source: rtems/cpukit/posix/src/mqueuerecvsupp.c @ 631b3c8

/**
 * @file
 *
 * @brief POSIX Message Queue Receive Support
 * @ingroup POSIX_MQUEUE_P Message Queues Private Support Information
 */

/*
 *  COPYRIGHT (c) 1989-2011.
 *  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/mqueueimpl.h>

#include <fcntl.h>

THREAD_QUEUE_OBJECT_ASSERT(
  POSIX_Message_queue_Control,
  Message_queue.Wait_queue
);

/*
 *  _POSIX_Message_queue_Receive_support
 *
 *  NOTE: XXX Document how size, priority, length, and the buffer go
 *        through the layers.
 */

ssize_t _POSIX_Message_queue_Receive_support(
  mqd_t               mqdes,
  char               *msg_ptr,
  size_t              msg_len,
  unsigned int       *msg_prio,
  bool                wait,
  Watchdog_Interval   timeout
)
{
  POSIX_Message_queue_Control *the_mq;
  Thread_queue_Context         queue_context;
  size_t                       length_out;
  bool                         do_wait;
  Thread_Control              *executing;

  the_mq = _POSIX_Message_queue_Get( mqdes, &queue_context );

  if ( the_mq == NULL ) {
    rtems_set_errno_and_return_minus_one( EBADF );
  }

  if ( ( the_mq->oflag & O_ACCMODE ) == O_WRONLY ) {
    _ISR_lock_ISR_enable( &queue_context.Lock_context );
    rtems_set_errno_and_return_minus_one( EBADF );
  }

  if ( msg_len < the_mq->Message_queue.maximum_message_size ) {
    _ISR_lock_ISR_enable( &queue_context.Lock_context );
    rtems_set_errno_and_return_minus_one( EMSGSIZE );
  }

  /*
   *  Now if something goes wrong, we return a "length" of -1
   *  to indicate an error.
   */

  length_out = -1;

  /*
   *  A timed receive with a bad time will do a poll regardless.
   */
  if ( wait ) {
    do_wait = ( the_mq->oflag & O_NONBLOCK ) == 0;
  } else {
    do_wait = wait;
  }

  _CORE_message_queue_Acquire_critical(
    &the_mq->Message_queue,
    &queue_context
  );

  if ( the_mq->open_count == 0 ) {
    _CORE_message_queue_Release( &the_mq->Message_queue, &queue_context );
    rtems_set_errno_and_return_minus_one( EBADF );
  }

  /*
   *  Now perform the actual message receive
   */
  executing = _Thread_Executing;
  _CORE_message_queue_Seize(
    &the_mq->Message_queue,
    executing,
    msg_ptr,
    &length_out,
    do_wait,
    timeout,
    &queue_context
  );

  if ( msg_prio != NULL ) {
    *msg_prio = _POSIX_Message_queue_Priority_from_core(
      executing->Wait.count
    );
  }

  if ( executing->Wait.return_code != CORE_MESSAGE_QUEUE_STATUS_SUCCESSFUL ) {
    rtems_set_errno_and_return_minus_one(
      _POSIX_Message_queue_Translate_core_message_queue_return_code(
        executing->Wait.return_code
      )
    );
  }

  return length_out;
}