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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).
Major code
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.
Requirements
| Requirement | Value |
|---|---|
| Header | mountdev.h (include Mountdev.h) |