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BUG: Freeing Resource DLLs in ExitInstance Causes Error

PSS ID Number: 202197

Article Last Modified on 10/16/2002

The information in this article applies to:

This article was previously published under Q202197

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 that this is 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

Keywords: kbBug kbDLL KB202197
Technology: kbAudDeveloper kbMFC kbVC32bitSearch kbVC500 kbVC500Search kbVC600 kbVCNET kbVCsearch


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