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Q148806: FIX: Cannot Open Document From Shell If EXE Has Long File Name

Article: Q148806
Product(s): Microsoft C Compiler
Version(s): 4.0,4.1,4.2,5.0,6.0
Operating System(s): 
Keyword(s): kbcode kbMFC kbVC400bug kbVC410bug kbVC420bug kbVC500bug kbVC600bug kbOSWin95 kbOSWin98
Last Modified: 11-FEB-2002

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The information in this article applies to:

- The Microsoft Foundation Classes (MFC), used with:
   - Microsoft Visual C++, 32-bit Editions, versions 4.0, 4.1, 4.2, 5.0, 6.0, used with:
      - the operating system: Microsoft Windows 95 
      - the operating system: Microsoft Windows 98 
      - the operating system: Microsoft Windows Millennium Edition 
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SYMPTOMS
========

When you try to open a document whose extension is associated with an MFC
application that has a long file name on Windows 95 or Windows 98, a dialog box
with an error message similar to the following appears:

  Cannot find the file 'filename' (or one of its components). Make sure the
  path and filename are correct and that all required libraries are available.

Closing the message box won't bring up the application's windows, but will leave
the executable file open.

On Windows Millennium Edition (Me), the error message is:

  Windows cannot find '<filename>'. You may have typed the name
  incorrectly in the Run dialog, or another open program cannot find a system
  file. To search for a file, click the Start button, and then click Search.


CAUSE
=====

The MFC function CWinApp::RegisterShellFileTypes() writes the application's 8.3
file name to the registry. However, CWinApp::EnableShellOpen() calls
::GlobalAddAtom() with the application's long file name. Windows 95 and Windows
98 cannot handle this situation.

RESOLUTION
==========

Override CWinApp::EnableShellOpen() using the sample code below to pass the
application's short file name to ::GlobalAddAtom().

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

This problem was corrected in Microsoft Visual C++ .NET.

MORE INFORMATION
================

Steps to Reproduce the Problem on a Computer with Windows 95 or 98
------------------------------------------------------------------

1. Select a new MFC AppWizard(exe) project to create an MDI application with a
  long project name.

2. At step 3 of the AppWizard select Automation Support.

3. Then at step 4 of the AppWizard, choose Advanced and specify a 3 letter file
  extension.

4. Build the application and run it once so the file type is registered by the
  call to RegisterShellFileTypes in InitInstance.

5. Save a file with the selected file extension and double-click to open it from
  the Windows Explorer.

This can be worked around by overriding CWinApp::EnableShellOpen() and
registering the application name atom using the short filename. Following is a
sample of what the code should look like:

  /* Compile options needed: Default MFC applications.
  */ 

  void CLongFileNameApp::EnableShellOpen()
  {
     ASSERT(m_atomApp == NULL && m_atomSystemTopic == NULL); // do once

     CString strShortName;
     TCHAR szLongPathName[_MAX_PATH];
     ::GetModuleFileName(m_hInstance, szLongPathName, _MAX_PATH);
     if (::GetShortPathName(szLongPathName,
         strShortName.GetBuffer(_MAX_PATH), _MAX_PATH) == 0)
     {
        // Rare failure case (especially on not-so-modern file systems)
        strShortName = szLongPathName;
     }
     strShortName.ReleaseBuffer();
     int nPos = strShortName.ReverseFind('\\');
     if (nPos != -1)
       strShortName = strShortName.Right(strShortName.GetLength()- nPos-1);
     nPos = strShortName.ReverseFind('.');
     if (nPos != -1)
       strShortName = strShortName.Left(nPos);
     m_atomApp = ::GlobalAddAtom(strShortName);
     m_atomSystemTopic = ::GlobalAddAtom(_T("system"));
  }

Additional query words: 8.3 filename EnableShellOpen

======================================================================
Keywords          : kbcode kbMFC kbVC400bug kbVC410bug kbVC420bug kbVC500bug kbVC600bug kbOSWin95 kbOSWin98 kbGrpDSMFCATL kbNoUpdate 
Technology        : kbAudDeveloper kbMFC
Version           : :4.0,4.1,4.2,5.0,6.0
Issue type        : kbbug
Solution Type     : kbfix

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