linux-kernel - Re: Should parent's WIFSIGNALED(siginfo->si_status) be true EVEN IF the SIGNAL was caught by the child?

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Message-Id: <1190487134.2712.2.camel@entropy>
Date:	Sat, 22 Sep 2007 11:52:14 -0700
From:	Nicholas Miell <nmiell@...cast.net>
To:	"John Z. Bohach" <jzb2@...orsyst.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Should parent's WIFSIGNALED(siginfo->si_status) be true EVEN
	IF the SIGNAL was caught by the child?

On Sat, 2007-09-22 at 11:22 -0700, John Z. Bohach wrote:
> Hello,
> 
> It is unclear from the various documentions in the kernel and glibc what 
> the proper behaviour should be for the case when a child process 
> catches a SIGNAL (say for instance, SIGTERM), and then calls exit() 
> from within its caught SIGNAL handler.
> 
> Since the exit() will cause a SIGCHLD to the parent, and the parent 
> (let's say) has a SIGCHLD sigaction (SA_SIGINFO sa_flags set), should 
> the parent's WIFSIGNALED(siginfo->si_status) be true?
> 
> To recap, the WIFSIGNALED section of the waitpid() manpage says:
> 
> WIFSIGNALED(status)
>     returns true if the child process was terminated by a signal.
> 
> So the dilemna:  the child caught the signal, so it wasn't terminated by 
> a signal, but rather its signal handler (let's say) called exit.

POSIX says

WIFSIGNALED(stat_val)
        Evaluates to a non-zero value if status was returned for a child
        process that terminated due to the receipt of a signal that was
        not caught (see <signal.h>).
        
So there's no dilemma at all and Linux is non-conformant.
 
-- 
Nicholas Miell <nmiell@...cast.net>

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