/****************************************************************************
* fs/mqueue/mq_open.c
*
* Copyright (C) 2007-2009, 2011, 2014-2015, 2017 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 <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: 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 inode *inode;
FAR struct mqueue_inode_s *msgq;
struct inode_search_s desc;
char fullpath[MAX_MQUEUE_PATH];
va_list ap;
struct mq_attr *attr;
mqd_t mqdes;
mode_t mode;
int errcode;
int ret;
/* Make sure that a non-NULL name is supplied */
if (mq_name == NULL || *mq_name == '\0')
{
errcode = 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))
{
errcode = 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))
{
errcode = 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)
{
errcode = 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 */
errcode = ENOENT;
goto errout_with_lock;
}
/* Create the mqueue. First 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);
/* Create an inode in the pseudo-filesystem at this path */
inode_semtake();
ret = inode_reserve(fullpath, &inode);
inode_semgive();
if (ret < 0)
{
errcode = -ret;
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)
{
errcode = ENOSPC;
goto errout_with_inode;
}
/* Create a message queue descriptor for the TCB */
mqdes = nxmq_create_des(NULL, msgq, oflags);
if (!mqdes)
{
errcode = 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 mqdes;
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:
set_errno(errcode);
return (mqd_t)ERROR;
}