Q141417: FIX: Problem Occurs During File Open on Win32s
Article: Q141417
Product(s): Microsoft C Compiler
Version(s): 4.0
Operating System(s):
Keyword(s): kbcode kbDocView kbMFC kbVC400bug kbVC410fix kbGrpDSMFCATL kbNoUpdate
Last Modified: 07-MAY-2001
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The information in this article applies to:
- Microsoft Visual C++, version 4.0
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SYMPTOMS
========
A problem occurs on Win32s when the user tries to open a file using the standard
MFC file opening procedures. This only occurs with an MFC application running
under Win32s version 1.3 that uses MFC in a shared DLL (Mfc40.dll for Win32s)
and the C runtime libraries in a DLL (Msvcrt40.dll for Win32s). Note that this
is the default configuration for a default AppWizard generated application.
Two known symptoms are access violation and EMM386 error #06 (Invalid opcode).
Symptoms will vary depending on the condition of the call stack.
CAUSE
=====
AfxResolveShortcut (an internal MFC function) calls SHGetFileInfo, which is not
correctly implemented on Win32s. This happens as a result of the ID_FILE_OPEN
command. AfxResolveShortcut is called from CDocManager::OpenDocumentFile, which
is in turn called from CWinApp::OpenDocumentFile.
RESOLUTION
==========
Derive a class from CDocManager and override the OpenDocumentFile function by
copying the existing code and make some small changes. Because this fix is
dependent on the internal MFC implementation, make sure you include the #if
_MFC_VER == 0x400 statements.
Copy the following code into your application's .cpp file above the
implementation of InitInstance. If you're looking at a paper copy of this
article, note that you can find most of the code for OpenDocumentFile in
Mfc\Src\Docmgr.cpp; rather than retyping the entire text, you could copy most of
the code and make the change noted below:
#if _MFC_VER == 0x400
static inline BOOL IsDirSep(TCHAR ch)
{
return (ch == _T('\\') || ch == _T('/'));
}
#ifndef _MAC
BOOL AFXAPI AfxResolveShortcut(CWnd* pWnd, LPCTSTR pszShortcutFile,
LPTSTR pszPath, int cchPath);
#endif
#define _countof(array) (sizeof(array)/sizeof(array[0]))
BOOL AFXAPI AfxFullPath(LPTSTR lpszPathOut, LPCTSTR lpszFileIn);
void AFXAPI AfxGetRoot(LPCTSTR lpszPath, CString& strRoot);
class CMyDocManager : public CDocManager
{
public:
CMyDocManager() {};
virtual ~CMyDocManager() {};
virtual CDocument* OpenDocumentFile(LPCTSTR lpszFileName);
};
CDocument* CMyDocManager::OpenDocumentFile(LPCTSTR lpszFileName)
{
// find the highest confidence
POSITION pos = m_templateList.GetHeadPosition();
CDocTemplate::Confidence bestMatch = CDocTemplate::noAttempt;
CDocTemplate* pBestTemplate = NULL;
CDocument* pOpenDocument = NULL;
TCHAR szPath[_MAX_PATH];
ASSERT(lstrlen(lpszFileName) < _countof(szPath));
#ifndef _MAC
TCHAR szTemp[_MAX_PATH];
if (lpszFileName[0] == '\"')
++lpszFileName;
lstrcpyn(szTemp, lpszFileName, _MAX_PATH);
LPTSTR lpszLast = _tcsrchr(szTemp, '\"');
if (lpszLast != NULL)
*lpszLast = 0;
AfxFullPath(szPath, szTemp);
TCHAR szLinkName[_MAX_PATH];
// CHANGE: check the windows version before calling AfxResolveShortcut
if((BYTE)GetVersion() >=4 && AfxResolveShortcut(AfxGetMainWnd(),
szPath, szLinkName,_MAX_PATH))
lstrcpy(szPath, szLinkName);
#else
lstrcpyn(szPath, lpszFileName, _MAX_PATH);
WIN32_FIND_DATA fileData;
HANDLE hFind = FindFirstFile(lpszFileName, &fileData);
if (hFind != INVALID_HANDLE_VALUE)
VERIFY(FindClose(hFind));
else
fileData.dwFileType = 0; // won't match any type
#endif
while (pos != NULL)
{
CDocTemplate* pTemplate =
(CDocTemplate*)m_templateList.GetNext(pos);
ASSERT_KINDOF(CDocTemplate, pTemplate);
CDocTemplate::Confidence match;
ASSERT(pOpenDocument == NULL);
#ifndef _MAC
match = pTemplate->MatchDocType(szPath, pOpenDocument);
#else
match = pTemplate->MatchDocType(szPath,
fileData.dwFileType, pOpenDocument);
#endif
if (match > bestMatch)
{
bestMatch = match;
pBestTemplate = pTemplate;
}
if (match == CDocTemplate::yesAlreadyOpen)
break; // stop here
}
if (pOpenDocument != NULL)
{
POSITION pos = pOpenDocument->GetFirstViewPosition();
if (pos != NULL)
{
CView* pView = pOpenDocument->GetNextView(pos);
// get first one
ASSERT_VALID(pView);
CFrameWnd* pFrame = pView->GetParentFrame();
if (pFrame != NULL)
pFrame->ActivateFrame();
else
TRACE0(
"Error: Cannot find frame for document to activate.\n");
CFrameWnd* pAppFrame;
if (pFrame !=
(pAppFrame = (CFrameWnd*)AfxGetApp()->m_pMainWnd))
{
ASSERT_KINDOF(CFrameWnd, pAppFrame);
pAppFrame->ActivateFrame();
}
}
else
{
TRACE0(
"Error: Can not find view for document to activate.\n");
}
return pOpenDocument;
}
if (pBestTemplate == NULL)
{
AfxMessageBox(AFX_IDP_FAILED_TO_OPEN_DOC);
return NULL;
}
return pBestTemplate->OpenDocumentFile(szPath);
}
#endif //mfc version 4.0 workaround
Now, include the following three lines to the first part of your
MyApp::InitInstance function:
#if _MFC_VER == 0x400
m_pDocManager = new CMyDocManager;
#endif
STATUS
======
Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This bug was corrected in Visual C++ 4.1.
MORE INFORMATION
================
Steps to Reproduce Problem
--------------------------
1. Open the scribble tutorial sample from:
\Msdev\Samples\Mfc\Tutorial\Scribble\Step6\Scribble.mdb
2. Open the Project Settings dialog box. In Settings For, select Win32 Release.
3. From the Project Settings dialog box, click the general tab. From the
Microsoft Foundation Classes list box, select Use MFC in a shared DLL
(MFC40(d).DLL). Click OK to dismiss the project settings dialog box.
4. Open the default configuration dialog box, and select the Release build.
5. Rebuild the program.
6. Run the program under Win32s.
7. Create, save, and close a scribble document.
8. Try to open the document you just closed. An access violation occurs.
Additional query words: kbVC400bug 4.00 4.10 1.30
======================================================================
Keywords : kbcode kbDocView kbMFC kbVC400bug kbVC410fix kbGrpDSMFCATL kbNoUpdate
Technology : kbVCsearch kbVC400 kbAudDeveloper
Version : :4.0
Issue type : kbbug
Solution Type : kbfix
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