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/* sem_timedwait -- wait on a semaphore. Generic futex-using version.
Copyright (C) 2003-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
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 <sysdep.h>
#include <lowlevellock.h>
#include <internaltypes.h>
#include <semaphore.h>
#include <sys/time.h>
#include <pthreadP.h>
#include <shlib-compat.h>
extern void __sem_wait_cleanup (void *arg) attribute_hidden;
/* This is in a seperate function in order to make sure gcc
puts the call site into an exception region, and thus the
cleanups get properly run. */
static int
__attribute__ ((noinline))
do_futex_timed_wait (struct new_sem *isem, struct timespec *rt)
{
int err, oldtype = __pthread_enable_asynccancel ();
err = lll_futex_timed_wait (&isem->value, 0, rt,
isem->private ^ FUTEX_PRIVATE_FLAG);
__pthread_disable_asynccancel (oldtype);
return err;
}
int
sem_timedwait (sem_t *sem, const struct timespec *abstime)
{
struct new_sem *isem = (struct new_sem *) sem;
int err;
if (atomic_decrement_if_positive (&isem->value) > 0)
return 0;
if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
{
__set_errno (EINVAL);
return -1;
}
atomic_increment (&isem->nwaiters);
pthread_cleanup_push (__sem_wait_cleanup, isem);
while (1)
{
struct timeval tv;
struct timespec rt;
int sec, nsec;
/* Get the current time. */
__gettimeofday (&tv, NULL);
/* Compute relative timeout. */
sec = abstime->tv_sec - tv.tv_sec;
nsec = abstime->tv_nsec - tv.tv_usec * 1000;
if (nsec < 0)
{
nsec += 1000000000;
--sec;
}
/* Already timed out? */
if (sec < 0)
{
__set_errno (ETIMEDOUT);
err = -1;
break;
}
/* Do wait. */
rt.tv_sec = sec;
rt.tv_nsec = nsec;
err = do_futex_timed_wait(isem, &rt);
if (err != 0 && err != -EWOULDBLOCK)
{
__set_errno (-err);
err = -1;
break;
}
if (atomic_decrement_if_positive (&isem->value) > 0)
{
err = 0;
break;
}
}
pthread_cleanup_pop (0);
atomic_decrement (&isem->nwaiters);
return err;
}
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