diff options
| author | Marco S Hyman <marc@cvs.openbsd.org> | 2001-11-09 00:20:27 +0000 |
|---|---|---|
| committer | Marco S Hyman <marc@cvs.openbsd.org> | 2001-11-09 00:20:27 +0000 |
| commit | d045f8e592f690233157fac54120699931cc0346 (patch) | |
| tree | 2c17071fab566782b80a476da7ab2bcb65837709 /lib/libpthread | |
| parent | 6173b5a2974ff4b0a0b528da6ceeba4cd6d0d87b (diff) | |
Fix problem found by espie (and other porters) where
system(...) hangs forever. From a comment in the fix:
* Note: a thread calling wait4 may have its state changed to waiting
* until awakened by a signal. Also note that system(3), for example,
* blocks SIGCHLD and calls waitpid (which calls wait4). If the process
* started by system(3) doesn't finish before this function is called the
* function will never awaken -- system(3) also ignores SIGINT and SIGQUIT.
Diffstat (limited to 'lib/libpthread')
| -rw-r--r-- | lib/libpthread/uthread/uthread_wait4.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/lib/libpthread/uthread/uthread_wait4.c b/lib/libpthread/uthread/uthread_wait4.c index b51d6b29d6c..51534808d0c 100644 --- a/lib/libpthread/uthread/uthread_wait4.c +++ b/lib/libpthread/uthread/uthread_wait4.c @@ -1,4 +1,4 @@ -/* $OpenBSD: uthread_wait4.c,v 1.6 2001/08/21 19:24:53 fgsch Exp $ */ +/* $OpenBSD: uthread_wait4.c,v 1.7 2001/11/09 00:20:26 marc Exp $ */ /* * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au> * All rights reserved. @@ -38,17 +38,31 @@ #include <pthread.h> #include "pthread_private.h" +/* + * Note: a thread calling wait4 may have its state changed to waiting + * until awakened by a signal. Also note that system(3), for example, + * blocks SIGCHLD and calls waitpid (which calls wait4). If the process + * started by system(3) doesn't finish before this function is called the + * function will never awaken -- system(3) also ignores SIGINT and SIGQUIT. + * + * Thus always unmask SIGCHLD here. + */ pid_t wait4(pid_t pid, int *istat, int options, struct rusage * rusage) { struct pthread *curthread = _get_curthread(); pid_t ret; + sigset_t mask, omask; /* This is a cancellation point: */ _thread_enter_cancellation_point(); _thread_kern_sig_defer(); + sigemptyset(&mask); + sigaddset(&mask, SIGCHLD); + sigprocmask(SIG_UNBLOCK, &mask, &omask); + /* Perform a non-blocking wait4 syscall: */ while ((ret = _thread_sys_wait4(pid, istat, options | WNOHANG, rusage)) == 0 && (options & WNOHANG) == 0) { /* Reset the interrupted operation flag: */ @@ -65,6 +79,8 @@ wait4(pid_t pid, int *istat, int options, struct rusage * rusage) } } + sigprocmask(SIG_SETMASK, &omask, NULL); + _thread_kern_sig_undefer(); /* No longer in a cancellation point: */ |