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 /* SPDX-License-Identifier: BSD-2-Clause */
 
 /**
  * @file
  *
  * @brief POSIX Message Queues
  * 
  * This file contains the definitions related to POSIX Message Queues.
  * 
  * 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) 1989-2011.
  *  On-Line Applications Research Corporation (OAR).
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef _MQUEUE_H
 #define _MQUEUE_H
 
 
 #include <unistd.h>
 
 #if defined(_POSIX_MESSAGE_PASSING)
 
 #include <sys/types.h>
 
 /**
  * @defgroup POSIX_MQUEUE POSIX Message Queues
  *
  * @ingroup POSIXAPI
  * 
  */
 /**@{**/
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 /*
  *  15.1.1 Data Structures, P1003.1b-1993, p. 271
  */
 
 /**
  * Message queue id type.
  *
  * NOTE: Use uint32_t since all POSIX Ids are 32-bit currently.
  */
 typedef uint32_t  mqd_t;
 
 /**
  * This is the message queue attributes structure.
  */
 struct mq_attr {
   /** This is the message queue flags */
   long  mq_flags;
   /** This is the maximum number of messages */
   long  mq_maxmsg;
   /** This is the maximum message size */
   long  mq_msgsize;
   /** This is the mumber of messages currently queued */
   long  mq_curmsgs;
 };
 
 /**
  * 15.2.2 Open a Message Queue, P1003.1b-1993, p. 272
  */
 mqd_t mq_open(
   const char *name,
   int         oflag,
   ...
 );
 
 /**
  * 15.2.2 Close a Message Queue, P1003.1b-1993, p. 275
  */
 int mq_close(
   mqd_t  mqdes
 );
 
 /**
  * @brief Remove a message queue.
  *
  * 15.2.2 Remove a Message Queue, P1003.1b-1993, p. 276
  *
  * 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.
  */
 int mq_unlink(
   const char *name
 );
 
 /**
  * 15.2.4 Send a Message to a Message Queue, P1003.1b-1993, p. 277
  *
  * NOTE; P1003.4b/D8, p. 45 adds mq_timedsend().
  */
 int mq_send(
   mqd_t         mqdes,
   const char   *msg_ptr,
   size_t        msg_len,
   unsigned int  msg_prio
 );
 
 #if defined(_POSIX_TIMEOUTS)
 
 #include <time.h>
 
 /**
  * @brief Send a message to a message queue.
  * 
  * @see mq_send()
  */
 int mq_timedsend(
   mqd_t                  mqdes,
   const char            *msg_ptr,
   size_t                 msg_len,
   unsigned int           msg_prio,
   const struct timespec *abstime
 );
 
 #endif /* _POSIX_TIMEOUTS */
 
 /**
  * @brief Receive a message from a message queue. 
  * 
  * 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_receive(
   mqd_t         mqdes,
   char         *msg_ptr,
   size_t        msg_len,
   unsigned int *msg_prio
 );
 
 #if defined(_POSIX_TIMEOUTS)
 
 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
 );
 
 #endif /* _POSIX_TIMEOUTS */
 
 #if defined(_POSIX_REALTIME_SIGNALS)
 
 /**
  * @brief Notify process that a message is available on a queue.
  *
  * 15.2.6 Notify Process that a Message is Available on a Queue,
  *        P1003.1b-1993, p. 280
  */
 int mq_notify(
   mqd_t                  mqdes,
   const struct sigevent *notification
 );
 
 #endif /* _POSIX_REALTIME_SIGNALS */
 
 /**
  * @brief Set message queue attributes.
  *
  * 15.2.7 Set Message Queue Attributes, P1003.1b-1993, p. 281
  */
 int mq_setattr(
   mqd_t                 mqdes,
   const struct mq_attr *__restrict mqstat,
   struct mq_attr       *__restrict omqstat
 );
 
 /*
  *  15.2.8 Get Message Queue Attributes, P1003.1b-1993, p. 283
  */
 
 int mq_getattr(
   mqd_t           mqdes,
   struct mq_attr *mqstat
 );
 
 /** @} */
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif /* _POSIX_MESSAGE_PASSING */
 
 #endif
 /* end of include file */

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