbacks);

MSDN的详细解释

File system filter drivers call the FsRtlRegisterFileSystemFilterCallbacks routine to register notification callback routines to be invoked when the underlying file system performs certain operations.

文件系统过滤驱动调用 FsRtlRegisterFileSystemFilterCallbacks 函数注册需通知回调函数，这些回调函数将在文件系统的相关操作之前被调用

				
						
NTSTATUS
				
  FsRtlRegisterFileSystemFilterCallbacks(
    IN PDRIVER_OBJECT  FilterDriverObject,
    IN PFS_FILTER_CALLBACKS  Callbacks
    ); 

Parameters

FilterDriverObject

Pointer to the driver object for the filter driver.

Callbacks

Pointer to a structure that contains the entry points of caller-supplied notification callback routines.

This structure is defined as follows.

Note: All of the callback entry points are optional and can be NULL.

typedef struct _FS_FILTER_CALLBACKS {
    ULONG SizeOfFsFilterCallbacks;
    ULONG Reserved;
    PFS_FILTER_CALLBACK PreAcquireForSectionSynchronization;
    PFS_FILTER_COMPLETION_CALLBACK PostAcquireForSectionSynchronization;
    PFS_FILTER_CALLBACK PreReleaseForSectionSynchronization;
    PFS_FILTER_COMPLETION_CALLBACK PostReleaseForSectionSynchronization;
    PFS_FILTER_CALLBACK PreAcquireForCcFlush;
    PFS_FILTER_COMPLETION_CALLBACK PostAcquireForCcFlush;
    PFS_FILTER_CALLBACK PreReleaseForCcFlush;
    PFS_FILTER_COMPLETION_CALLBACK PostReleaseForCcFlush;
    PFS_FILTER_CALLBACK PreAcquireForModifiedPageWriter;
    PFS_FILTER_COMPLETION_CALLBACK PostAcquireForModifiedPageWriter;
    PFS_FILTER_CALLBACK PreReleaseForModifiedPageWriter;
    PFS_FILTER_COMPLETION_CALLBACK PostReleaseForModifiedPageWriter;
} FS_FILTER_CALLBACKS, *PFS_FILTER_CALLBACKS;

The filter callback routine and its parameters are defined as follows:

typedef
NTSTATUS (*PFS_FILTER_CALLBACK) (
              IN PFS_FILTER_CALLBACK_DATA Data,
              OUT PVOID *CompletionContext
              );

Parameter	Meaning
Data	Pointer to the callback data structure for this operation.  指向这个操作的回调数据结构
CompletionContext	Context information to be passed to the filter completion callback routine. Set to NULL if no context information is to be passed or if there is no corresponding filter completion callback routine.  传给过滤器完成回调函数的上下文信息

The filter completion callback routine and its parameters are defined as follows:

typedef
VOID (*PFS_FILTER_COMPLETION_CALLBACK) (
          IN PFS_FILTER_CALLBACK_DATA Data,
          IN NTSTATUS OperationStatus,
          IN PVOID CompletionContext
          );

Parameter	Meaning
Data	Pointer to the callback data structure for this operation.
OperationStatus	Status of the operation. If the file system successfully performed the operation, this parameter is set to STATUS_SUCCESS. Otherwise, it is set to an appropriate error status value.
CompletionContext	Context information that was set in the filter callback routine. This is set to NULL if no information is passed or if there is no corresponding filter callback routine.

The callback data structure and its members are defined as follows:

typedef struct _FS_FILTER_CALLBACK_DATA {
    ULONG SizeOfFsFilterCallbackData;
    UCHAR Operation;
    UCHAR Reserved;
    struct _DEVICE_OBJECT *DeviceObject;
    struct _FILE_OBJECT *FileObject;
    FS_FILTER_PARAMETERS Parameters;
} FS_FILTER_CALLBACK_DATA, *PFS_FILTER_CALLBACK_DATA;

Member	Meaning
SizeOfFsFilterCallbackData	Size of the callback data structure.
Operation	File system operation for which the callback routine is to be invoked. This operation can be of the following: FS_FILTER_ACQUIRE_FOR_SECTION_SYNCHRONIZATION FS_FILTER_RELEASE_FOR_SECTION_SYNCHRONIZATION FS_FILTER_ACQUIRE_FOR_MOD_WRITE FS_FILTER_RELEASE_FOR_MOD_WRITE FS_FILTER_ACQUIRE_FOR_CC_FLUSH FS_FILTER_RELEASE_FOR_CC_FLUSH
Reserved	Reserved for system use.
DeviceObject	Device object for this operation.
FileObject	File object for this operation.
Parameters	Union containing any operation-specific parameters.

