Article: Q202197
Product(s): Microsoft C Compiler
Version(s): 5.0,6.0
Operating System(s):
Keyword(s): kbole kbDLL kbMFC kbVC kbVC500bug kbVC600bug kbOSWin95bug kbGrpDSMFCATL
Last Modified: 07-FEB-2002
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The information in this article applies to:
- The Microsoft Foundation Classes (MFC), included with:
- Microsoft Visual C++, 32-bit Enterprise Edition, versions 5.0, 6.0
- Microsoft Visual C++, 32-bit Professional Edition, versions 5.0, 6.0
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0
- Microsoft Visual C++.NET (2002)
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SYMPTOMS
========
In Windows 95, calling FreeLibrary() on the resource DLLs in the ExitInstance()
function of the COleControl-derived class causes an application error.
CAUSE
=====
This is a bug in Windows 95. When FreeLibrary() is called on resource DLLs,
Windows 95 is running through the chain of DLLs in that process and looking for
other DLLs that have a zero reference count. This causes other DLLs to be
unloaded too soon.
RESOLUTION
==========
Move the FreeLibrary() calls to the destructor function of the
COleControl-derived class.
STATUS
======
Microsoft has confirmed this to be a problem in the Microsoft products that are
listed at the beginning of this article.
MORE INFORMATION
================
Steps to Reproduce Behavior
---------------------------
1. Use Control Wizard to generate an ActiveX control project.
2. Create a non-MFC resource-ONLY DLL. Make sure you specify the /NOENTRY switch
in the Project, Settings dialog box.
3. Call LoadLibrary in InitInstance() of the control's CWinApp-derived class.
4. Call FreeLIbrary in ExitInstance() of the control's CWinApp-derived class.
5. Build the resource-ONLY DLL and the ActiveX control projects. Make sure the
.dll file is being placed in the same directory as the .ocx file.
6. At the MS-DOS prompt, change to the directory where both the .ocx and .dll
files are found. Type "REGSVR32 mycontrol.OCX".
RESULTS: You will get an application error dialog box and the "control is
registered successfully" dialog box.
REFERENCES
==========
(c) Microsoft Corporation 1999, All Rights Reserved. Contributions by Yeong-Kah
Tam, Microsoft Corporation.
Additional query words: ocx ExitInstance FreeLibrary LoadLibraryEx LoadLibrary
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Keywords : kbole kbDLL kbMFC kbVC kbVC500bug kbVC600bug kbOSWin95bug kbGrpDSMFCATL
Technology : kbAudDeveloper kbMFC
Version : :5.0,6.0
Issue type : kbbug
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