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Date: Wed, 5 May 2004 02:38:52 +0200
From: Edgar Toernig <froese@gmx.de>
To: Steve Beaty <beaty@emess.mscd.edu>
Cc: linux-kernel@vger.kernel.org
Subject: Re: sigaction, fork, malloc, and futex
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Steve Beaty wrote:
>
>... the signal handler fork another child.

Uhh... just read that POSIX actually allows that.  Evil!
I guess you're entering undiscovered land...

> void sig_handler (int signum)
> {
> 	int     child;
> 
> 	fprintf (stderr, "Process %d received a SIGALRM signal\n", getpid());
> 	if ((child = fork ()) == 0)
> 	{
> 		fprintf (stderr, "%d exiting\n", getpid());
> 		exit (0);
> 	}
> 	fprintf (stderr, "%d waiting for %d\n", getpid(), child);
> 	waitpid (child, NULL, 0);
> }

No fprintf and exit in a signal handler!  Use write and _exit instead.

> 	if ((child = fork ()) == 0)
> 	{
> 		fprintf (stderr, "%d sending SIGALRM to %d\n", getpid(), parent);
> 		if (kill (parent, SIGALRM) == -1) perror ("kill 1");
> 		fprintf (stderr, "%d exiting\n", getpid());
> 		exit (0);
> 	}

This exit is dubious too.  _exit is better.

Good luck, you may need it - ET.