FIX: BSTR Passed to Method is Truncated at Double NULL When Marshalled in COM+ (277660)

MORE INFORMATION

Steps to Reproduce Behavior

1. With Microsoft Visual C++ 6.0 on a Windows 2000 computer, create a new Active Template Library (ATL) Project (DLL) and name the project PassBinaryBSTR.
2. On the Insert ATL Object menu, add a Simple Object to the DLL. Name the object PassBSTR, and accept all default settings.
3. Add the following methods to the IPassBSTR interface:

   [id(1)] HRESULT SaveData([in] BSTR bstrBinaryData);
   [id(2)] HRESULT DoTest();
   					

4. In PassBSTR.cpp, add the following code to implement the methods:

   /////////////////////////////////////////////////////////// 
   // Change these values to point to the location to output
   // the test results...
   // 
   LPCSTR pszNoMarshalResults = "C:\\ResultsInContext.txt";
   LPCSTR pszMarshaledResults = "C:\\ResultsOutOfContext.txt";
   
   STDMETHODIMP CPassBSTR::SaveData(BSTR bstrBinaryData)
   {
      HANDLE hFile;
      DWORD dwLen, dwWritten;
   
      hFile = CreateFile(pszMarshaledResults, 
                         GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, 0, NULL);
      if (hFile == INVALID_HANDLE_VALUE)
         return HRESULT_FROM_WIN32(GetLastError());
   
      dwLen = SysStringByteLen(bstrBinaryData);
   
      WriteFile(hFile, (void*)bstrBinaryData, dwLen, &dwWritten, NULL);
      CloseHandle(hFile);
      return (dwLen == dwWritten) ? S_OK : E_FAIL;
   }
   
   STDMETHODIMP CPassBSTR::DoTest()
   {
      HRESULT hr;
      HANDLE hFile;
      DWORD dwLen, dwWritten;
   
      IPassBSTR* ptest = NULL;
   
    // Create the binary data in a BSTR...
      BSTR bstrData = SysAllocStringByteLen("Test\0\0Binary Data!", 18);
      if (bstrData == NULL) return E_OUTOFMEMORY;
   
    // Do same code as the SaveData but runs inside context and works...
      hFile = CreateFile(pszNoMarshalResults,
                        GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, 0, NULL);
      if (hFile == INVALID_HANDLE_VALUE)
      {
         SysFreeString(bstrData);
         return HRESULT_FROM_WIN32(GetLastError());
      }
   
      dwLen = SysStringByteLen(bstrData);
      WriteFile(hFile, (void*)bstrData, dwLen, &dwWritten, NULL);
      CloseHandle(hFile);
   
    // Now create a new instance of this object in a different
    // context (that's why it's called CoCreateInstance). If this object is
    // configured in COM+, it loads in a new context and the problem
    // occurs. If it is loaded under normal COM/DCOM for cross-apartment 
    // calls, the problem does not occur...
    // 
      hr = CoCreateInstance(CLSID_PassBSTR, NULL, CLSCTX_SERVER,
                           IID_IPassBSTR, (void**)&ptest);
      if (FAILED(hr) || (ptest == NULL))
      {
         SysFreeString(bstrData);
         return (hr) ? hr : E_UNEXPECTED;
      }
   
    // Have the out-of-context object save the binary data...
      hr = ptest->SaveData(bstrData);
   
      ptest->Release();
      SysFreeString(bstrData);
      return hr;
   }
   					

5. Compile the ATL DLL. ATL registers the DLL as a COM component.
6. On the Start menu, select Administrative Tools, and then select the Component Services tool to create a new COM+ package.
7. Add the PassBinaryBSTR.PassBSTR object to the package.
8. From Visual Basic, Visual Basic for Applications, or VBScript, run the following code to run the DLL:

   Sub RunIt()
      Dim x
      Set x = CreateObject("PassBinaryBSTR.PassBSTR")
      x.DoTest
      MsgBox "Done. Check the files for results."
   End Sub
   					

9. Note that the ResultsInContext.txt file contains the full binary string in the BSTR. The ResultsOutOfContext.txt file shows that the string was truncated at the double NULL bytes when the BSTR was passed, leaving just the word "Test" in the file.