esp-idf/components/rt/include/mqueue.h

/*
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/**
 * @file mqueue.h
 * @brief Message queues.
 *
 * http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/mqueue.h.html
 */

#pragma once

#include <time.h>

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @brief Message queue descriptor.
 */
typedef void * mqd_t;

/**
 * @brief Message queue attributes.
 */
struct mq_attr
{
    long mq_flags;   /**< Message queue flags. */
    long mq_maxmsg;  /**< Maximum number of messages. */
    long mq_msgsize; /**< Maximum message size. */
    long mq_curmsgs; /**< Number of messages currently queued. */
};

/**
 * @brief Close a message queue.
 *
 * Please refer to http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_close.html for more details.
 */
int mq_close( mqd_t mqdes );

/**
 * @brief Get message queue attributes.
 *
 * Please refer to http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_getattr.html for more details.
 */
int mq_getattr( mqd_t mqdes,
                struct mq_attr * mqstat );

/**
 * @brief Open a message queue.
 *
 * Please refer to http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_open.html for more details.
 *
 * @note Supported name pattern: leading &lt;slash&gt; character in name is always required;
 * the maximum length (excluding null-terminator) of the name argument can be NAME_MAX + 2.
 * @note mode argument is not supported.
 * @note Supported oflags: O_RDWR, O_CREAT, O_EXCL, and O_NONBLOCK.
 */
mqd_t mq_open( const char * name,
               int oflag,
               ... );

/**
 * @brief Receive a message from a message queue.
 *
 * Please refer to http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_receive.html for more details.
 *
 * @note msg_prio argument is not supported. Messages are not checked for corruption.
 */
ssize_t mq_receive( mqd_t mqdes,
                    char * msg_ptr,
                    size_t msg_len,
                    unsigned int * msg_prio );

/**
 * @brief Send a message to a message queue.
 *
 * Please refer to http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_send.html for more details.
 *
 * @note msg_prio argument is not supported.
 */
int mq_send( mqd_t mqdes,
             const char * msg_ptr,
             size_t msg_len,
             unsigned msg_prio );

/**
 * @brief Receive a message from a message queue with timeout.
 *
 * Please refer to http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_timedreceive.html for more details.
 *
 * @note msg_prio argument is not supported. Messages are not checked for corruption.
 */
ssize_t mq_timedreceive( mqd_t mqdes,
                         char * msg_ptr,
                         size_t msg_len,
                         unsigned * msg_prio,
                         const struct timespec * abstime );

/**
 * @brief Send a message to a message queue with timeout.
 *
 * Please refer to http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_timedsend.html for more details.
 *
 * @note msg_prio argument is not supported.
 */
int mq_timedsend( mqd_t mqdes,
                  const char * msg_ptr,
                  size_t msg_len,
                  unsigned msg_prio,
                  const struct timespec * abstime );

/**
 * @brief Remove a message queue.
 *
 * Please refer to http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_unlink.html for more details.
 */
int mq_unlink( const char * name );

/* Added by Espressif - specified but not implemented functions, return ENOSYS */
int mq_notify( mqd_t, const struct sigevent * );
int mq_setattr( mqd_t, const struct mq_attr *, struct mq_attr * );

#ifdef __cplusplus
}
#endif