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Posted to c-dev@xerces.apache.org by "cargilld (JIRA)" <xe...@xml.apache.org> on 2005/08/10 12:01:35 UTC

[jira] Commented: (XERCESC-1368) Catch-all handler are problematic on Windows

    [ http://issues.apache.org/jira/browse/XERCESC-1368?page=comments#action_12318304 ] 

cargilld commented on XERCESC-1368:
-----------------------------------

Hi Dave,
Do you have more patches coming for this bug or should we close it?

Thanks,
David


> Catch-all handler are problematic on Windows
> --------------------------------------------
>
>          Key: XERCESC-1368
>          URL: http://issues.apache.org/jira/browse/XERCESC-1368
>      Project: Xerces-C++
>         Type: Bug
>   Components: Miscellaneous
>     Versions: 2.6.0
>  Environment: Windows XP with Visual Studio .NET 2003
>     Reporter: David Bertoni
>     Assignee: David Bertoni
>  Attachments: patch.txt
>
> Exception handlers of the form "catch(...)" are causing problems in our product code on Windows, because they are catching hardware exceptions, such as access violations.
> There is an article in the MSDN Knowledge Base that describes how this has changed between Visual Studio 6, and Visual Studio .NET:
> http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vclang/html/_core_exception_handling.3a_.default_synchronous_exception_model.asp
> However, my experience with Xerces-C using Visual Studio .NET 2003 is that hardware exceptions (asynchronous exceptions, in the Microsoft parlance) are still being caught in Xerces-C in catch-all handlers.  This is problematic because it interferes with normal diagnosis of hardware faults, and can lead to code being executed in Xerces-C when the system is in an unknown state.  It is also a makes it difficult to write code that will behave the same on other platforms.
> Looking into the code reveals multiple places where a catch-all handler resets some object (or some other similar behavior), then rethrows the same exception.  I'd like to propose that we try to eliminate as many of these catch handlers as possible by replaces these actions with stack objects that perform these actions automatically whether or not an exception is thrown (auto_ptr-like behavior).  This will also have the benefit of simplifying the code.  From a "philosophical" perspective, I also think its better for code to catch the exceptions it's concerned with, and avoid catch-all handlers except when absolutely necessary.
> I will attach a proposed patch for a class that does this sort of thing, and some modified code that uses this class.  I would also like to see if anyone else has observed this behavior in their Windows applications.

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