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glibc/sysdeps/unix/sysv/linux/sleep.c
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/* Implementation of the POSIX sleep function using nanosleep. | |
Copyright (C) 1996-2015 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 Lesser General Public | |
License as published by the Free Software Foundation; either | |
version 2.1 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 | |
Lesser General Public License for more details. | |
You should have received a copy of the GNU Lesser General Public | |
License along with the GNU C Library; if not, see | |
<http://www.gnu.org/licenses/>. */ | |
#include <errno.h> | |
#include <time.h> | |
#include <signal.h> | |
#include <string.h> /* For the real memset prototype. */ | |
#include <unistd.h> | |
#include <sys/param.h> | |
#include <nptl/pthreadP.h> | |
#if 0 | |
static void | |
cl (void *arg) | |
{ | |
(void) __sigprocmask (SIG_SETMASK, arg, (sigset_t *) NULL); | |
} | |
#endif | |
/* We are going to use the `nanosleep' syscall of the kernel. But the | |
kernel does not implement the stupid SysV SIGCHLD vs. SIG_IGN | |
behaviour for this syscall. Therefore we have to emulate it here. */ | |
unsigned int | |
__sleep (unsigned int seconds) | |
{ | |
const unsigned int max | |
= (unsigned int) (((unsigned long int) (~((time_t) 0))) >> 1); | |
struct timespec ts; | |
sigset_t set, oset; | |
unsigned int result; | |
/* This is not necessary but some buggy programs depend on this. */ | |
if (__glibc_unlikely (seconds == 0)) | |
{ | |
#ifdef CANCELLATION_P | |
CANCELLATION_P (THREAD_SELF); | |
#endif | |
return 0; | |
} | |
ts.tv_sec = 0; | |
ts.tv_nsec = 0; | |
again: | |
if (sizeof (ts.tv_sec) <= sizeof (seconds)) | |
{ | |
/* Since SECONDS is unsigned assigning the value to .tv_sec can | |
overflow it. In this case we have to wait in steps. */ | |
ts.tv_sec += MIN (seconds, max); | |
seconds -= (unsigned int) ts.tv_sec; | |
} | |
else | |
{ | |
ts.tv_sec = (time_t) seconds; | |
seconds = 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. */ | |
__sigemptyset (&set); | |
__sigaddset (&set, SIGCHLD); | |
if (__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; | |
__sigemptyset (&set); | |
__sigaddset (&set, 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; | |
} | |
/* Note the sleep() is a cancellation point. But since we call | |
nanosleep() which itself is a cancellation point we do not | |
have to do anything here. */ | |
if (oact.sa_handler == SIG_IGN) | |
{ | |
//__libc_cleanup_push (cl, &oset); | |
/* We should leave SIGCHLD blocked. */ | |
while (1) | |
{ | |
result = __nanosleep (&ts, &ts); | |
if (result != 0 || seconds == 0) | |
break; | |
if (sizeof (ts.tv_sec) <= sizeof (seconds)) | |
{ | |
ts.tv_sec = MIN (seconds, max); | |
seconds -= (unsigned int) ts.tv_nsec; | |
} | |
} | |
//__libc_cleanup_pop (0); | |
saved_errno = errno; | |
/* Restore the original signal mask. */ | |
(void) __sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL); | |
__set_errno (saved_errno); | |
goto out; | |
} | |
/* We should unblock SIGCHLD. Restore the original signal mask. */ | |
(void) __sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL); | |
} | |
result = __nanosleep (&ts, &ts); | |
if (result == 0 && seconds != 0) | |
goto again; | |
out: | |
if (result != 0) | |
/* Round remaining time. */ | |
result = seconds + (unsigned int) ts.tv_sec + (ts.tv_nsec >= 500000000L); | |
return result; | |
} | |
weak_alias (__sleep, sleep) |