FILE_ID_BOTH_DIR_INFORMATION structure (ntifs.h)

The FILE_ID_BOTH_DIR_INFORMATION structure is used to query file reference number information for the files in a directory.

Syntax

typedef struct _FILE_ID_BOTH_DIR_INFORMATION {
  ULONG         NextEntryOffset;
  ULONG         FileIndex;
  LARGE_INTEGER CreationTime;
  LARGE_INTEGER LastAccessTime;
  LARGE_INTEGER LastWriteTime;
  LARGE_INTEGER ChangeTime;
  LARGE_INTEGER EndOfFile;
  LARGE_INTEGER AllocationSize;
  ULONG         FileAttributes;
  ULONG         FileNameLength;
  ULONG         EaSize;
  CCHAR         ShortNameLength;
  WCHAR         ShortName[12];
  LARGE_INTEGER FileId;
  WCHAR         FileName[1];
} FILE_ID_BOTH_DIR_INFORMATION, *PFILE_ID_BOTH_DIR_INFORMATION;

Members

NextEntryOffset

Byte offset of the next FILE_ID_BOTH_DIR_INFORMATION entry, if multiple entries are present in a buffer. This member is zero if no other entries follow this one.

FileIndex

Byte offset of the file within the parent directory. This member is undefined for file systems, such as NTFS, in which the position of a file within the parent directory is not fixed and can be changed at any time to maintain sort order.

CreationTime

Time when the file was created.

LastAccessTime

Last time the file was accessed.

LastWriteTime

Last time information was written to the file.

ChangeTime

Last time the file was changed.

EndOfFile

Absolute new end-of-file position as a byte offset from the start of the file. EndOfFile specifies the byte offset to the end of the file. Because this value is zero-based, it actually refers to the first free byte in the file. In other words, EndOfFile is the offset to the byte immediately following the last valid byte in the file.

AllocationSize

File allocation size, in bytes. Usually, this value is a multiple of the sector or cluster size of the underlying physical device.

FileAttributes

File attributes, which can be any valid combination of the following:

• FILE_ATTRIBUTE_READONLY
• FILE_ATTRIBUTE_HIDDEN
• FILE_ATTRIBUTE_SYSTEM
• FILE_ATTRIBUTE_DIRECTORY
• FILE_ATTRIBUTE_ARCHIVE
• FILE_ATTRIBUTE_NORMAL
• FILE_ATTRIBUTE_TEMPORARY
• FILE_ATTRIBUTE_COMPRESSED

FileNameLength

Specifies the length, in bytes, of the file name string.

EaSize

Combined length, in bytes, of the extended attributes (EA) for the file.

ShortNameLength

Specifies the length of the short file name string.

ShortName[12]

Unicode string containing the short (8.3) name for the file.

FileId

The 8-byte file reference number for the file. This number is generated and assigned to the file by the file system. (Note that the FileId is not the same as the 16-byte "file object ID" that was added to NTFS for Microsoft Windows 2000.)

FileName[1]

Specifies the first character of the file name string. This is followed in memory by the remainder of the string.

Remarks

This information can be queried in either of the following ways:

• Call ZwQueryDirectoryFile, passing FileIdBothDirectoryInformation as the value of FileInformationClass and passing a caller-allocated, FILE_ID_BOTH_DIR_INFORMATION-structured buffer as the value of FileInformation.

• Create an IRP with major function code IRP_MJ_DIRECTORY_CONTROL and minor function code IRP_MN_QUERY_DIRECTORY.

No specific access rights are required to query this information.

File reference numbers, also called file IDs, are guaranteed to be unique only within a static file system. They are not guaranteed to be unique over time, because file systems are free to reuse them. Nor are they guaranteed to remain constant. For example, the FAT file system generates the file reference number for a file from the byte offset of the file's directory entry record (DIRENT) on the disk. Defragmentation can change this byte offset. Thus a FAT file reference number can change over time.

All dates and times are in absolute system-time format. Absolute system time is the number of 100-nanosecond intervals since the start of the year 1601.

This structure must be aligned on a LONGLONG (8-byte) boundary. If a buffer contains two or more of these structures, the NextEntryOffset value in each entry, except the last, falls on an 8-byte boundary.

Requirements

Requirement	Value
Header	ntifs.h (include Ntifs.h, Fltkernel.h)

See also

FsRtlNotifyFullChangeDirectory

IRP_MJ_DIRECTORY_CONTROL

ZwQueryDirectoryFile