+ node = _mime_node_create (parent, sub);
+
+ if (child == parent->next_child && parent->next_part_num != -1) {
+ /* We're traversing in depth-first order. Record the child's
+ * depth-first numbering. */
+ node->part_num = parent->next_part_num;
+ node->next_part_num = node->part_num + 1;
+
+ /* Prepare the parent for its next depth-first child. */
+ parent->next_child++;
+ parent->next_part_num = -1;
+
+ if (node->nchildren == 0) {
+ /* We've reached a leaf, so find the parent that has more
+ * children and set it up to number its next child. */
+ mime_node_t *iter = node->parent;
+ while (iter && iter->next_child == iter->nchildren)
+ iter = iter->parent;
+ if (iter)
+ iter->next_part_num = node->part_num + 1;
+ }
+ }
+
+ return node;
+}
+
+static mime_node_t *
+_mime_node_seek_dfs_walk (mime_node_t *node, int *n)
+{
+ mime_node_t *ret = NULL;
+ int i;
+
+ if (*n == 0)
+ return node;
+
+ *n -= 1;
+ for (i = 0; i < node->nchildren && !ret; i++) {
+ mime_node_t *child = mime_node_child (node, i);
+ ret = _mime_node_seek_dfs_walk (child, n);
+ if (!ret)
+ talloc_free (child);
+ }
+ return ret;
+}
+
+mime_node_t *
+mime_node_seek_dfs (mime_node_t *node, int n)
+{
+ if (n < 0)
+ return NULL;
+ return _mime_node_seek_dfs_walk (node, &n);