Function mqfs_fileno_alloc

freebsd/kern/uipc_mqueue.c:318–354

* Allocate a file number */

 * Allocate a file number
 */
static void
mqfs_fileno_alloc(struct mqfs_info *mi, struct mqfs_node *mn)
{
	/* make sure our parent has a file number */
	if (mn->mn_parent && !mn->mn_parent->mn_fileno)
		mqfs_fileno_alloc(mi, mn->mn_parent);

	switch (mn->mn_type) {
	case mqfstype_root:
	case mqfstype_dir:
	case mqfstype_file:
	case mqfstype_symlink:
		mn->mn_fileno = alloc_unr(mi->mi_unrhdr);
		break;
	case mqfstype_this:
		KASSERT(mn->mn_parent != NULL,
		    ("mqfstype_this node has no parent"));
		mn->mn_fileno = mn->mn_parent->mn_fileno;
		break;
	case mqfstype_parent:
		KASSERT(mn->mn_parent != NULL,
		    ("mqfstype_parent node has no parent"));
		if (mn->mn_parent == mi->mi_root) {
			mn->mn_fileno = mn->mn_parent->mn_fileno;
			break;
		}
		KASSERT(mn->mn_parent->mn_parent != NULL,
		    ("mqfstype_parent node has no grandparent"));
		mn->mn_fileno = mn->mn_parent->mn_parent->mn_fileno;
		break;
	default:
		KASSERT(0,
		    ("mqfs_fileno_alloc() called for unknown type node: %d",
			mn->mn_type));
		break;
	}
}

/*
 * Release a file number