Removes the object identifier from a specified file or directory. The underlying object is not deleted.

BOOL DeviceIoControl(
  (HANDLE) hDevice,            // handle to device
  FSCTL_DELETE_OBJECT_ID,      // dwIoControlCode
  NULL,                        // lpInBuffer
  0,                           // nInBufferSize
  NULL,                        // lpOutBuffer
  0,                           // nOutBufferSize
  (LPDWORD) lpBytesReturned,   // number of bytes returned
  (LPOVERLAPPED) lpOverlapped  // OVERLAPPED structure
);

Parameters

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

hDevice

The handle to the file or directory from the object identifier that is to be deleted.

The process of opening the file must have restore privilege, and the file must be opened with restore intent and write access. To retrieve a handle, call the CreateFile function.

dwIoControlCode

The control code for the operation.

Use FSCTL_DELETE_OBJECT_ID for this operation.

lpInBuffer

Not used with this operation; set to NULL.

nInBufferSize

Not used with this operation; set to 0 (zero).

lpOutBuffer

Not used with this operation; set to NULL.

nOutBufferSize

Not used with this operation; set to 0 (zero).

lpBytesReturned

A pointer to a variable that receives the size of the data stored in the output buffer, in bytes.

If lpOverlapped is NULL, lpBytesReturned cannot be NULL. Even when an operation returns no output data and lpOutBuffer is NULL, DeviceIoControl uses lpBytesReturned. After such an operation, the value of lpBytesReturned is meaningless.

If lpOverlapped is not NULL, lpBytesReturned can be NULL. If this parameter is not NULL and the operation returns data, lpBytesReturned is meaningless until the overlapped operation is complete. To retrieve the number of bytes returned, call GetOverlappedResult. If hDevice is associated with an I/O completion port, you can retrieve the number of bytes returned by calling GetQueuedCompletionStatus.

lpOverlapped

A pointer to an OVERLAPPED structure.

If hDevice is opened without specifying FILE_FLAG_OVERLAPPED, lpOverlapped is ignored.

If hDevice is opened with the FILE_FLAG_OVERLAPPED flag, the operation is performed as an overlapped (asynchronous) operation. In this case, lpOverlapped must point to a valid OVERLAPPED structure that contains a handle to an event object. Otherwise, the function fails in unpredictable ways.

For overlapped operations, DeviceIoControl returns immediately, and the event object is signaled when the operation is complete. Otherwise, the function does not return until the operation is complete or an error occurs.

Return Value

If the operation completes successfully, DeviceIoControl returns a nonzero value.

If the operation fails or is pending, DeviceIoControl returns 0 (zero). To get extended error information, call GetLastError.

Remarks

Object identifiers are used to track 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.

Requirements

See Also

CreateFile

DeviceIoControl

FSCTL_CREATE_OR_GET_OBJECT_ID

FSCTL_GET_OBJECT_ID

FSCTL_SET_OBJECT_ID

FSCTL_SET_OBJECT_ID_EXTENDED

Object Identifiers

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Build date: 11/12/2009