NTSTATUS
TdiMapUserRequest(
  IN  PDEVICE_OBJECT DeviceObject,
  IN  PIRP Irp,
  IN  PIO_STACK_LOCATION IrpSp
  );

Routine Description:

    This routine maps a user request from the NtDeviceIoControlFile format
    to the kernel mode request format. It does this by probing and locking all
    buffers of interest, copying parameter sets to the stack pointer as
    appropriate, and generally preparing for the kernel IO form.

Arguments:

    Irp - pointer to the irp containing this request.

Return Value:

    NTSTATUS - status of operation. STATUS_UNSUCCESSFUL if the request could
    not be mapped, STATUS_NOT_IMPLEMENTED if the IOCTL is not recognized
    (allowing driver writers to extend the supported IOCTLs if needed), and
    STATUS_SUCCESS if the request was mapped successfully.