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To: libc-hacker@sources.redhat.com
Subject: getpid/vfork broken
From: Andreas Schwab <schwab@suse.de>
X-Yow: After THIS, let's go to PHILADELPHIA and have TRIPLETS!!
Date: Sun, 07 Mar 2004 23:18:00 -0000
Message-ID: <jek71wckku.fsf@sykes.suse.de>
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getpid does not return the correct result after vfork:

$ cat getpid.c
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

int
main (void)
{
  if (vfork () == 0)
    {
      printf ("%d\n", getpid ());
      exit (0);
    }
  wait (0);
  if (vfork () == 0)
    {
      printf ("%d\n", getpid ());
      exit (0);
    }
  wait (0);
  printf ("%d\n", getpid ());
  return 0;
}
$ ./getpid
31302
31302
31302

Note that the number is actually the pid of the first child, not the
parent.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."