avltree_position_dirent_sorted

int avltree_position_dirent_sorted(const struct avltree_node *key,
                   const struct avltree *tree,
                   struct avltree_node **left,
                   struct avltree_node **right)
{
    struct avltree_node *node = tree->root;
    struct avltree_node *parent = NULL;
    int res = 0;

    *left = NULL;
    *right = NULL;

    while (node) {
        res = avl_dirent_dirent_sorted_cmpf(node, key);
        if (res == 0)
            break;
        parent = node;
        if (res > 0))
            node = node->left;
        else
            node = node->right;
    }

    if (parent != NULL) {
        switch (res) {
        case -1:
            *left = avltree_prev(parent);
            *right = parent;
            break;
        case 0:
            break;
        case 1:
            *left = parent;
            *right = avltree_next(parent);
            break;
        default:
            assert(false);
        }
    }

    return res;
}