popen/pclose bug in 2.1 with Linux 2.2.1?

[Andreas Jaeger <aj@arthur.rhein-neckar.de>]

Below is a bug report (PR libc/966+967) about pclose.  I'm not sure if 
this is really a bug, could somebody look into it, please?

Stracing the program and looking at libio/iopopen.c, I noticed that
iopopen.c uses vfork.  Could this be the problem?

Andreas

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
From: Juergen Heinzl <juergen@monocerus.demon.co.uk>
To: bugs@gnu.org
Subject: glibc-2.1 :: broken pclose() ?

Hello,

since I found nothing in the FAQ about that one ...
configuring man_db-2.3.10 tells me pclose() is broken with this version
of the library. With some really old programme I get this too ...

   96   1 S    0:00 /sbin/restore 
   97   1 S    0:00 /bin/gunzip -c /var/archive/sun/cpio.22.mar.98.gz 
  102   1 S    0:00 /bin/gunzip -c /var/archive/mon/cpio.30.nov.98.gz 
  107   1 S    0:00 /bin/gunzip -c /var/archive/mon/cpio.08.feb.99.gz 
  109   1 S    0:00 /bin/gunzip -c /var/archive/sun/cpio.14.feb.99.gz 

.. where restore call gunzip via popen() but only one at a time. All
instances of gunzip go away as soon as one leaves restore and the ones
above hang around after calling pclose(). I wrote it years ago and never
have had that effect, cannot tell for sure about 2.0.112 of the glibc
though.

With man_db the effect was an ESPIPE (Illegal seek) error and I yet try
to reproduce it within a smaller test programme.

The glibc is compiled with egcs-1.1.1 and binutils-2.9.1.0.18 with the
following flags ...
-Os -march=i686 -mcpu=i686 -malign-loops=2 -malign-jumps=2 \
-malign-functions=2 -fno-strength-reduce
.. on a Linux 2.2.1 machine.

If it is not a known problem I shall try to reproduce it with a smaller
programme. Using the ksh as /bin/sh yields the same result, so it might
not be a shell problem.

Thanks a lot,
Juergen

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From: Juergen Heinzl <juergen@monocerus.demon.co.uk>
To: bugs@gnu.org
Subject: glibc-2.1 :: broken pclose() ... short config code

>Unformatted:
Me again,

it was *very* late due to that, so forgive me 8-} ... here's the code
of the man_db configure script that fails ...

#include <stdio.h>
#include <sys/wait.h>
int
try_pclose (FILE *f, int expected)
{
  int s;
  s = pclose (f);
  if (s != -1 && WIFEXITED (s))
    return WEXITSTATUS (s) != expected;
  else 
    return 1;
}
int
main (void)
{
  FILE *f, *t;
  int i, sf, st;
  for (i = 0;  i <= 1;  ++i) {
    f = popen ("false", "r");
    sleep (1);
    t = popen ("true", "r");
    sleep (1);
    if (i) {
      st = try_pclose (t, 0);
      sf = try_pclose (f, 1);
    } else {
      sf = try_pclose (f, 1);
      st = try_pclose (t, 0);
    }
    if (sf || st) exit(1);
  }
  exit(0);
}

..

Cheers,
Juergen

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- 
 Andreas Jaeger   aj@arthur.rhein-neckar.de    jaeger@informatik.uni-kl.de
  for pgp-key finger ajaeger@aixd1.rhrk.uni-kl.de