Date: 08 Feb 2002 07:46:34 +0200 From: Maxim Sobolev <sobomax@FreeBSD.org> To: jdp@FreeBSD.org, deischen@FreeBSD.org, jasone@FreeBSD.org, hackers@FreeBSD.org, jlemon@FreeBSD.org Subject: Linking libc before libc_r into application causes weird problems Message-ID: <1013147180.73417.2.camel@notebook>
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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
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#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));
}
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