Description

IOCTL_MOUNTDEV_QUERY_UNIQUE_ID retrieves a unique identifier for a device or volume.

Mount manager clients must support this IOCTL. Upon receiving this IOCTL, the mount manager client must provide a counted byte string identifier that is unique to the client (that is, the device or the volume).

Parameters

Major code

IRP_MJ_DEVICE_CONTROL

Input buffer

None.

Input buffer length

None.

Output buffer

The device class or volume driver returns the MOUNTDEV_UNIQUE_ID structure in the buffer at Irp->AssociatedIrp.SystemBuffer.

Output buffer length

Parameters.DeviceIoControl.OutputBufferLength in the I/O stack location of the IRP indicates the size, in bytes, of the output buffer, which must be greater than or equal to sizeof(MOUNTDEV_UNIQUE_ID).

Input/output buffer

N/A

Input/output buffer length

N/A

Status block

The Information field is set to FIELD_OFFSET(MOUNTDEV_UNIQUE_ID, UniqueId) + output->UniqueIdLength; or alternatively to sizeof(USHORT) + output->UniqueIdLength, where output points to the buffer at Irp->AssociatedIrp.SystemBuffer.

Remarks

The implementer of this function must not thread synchronize and must not make blocking and/or Interprocess Communication (IPC) function calls.

For more information, see Supporting Mount Manager Requests in a Storage Class Driver.

See also

MOUNTDEV_UNIQUE_ID