/**************************************************************************** * sched/mq_open.c * * Copyright (C) 2007-2009, 2011 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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 #include #include #include #include #include #include #include #include #include #include #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 */ mode_t mode; /* MQ creation mode parameter (ignored) */ 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); mode = va_arg(arg, mode_t); 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; } }