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Message-ID: <c0d0ffe7-e499-4250-9777-dd47de56174a@dronecode.org.uk>
Date: Sat, 17 May 2025 15:01:58 +0100
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Subject: Re: strace: infinite exception c0000005 loop on segmentation fault
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From: Jon Turney via Cygwin <cygwin AT cygwin DOT com>
Reply-To: Jon Turney <jon DOT turney AT dronecode DOT org DOT uk>
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On 16/05/2025 22:37, Jon Turney via Cygwin wrote:
> On 16/05/2025 16:43, Takashi Yano wrote:
>> Hi Jon,
> [...]
>>>
>>> I could reproduce that. And also found cygwin 3.4.10 does not have this
>>> issue. I'll look into this.
>>
>> I could bisect the issue and found the next commit triggered the issue.
>>
>> commit 91457377d6c9f89a08b1b70e45cbae87ef467119
>> Author: Jon Turney <jon DOT turney AT dronecode DOT org DOT uk>
>> Date:   Thu Jan 11 20:00:14 2024 +0000
>>
> [...]
> 
> Thanks for looking into this.
> 
>> I also found the following patch fixes the issue. I'm not sure
>> this is the right thing, so could you please have a look?
>>
>> diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
>> index 9763a1b04..aea2821f6 100644
>> --- a/winsup/cygwin/exceptions.cc
>> +++ b/winsup/cygwin/exceptions.cc
>> @@ -597,7 +597,7 @@ try_to_debug ()
>>       {
>>         extern void break_here ();
>>         break_here ();
>> -      return 1;
>> +      return 0;
>>       }
>>     /* Otherwise, invoke the JIT debugger, if set */
> 
> Hmm... at this remove in time, I'm not sure why I made that change.
> 
> Well, "consistently return non-zero from try_to_debug() if we debugged", 
> but maybe that misunderstands the meaning of the return value...

See yeah, it seems I came to understand that a bit better at:

https://cygwin.com/pipermail/cygwin-patches/2024q1/012605.html

but never got back to this piece of code.


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