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Subject: Re: Can't debug bash with gdb 8.2.1-1
To: The Cygwin Mailing List <cygwin AT cygwin DOT com>
References: <37d412b3-f0ff-b079-4d64-16b01898b420 AT cornell DOT edu>
From: Jon Turney <jon DOT turney AT dronecode DOT org DOT uk>
Cc: Ken Brown <kbrown AT cornell DOT edu>
Message-ID: <73dcccf2-33a0-7608-269b-e9cb9abc2238@dronecode.org.uk>
Date: Tue, 23 Jul 2019 14:51:57 +0100
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On 22/07/2019 15:59, Ken Brown wrote:
> With the test version of gdb, attempting to debug bash fails as follows:
> 
> $ gdb bash
> GNU gdb (GDB) (Cygwin 8.2.1-1) 8.2.1
> [...]
> Reading symbols from bash...Reading symbols from
> /usr/lib/debug//usr/bin/bash.exe.dbg...done.
> done.
> (gdb) r -c ls
> Starting program: /usr/bin/bash -c ls
> [...]
> /usr/bin/bash: initialize_job_control: getpgrp failed: No error
> [...]
> [Inferior 1 (process 31876) exited with code 01]
> 
> This problem doesn't occur with gdb-8.1.1-1.
Thanks for reporting this.

I had also tripped over this problem recently: It seems that changes in 
gdb (bisection lands on [1]) mean that any call to getpgrp() in the 
inferior fails (this can be demonstrated with a test program that just 
calls that).

I believe this is behaviour is caused by some kind of defect in the 
cygwin DLL, but I haven't made much progress in investigating it. (I 
don't really understand how the inferior gets into a state where 
getpgrp() fails, which isn't really supposed to happen...)

[1] 
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=e671cd59d74cec9f53e110ce887128d1eeadb7f2


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