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/**
* @file
*
* @brief Attempt to Obtain a Read Lock on a RWLock Instance
* @ingroup POSIXAPI
*/
/*
* 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 <rtems/posix/rwlockimpl.h>
#include <rtems/posix/posixapi.h>
#include <rtems/score/todimpl.h>
int pthread_rwlock_timedrdlock(
pthread_rwlock_t *rwlock,
const struct timespec *abstime
)
{
POSIX_RWLock_Control *the_rwlock;
Thread_queue_Context queue_context;
Watchdog_Interval ticks;
bool do_wait;
TOD_Absolute_timeout_conversion_results timeout_status;
Status_Control 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 STATUS_UNAVAILABLE
* status into the appropriate error.
*
* If the timeout status is TOD_ABSOLUTE_TIMEOUT_INVALID,
* TOD_ABSOLUTE_TIMEOUT_IS_IN_PAST, or TOD_ABSOLUTE_TIMEOUT_IS_NOW,
* then we should not wait.
*/
timeout_status = _TOD_Absolute_timeout_to_ticks( abstime, CLOCK_REALTIME, &ticks );
do_wait = ( timeout_status == TOD_ABSOLUTE_TIMEOUT_IS_IN_FUTURE );
the_rwlock = _POSIX_RWLock_Get( rwlock, &queue_context );
if ( the_rwlock == NULL ) {
return EINVAL;
}
_Thread_queue_Context_set_relative_timeout( &queue_context, ticks );
status = _CORE_RWLock_Seize_for_reading(
&the_rwlock->RWLock,
_Thread_Executing,
do_wait,
&queue_context
);
if ( !do_wait && status == STATUS_UNAVAILABLE ) {
if ( timeout_status == TOD_ABSOLUTE_TIMEOUT_INVALID ) {
return EINVAL;
}
if (
timeout_status == TOD_ABSOLUTE_TIMEOUT_IS_IN_PAST
|| timeout_status == TOD_ABSOLUTE_TIMEOUT_IS_NOW
) {
return ETIMEDOUT;
}
}
return _POSIX_Get_error( status );
}
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