FSCTL_SET_OBJECT_ID

Using the FSCTL_SET_OBJECT_ID control code sets a file system object identifier for an existing, open object in a Windows 2000 NTFS file system.

To perform this operation, call the DeviceIoControl function with the following parameters.

BOOL DeviceIoControl(
  (HANDLE) hDevice,           // handle to device
  FSCTL_SET_OBJECT_ID,        // dwIoControlCode operation
  (LPVOID) lpInBuffer,        // input buffer
  (DWORD) nInBufferSize,      // size of input buffer
  NULL,                       // lpOutBuffer; must be NULL
  0,                          // nOutBufferSize; must be zero
  (LPDWORD) lpBytesReturned,  // number of bytes returned
  (LPOVERLAPPED) lpOverlapped // OVERLAPPED structure
);

Parameters

hDevice

[in] Handle to the directory, file, or alternate stream on which the object identifier is to be set. The HANDLE object must describe a file or directory that is open with restore privilege. To obtain a device handle, call the CreateFile function.

dwIoControlCode

[in] Control code for the operation. This value identifies the specific operation to be performed and the type of device on which to perform it. Use FSCTL_SET_OBJECT_ID for this operation.

lpInBuffer

[in] Pointer to the input buffer, a FILE_OBJECTID_BUFFER structure.

nInBufferSize

[in] Size, in bytes, of the input buffer, FILE_OBJECTID_BUFFER.

lpOutBuffer

[out] Pointer to the output buffer. Not used; must be NULL.

nOutBufferSize

[in] Size, in bytes, of the output buffer. Not used; must be zero.

lpBytesReturned

[out] Pointer to a variable that receives the actual count of bytes returned by the function in the output buffer. The lpBytesReturned value is meaningless because there is no output buffer. With an asynchronous call, the programmer must provide a non-NULL pointer to a valid value.

If lpOverlapped is NULL (nonoverlapped I/O), lpBytesReturned is used internally and cannot be NULL.

If lpOverlapped is not NULL (overlapped I/O), lpBytesReturned can be NULL.

lpOverlapped

[in] Pointer to an OVERLAPPED structure.

If hDevice was opened with the FILE_FLAG_OVERLAPPED flag, lpOverlapped must point to a valid OVERLAPPED structure. In this case, DeviceIoControl is performed as an overlapped (asynchronous) operation. If the device was opened with the FILE_FLAG_OVERLAPPED flag and lpOverlapped is NULL, the function fails in unpredictable ways.

If hDevice was opened without specifying the FILE_FLAG_OVERLAPPED flag, lpOverlapped is ignored and DeviceIoControl does not return until the operation has been completed, or until an error occurs.

Return Values

If the operation succeeds, DeviceIoControl returns a nonzero value.

If the operation fails, DeviceIoControl returns zero. To get extended error information, call GetLastError.

Remarks

Object identifiers are Windows 2000 internal objects used by the operating system to track other objects such as files and directories. They are invisible to most applications and should never be modified by applications. Modifying an object identifier can result in the loss of data from portions of a file, up to and including entire volumes of data. Also, there is no guarantee that code to manipulate object identifiers will be forward compatible with future versions of Windows. Therefore, use standard Win32 functions to manipulate object identifiers and other operating system objects.

Use this operation to explicitly set an object identifier to a value you provide. The value must be a value unique to the volume. Use the FSCTL_CREATE_OR_GET_OBJECT_ID operation to have NTFS generate an object identifier if the object does not already have one.

An attempt to set an object identifier on an object that already has an object identifier will fail. An attempt to use an object identifier that already exists in the volume will also fail.

Requirements

  Windows NT/2000: Requires Windows 2000.
  Windows 95/98: Unsupported.
  Header: Declared in Winioctl.h.

See Also

Device Input and Output Overview, Device Input and Output Control Codes, DeviceIoControl, CreateFile, FILE_OBJECTID_BUFFER, FSCTL_CREATE_OR_GET_OBJECT_ID, FSCTL_GET_OBJECT_ID, FSCTL_SET_OBJECT_ID, FSCTL_SET_OBJECT_ID_EXTENDED