CFileDialog crash in Platform SDK

[cilu]

I have installed Platform SDK Windows Server 2003 (I work in VS 6.0 on WinXP) and I have a problem with CFileDialog.

This code

void CFileTestView::OnViewFile() 
{
  CFileDialog dlg(TRUE);
  dlg.DoModal();
}

worked just fine before defining _WIN32_WINNT, which I need to use different functions and constants. Now, when I define it

#ifndef _WIN32_WINNT
#define _WIN32_WINNT  0x0501
#endif

my code just crashes in ~CFileDialog (when dlg does out of scope and is destroyed). Since m_ofn member of CFileDialog depends on this _WIN32_WINT:

typedef struct tagOFN { 
// ...
#if (_WIN32_WINNT >= 0x0500)
  void *        pvReserved;
  DWORD         dwReserved;
  DWORD         FlagsEx;
#endif // (_WIN32_WINNT >= 0x0500)
} OPENFILENAME

I rewrote the code this way:

void CFileTestView::OnViewFile() 
{
CFileDialog dlg(TRUE);

#if (_WIN32_WINNT >= 0x0500)
	dlg.m_ofn.pvReserved = NULL;
	dlg.m_ofn.dwReserved = 0;
	dlg.m_ofn.FlagsEx = 0;
#endif

dlg.DoModal();
}

but I still get a first-chance exception in FileTest.Exe (KERNEL32.dll) 0xC0000005: Access Violation (the usual stuff).

Any ideas? Thanks!

[TSYS]

Yeah. It's a bug in Windows, brought out by declaring WINVER equal to or greater than 500. I've had the same problem in VC++ 6.0.

You can get around it by declaring your CFileDialog object on the stack, eg.:

{
   CFileDialog *pFD = new CFileDialog( TRUE );
   pFD->DoModal();
  // etc.
  // etc.
  delete pFD;
}

[cilu]

Thanks TSYS. It worked.

Now I have to go back in this 200 KLOC project and replace dozens of CFileDialog with CFileDialog*...

[cilu]

Now, there's a real bad news: if I derive CFileDialog I still have that problem:

CMyFileDialog : public CFileDialog
{
  // all the stuff
};

{
   CMyFileDialog *pFD = new CMyFileDialog( TRUE );
   pFD->DoModal();
   delete pFD;  // first-chance exception...
}

[TSYS]

Haven't run into that, but then I rarely derive from CFileDialog. You may have to lift the source code from Microsoft and fix the bug yourself.

[Ajay Vijay]

Now, there's a real bad news: if I derive CFileDialog I still have that problem:

CMyFileDialog : public CFileDialog
{
  // all the stuff
};

{
   CMyFileDialog *pFD = new CMyFileDialog( TRUE );
   pFD->DoModal();
   delete pFD;  // first-chance exception...
}

After you call DoModal, try calling other method - if it fails, you need to remove the 'delete'. WHY?

Well, that just a guess/suggestion - it may be that CFileDialog, when allocated in heap, might be calling "delete this" in it's PostNCDestroy. Just like Frame and Views - I know frame/views are always allocated in heap not in stack. But this may be the case...

[cilu]

No, that's not the case. I can call any method after DoModal() and it works. It only crashes at delete.

[Ajay Vijay]

All this seems to be problem with 'pvReserved' data member. Try setting it to NULL before you delete. You may also try IsBadWritePtr/IsBadReadPtr on 'pvReserved' and/or to dialog object itself.

[cilu]

If you look at my first post you see that I already set pvReserved to NULL and dwReserved to 0. After calling DoModal(), they are unchanged, NULL and 0. And I also set lStructSize = sizeof(OPENFILENAME).

dlg->m_ofn.lStructSize = sizeof (OPENFILENAME);

[Ajay Vijay]

I suggest you to find out the solution in stack version of your class, because making changes this way would increase problems. For the time being, it is better to "ignore" something and move forward...

[Ajay Vijay]

I am also having the same error....

	CFileDialog f(true,NULL,NULL,OFN_PATHMUSTEXIST|OFN_FILEMUSTEXIST|OFN_HIDEREADONLY,
		"...",
		this);
	
	
 	if(f.DoModal() != IDOK)
			return; // HERE

[PadexArt]

From what I see in MSDN, 0x0501 means Windows XP and Windows .NET Server. Perhaps you need a different value for 2003?

EDIT: I see now you've mentioned 2003.

[Ajay Vijay]

MFC70 has 7th parameter to give the sizeof OPENFILENAME structure, which does not exist in MFC42 (6.0v). We can set it as:

f.m_ofn.lStructSize = sizeof(OPENFILENAME);

While debugging this thing, I found that 'lStructSize' is 76, which when the above code comes, becomes 88. I have defined

#define _WIN32_WINNT 0x500

in stdafx.h (before ALL headers).
Instead of this CFileDialog is compiled using OLD value of _WIN32_WINNT, and my code is compiled using new value (88 shows!).

WHY??

[Ajay Vijay]

Worth mentioning that I am using this thing, so that new-style dialog box (History, My computer, Network Places) appear on my dialog. I got success in that, but not AV problem!

[PadexArt]

I think your problem might have something to do with the precompiled headers.Try defininning that value in the project settings ( ++ options) and not in your code.