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Message-ID:	<516C3D0D.6080508@cs.utoronto.ca>
Date:	Mon, 15 Apr 2013 13:46:53 -0400
From:	Ryan Johnson <ryan DOT johnson AT cs DOT utoronto DOT ca>
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To:	cygwin AT cygwin DOT com
Subject:	Re: Debugging totally broken with latest everything?
References:	<516C24C5 DOT 80107 AT gmail DOT com> <20130415171412 DOT GA3356 AT ednor DOT casa DOT cgf DOT cx>
In-Reply-To:	<20130415171412.GA3356@ednor.casa.cgf.cx>

On 15/04/2013 1:14 PM, Christopher Faylor wrote:
> On Mon, Apr 15, 2013 at 05:03:17PM +0100, Dave Korn wrote:
>>   Some notes on the above:
>>
>>   The same happens with both the previous version and current snapshot of the
>> cygwin dll.  It also happens with both current gdb and an old gdb
>> 6.8.0.20080328-cvs that I have lying around.
>>
>>   The hw.exe in question is your bog-standard hello world, compiled with "-g
>> -O0" using gcc4-4.5.3-3.
>>
>>   "kill -9" won't kill gdb; I have to use Windows task manager.  If I've
>> attached gdb to the hung gdb, I can kill it from there using the "k" instruction.
>>
>>   Anyone else having similar problems?
> You're probably seeing a known bug in gdb where it no longer works well
> when run from a console window.  There is a race where gdb tries to get
> tty information from a stopped cygwin process.  Although I didn't
> introduce the problem, I have tried to fix it from time to time without
> much luck.
I've also seen the problem, my workaround so far has been to ensure the 
process is running again before attaching gdb to it (assuming you 
stopped it with ^Z so that jobs -p could report its pid). Not that I 
actually remember to do this most of the time...

> Debugging from mintty will probably work better.
That's a rather unfortunate interaction with the long-standing "feature" 
that interrupting programs with ^C only works if gdb runs in a console 
window (STC I used today is below in case I've gotten something wrong).

Am I missing some obvious workaround?

Ryan

STC: when compiling and running this:

#include <unistd.h>
#include <stdio.h>
int main() {
     printf("pid: %d\n", getpid());
     sleep(10);
}

... ^C does not break in (it exits normally) when gdb runs inside 
mintty; putting in a cmd.exe window allows ^C to break in with SIGTRAP 
(though the stack trace is utterly useless since the thread is in 
windows land at that point).



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