/****************************************************************************
* sched/mq_rcvinternal.c
*
* Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <sys/types.h>
#include <fcntl.h> /* O_NONBLOCK */
#include <string.h>
#include <assert.h>
#include <errno.h>
#include <mqueue.h>
#include <sched.h>
#include <debug.h>
#include <nuttx/arch.h>
#include "os_internal.h"
#include "mq_internal.h"
/****************************************************************************
* Definitions
****************************************************************************/
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Global Variables
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: mq_verifyreceive
*
* Description:
* This is internal, common logic shared by both mq_receive
* and mq_timedreceive. This function verifies the
* input parameters that are common to both functions.
*
* Parameters:
* mqdes - Message Queue Descriptor
* msg - Buffer to receive the message
* msglen - Size of the buffer in bytes
*
* Return Value:
* One success, 0 (OK) is returned. On failure, -1 (ERROR) is
* returned and the errno is set appropriately:
*
* EPERM Message queue opened not opened for reading.
* EMSGSIZE 'msglen' was less than the maxmsgsize attribute of the
* message queue.
* EINVAL Invalid 'msg' or 'mqdes'
*
* Assumptions:
*
****************************************************************************/
int mq_verifyreceive(mqd_t mqdes, void *msg, size_t msglen)
{
/* Verify the input parameters */
if (!msg || !mqdes)
{
*get_errno_ptr() = EINVAL;
return ERROR;
}
if ((mqdes->oflags & O_RDOK) == 0)
{
*get_errno_ptr() = EPERM;
return ERROR;
}
if (msglen < (size_t)mqdes->msgq->maxmsgsize)
{
*get_errno_ptr() = EMSGSIZE;
return ERROR;
}
return OK;
}
/****************************************************************************
* Function: mq_waitreceive
*
* Description:
* This is internal, common logic shared by both mq_receive
* and mq_timedreceive. This function waits for a message to
* be received on the specified message queue, removes the
* message from the queue, and returns it.
*
* Parameters:
* mqdes - Message queue descriptor
*
* Return Value:
* On success, a reference to the received message. If the
* wait was interrupted by a signal or a timeout, then the
* errno will be set appropriately and NULL will be returned.
*
* Assumptions:
* - The caller has provided all validity checking of the
* input parameters using mq_verifyreceive.
* - Interrupts should be disabled throughout this call. This
* is necessary because messages can be sent from interrupt
* level processing.
* - For mq_timedreceive, setting of the timer and this wait
* must be atomic.
*
****************************************************************************/
FAR mqmsg_t *mq_waitreceive(mqd_t mqdes)
{
FAR _TCB *rtcb;
FAR msgq_t *msgq;
FAR mqmsg_t *rcvmsg;
/* Get a pointer to the message queue */
msgq = mqdes->msgq;
/* Get the message from the head of the queue */
while ((rcvmsg = (FAR mqmsg_t*)sq_remfirst(&msgq->msglist)) == NULL)
{
/* The queue is empty! Should we block until there the above condition
* has been satisfied?
*/
if ((mqdes->oflags & O_NONBLOCK) == 0)
{
/* Yes.. Block and try again */
rtcb = (FAR _TCB*)g_readytorun.head;
rtcb->msgwaitq = msgq;
msgq->nwaitnotempty++;
*get_errno_ptr() = OK;
up_block_task(rtcb, TSTATE_WAIT_MQNOTEMPTY);
/* When we resume at this point, either (1) the message queue
* is no longer empty, or (2) the wait has been interrupted by
* a signal. We can detect the latter case be examining the
* errno value (should be either EINTR or ETIMEDOUT).
*/
if (*get_errno_ptr() != OK)
{
break;
}
}
else
{
/* The queue was empty, and the O_NONBLOCK flag was set for the
* message queue description referred to by 'mqdes'.
*/
*get_errno_ptr() = EAGAIN;
break;
}
}
/* If we got message, then decrement the number of messages in
* the queue while we are still in the critical section
*/
if (rcvmsg)
{
msgq->nmsgs--;
}
return rcvmsg;
}
/****************************************************************************
* Function: mq_doreceive
*
* Description:
* This is internal, common logic shared by both mq_receive
* and mq_timedreceive. This function accepts the message
* obtained by mq_waitmsg, provides the message content to
* the user, notifies any threads that were waiting for
* the message queue to become non-full, and disposes of the
* message structure
*
* Parameters:
* mqdes - Message queue descriptor
* mqmsg - The message obtained by mq_waitmsg()
* ubuffer - The address of the user provided buffer to
* receive the message
* prio - The user-provided location to return the
* message priority.
*
* Return Value:
* Returns the length of the received message. This
* function does not fail.
*
* Assumptions:
* - The caller has provided all validity checking of the
* input parameters using mq_verifyreceive.
* - The user buffer, ubuffer, is known to be large enough
* to accept the largest message that an be sent on this
* message queue
* - Pre-emption should be disabled throughout this call.
*
****************************************************************************/
ssize_t mq_doreceive(mqd_t mqdes, mqmsg_t *mqmsg, void *ubuffer, int *prio)
{
FAR _TCB *btcb;
irqstate_t saved_state;
FAR msgq_t *msgq;
ssize_t rcvmsglen;
/* Get the length of the message (also the return value) */
rcvmsglen = mqmsg->msglen;
/* Copy the message into the caller's buffer */
memcpy(ubuffer, (const void*)mqmsg->mail, rcvmsglen);
/* Copy the message priority as well (if a buffer is provided) */
if (prio)
{
*prio = mqmsg->priority;
}
/* We are done with the message. Deallocate it now. */
mq_msgfree(mqmsg);
/* Check if any tasks are waiting for the MQ not full event. */
msgq = mqdes->msgq;
if (msgq->nwaitnotfull > 0)
{
/* Find the highest priority task that is waiting for
* this queue to be not-full in g_waitingformqnotfull list.
* This must be performed in a critical section because
* messages can be sent from interrupt handlers.
*/
saved_state = irqsave();
for (btcb = (FAR _TCB*)g_waitingformqnotfull.head;
btcb && btcb->msgwaitq != msgq;
btcb = btcb->flink);
/* If one was found, unblock it. NOTE: There is a race
* condition here: the queue might be full again by the
* time the task is unblocked
*/
if (!btcb)
{
PANIC(OSERR_MQNOTFULLCOUNT);
}
else
{
btcb->msgwaitq = NULL;
msgq->nwaitnotfull--;
up_unblock_task(btcb);
}
irqrestore(saved_state);
}
/* Return the length of the message transferred to the user buffer */
return rcvmsglen;
}
