Function kern_kmq_open

freebsd/kern/uipc_mqueue.c:2012–2114

}

static int
kern_kmq_open(struct thread *td, const char *upath, int flags, mode_t mode,
    const struct mq_attr *attr)
{
	char path[MQFS_NAMELEN + 1];
	struct mqfs_node *pn;
	struct pwddesc *pdp;
	struct file *fp;
	struct mqueue *mq;
	int fd, error, len, cmode;

	AUDIT_ARG_FFLAGS(flags);
	AUDIT_ARG_MODE(mode);

	pdp = td->td_proc->p_pd;
	cmode = (((mode & ~pdp->pd_cmask) & ALLPERMS) & ~S_ISTXT);
	mq = NULL;
	if ((flags & O_CREAT) != 0 && attr != NULL) {
		if (attr->mq_maxmsg <= 0 || attr->mq_maxmsg > maxmsg)
			return (EINVAL);
		if (attr->mq_msgsize <= 0 || attr->mq_msgsize > maxmsgsize)
			return (EINVAL);
	}

	error = copyinstr(upath, path, MQFS_NAMELEN + 1, NULL);
        if (error)
		return (error);

	/*
	 * The first character of name must be a slash  (/) character
	 * and the remaining characters of name cannot include any slash
	 * characters. 
	 */
	len = strlen(path);
	if (len < 2 || path[0] != '/' || strchr(path + 1, '/') != NULL)
		return (EINVAL);
	/*
	 * "." and ".." are magic directories, populated on the fly, and cannot
	 * be opened as queues.
	 */
	if (strcmp(path, "/.") == 0 || strcmp(path, "/..") == 0)
		return (EINVAL);
	AUDIT_ARG_UPATH1_CANON(path);

	error = falloc(td, &fp, &fd, O_CLOEXEC);
	if (error)
		return (error);

	sx_xlock(&mqfs_data.mi_lock);
	pn = mqfs_search(mqfs_data.mi_root, path + 1, len - 1, td->td_ucred);
	if (pn == NULL) {
		if (!(flags & O_CREAT)) {
			error = ENOENT;
		} else {
			mq = mqueue_alloc(attr);
			if (mq == NULL) {
				error = ENFILE;
			} else {