The filter parameter union is defined as follows:

typedef union _FS_FILTER_PARAMETERS {
    struct {
        PLARGE_INTEGER EndingOffset;
        PERESOURCE *ResourceToRelease;
    } AcquireForModifiedPageWriter;
    struct {
        PERESOURCE ResourceToRelease;
    } ReleaseForModifiedPageWriter;
    struct {
        FS_FILTER_SECTION_SYNC_TYPE SyncType;
        ULONG PageProtection;
    } AcquireForSectionSynchronization;
    struct {
        PVOID Argument1;
        PVOID Argument2;
        PVOID Argument3;
        PVOID Argument4;
        PVOID Argument5;
    } Others;
} FS_FILTER_PARAMETERS, *PFS_FILTER_PARAMETERS;

Parameter	Meaning
EndingOffset	Offset of the last byte being written plus one.
ResourceToRelease	Resource to be released.
SyncType	Type of synchronization requested for the section: SyncTypeCreateSection if a section is being created, SyncTypeOther otherwise.
PageProtection	Type of page protection requested for the section. Must be zero if SyncType is SyncTypeOther. Otherwise, one of the following flags, possibly ORed with PAGE_NOCACHE: PAGE_READONLY PAGE_READWRITE PAGE_WRITECOPY PAGE_EXECUTE
Argument1	Reserved for future use.
Argument2	Reserved for future use.
Argument3	Reserved for future use.
Argument4	Reserved for future use.
Argument5	Reserved for future use.

Return Value

FsRtlRegisterFileSystemFilterCallbacks can return one of the following status values:

STATUS_SUCCESS

The callback routines were successfully registered.

STATUS_INSUFFICIENT_RESOURCES

FsRtlRegisterFileSystemFilterCallbacks encountered a pool allocation failure when allocating memory to store the callback information.

STATUS_INVALID_PARAMETER

One of the parameters is invalid.

Comments

FsRtlRegisterFileSystemFilterCallbacks should only be called by file system filter drivers, and only from the filter's DriverEntry routine.

FsRtlRegisterFileSystemFilterCallbacks registers the notification callback routines that were specified in the Callbacks parameter to be invoked when requests for certain file operations are sent to the underlying file system.

Callback routines are currently defined for the following operations:

Operation	Notification Callback Routine and Callback Completion Routine
The memory manager acquires a file exclusively before creating a memory-mapped section for a portion of the file. Note: For this operation, SyncType is set to SyncTypeCreateSection.	PreAcquireForSectionSynchronization PostAcquireForSectionSynchronization
The memory manager releases a file after creating a memory-mapped section for a portion of the file.	PreReleaseForSectionSynchronization PostReleaseForSectionSynchronization
A kernel component (such as the cache manager) acquires a file exclusively before temporarily disabling section creation for a portion of the file. Note: For this operation, SyncType is set to SyncTypeOther.	PreAcquireForSectionSynchronization PostAcquireForSectionSynchronization Note: PreAcquireForSectionSynchronization should always return a success status code (such as STATUS_SUCCESS) for this operation. Returning any other type of status code causes the system to ASSERT on a checked build. (On free builds, the status code is ignored.)
A kernel component (such as the cache manager) releases a file after temporarily disabling section creation for a portion of the file.	PreReleaseForSectionSynchronization PostReleaseForSectionSynchronization
The cache manager acquires a file exclusively before flushing a portion of the file from the cache.	PreAcquireForCcFlush PostAcquireForCcFlush
The cache manager releases a file after flushing a portion of the file from the cache.	PreReleaseForCcFlush PostReleaseForCcFlush
The modified page writer acquires a file exclusively before writing a portion of the file to disk.	PreAcquireForModifiedPageWriter PostAcquireForModifiedPageWriter
The modified page writer releases a file after writing a portion of the file to disk.	PreReleaseForModifiedPageWriter PostReleaseForModifiedPageWriter

The filter notification callback routine is invoked before the operation request is passed to lower-level filter drivers and the underlying file system. In the callback routine, the filter driver should perform any needed processing and immediately return STATUS_SUCCESS. If a filter driver's callback routine returns a status value other than STATUS_SUCCESS, this causes the operation request to fail. Repeated failure of certain requests, such as locking requests, can halt system progress. Thus, filter drivers should fail such a request only when absolutely necessary. When failing these requests, the filter driver should return an error status value that describes the error as completely and accurately as possible.

Note  A filter driver's notification callback routine cannot fail a request to release a file system resource. If a filter driver returns a status value other than STATUS_SUCCESS from any of the following notification callback routines, the status value is ignored.

• PreReleaseForSectionSynchronization
• PreReleaseForCcFlush
• PreReleaseForModifiedPageWriter

The filter completion callback routine is invoked after the operation request is passed to lower-level filter drivers and the underlying file system. In the completion callback routine, the filter driver must perform any needed processing and immediately return.

The callback routines defined by FsRtlRegisterFileSystemFilterCallbacks supersede the following fast I/O callback routines, which are obsolete and should not be used by file system filter drivers:

• AcquireForCcFlush
• AcquireFileForNtCreateSection
• AcquireForModWrite
• ReleaseForCcFlush
• ReleaseFileForNtCreateSection
• ReleaseForModWrite

Requirements

Versions: This routine is available on Update Rollup for Windows 2000 Service Pack 4 (SP4) and on Microsoft Windows XP and later.

IRQL: Any level

Headers: Declared in Ntifs.h. Include Ntifs.h.