182 lines
6.5 KiB
C
182 lines
6.5 KiB
C
/****************************************************************************
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* sched/mqueue/mq_send.c
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*
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* Copyright (C) 2007, 2009, 2016 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <mqueue.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/irq.h>
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#include <nuttx/arch.h>
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#include "mqueue/mqueue.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: mq_send
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*
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* Description:
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* This function adds the specified message (msg) to the message queue
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* (mqdes). The "msglen" parameter specifies the length of the message
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* in bytes pointed to by "msg." This length must not exceed the maximum
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* message length from the mq_getattr().
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*
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* If the message queue is not full, mq_send() place the message in the
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* message queue at the position indicated by the "prio" argument.
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* Messages with higher priority will be inserted before lower priority
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* messages. The value of "prio" must not exceed MQ_PRIO_MAX.
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*
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* If the specified message queue is full and O_NONBLOCK is not set in the
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* message queue, then mq_send() will block until space becomes available
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* to the queue the message.
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*
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* If the message queue is full and O_NONBLOCK is set, the message is not
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* queued and ERROR is returned.
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*
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* Parameters:
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* mqdes - Message queue descriptor
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* msg - Message to send
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* msglen - The length of the message in bytes
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* prio - The priority of the message
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*
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* Return Value:
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* On success, mq_send() returns 0 (OK); on error, -1 (ERROR)
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* is returned, with errno set to indicate the error:
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*
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* EAGAIN The queue was full and the O_NONBLOCK flag was set for the
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* message queue description referred to by mqdes.
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* EINVAL Either msg or mqdes is NULL or the value of prio is invalid.
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* EPERM Message queue opened not opened for writing.
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* EMSGSIZE 'msglen' was greater than the maxmsgsize attribute of the
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* message queue.
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* EINTR The call was interrupted by a signal handler.
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*
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* Assumptions/restrictions:
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*
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****************************************************************************/
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int mq_send(mqd_t mqdes, FAR const char *msg, size_t msglen, int prio)
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{
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FAR struct mqueue_inode_s *msgq;
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FAR struct mqueue_msg_s *mqmsg = NULL;
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irqstate_t flags;
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int ret = ERROR;
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/* Verify the input parameters -- setting errno appropriately
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* on any failures to verify.
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*/
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if (mq_verifysend(mqdes, msg, msglen, prio) != OK)
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{
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return ERROR;
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}
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/* Get a pointer to the message queue */
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sched_lock();
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msgq = mqdes->msgq;
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/* Allocate a message structure:
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* - Immediately if we are called from an interrupt handler.
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* - Immediately if the message queue is not full, or
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* - After successfully waiting for the message queue to become
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* non-FULL. This would fail with EAGAIN, EINTR, or ETIMEOUT.
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*/
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flags = enter_critical_section();
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if (up_interrupt_context() || /* In an interrupt handler */
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msgq->nmsgs < msgq->maxmsgs || /* OR Message queue not full */
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mq_waitsend(mqdes) == OK) /* OR Successfully waited for mq not full */
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{
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/* Allocate the message */
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leave_critical_section(flags);
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mqmsg = mq_msgalloc();
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/* Check if the message was sucessfully allocated */
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if (mqmsg == NULL)
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{
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/* No... mq_msgalloc() does not set the errno value */
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set_errno(ENOMEM);
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}
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}
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else
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{
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/* We cannot send the message (and didn't even try to allocate it)
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* because:
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* - We are not in an interrupt handler AND
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* - The message queue is full AND
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* - When we tried waiting, the wait was unsuccessful.
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*
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* In this case mq_waitsend() has already set the errno value.
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*/
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leave_critical_section(flags);
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}
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/* Check if we were able to get a message structure -- this can fail
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* either because we cannot send the message (and didn't bother trying
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* to allocate it) or because the allocation failed.
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*/
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if (mqmsg != NULL)
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{
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/* The allocation was successful (implying that we can also send the
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* message). Perform the message send.
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*
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* NOTE: There is a race condition here: What if a message is added by
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* interrupt related logic so that queue again becomes non-empty.
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* That is handled because mq_dosend() will permit the maxmsgs limit
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* to be exceeded in that case.
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*/
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ret = mq_dosend(mqdes, mqmsg, msg, msglen, prio);
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}
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sched_unlock();
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return ret;
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}
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