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907ea199d0
1999-10-14 Andreas Jaeger <aj@suse.de> * sysdeps/unix/sysv/linux/sleep.c (__sleep): Optimize for zero seconds.
94 lines
3.1 KiB
C
94 lines
3.1 KiB
C
/* Implementation of the POSIX sleep function using nanosleep.
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Copyright (C) 1996, 1997, 1998, 1999 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <errno.h>
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#include <time.h>
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#include <signal.h>
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#include <unistd.h>
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/* We are going to use the `nanosleep' syscall of the kernel. But the
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kernel does not implement the sstupid SysV SIGCHLD vs. SIG_IGN
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behaviour for this syscall. Therefore we have to emulate it here. */
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unsigned int
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__sleep (unsigned int seconds)
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{
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struct timespec ts = { tv_sec: (long int) seconds, tv_nsec: 0 };
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sigset_t set, oset;
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unsigned int result;
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/* This is not necessary but some buggy programs depend on this. */
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if (seconds == 0)
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return 0;
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/* Linux will wake up the system call, nanosleep, when SIGCHLD
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arrives even if SIGCHLD is ignored. We have to deal with it
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in libc. We block SIGCHLD first. */
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if (__sigemptyset (&set) < 0
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|| __sigaddset (&set, SIGCHLD) < 0
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|| __sigprocmask (SIG_BLOCK, &set, &oset))
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return -1;
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/* If SIGCHLD is already blocked, we don't have to do anything. */
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if (!__sigismember (&oset, SIGCHLD))
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{
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int saved_errno;
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struct sigaction oact;
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if (__sigemptyset (&set) < 0 || __sigaddset (&set, SIGCHLD) < 0)
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return -1;
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/* We get the signal handler for SIGCHLD. */
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if (__sigaction (SIGCHLD, (struct sigaction *) NULL, &oact) < 0)
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{
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saved_errno = errno;
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/* Restore the original signal mask. */
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(void) __sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
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__set_errno (saved_errno);
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return -1;
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}
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if (oact.sa_handler == SIG_IGN)
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{
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/* We should leave SIGCHLD blocked. */
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result = __nanosleep (&ts, &ts);
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saved_errno = errno;
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/* Restore the original signal mask. */
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(void) __sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
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__set_errno (saved_errno);
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}
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else
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{
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/* We should unblock SIGCHLD. Restore the original signal mask. */
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(void) __sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
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result = __nanosleep (&ts, &ts);
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}
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}
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else
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result = __nanosleep (&ts, &ts);
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if (result != 0)
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/* Round remaining time. */
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result = (unsigned int) ts.tv_sec + (ts.tv_nsec >= 500000000L);
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return result;
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}
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weak_alias (__sleep, sleep)
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