FIX: ADO Recordset GetString() Function Throws an Access Violation in Oleaut32.dll (230276)

MORE INFORMATION

Steps to Reproduce the Behavior

1. Create a Win32 console application (Simple application) in Visual C++.
2. Paste the following code to replace code generated in the .cpp file:
   
   Note You must change User ID=<username> and Password =<strong password> to the correct values before you run this code. Make sure that User ID has the appropriate permissions to perform this operation on the database.

   #include "stdafx.h"
   #include <iostream.h>
   
   #import "C:\Program Files\Common Files\System\ado\msado15.dll" no_namespace rename( "EOF", "adoEOF" )
   
   struct InitOle {
     InitOle()  { ::CoInitialize(NULL); }
     ~InitOle() { ::CoUninitialize();   }
   } _init_InitOle_;
   
   int main(int argc, char* argv[])
   {
   
   	try {
   		_ConnectionPtr pCon(__uuidof(Connection));
   		_RecordsetPtr pRs(__uuidof(Recordset));
   
   		pCon->ConnectionString = L"Provider=SQLOLEDB.1; Server=(local);Initial Catalog=pubs; User Id=<username>; Password=<strong password>;";
   		pCon->Open(L"",L"",L"",-1);
   
   		pRs->Open(L"SELECT * FROM authors",pCon.GetInterfacePtr(),adOpenStatic,adLockOptimistic,-1);
   
   		_bstr_t btRecordset;
   		btRecordset = pRs->GetString(adClipString,-1,L",",L"\r\n",L"<NULL>");
   		cout << (char*) btRecordset << endl;
   	}
   	catch (_com_error& e)
   	{
   		cout << e.ErrorMessage() << endl;
   	}
   
   	return 0;
   }
   
   						

3. Run the code and observe the results.

Resolution

• Use ADO 2.5 -or-
  
  
• Call the raw_GetString() function directly with a BSTR pointer that is initialized to point to NULL.
  
  Use the following code to replace the call to GetString():
  

  		BSTR bstrResult = NULL;
  		_bstr_t btColDelim(L",");
  		_bstr_t btRowDelim(L"\r\n");
  		_bstr_t btNullExp(L"<NULL>");
  		HRESULT hr = pRs->raw_GetString(adClipString,-1,btColDelim,btRowDelim,btNullExp,&bstrResult);
  		if (FAILED(hr)) _com_issue_errorex(hr, pRs, __uuidof(pRs));
  		btRecordset = bstrResult;
  
  						

  -or-
• Create an inline function similar to GetString() that calls the raw_GetString function, but initialize the BSTR variable to NULL.
  
  Note: Do not modify the generated .tli file to make the changes directly to the GetString() wrapper implementation because this file is gegenerated at compile time. Instead, use the function below or copy and paste the GetString() function from the .tli file and modify it as follows:

  inline _bstr_t GetString2 ( _RecordsetPtr pRs, enum StringFormatEnum StringFormat, long NumRows, _bstr_t ColumnDelimeter, _bstr_t RowDelimeter, _bstr_t NullExpr ) 
  {
      BSTR _result = NULL;
      HRESULT _hr = pRs->raw_GetString(StringFormat, NumRows, ColumnDelimeter, RowDelimeter, NullExpr, &_result);
      if (FAILED(_hr)) _com_issue_errorex(_hr, pRs, __uuidof(pRs));
      return _bstr_t(_result, false);
  }
  
  						

  You can call this function in the main() function as follows:

  		btRecordset = GetString2(pRs,adClipString,-1,L",",L"\r\n",L"<NULL>");