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px4-firmware/nuttx/sched/mq_open.c

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/****************************************************************************
* sched/mq_open.c
*
* Copyright (C) 2007-2009, 2011 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 <sys/types.h>
#include <stdint.h>
#include <stdarg.h>
#include <mqueue.h>
#include <fcntl.h>
#include <string.h>
#include <sched.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include "os_internal.h"
#include "mq_internal.h"
/****************************************************************************
* Definitions
****************************************************************************/
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Global Variables
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* 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().
*
* 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.
*
* Return Value:
* A message queue descriptor or -1 (ERROR)
*
* Assumptions:
*
****************************************************************************/
mqd_t mq_open(const char *mq_name, int oflags, ...)
{
FAR _TCB *rtcb = (FAR _TCB*)g_readytorun.head;
FAR msgq_t *msgq;
mqd_t mqdes = NULL;
va_list arg; /* Points to each un-named argument */
struct mq_attr *attr; /* MQ creation attributes */
int namelen; /* Length of MQ name */
/* Make sure that a non-NULL name is supplied */
if (mq_name)
{
sched_lock();
namelen = strlen(mq_name);
if (namelen > 0)
{
/* See if the message queue already exists */
msgq = mq_findnamed(mq_name);
if (msgq)
{
/* It does. Check if the caller wanted to create a new
* message queue with this name (i.e., O_CREAT|O_EXCL)
*/
if ((oflags & O_CREAT) == 0 || (oflags & O_EXCL) == 0)
{
/* Create a message queue descriptor for the TCB */
mqdes = mq_descreate(rtcb, msgq, oflags);
if (mqdes)
{
/* Allow a new connection to the message queue */
msgq->nconnect++;
}
}
}
/* It doesn't exist. Should we create one? */
else if ((oflags & O_CREAT) != 0)
{
/* Allocate memory for the new message queue. The size to
* allocate is the size of the msgq_t header plus the size
* of the message queue name+1.
*/
msgq = (FAR msgq_t*)kzalloc(SIZEOF_MQ_HEADER + namelen + 1);
if (msgq)
{
/* Create a message queue descriptor for the TCB */
mqdes = mq_descreate(rtcb, msgq, oflags);
if (mqdes)
{
/* Set up to get the optional arguments needed to create
* a message queue.
*/
va_start(arg, oflags);
(void)va_arg(arg, mode_t); /* MQ creation mode parameter (ignored) */
attr = va_arg(arg, struct mq_attr*);
/* Initialize the new named message queue */
sq_init(&msgq->msglist);
if (attr)
{
msgq->maxmsgs = (int16_t)attr->mq_maxmsg;
if (attr->mq_msgsize <= MQ_MAX_BYTES)
{
msgq->maxmsgsize = (int16_t)attr->mq_msgsize;
}
else
{
msgq->maxmsgsize = MQ_MAX_BYTES;
}
}
else
{
msgq->maxmsgs = MQ_MAX_MSGS;
msgq->maxmsgsize = MQ_MAX_BYTES;
}
msgq->nconnect = 1;
#ifndef CONFIG_DISABLE_SIGNALS
msgq->ntpid = INVALID_PROCESS_ID;
#endif
strcpy(msgq->name, mq_name);
/* Add the new message queue to the list of
* message queues
*/
sq_addlast((FAR sq_entry_t*)msgq, &g_msgqueues);
/* Clean-up variable argument stuff */
va_end(arg);
}
else
{
/* Deallocate the msgq structure. Since it is
* uninitialized, mq_deallocate() is not used.
*/
sched_free(msgq);
}
}
}
}
sched_unlock();
}
if (mqdes == NULL)
{
return (mqd_t)ERROR;
}
else
{
return mqdes;
}
}
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