From owner-freebsd-hackers  Thu Feb  7 21:47: 8 2002
Delivered-To: freebsd-hackers@freebsd.org
Received: from alcatraz.iptelecom.net.ua (alcatraz.iptelecom.net.ua [212.9.224.15])
	by hub.freebsd.org (Postfix) with ESMTP
	id 067CF37B421; Thu,  7 Feb 2002 21:46:54 -0800 (PST)
Received: from ipcard.iptcom.net (ipcard.iptcom.net [212.9.224.5])
	by alcatraz.iptelecom.net.ua (8.9.3/8.9.3) with ESMTP id HAA32528;
	Fri, 8 Feb 2002 07:46:49 +0200 (EET)
	(envelope-from sobomax@FreeBSD.org)
Received: from h12.229.dialup.iptcom.net (h12.229.dialup.iptcom.net [212.9.229.12])
	by ipcard.iptcom.net (8.9.3/8.9.3) with ESMTP id HAA67834;
	Fri, 8 Feb 2002 07:46:45 +0200 (EET)
	(envelope-from sobomax@FreeBSD.org)
Subject: Linking libc before libc_r into application causes weird problems
From: Maxim Sobolev <sobomax@FreeBSD.org>
To: jdp@FreeBSD.org, deischen@FreeBSD.org, jasone@FreeBSD.org,
	hackers@FreeBSD.org, jlemon@FreeBSD.org
Content-Type: multipart/mixed; boundary="=-HwruOWPo7n3Nq8WN5HEs"
Message-Id: <1013147180.73417.2.camel@notebook>
Mime-Version: 1.0
X-Mailer: Evolution/1.0.2 
Date: 08 Feb 2002 07:46:34 +0200
Sender: owner-freebsd-hackers@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-hackers.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-hackers>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-hackers>
X-Loop: FreeBSD.ORG


--=-HwruOWPo7n3Nq8WN5HEs
Content-Type: text/plain
Content-Transfer-Encoding: 7bit

Hi,

When working on updating port of Ximian Evolution to the latest released
version I have stuck to the problem - the new version of application
just hanged on startup on my 5-CURRENT box. After lot of digging and
debugging I found that the source of the problem is that the resulting
application had libc linked in before libc_r, which caused waitpid() in
the ORBit library just hang forever, even though child process died
almost instantly (I see zombie in the ps(1) output). When program was
relinked with -pthread flag, which seemingly forcing "right" order of
libc/libc_r (libc_r first) the problem disappeared. 

Based on the problematic code in the ORBit I had prepared short testcase
illustrating the problem and attaching it with this message. The problem
could be exposed by compiling the test.c using the following command: 

$ cc test.c -o test -lc -lc_r 

When either of -lc or -lc_r is omitted, or their order is reversed the
problem disappears. The problem doesn't exist on 4-STABLE. 

Any ideas, comments and suggestions are welcome. 

Thanks!

-Maxim



--=-HwruOWPo7n3Nq8WN5HEs
Content-Disposition: attachment; filename=test.c
Content-Transfer-Encoding: quoted-printable
Content-Type: text/x-c; charset=KOI8-R

#include <sys/types.h>
#include <sys/wait.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>

int main()
{
    int childpid, exitstatus, itmp;
    sigset_t mask, omask;

    /* Block SIGCHLD so no one else can wait() on the child before we do. *=
/
    sigemptyset(&mask);
    sigaddset(&mask, SIGCHLD);
    sigprocmask(SIG_BLOCK, &mask, &omask);

    childpid =3D fork();

    if(!childpid) {
	int i;

	/* Do something useful */
	sleep(1);

	_exit(0);
    }

    while ((itmp =3D waitpid(childpid, &exitstatus, 0)) =3D=3D -1 && errno =
=3D=3D EINTR)
	continue;
    sigprocmask (SIG_SETMASK, &omask, NULL);
    exit(WEXITSTATUS(exitstatus));
}

--=-HwruOWPo7n3Nq8WN5HEs--



To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message