Lock floppy drive functions

Problem/Question/Abstract:

How can I lock a floppy drive so that it cannot access system functions like copy, move between hard disks etc.?

Answer:

The following code works for WinNT. You may need to enclose the main calls (CreateFile, DeviceIoControl, CloseHandle) inside a loop with a sleep interval because it fails sometimes.

{ ... }
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('Drive locked. Press OK to unlock.')
    else
    begin
      if FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER or
        FORMAT_MESSAGE_FROM_SYSTEM, nil, GetLastError(), 0, @MsgBuf, 0, nil) > 0 then
      begin
        ShowMessage('DeviceIOControl failed: ' + MsgBuf);
        LocalFree(Cardinal(MsgBuf));
      end
      else
        ShowMessage('DeviceIOControl failed!');
    end;
    CloseHandle(LHandle);
  end
  else
    ShowMessage('CreateFile failed!');
end;