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/**
* @file
*
* @brief Lock a Semaphore
* @ingroup POSIX_SEMAPHORE POSIX Semaphores Support
*/
/*
* COPYRIGHT (c) 1989-2008.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdarg.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <semaphore.h>
#include <limits.h>
#include <rtems/system.h>
#include <rtems/score/todimpl.h>
#include <rtems/posix/semaphoreimpl.h>
#include <rtems/seterr.h>
/*
* 11.2.6 Lock a Semaphore, P1003.1b-1993, p.226
*
* NOTE: P1003.4b/D8 adds sem_timedwait(), p. 27
*/
int sem_timedwait(
sem_t *__restrict sem,
const struct timespec *__restrict abstime
)
{
Watchdog_Interval ticks;
bool do_wait = true;
TOD_Absolute_timeout_conversion_results status;
int lock_status;
/*
* POSIX requires that blocking calls with timeouts that take
* an absolute timeout must ignore issues with the absolute
* time provided if the operation would otherwise succeed.
* So we check the abstime provided, and hold on to whether it
* is valid or not. If it isn't correct and in the future,
* then we do a polling operation and convert the UNSATISFIED
* status into the appropriate error.
*
* If the status is TOD_ABSOLUTE_TIMEOUT_INVALID,
* TOD_ABSOLUTE_TIMEOUT_IS_IN_PAST, or TOD_ABSOLUTE_TIMEOUT_IS_NOW,
* then we should not wait.
*/
status = _TOD_Absolute_timeout_to_ticks( abstime, CLOCK_REALTIME, &ticks );
if ( status != TOD_ABSOLUTE_TIMEOUT_IS_IN_FUTURE )
do_wait = false;
lock_status = _POSIX_Semaphore_Wait_support( sem, do_wait, ticks );
/*
* This service only gives us the option to block. We used a polling
* attempt to obtain if the abstime was not in the future. If we did
* not obtain the semaphore, then not look at the status immediately,
* make sure the right reason is returned.
*/
if ( !do_wait && (lock_status == EBUSY) ) {
if ( lock_status == TOD_ABSOLUTE_TIMEOUT_INVALID )
rtems_set_errno_and_return_minus_one( EINVAL );
if ( lock_status == TOD_ABSOLUTE_TIMEOUT_IS_IN_PAST ||
lock_status == TOD_ABSOLUTE_TIMEOUT_IS_NOW )
rtems_set_errno_and_return_minus_one( ETIMEDOUT );
}
return lock_status;
}
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