mqd_t mq_open(FAR const char *mq_name, int oflags, ...)
{
FAR struct inode *inode;
FAR const char *relpath = NULL;
FAR struct mqueue_inode_s *msgq;
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)
{
errcode = EINVAL;
goto errout;
}
/* 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.
*/
inode = inode_find(fullpath, &relpath);
if (inode)
{
/* It exists. 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 = mq_descreate(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. */
msgq = (FAR struct mqueue_inode_s*)mq_msgqalloc(mode, attr);
if (!msgq)
{
errcode = ENOSPC;
goto errout_with_inode;
}
/* Create a message queue descriptor for the TCB */
mqdes = mq_descreate(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;
}
sched_unlock();
return mqdes;
errout_with_msgq:
mq_msgqfree(msgq);
inode->u.i_mqueue = NULL;
errout_with_inode:
inode_release(inode);
errout_with_lock:
sched_unlock();
errout:
set_errno(errcode);
return (mqd_t)ERROR;
}
mqd_t mq_open(const char *mq_name, int oflags, ...)
{
FAR struct tcb_s *rtcb = (FAR struct tcb_s*)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*)kmm_zalloc(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_kfree(msgq);
}
}
}
