mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-02 17:50:20 +00:00
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.
|
|
Copyright (C) 1996, 1997, 1998, 1999 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
|
|
|
|
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 <errno.h>
|
|
#include <time.h>
|
|
#include <signal.h>
|
|
#include <unistd.h>
|
|
|
|
/* We are going to use the `nanosleep' syscall of the kernel. But the
|
|
kernel does not implement the sstupid SysV SIGCHLD vs. SIG_IGN
|
|
behaviour for this syscall. Therefore we have to emulate it here. */
|
|
unsigned int
|
|
__sleep (unsigned int seconds)
|
|
{
|
|
struct timespec ts = { tv_sec: (long int) seconds, tv_nsec: 0 };
|
|
sigset_t set, oset;
|
|
unsigned int result;
|
|
|
|
/* This is not necessary but some buggy programs depend on this. */
|
|
if (seconds == 0)
|
|
return 0;
|
|
|
|
/* 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))
|
|
{
|
|
int saved_errno;
|
|
struct sigaction oact;
|
|
|
|
if (__sigemptyset (&set) < 0 || __sigaddset (&set, SIGCHLD) < 0)
|
|
return -1;
|
|
|
|
/* 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. */
|
|
result = __nanosleep (&ts, &ts);
|
|
|
|
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);
|
|
result = __nanosleep (&ts, &ts);
|
|
}
|
|
}
|
|
else
|
|
result = __nanosleep (&ts, &ts);
|
|
|
|
if (result != 0)
|
|
/* Round remaining time. */
|
|
result = (unsigned int) ts.tv_sec + (ts.tv_nsec >= 500000000L);
|
|
|
|
return result;
|
|
}
|
|
weak_alias (__sleep, sleep)
|