nuttx/sched/mqueue/mq_receive.c

224 lines
7.3 KiB
C
Raw Normal View History

/****************************************************************************
* sched/mqueue/mq_receive.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdbool.h>
#include <assert.h>
#include <errno.h>
#include <mqueue.h>
#include <debug.h>
#include <nuttx/irq.h>
#include <nuttx/arch.h>
#include <nuttx/mqueue.h>
#include <nuttx/cancelpt.h>
#include "mqueue/mqueue.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: file_mq_receive
*
* Description:
* This function receives the oldest of the highest priority messages
* from the message queue specified by "mq." This is an internal OS
* interface. It is functionally equivalent to mq_receive except that:
*
* - It is not a cancellation point, and
* - It does not modify the errno value.
*
* See comments with mq_receive() for a more complete description of the
* behavior of this function
*
* Input Parameters:
* mq - Message Queue Descriptor
* msg - Buffer to receive the message
* msglen - Size of the buffer in bytes
* prio - If not NULL, the location to store message priority.
*
* Returned Value:
* This is an internal OS interface and should not be used by applications.
* It follows the NuttX internal error return policy: Zero (OK) is
* returned on success. A negated errno value is returned on failure.
* (see mq_receive() for the list list valid return values).
*
****************************************************************************/
ssize_t file_mq_receive(FAR struct file *mq, FAR char *msg, size_t msglen,
FAR unsigned int *prio)
{
FAR struct mqueue_inode_s *msgq;
FAR struct mqueue_msg_s *mqmsg;
irqstate_t flags;
ssize_t ret;
DEBUGASSERT(up_interrupt_context() == false);
/* Verify the input parameters and, in case of an error, set
* errno appropriately.
*/
ret = nxmq_verify_receive(mq, msg, msglen);
if (ret < 0)
{
return ret;
}
msgq = mq->f_inode->i_private;
/* Furthermore, nxmq_wait_receive() expects to have interrupts disabled
* because messages can be sent from interrupt level.
*/
flags = enter_critical_section();
/* Get the message from the message queue */
ret = nxmq_wait_receive(msgq, mq->f_oflags, &mqmsg);
/* Check if we got a message from the message queue. We might
* not have a message if:
*
* - The message queue is empty and O_NONBLOCK is set in the mq
* - The wait was interrupted by a signal
*/
if (ret == OK)
{
ret = nxmq_do_receive(msgq, mqmsg, msg, prio);
}
leave_critical_section(flags);
return ret;
}
/****************************************************************************
* Name: nxmq_receive
*
* Description:
* This function receives the oldest of the highest priority messages
* from the message queue specified by "mqdes." This is an internal OS
* interface. It is functionally equivalent to mq_receive except that:
*
* - It is not a cancellation point, and
* - It does not modify the errno value.
*
* See comments with mq_receive() for a more complete description of the
* behavior of this function
*
* Input Parameters:
* mqdes - Message Queue Descriptor
* msg - Buffer to receive the message
* msglen - Size of the buffer in bytes
* prio - If not NULL, the location to store message priority.
*
* Returned Value:
* This is an internal OS interface and should not be used by applications.
* It follows the NuttX internal error return policy: Zero (OK) is
* returned on success. A negated errno value is returned on failure.
* (see mq_receive() for the list list valid return values).
*
****************************************************************************/
ssize_t nxmq_receive(mqd_t mqdes, FAR char *msg, size_t msglen,
FAR unsigned int *prio)
{
FAR struct file *filep;
int ret;
ret = fs_getfilep(mqdes, &filep);
if (ret < 0)
{
return ret;
}
return file_mq_receive(filep, msg, msglen, prio);
}
/****************************************************************************
* Name: mq_receive
*
* Description:
* This function receives the oldest of the highest priority messages
* from the message queue specified by "mqdes." If the size of the
* buffer in bytes (msglen) is less than the "mq_msgsize" attribute of
* the message queue, mq_receive will return an error. Otherwise, the
* selected message is removed from the queue and copied to "msg."
*
* If the message queue is empty and O_NONBLOCK was not set,
* mq_receive() will block until a message is added to the message
* queue. If more than one task is waiting to receive a message, only
* the task with the highest priority that has waited the longest will
* be unblocked.
*
* If the queue is empty and O_NONBLOCK is set, ERROR will be returned.
*
* Input Parameters:
* mqdes - Message Queue Descriptor
* msg - Buffer to receive the message
* msglen - Size of the buffer in bytes
* prio - If not NULL, the location to store message priority.
*
* Returned Value:
* On success, the length of the selected message in bytes is returned.
* On failure, -1 (ERROR) is returned and the errno is set appropriately:
*
* EAGAIN The queue was empty, and the O_NONBLOCK flag was set
* for the message queue description referred to by 'mqdes'.
* EPERM Message queue opened not opened for reading.
* EMSGSIZE 'msglen' was less than the maxmsgsize attribute of the
* message queue.
* EINTR The call was interrupted by a signal handler.
* EINVAL Invalid 'msg' or 'mqdes'
*
****************************************************************************/
ssize_t mq_receive(mqd_t mqdes, FAR char *msg, size_t msglen,
FAR unsigned int *prio)
{
int ret;
/* mq_receive() is a cancellation point */
enter_cancellation_point();
/* Let nxmq_receive do all of the work */
ret = nxmq_receive(mqdes, msg, msglen, prio);
if (ret < 0)
{
set_errno(-ret);
ret = ERROR;
}
2016-12-09 23:50:34 +01:00
leave_cancellation_point();
return ret;
}