PRB: GetOpenFileName fails If lpstrFile Buffer Is Not NULL Terminated

• Microsoft Win32 Application Programming Interface (API), included with:
  • Microsoft Windows NT 4.0

SYMPTOMS

The GetOpenFileName function fails with a CommDlgExtendedError of CDERR_INITIALIZATION(0x0002).

CAUSE

The lpstrFile buffer of the OPENFILENAME structure is not NULL terminated.

RESOLUTION

According to the Platform SDK documentation, the first character of the lpstrFile buffer must be NULL if the buffer is not being used for initialization of the File Name edit box.

STATUS

This behavior is by design.

MORE INFORMATION

The following Win32 Application demonstrates the problem:

#include <Windows.h>

// If the next line is commented out, GetOpenFileName fails.
//#define NULL_TERMINATE

int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, 
                            LPSTR szCmdLine, int nCmdShow)
{
   long	lErrMsg = 0;
   OPENFILENAME ofn;
   TCHAR sfile[MAX_PATH];

   ZeroMemory(&ofn, sizeof(ofn));

   ZeroMemory(sfile, sizeof(TCHAR)*MAX_PATH);

   #ifndef	NULL_TERMINATE
   // Not NULL terminated.
   {
   int i;
   for (i = 0; i < MAX_PATH; i++)
	   sfile[i] = ' ';
   }
   #else
      // NULL terminated.
   sfile[0] = '\0';
   #endif
 

   // Initialize OPENFILENAME structure.
   ofn.lStructSize = sizeof(ofn);
   ofn.hwndOwner = NULL; 
   ofn.lpstrFile = sfile; 
   ofn.nMaxFile = MAX_PATH;
   ofn.lpstrFilter = NULL;
   ofn.nFilterIndex = 1;
   ofn.lpstrTitle = TEXT("Please Select a File");
   ofn.lpstrInitialDir = NULL;
   ofn.lpstrCustomFilter = NULL;
   ofn.nMaxCustFilter = 0;
   ofn.lpstrFileTitle = NULL;
   ofn.nMaxFileTitle = 0;
   ofn.nFileOffset = 0;
   ofn.nFileExtension = 0;
   ofn.lpstrDefExt = NULL;
   ofn.lCustData = 0;
   ofn.lpfnHook = 0;
   ofn.lpTemplateName = 0;
   ofn.Flags = OFN_PATHMUSTEXIST | OFN_FILEMUSTEXIST | OFN_HIDEREADONLY;

   // Call GetOpenFileName().
   if (GetOpenFileName(&ofn))
   {
	   MessageBox(NULL, TEXT("GetOpenFileName() Successful"), TEXT("OpenDialog"), MB_OK);
   }
   else
   {
      TCHAR		sErrMsg[256];
      lErrMsg = CommDlgExtendedError();
      wsprintf(sErrMsg,TEXT("Error %d returned from GetOpenFileName()"), lErrMsg);
      MessageBox(NULL, sErrMsg, TEXT("OpenDialog"), MB_OK);
   }

   return lErrMsg;
} 

Additional query words:

Keywords          : kbdocfix kbCmnDlgFileO kbNTOS400 kbGrpUser 
Version           : winnt:4.0
Platform          : winnt 
Issue type        : kbprb 

Last Reviewed: May 20, 1999