source: rtems/cpukit/posix/src/mqueuetimedreceive.c @ dbb30e26

/**
 * @file
 *
 * @brief Receive Message from Message Queue
 * @ingroup POSIXAPI
 */

/*
 *  NOTE:  The structure of the routines is identical to that of POSIX
 *         Message_queues to leave the option of having unnamed message
 *         queues at a future date.  They are currently not part of the
 *         POSIX standard but unnamed message_queues are.  This is also
 *         the reason for the apparently unnecessary tracking of
 *         the process_shared attribute.  [In addition to the fact that
 *         it would be trivial to add pshared to the mq_attr structure
 *         and have process private message queues.]
 *
 *         This code ignores the O_RDONLY/O_WRONLY/O_RDWR flag at open
 *         time.
 */

/*
 *  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 <pthread.h>
#include <limits.h>
#include <errno.h>
#include <fcntl.h>
#include <mqueue.h>

#include <rtems/system.h>
#include <rtems/score/todimpl.h>
#include <rtems/seterr.h>
#include <rtems/posix/mqueueimpl.h>

/*
 *  15.2.5 Receive a Message From a Message Queue, P1003.1b-1993, p. 279
 *
 *  NOTE: P1003.4b/D8, p. 45 adds mq_timedreceive().
 */

ssize_t mq_timedreceive(
  mqd_t                  mqdes,
  char                  *__restrict msg_ptr,
  size_t                 msg_len,
  unsigned int          *__restrict msg_prio,
  const struct timespec *__restrict abstime
)
{
  Watchdog_Interval                            ticks;
  bool                                         do_wait = true;
  TOD_Absolute_timeout_conversion_results  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;

  return _POSIX_Message_queue_Receive_support(
    mqdes,
    msg_ptr,
    msg_len,
    msg_prio,
    do_wait,
    ticks
  );
}