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Q175778: Invalid Page Fault in Wappc32.dll Using WinAPPCSetBlockingHook

Article: Q175778
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.11,2.11 SP1,2.11 SP2,3.0,3.0 SP1,3.0 SP2
Operating System(s): 
Keyword(s): 
Last Modified: 13-JUN-2001

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft SNA Server, versions 2.11, 2.11 SP1, 2.11 SP2, 3.0, 3.0 SP1, 3.0 SP2 
-------------------------------------------------------------------------------

SYMPTOMS
========

A 32-bit APPC application that initiates multiple conversations and uses the
WinAPPCSetBlockingHook() call causes a general protection fault (GP fault) in
Wappc32.dll on a computer running Windows 95 and using the SNA Server Client for
Windows 95. The GP fault will be similar to the following:

  This program has performed an illegal operation and will be shut down.

  If the problem persists, contact the program vendor.

  <Program Name> caused an invalid page fault in module WAPPC32.DLL at
  <memory location>.

  Registers:

  ..data omitted..


CAUSE
=====

The 32-bit APPC library does not correctly handle the case where the
WinAPPCSetBlockingHook() call returns FALSE on multiple threads.


WORKAROUND
==========

If the WinAPPCSetBlockingHook() call is being used to cancel one conversation
when the MC_ALLOCATE() takes too long. The application should call
WinAPPCCancelBlockingCall() from within the WinAPPCSetBlockingHook() call. If
this is done, the WinAPPCSetBlockingHook() call would continue to return TRUE
instead of FALSE.


Another alternative is to have the application use the Asynchronous APPC API and
the WinAPPCCancelAsyncRequest() call.

Please refer to the SNA Server "APPC Programmer's Guide" for more details on the
APPC functions mentioned in this article.

STATUS
======

Microsoft has confirmed this to be a problem in SNA Server versions 2.11, 2.11
Service Pack 1, 2.11 Service Pack 2, 3.0, 3.0 Service Pack 1, 3.0 Service Pack
2.

The 32-bit APPC library has been updated to correctly handle cases where a
WinAPPCSetBlockingHook() call returns FALSE. The updated module is Wappc32.dll.

This problem was corrected in the latest SNA Server version 3.0 U.S. Service
Pack. For information on obtaining this Service Pack, query on the following
word in the Microsoft Knowledge Base (without the spaces):

  S E R V P A C K


A supported fix for SNA Server version 2.11 is now available, but has not been
fully regression tested and should be applied only to systems experiencing this
specific problem. Unless you are severely impacted by this specific problem,
Microsoft recommends that you wait for the next Service Pack that contains this
fix. Contact Microsoft Technical Support for more information.



Additional query words: Application Exception AE

======================================================================
Keywords          :  
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ211 kbSNAServ211SP1 kbSNAServ211SP2 kbSNAServ300SP1 kbSNAServ300SP2
Version           : WINDOWS:2.11,2.11 SP1,2.11 SP2,3.0,3.0 SP1,3.0 SP2
Issue type        : kbbug
Solution Type     : kbfix

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