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Date: Tue, 23 May 2006 20:13:24 +0200
From: Ralf Habacker <ralf DOT habacker AT freenet DOT de>
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Subject: Re: 1.5.19: changes have broken Qt3
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Dave Korn schrieb:
> On 23 May 2006 18:10, Ralf Habacker wrote:
> 
>   Oh no, not this old saw again!
> 
>> C:\cygwin\home\Habacker\src\pthreads-snap-2005-03-08\tests>strace
>> mutex1n | grep  C0000005
>> - --- Process 4872, exception C0000005 at 610B1005
>>   155   78759 [main] mutex1n 4872 _cygtls::handle_exceptions: In
>> cygwin_except_handler exc 0xC0000005 at 0x610B1005 sp 0x22CC00
> 
> [ snip many more ].
> 
>> I identified the problem to the function pthread_mutexattr_init address
>> 0x610b1005 in which a null pointer (%eax below) causes this seg fault
> 
>   Yes, but it's wrapped in an exception handler.  That's why you get to see an
> strace error message, rather than having the process exit.  Names like
> "cygwin_except_handler" and "_cygtls::handle_exceptions" should have given you
> some clues about this

Hmmh, I have learned to fix obviously problems instead let it handle by
an exception handler, which has several disadvantages.

1. It costs additional runtime. In the mentioned designer i count 1653
internal exceptions, which are caused by the null pointer issue.

2. 70% of my strace output (1000 lines) are polluted by this internal
exceptions messages, which could be avoided by changing only on lines of
code. Do you think that this is the effort worth ?

Are there more problems with this simple patch ?

Regards
Ralf


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