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/*
* POSIX RWLock Manager -- Attempt to Obtain a Read Lock on a RWLock Instance
*
* 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.com/license/LICENSE.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <pthread.h>
#include <errno.h>
#include <rtems/system.h>
#include <rtems/posix/rwlock.h>
#include <rtems/posix/time.h>
/*
* pthread_rwlock_timedrdlock
*
* This directive attempts to obtain a read only lock on an rwlock instance.
*
* Input parameters:
* rwlock - pointer to rwlock id
*
* Output parameters:
* 0 - if successful
* error code - if unsuccessful
*/
int pthread_rwlock_timedrdlock(
pthread_rwlock_t *rwlock,
const struct timespec *abstime
)
{
POSIX_RWLock_Control *the_rwlock;
Objects_Locations location;
Watchdog_Interval ticks;
bool do_wait = true;
POSIX_Absolute_timeout_conversion_results_t status;
if ( !rwlock )
return EINVAL;
/*
* 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 POSIX_ABSOLUTE_TIMEOUT_INVALID,
* POSIX_ABSOLUTE_TIMEOUT_IS_IN_PAST, or POSIX_ABSOLUTE_TIMEOUT_IS_NOW,
* then we should not wait.
*/
status = _POSIX_Absolute_timeout_to_ticks( abstime, &ticks );
if ( status != POSIX_ABSOLUTE_TIMEOUT_IS_IN_FUTURE )
do_wait = false;
the_rwlock = _POSIX_RWLock_Get( rwlock, &location );
switch ( location ) {
case OBJECTS_LOCAL:
_CORE_RWLock_Obtain_for_reading(
&the_rwlock->RWLock,
*rwlock,
do_wait,
ticks,
NULL
);
_Thread_Enable_dispatch();
if ( !do_wait ) {
if ( _Thread_Executing->Wait.return_code == CORE_RWLOCK_UNAVAILABLE ) {
if ( status == POSIX_ABSOLUTE_TIMEOUT_INVALID )
return EINVAL;
if ( status == POSIX_ABSOLUTE_TIMEOUT_IS_IN_PAST ||
status == POSIX_ABSOLUTE_TIMEOUT_IS_NOW )
return ETIMEDOUT;
}
}
return _POSIX_RWLock_Translate_core_RWLock_return_code(
(CORE_RWLock_Status) _Thread_Executing->Wait.return_code
);
#if defined(RTEMS_MULTIPROCESSING)
case OBJECTS_REMOTE:
#endif
case OBJECTS_ERROR:
break;
}
return EINVAL;
}
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