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- /****************************************************************************
- * fs/mqueue/mq_open.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 <stdbool.h>
- #include <stdarg.h>
- #include <stdio.h>
- #include <sched.h>
- #include <mqueue.h>
- #include <fcntl.h>
- #include <errno.h>
- #include <nuttx/mqueue.h>
- #include <nuttx/fs/fs.h>
- #include "inode/inode.h"
- #include "mqueue/mqueue.h"
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: nxmq_open
- *
- * Description:
- * This function establish a connection between a named message queue and
- * the calling task. This is an internal OS interface. It is functionally
- * equivalent to mq_open() except that:
- *
- * - It is not a cancellation point, and
- * - It does not modify the errno value.
- *
- * See comments with mq_open() for a more complete description of the
- * behavior of this function
- *
- * Input Parameters:
- * mq_name - Name of the queue to open
- * oflags - open flags
- * Optional parameters. When the O_CREAT flag is specified, two optional
- * parameters are expected:
- *
- * 1. mode_t mode (ignored), and
- * 2. struct mq_attr *attr. The mq_maxmsg attribute
- * is used at the time that the message queue is
- * created to determine the maximum number of
- * messages that may be placed in the message queue.
- *
- * 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, mqdes point to the new message queue descriptor.
- * A negated errno value is returned on failure.
- *
- ****************************************************************************/
- int nxmq_open(FAR const char *mq_name, int oflags, mode_t mode,
- FAR struct mq_attr *attr, FAR mqd_t *mqdes)
- {
- FAR struct inode *inode;
- FAR struct mqueue_inode_s *msgq;
- struct inode_search_s desc;
- char fullpath[MAX_MQUEUE_PATH];
- int ret;
- /* Make sure that a non-NULL name is supplied */
- if (mq_name == NULL || *mq_name == '\0')
- {
- ret = -EINVAL;
- goto errout;
- }
- /* Skip over any leading '/'. All message queue paths are relative to
- * CONFIG_FS_MQUEUE_MPATH.
- */
- while (*mq_name == '/')
- {
- mq_name++;
- }
- /* Get the full path to the message queue */
- snprintf(fullpath, MAX_MQUEUE_PATH, CONFIG_FS_MQUEUE_MPATH "/%s", mq_name);
- /* Make sure that the check for the existence of the message queue
- * and the creation of the message queue are atomic with respect to
- * other processes executing mq_open(). A simple sched_lock() should
- * be sufficient.
- */
- sched_lock();
- /* Get the inode for this mqueue. This should succeed if the message
- * queue has already been created. In this case, inode_find() will
- * have incremented the reference count on the inode.
- */
- SETUP_SEARCH(&desc, fullpath, false);
- ret = inode_find(&desc);
- if (ret >= 0)
- {
- /* Something exists at this path. Get the search results */
- inode = desc.node;
- DEBUGASSERT(inode != NULL);
- /* Verify that the inode is a message queue */
- if (!INODE_IS_MQUEUE(inode))
- {
- ret = -ENXIO;
- goto errout_with_inode;
- }
- /* It exists and is a message queue. Check if the caller wanted to
- * create a new mqueue with this name.
- */
- if ((oflags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
- {
- ret = -EEXIST;
- goto errout_with_inode;
- }
- /* Create a message queue descriptor for the current thread */
- msgq = inode->u.i_mqueue;
- *mqdes = nxmq_create_des(NULL, msgq, oflags);
- if (!*mqdes)
- {
- ret = -ENOMEM;
- goto errout_with_inode;
- }
- }
- else
- {
- /* The mqueue does not exists. Were we asked to create it? */
- if ((oflags & O_CREAT) == 0)
- {
- /* The mqueue does not exist and O_CREAT is not set */
- ret = -ENOENT;
- goto errout_with_lock;
- }
- /* Create an inode in the pseudo-filesystem at this path */
- ret = inode_semtake();
- if (ret < 0)
- {
- goto errout_with_lock;
- }
- ret = inode_reserve(fullpath, &inode);
- inode_semgive();
- if (ret < 0)
- {
- goto errout_with_lock;
- }
- /* Allocate memory for the new message queue. The new inode will
- * be created with a reference count of zero.
- */
- msgq = (FAR struct mqueue_inode_s *)nxmq_alloc_msgq(mode, attr);
- if (!msgq)
- {
- ret = -ENOSPC;
- goto errout_with_inode;
- }
- /* Create a message queue descriptor for the TCB */
- *mqdes = nxmq_create_des(NULL, msgq, oflags);
- if (!*mqdes)
- {
- ret = -ENOMEM;
- goto errout_with_msgq;
- }
- /* Bind the message queue and the inode structure */
- INODE_SET_MQUEUE(inode);
- inode->u.i_mqueue = msgq;
- msgq->inode = inode;
- /* Set the initial reference count on this inode to one */
- inode->i_crefs = 1;
- }
- RELEASE_SEARCH(&desc);
- sched_unlock();
- return OK;
- errout_with_msgq:
- nxmq_free_msgq(msgq);
- inode->u.i_mqueue = NULL;
- errout_with_inode:
- inode_release(inode);
- errout_with_lock:
- RELEASE_SEARCH(&desc);
- sched_unlock();
- errout:
- return ret;
- }
- /****************************************************************************
- * Name: mq_open
- *
- * Description:
- * This function establish a connection between a named message queue and
- * the calling task. After a successful call of mq_open(), the task can
- * reference the message queue using the address returned by the call. The
- * message queue remains usable until it is closed by a successful call to
- * mq_close().
- *
- * Input Parameters:
- * mq_name - Name of the queue to open
- * oflags - open flags
- * Optional parameters. When the O_CREAT flag is specified, two optional
- * parameters are expected:
- *
- * 1. mode_t mode (ignored), and
- * 2. struct mq_attr *attr. The mq_maxmsg attribute
- * is used at the time that the message queue is
- * created to determine the maximum number of
- * messages that may be placed in the message queue.
- *
- * Returned Value:
- * A message queue descriptor or (mqd_t)-1 (ERROR)
- *
- * Assumptions:
- *
- ****************************************************************************/
- mqd_t mq_open(FAR const char *mq_name, int oflags, ...)
- {
- FAR struct mq_attr *attr = NULL;
- mode_t mode = 0;
- mqd_t mqdes;
- va_list ap;
- int ret;
- /* Were we asked to create it? */
- if ((oflags & O_CREAT) != 0)
- {
- /* We have to extract the additional
- * parameters from the variable argument list.
- */
- va_start(ap, oflags);
- mode = va_arg(ap, mode_t);
- attr = va_arg(ap, FAR struct mq_attr *);
- va_end(ap);
- }
- ret = nxmq_open(mq_name, oflags, mode, attr, &mqdes);
- if (ret < 0)
- {
- set_errno(-ret);
- mqdes = (mqd_t)ERROR;
- }
- return mqdes;
- }
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