glibc/sysdeps/posix/sleep.c

76 lines
2.5 KiB
C

/* Sleep for a given number of seconds. POSIX.1 version.
Copyright (C) 1991-2012 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 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 <time.h>
#include <unistd.h>
#include <errno.h>
#include <sys/param.h>
/* Make the process sleep for SECONDS seconds, or until a signal arrives
and is not ignored. The function returns the number of seconds less
than SECONDS which it actually slept (zero if it slept the full time).
If a signal handler does a `longjmp' or modifies the handling of the
SIGALRM signal while inside `sleep' call, the handling of the SIGALRM
signal afterwards is undefined. There is no return value to indicate
error, but if `sleep' returns SECONDS, it probably didn't work. */
unsigned int
__sleep (unsigned int seconds)
{
/* This is not necessary but some buggy programs depend on it. */
if (__builtin_expect (seconds == 0, 0))
{
#ifdef CANCELLATION_P
CANCELLATION_P (THREAD_SELF);
#endif
return 0;
}
int save_errno = errno;
const unsigned int max
= (unsigned int) (((unsigned long int) (~((time_t) 0))) >> 1);
struct timespec ts = { 0, 0 };
do
{
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;
}
if (__nanosleep (&ts, &ts) < 0)
/* We were interrupted.
Return the number of (whole) seconds we have not yet slept. */
return seconds + ts.tv_sec;
}
while (seconds > 0);
__set_errno (save_errno);
return 0;
}
weak_alias (__sleep, sleep)