GetVolumeInformation Function (Windows)

GetVolumeInformation Function

Language Filter

GetVolumeInformation Function

Retrieves information about the file system and volume associated with the specified root directory.

To specify a handle when retrieving this information, use the GetVolumeInformationByHandleW function.

To retrieve the current compression state of a file or directory, use FSCTL_GET_COMPRESSION.

Syntax

C++

BOOL WINAPI GetVolumeInformation(
  __in_opt   LPCTSTR lpRootPathName,
  __out      LPTSTR lpVolumeNameBuffer,
  __in       DWORD nVolumeNameSize,
  __out_opt  LPDWORD lpVolumeSerialNumber,
  __out_opt  LPDWORD lpMaximumComponentLength,
  __out_opt  LPDWORD lpFileSystemFlags,
  __out      LPTSTR lpFileSystemNameBuffer,
  __in       DWORD nFileSystemNameSize
);

Parameters

lpRootPathName [in, optional]

A pointer to a string that contains the root directory of the volume to be described.

If this parameter is NULL, the root of the current directory is used. A trailing backslash is required. For example, you specify \\MyServer\MyShare as "\\MyServer\MyShare\", or the C drive as "C:\".

lpVolumeNameBuffer [out]

A pointer to a buffer that receives the name of a specified volume. The maximum buffer size is MAX_PATH+1.

nVolumeNameSize [in]

The length of a volume name buffer, in TCHARs. The maximum buffer size is MAX_PATH+1.

This parameter is ignored if the volume name buffer is not supplied.

lpVolumeSerialNumber [out, optional]

A pointer to a variable that receives the volume serial number.

This parameter can be NULL if the serial number is not required.

This function returns the volume serial number that the operating system assigns when a hard disk is formatted. To programmatically obtain the hard disk's serial number that the manufacturer assigns, use the Windows Management Instrumentation (WMI) Win32_PhysicalMedia property SerialNumber.

lpMaximumComponentLength [out, optional]

A pointer to a variable that receives the maximum length, in TCHARs, of a file name component that a specified file system supports.

A file name component is the portion of a file name between backslashes.

The value that is stored in the variable that *lpMaximumComponentLength points to is used to indicate that a specified file system supports long names. For example, for a FAT file system that supports long names, the function stores the value 255, rather than the previous 8.3 indicator. Long names can also be supported on systems that use the NTFS file system.

lpFileSystemFlags [out, optional]

A pointer to a variable that receives flags associated with the specified file system.

This parameter can be one or more of the following flags. However, FS_FILE_COMPRESSION and FS_VOL_IS_COMPRESSED are mutually exclusive.

Value	Meaning
FILE_CASE_PRESERVED_NAMES 0x00000002	The specified volume supports preserved case of file names when it places a name on disk.
FILE_CASE_SENSITIVE_SEARCH 0x00000001	The specified volume supports case-sensitive file names.
FILE_FILE_COMPRESSION 0x00000010	The specified volume supports file-based compression.
FILE_NAMED_STREAMS 0x00040000	The specified volume supports named streams.
FILE_PERSISTENT_ACLS 0x00000008	The specified volume preserves and enforces access control lists (ACL). For example, the NTFS file system preserves and enforces ACLs, and the FAT file system does not.
FILE_READ_ONLY_VOLUME 0x00080000	The specified volume is read-only. Windows 2000: This value is not supported.
FILE_SEQUENTIAL_WRITE_ONCE 0x00100000	The specified volume supports a single sequential write. Windows 2000: This value is not supported.
FILE_SUPPORTS_ENCRYPTION 0x00020000	The specified volume supports the Encrypted File System (EFS). For more information, see File Encryption.
FILE_SUPPORTS_EXTENDED_ATTRIBUTES 0x00800000	The specified volume supports extended attributes. An extended attribute is a piece of application-specific metadata that an application can associate with a file and is not part of the file's data. Windows Server 2008, Windows Vista, Windows Server 2003, and Windows XP/2000: This value is not supported until Windows Server 2008 R2 and Windows 7.
FILE_SUPPORTS_HARD_LINKS 0x00400000	The specified volume supports hard links. For more information, see Hard Links and Junctions. Windows Server 2008, Windows Vista, Windows Server 2003, and Windows XP/2000: This value is not supported until Windows Server 2008 R2 and Windows 7.
FILE_SUPPORTS_OBJECT_IDS 0x00010000	The specified volume supports object identifiers.
FILE_SUPPORTS_OPEN_BY_FILE_ID 0x01000000	The file system supports open by FileID. For more information, see FILE_ID_BOTH_DIR_INFO. Windows Server 2008, Windows Vista, Windows Server 2003, and Windows XP/2000: This value is not supported until Windows Server 2008 R2 and Windows 7.
FILE_SUPPORTS_REPARSE_POINTS 0x00000080	The specified volume supports re-parse points.
FILE_SUPPORTS_SPARSE_FILES 0x00000040	The specified volume supports sparse files.
FILE_SUPPORTS_TRANSACTIONS 0x00200000	The specified volume supports transactions. For more information, see About KTM. Windows 2000: This value is not supported.
FILE_SUPPORTS_USN_JOURNAL 0x02000000	The specified volume supports update sequence number (USN) journals. For more information, see Change Journal Records. Windows Server 2008, Windows Vista, Windows Server 2003, and Windows XP/2000: This value is not supported until Windows Server 2008 R2 and Windows 7.
FILE_UNICODE_ON_DISK 0x00000004	The specified volume supports Unicode in file names as they appear on disk.
FILE_VOLUME_IS_COMPRESSED 0x00008000	The specified volume is a compressed volume, for example, a DoubleSpace volume.
FILE_VOLUME_QUOTAS 0x00000020	The specified volume supports disk quotas.

lpFileSystemNameBuffer [out]

A pointer to a buffer that receives the name of the file system, for example, the FAT file system or the NTFS file system. The maximum buffer size is MAX_PATH+1.

nFileSystemNameSize [in]

The length of the file system name buffer, in TCHARs. The maximum buffer size is MAX_PATH+1.

This parameter is ignored if the file system name buffer is not supplied.

Return Value

If all the requested information is retrieved, the return value is nonzero.

If not all the requested information is retrieved, the return value is zero. To get extended error information, call GetLastError.

Remarks

When a user attempts to get information about a floppy drive that does not have a floppy disk, or a CD-ROM drive that does not have a compact disc, the system displays a message box for the user to insert a floppy disk or a compact disc, respectively. To prevent the system from displaying this message box, call the SetErrorMode function with SEM_FAILCRITICALERRORS.

The FS_VOL_IS_COMPRESSED flag is the only indicator of volume-based compression. The file system name is not altered to indicate compression, for example, this flag is returned set on a DoubleSpace volume. When compression is volume-based, an entire volume is compressed or not compressed.

The FS_FILE_COMPRESSION flag indicates whether a file system supports file-based compression. When compression is file-based, individual files can be compressed or not compressed.

The FS_FILE_COMPRESSION and FS_VOL_IS_COMPRESSED flags are mutually exclusive. Both bits cannot be returned set.

The maximum component length value that is stored in lpMaximumComponentLength is the only indicator that a volume supports longer-than-normal FAT file system (or other file system) file names. The file system name is not altered to indicate support for long file names.

The GetCompressedFileSize function obtains the compressed size of a file. The GetFileAttributes function can determine whether an individual file is compressed.

Symbolic link behavior—

If the path points to a symbolic link, the function returns volume information for the target.

Transacted Operations

If the volume supports file system transactions, the function returns FILE_SUPPORTS_TRANSACTIONS in lpFileSystemFlags.

Requirements