From owner-freebsd-bugs  Wed Feb 13  2:50: 8 2002
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Date: Wed, 13 Feb 2002 02:50:01 -0800 (PST)
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Cc: 
From: Bruce Evans <bde@zeta.org.au>
Subject: Re: bin/34898: [PATCH] rev 1.7 of xargs.c broke documented exit
 status
Reply-To: Bruce Evans <bde@zeta.org.au>
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The following reply was made to PR bin/34898; it has been noted by GNATS.

From: Bruce Evans <bde@zeta.org.au>
To: Tim Robbins <tim@robbins.dropbear.id.au>
Cc: <FreeBSD-gnats-submit@FreeBSD.ORG>
Subject: Re: bin/34898: [PATCH] rev 1.7 of xargs.c broke documented exit
 status
Date: Wed, 13 Feb 2002 21:44:16 +1100 (EST)

 On Wed, 13 Feb 2002, Tim Robbins wrote:
 
 > >Description:
 > Revision 1.7 of src/usr.bin/xargs/xargs.c, which changed the vfork() call
 > to a fork(), broke the exit status 127 documented in xargs(1).
 >
 > It's broken in -STABLE and -CURRENT.
 
 execvp() now uses alloca(), so it might be safe for xargs to use vfork()
 again.
 
 > >Fix:
 >
 > Index: xargs/xargs.c
 > ===================================================================
 > RCS file: /home/ncvs/src/usr.bin/xargs/xargs.c,v
 > retrieving revision 1.11
 > diff -u -r1.11 xargs.c
 > --- xargs/xargs.c	2001/12/11 22:36:26	1.11
 > +++ xargs/xargs.c	2002/02/13 05:32:54
 > @@ -296,7 +296,6 @@
 >  run(argv)
 >  	char **argv;
 >  {
 > -	volatile int noinvoke;
 >  	char **p;
 >  	pid_t pid;
 >  	int status;
 > @@ -308,21 +307,19 @@
 >  		(void)fprintf(stderr, "\n");
 >  		(void)fflush(stderr);
 >  	}
 > -	noinvoke = 0;
 >  	switch(pid = fork()) {
 >  	case -1:
 >  		err(1, "fork");
 >  	case 0:
 >  		execvp(argv[0], argv);
 >  		warn("%s", argv[0]);
 > -		noinvoke = 1;
 > -		_exit(1);
 > +		_exit(254);
 >  	}
 >  	pid = waitpid(pid, &status, 0);
 >  	if (pid == -1)
 >  		err(1, "waitpid");
 >  	/* If we couldn't invoke the utility, exit 127. */
 > -	if (noinvoke)
 > +	if (WEXITSTATUS(status) == 254)
 >  		exit(127);
 >  	/* If utility signaled or exited with a value of 255, exit 1-125. */
 >  	if (WIFSIGNALED(status) || WEXITSTATUS(status) == 255)
 
 The noinvoke hack has some advantages.  Status 254 is a bit more fragile
 than it used to be.  There is now a signal 126 and killing any process
 with this signal gives status 254.
 
 Bugs found while testing this:
 - /bin/kill doesn't support signals >= NSIG (32).
 - I use an old version of bash-1 for a shell.  It dumps core when a process
   is killed by a signal >= 32.  I think it was compiled when NSIG actually
   gave the number of signals.
 
 Bruce
 

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