314 lines
9.9 KiB
C
314 lines
9.9 KiB
C
/****************************************************************************
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* sched/mq_rcvinternal.c
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*
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* Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
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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 <sys/types.h>
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#include <fcntl.h> /* O_NONBLOCK */
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#include <string.h>
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#include <assert.h>
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#include <errno.h>
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#include <mqueue.h>
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#include <sched.h>
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#include <debug.h>
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#include <nuttx/arch.h>
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#include "os_internal.h"
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#include "mq_internal.h"
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/****************************************************************************
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* Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Type Declarations
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****************************************************************************/
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/****************************************************************************
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* Global Variables
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****************************************************************************/
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/****************************************************************************
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* Private Variables
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****************************************************************************/
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: mq_verifyreceive
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*
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* Description:
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* This is internal, common logic shared by both mq_receive
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* and mq_timedreceive. This function verifies the
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* input parameters that are common to both functions.
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*
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* Parameters:
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* mqdes - Message Queue Descriptor
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* msg - Buffer to receive the message
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* msglen - Size of the buffer in bytes
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*
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* Return Value:
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* One success, 0 (OK) is returned. On failure, -1 (ERROR) is
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* returned and the errno is set appropriately:
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*
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* EPERM Message queue opened not opened for reading.
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* EMSGSIZE 'msglen' was less than the maxmsgsize attribute of the
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* message queue.
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* EINVAL Invalid 'msg' or 'mqdes'
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*
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* Assumptions:
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*
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****************************************************************************/
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int mq_verifyreceive(mqd_t mqdes, void *msg, size_t msglen)
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{
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/* Verify the input parameters */
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if (!msg || !mqdes)
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{
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*get_errno_ptr() = EINVAL;
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return ERROR;
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}
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if ((mqdes->oflags & O_RDOK) == 0)
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{
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*get_errno_ptr() = EPERM;
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return ERROR;
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}
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if (msglen < (size_t)mqdes->msgq->maxmsgsize)
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{
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*get_errno_ptr() = EMSGSIZE;
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return ERROR;
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}
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return OK;
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}
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/****************************************************************************
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* Function: mq_waitreceive
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*
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* Description:
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* This is internal, common logic shared by both mq_receive
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* and mq_timedreceive. This function waits for a message to
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* be received on the specified message queue, removes the
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* message from the queue, and returns it.
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*
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* Parameters:
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* mqdes - Message queue descriptor
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*
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* Return Value:
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* On success, a reference to the received message. If the
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* wait was interrupted by a signal or a timeout, then the
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* errno will be set appropriately and NULL will be returned.
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*
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* Assumptions:
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* - The caller has provided all validity checking of the
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* input parameters using mq_verifyreceive.
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* - Interrupts should be disabled throughout this call. This
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* is necessary because messages can be sent from interrupt
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* level processing.
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* - For mq_timedreceive, setting of the timer and this wait
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* must be atomic.
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*
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****************************************************************************/
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FAR mqmsg_t *mq_waitreceive(mqd_t mqdes)
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{
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FAR _TCB *rtcb;
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FAR msgq_t *msgq;
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FAR mqmsg_t *rcvmsg;
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/* Get a pointer to the message queue */
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msgq = mqdes->msgq;
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/* Get the message from the head of the queue */
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while ((rcvmsg = (FAR mqmsg_t*)sq_remfirst(&msgq->msglist)) == NULL)
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{
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/* The queue is empty! Should we block until there the above condition
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* has been satisfied?
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*/
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if ((mqdes->oflags & O_NONBLOCK) == 0)
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{
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/* Yes.. Block and try again */
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rtcb = (FAR _TCB*)g_readytorun.head;
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rtcb->msgwaitq = msgq;
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msgq->nwaitnotempty++;
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*get_errno_ptr() = OK;
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up_block_task(rtcb, TSTATE_WAIT_MQNOTEMPTY);
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/* When we resume at this point, either (1) the message queue
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* is no longer empty, or (2) the wait has been interrupted by
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* a signal. We can detect the latter case be examining the
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* errno value (should be either EINTR or ETIMEDOUT).
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*/
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if (*get_errno_ptr() != OK)
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{
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break;
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}
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}
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else
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{
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/* The queue was empty, and the O_NONBLOCK flag was set for the
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* message queue description referred to by 'mqdes'.
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*/
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*get_errno_ptr() = EAGAIN;
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break;
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}
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}
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/* If we got message, then decrement the number of messages in
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* the queue while we are still in the critical section
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*/
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if (rcvmsg)
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{
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msgq->nmsgs--;
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}
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return rcvmsg;
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}
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/****************************************************************************
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* Function: mq_doreceive
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*
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* Description:
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* This is internal, common logic shared by both mq_receive
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* and mq_timedreceive. This function accepts the message
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* obtained by mq_waitmsg, provides the message content to
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* the user, notifies any threads that were waiting for
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* the message queue to become non-full, and disposes of the
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* message structure
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*
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* Parameters:
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* mqdes - Message queue descriptor
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* mqmsg - The message obtained by mq_waitmsg()
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* ubuffer - The address of the user provided buffer to
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* receive the message
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* prio - The user-provided location to return the
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* message priority.
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*
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* Return Value:
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* Returns the length of the received message. This
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* function does not fail.
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*
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* Assumptions:
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* - The caller has provided all validity checking of the
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* input parameters using mq_verifyreceive.
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* - The user buffer, ubuffer, is known to be large enough
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* to accept the largest message that an be sent on this
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* message queue
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* - Pre-emption should be disabled throughout this call.
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*
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****************************************************************************/
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ssize_t mq_doreceive(mqd_t mqdes, mqmsg_t *mqmsg, void *ubuffer, int *prio)
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{
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FAR _TCB *btcb;
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irqstate_t saved_state;
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FAR msgq_t *msgq;
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ssize_t rcvmsglen;
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/* Get the length of the message (also the return value) */
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rcvmsglen = mqmsg->msglen;
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/* Copy the message into the caller's buffer */
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memcpy(ubuffer, (const void*)mqmsg->mail, rcvmsglen);
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/* Copy the message priority as well (if a buffer is provided) */
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if (prio)
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{
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*prio = mqmsg->priority;
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}
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/* We are done with the message. Deallocate it now. */
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mq_msgfree(mqmsg);
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/* Check if any tasks are waiting for the MQ not full event. */
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msgq = mqdes->msgq;
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if (msgq->nwaitnotfull > 0)
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{
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/* Find the highest priority task that is waiting for
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* this queue to be not-full in g_waitingformqnotfull list.
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* This must be performed in a critical section because
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* messages can be sent from interrupt handlers.
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*/
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saved_state = irqsave();
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for (btcb = (FAR _TCB*)g_waitingformqnotfull.head;
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btcb && btcb->msgwaitq != msgq;
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btcb = btcb->flink);
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/* If one was found, unblock it. NOTE: There is a race
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* condition here: the queue might be full again by the
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* time the task is unblocked
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*/
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if (!btcb)
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{
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PANIC(OSERR_MQNOTFULLCOUNT);
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}
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else
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{
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btcb->msgwaitq = NULL;
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msgq->nwaitnotfull--;
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up_unblock_task(btcb);
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}
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irqrestore(saved_state);
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}
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/* Return the length of the message transferred to the user buffer */
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return rcvmsglen;
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}
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