FSRTL_COMMON_FCB_HEADER structure (ntifs.h)

Do not use the FSRTL_COMMON_FCB_HEADER structure outside of the FSRTL_ADVANCED_FCB_HEADER structure. The FSRTL_COMMON_FCB_HEADER structure contains context information that a file system maintains about a file, directory, volume, or alternate data stream.

Syntax

typedef struct _FSRTL_COMMON_FCB_HEADER {
  CSHORT        NodeTypeCode;
  CSHORT        NodeByteSize;
  UCHAR         Flags;
  UCHAR         IsFastIoPossible;
  UCHAR         Flags2;
  UCHAR         Reserved : 4;
  UCHAR         Version : 4;
  PERESOURCE    Resource;
  PERESOURCE    PagingIoResource;
  LARGE_INTEGER AllocationSize;
  LARGE_INTEGER FileSize;
  LARGE_INTEGER ValidDataLength;
} FSRTL_COMMON_FCB_HEADER;

Members

NodeTypeCode

Reserved for system use.

NodeByteSize

Reserved for system use.

Flags

Bitmask of flags that indicate support for various features. This member must be a bitwise OR combination of one or more of the following values:

IsFastIoPossible

This member must be one of the following values:

For more information about these values, see the reference entries for FsRtlAreThereCurrentFileLocks, FsRtlCopyRead, and FsRtlCopyWrite.

Flags2

Bitmask of flags that the file system sets to indicate support for various features. This member must be one or more of the following values:

The FSRTL_FLAG2_DO_MODIFIED_WRITE flag is used together with the FsContext2 member of the file object for the file stream as follows:

• If the FsContext2 member of the file object is non-NULL, the file stream represents an open instance of a file or a directory, and the value of this flag is ignored by the operating system.

• If the FsContext2 member of the file object is NULL, and this flag is not set, the file object is a stream file object, and the stream is a modified-no-write (MNW) stream.

• If the FsContext2 member of the file object is NULL, and this flag is set, the file object is a stream file object, and the stream is writable.

Reserved

Reserved for system use. Drivers must set this bit-field to zero.

Version

Reserved for system use. This bit-field is set by the FsRtlSetupAdvancedHeader or FsRtlSetupAdvancedHeaderEx macro. Starting with Windows Vista, the value of this bit-field is FSRTL_FCB_HEADER_V1 or greater; otherwise, the value is FSRTL_FCB_HEADER_V0. See FSRTL_ADVANCED_FCB_HEADER for more information.

Resource

Pointer to an initialized resource variable, for which the file system supplies the storage that will be used to synchronize I/O access to the FCB. The resource variable must be allocated from nonpaged pool.

Filter drivers should treat this member as opaque.

PagingIoResource

Pointer to an additional resource variable, for which the file system supplies the storage that will be used to synchronize paging I/O access to the FCB. The resource variable must be allocated from nonpaged pool.

Filter drivers should treat this member as opaque.

AllocationSize

Allocation size for the file stream.

For more information about the AllocationSize, FileSize, and ValidDataLength members, see CcInitializeCacheMap.

FileSize

File size of the file stream.

ValidDataLength

Valid data length of the file stream.

Remarks

File systems must set the FsContext member of every file object to point to an FSRTL_ADVANCED_FCB_HEADER structure. This structure can be embedded inside of a file-system-specific stream context object structure (the remainder of this structure is file-system-specific). Usually, the FSRTL_ADVANCED_FCB_HEADER structure is a file control block (FCB). However, on some file systems that support multiple data streams, such as NTFS, it is a stream control block (SCB).

To support filter manager and filter contexts, file systems must use the FSRTL_ADVANCED_FCB_HEADER structure in their stream context objects. All Microsoft file systems use this structure, and all third-party file system developers must do so as well. FCBs and SCBs for all classes of open requests, including volume open requests, must include this structure.

If the file is used as a paging file, the FSRTL_ADVANCED_FCB_HEADER structure must be allocated from nonpaged pool. Otherwise, it can be allocated from paged or nonpaged pool.

Requirements

See also

CcInitializeCacheMap

FSRTL_ADVANCED_FCB_HEADER

FSRTL_PER_STREAM_CONTEXT

FsRtlAreThereCurrentFileLocks

FsRtlCopyRead

FsRtlCopyWrite

FsRtlSetupAdvancedHeader

FsRtlSetupAdvancedHeaderEx