I don't think so. If SIGCHLD is ignored, we have to block SIGCHLD in
nanosleep. Otherwise, we have to restore the original signal mask.
Here is an update. I hope it is easier to understand.
-- H.J. Lu (hjl@gnu.org) ---- /* Copyright (C) 1998 Free Software Foundation, Inc. This file is part of the GNU C Library.The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for more details.
You should have received a copy of the GNU Library General Public License along with the GNU C Library; see the file COPYING.LIB. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
#include <signal.h> #include <time.h> #include <unistd.h> #include <errno.h>
extern int __syscall_nanosleep (const struct timespec *req, struct timespec *rem);
int __nanosleep(const struct timespec *req, struct timespec *rem) { sigset_t set, oset; struct sigaction oact; int saved_errno; int ret;
/* Linux will wake up the system call, nanosleep, when SIGCHLD arrives even if SIGCHLD is ignored. We have to deal with it in libc. We block SIGCHLD first. */ if (sigemptyset (&set) < 0 || sigaddset (&set, SIGCHLD) < 0 || sigprocmask (SIG_BLOCK, &set, &oset)) return -1;
/* If SIGCHLD is already blocked, we don't have to do anything. */ if (!sigismember (&oset, SIGCHLD)) { /* We get the signal handler for SIGCHLD. */ if (sigaction (SIGCHLD, (struct sigaction *) NULL, &oact) < 0) { saved_errno = errno; /* Restore the original signal mask. */ (void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL); __set_errno (saved_errno); return -1; }
if (oact.sa_handler == SIG_IGN) { /* We should leave SIGCHLD blocked. */ ret = __syscall_nanosleep (req, rem);
saved_errno = errno; /* Restore the original signal mask. */ (void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL); __set_errno (saved_errno); } else { /* We should unblock SIGCHLD. Restore the original signal mask. */ (void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL); ret = __syscall_nanosleep (req, rem); } } else ret = __syscall_nanosleep (req, rem);
return ret; }
weak_alias (__nanosleep, nanosleep)
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/