Wie DVD Transfer mit ShrinkTo5.DLL?

[Garfield]

In der Unit mit dem Formular:

Delphi-Quellcode:

function CallBack(alert, param: Integer; pTransfer, pUser: Pointer): Integer;
begin
  beep;
end;

...

  ShrinkTo5.CallBack        := CallBack;

...

Und in der Class TShrinkTo5:

Delphi-Quellcode:

type
  ...
  TFNCallBack                  = function(alert, param: Integer; pTransfer, pUser: Pointer): Integer; stdcall;
  TFNSetCallBack               = procedure(pCallBack, pUser: Pointer); stdcall;

type
  TShrinkTo5 = Class
  private
    fCallBack                   : TFNCallBack;
    pUser                       : Pointer;
    ...
  public
    property  CallBack          : TFNCallBack write FCallBack;
    ...
  end;


function TShrinkTo5.GetExecute: Integer;
{*******************************************************************************
*  Den Transfer beginnen.
}
type
  TThreadParams = record
    FNTransferPath : TFNTransferPath;
    TransferPath   : String;         
  end;
  PThreadParams = ^TThreadParams;
var
  ThreadParams : PThreadParams;
  hThread      : THandle;
  ThreadID     : Cardinal;
  lResult      : Cardinal;

  function Thread(p: PThreadParams): Cardinal;
  var
    PTransferPath  : PChar;
    PstopFlag      : PChar;
    FNTransferPath : TFNTransferPath;
    lResult        : Integer;
  begin
    PTransferPath  := PChar(PThreadParams(p)^.TransferPath);
    PstopFlag      := PChar('0');
    FNTransferPath := PThreadParams(p)^.FNTransferPath;
    lResult        := FNTransferPath(PTransferPath, PstopFlag);
    FreeMem(p, sizeof(TThreadParams));
    if lResult < 0
    then Result := $0FFFFFFF - lResult
    else Result := lResult;
  end;

begin
  Result := 0;
  if DirectoryExists(fTransferPath)
  and Assigned(FNTransferPath)
  then try
    {
    *  Das Callback setzen
    }
    pUser := nil;
    FNSetCallBack(@FCallBack, pUser);
    {
    *  Den Arbeitsthread erstellen
    }
    GetMem(ThreadParams, sizeof(TThreadParams));
    ThreadParams.FNTransferPath := FNTransferPath;
    ThreadParams.TransferPath   := fTransferPath;
    hThread := BeginThread(nil, 0, @Thread, ThreadParams, 0, ThreadID);
    if hThread <> INVALID_HANDLE_VALUE
    then begin
      while WaitForSingleObject(hThread, 300) = WAIT_TIMEOUT
      do Application.ProcessMessages;
      {
      *  return codes for TransferPath
      *    >0 success - number of MegaBytes written
      *     0 user aborted (stopFlag == 1)
      *    -2 if stream is scrambled and either descrambling failed or is disabled
      *    -5 source was not opened with "Open"
      *    -6 cannot authorize driveend;
      }
    end;
  finally
    GetExitCodeThread(hThread, lResult);
  end;
  if lResult > $0FFFfff0
  then Result := lResult - $0FFFFFFF
  else Result := lResult;
end;

So sieht die Procedure aus. Bin jetzt auf die Idee gekommen, das Projekt in OllyDebug (v2.0.0k von heute) anzusehen. Da steht dann

Code:

1000D23D | 8038 01 | CMP Byte PTR DS: [EAX], 1

Bei EAX steht 0000030. Was dann die Zugriffsverletzung darstellt.

Ich finde es irritierend, dass der Parameter pUser nicht mitgegeben wird. pUser als PInteger zu deklarieren, bringt keine Änderung.