[Rcom-l] Passing a COM object pointer does not work in the new rcom package

[Prokaj Vilmos]

Dear Thomas,

I think I finally catched the bug. In the bdx_com.c file in the
BDXScalar2Variant function the BDX_HANDLE case was handled in the 
following way:

case BDX_HANDLE:
      {
        LPSTREAM lStream = pBDXData->data.raw_data[0].ptr;
        void* lTmpPtr = (void*) V_DISPATCH(pVariantData);
        HRESULT lRc = CoUnmarshalInterface(lStream,&IID_IDispatch,
                                           &lTmpPtr);
//                      the problem is here ^
//      lTmpPtr first receives the value of V_DISPATCH(pvariantData),
// which is NULL, then this is overwritten with the required ptr,
// however V_DISPATCH(pvariantData) remains untouched,
        if(FAILED(lRc)) {
          BDX_ERR(printf("unmarshalling stream ptr %08x failed with hr=%08x\n",
                         lStream,lRc));
          return -1;
        } else {
          BDX_ERR(printf("successfully marshalled COM interface\n"));
// to see that this is really the problem change this line to
//   BDX_ERR(printf("successfully marshalled COM interface (%p %p)\n",
//   lTmpPtr,V_DISPATCH(pvariantData)));
        }

        /* create SEXP for COM object */
        V_VT(pVariantData) = VT_DISPATCH;
        break;
      }
A simple soultion is not to use a temporary pointer like below
case BDX_HANDLE:
      {
        LPSTREAM lStream = pBDXData->data.raw_data[0].ptr;
        //void* lTmpPtr;
        HRESULT lRc = CoUnmarshalInterface(lStream,&IID_IDispatch,
                                           (void *) &V_DISPATCH(pVariantData));
        if(FAILED(lRc)) {
          BDX_ERR(printf("unmarshalling stream ptr %08x failed with hr=%08x\n",
                         lStream,lRc));
          return -1;
        } else {
// Or copy the received value to the variant data structure like the
// commented line here
//          V_DISPATCH(pVariantData)=lTmpPtr ;
            BDX_ERR(printf("successfully marshalled COM interface (%p) \n",
                           //lTmpPtr,
                           V_DISPATCH(pVariantData)));
        }

        /* create SEXP for COM object */
        V_VT(pVariantData) = VT_DISPATCH;
        break;
      }

With either modification the reported problems disappear.

Best wishes
 Vilmos

--
Vilmos Prokaj
Eötvös Loránd University,
Department of Probability and Statistics
Pázmány Péter sétány 1/C
Budapest, 1117
Hungary

e-mail:[EMAIL PROTECTED]


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