Как заблокировать доступ к дисководу?

const


 FILE_DEVICE_FILE_SYSTEM: Integer = $00000009;
 METHOD_BUFFERED: Integer = $00000000;
 FILE_ANY_ACCESS: Integer = $00000000;

function CTL_CODE(DeviceType, FunctionNo, Method, Access: Integer): Integer;
begin
 Result := (DeviceType shl 16) or (Access shl 14) or (FunctionNo shl 2) or (Method);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
 LHandle: THandle;
 BytesReturned: Cardinal;
 MsgBuf: PChar;
 FSCTL_LOCK_VOLUME: Integer;
begin
 FSCTL_LOCK_VOLUME := CTL_CODE(FILE_DEVICE_FILE_SYSTEM, 6,
                               METHOD_BUFFERED, FILE_ANY_ACCESS);
 LHandle := CreateFile('\\.\A:', GENERIC_READ or GENERIC_WRITE,
                       FILE_SHARE_READ or FILE_SHARE_WRITE, nil,
                       OPEN_EXISTING,
                       FILE_ATTRIBUTE_NORMAL or FILE_FLAG_DELETE_ON_CLOSE, 0);
 if LHandle <> 0 then
 begin
   if DeviceIOControl(LHandle, FSCTL_LOCK_VOLUME, nil, 0, nil, 0, BytesReturned, nil) then
     ShowMessage('Дисковод заблокирован. Нажмите ОК для разблокирования.')
   else
   begin
     if FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER or
          FORMAT_MESSAGE_FROM_SYSTEM, nil, GetLastError(), 0, @MsgBuf, 0, nil) > 0 then
     begin
       ShowMessage('Ошибка DeviceIOControl: ' + MsgBuf);
       LocalFree(Cardinal(MsgBuf));
     end
     else
       ShowMessage('Ошибка при вызове DeviceIOControl!');
   end;
   CloseHandle(LHandle);
 end
 else
   ShowMessage('Ошибка при вызове CreateFile!');
end;