Catch signals produced by PRED in tree-sitter search functions

Earlier we switched to using cursors rather than nodes to traverse the
parse tree.  Because cursors need cleanup, we have to catch signals
thrown by the predicate functions and free the cursor. Failing to do
this will result in leaking the cursor whenever the predicate function
signals in a search function.  This change fixes the leak.
* src/treesit.c (treesit_traverse_cleanup_cursor): New function.
(Ftreesit_search_subtree)
(Ftreesit_search_forward)
(Ftreesit_induce_sparse_tree): Catch signals.  (Bug#62823)

(cherry picked from commit a5eb9f6ad4e6f5a2819b540a477f1e889f6ef355)

1 files changed, 24 insertions, 0 deletions

diff --git a/src/treesit.c b/src/treesit.c
index 1bb52888f4b..7d5d033c02c 100644
--- a/src/treesit.c
+++ b/src/treesit.c
@@ -3156,6 +3156,12 @@ treesit_search_forward (TSTreeCursor *cursor,
     }
 }
 
+/** Cleanup function for cursor.  */
+static void treesit_traverse_cleanup_cursor(void *cursor)
+{
+  ts_tree_cursor_delete ((TSTreeCursor *) cursor);
+}
+
 DEFUN ("treesit-search-subtree",
        Ftreesit_search_subtree,
        Streesit_search_subtree, 2, 5, 0,
@@ -3197,12 +3203,18 @@ Return the first matched node, or nil if none matches.  */)
   if (!treesit_cursor_helper (&cursor, XTS_NODE (node)->node, parser))
     return return_value;
 
+  specpdl_ref count = SPECPDL_INDEX ();
+  record_unwind_protect_ptr (treesit_traverse_cleanup_cursor, &cursor);
+
   if (treesit_search_dfs (&cursor, predicate, parser, NILP (backward),
 			  NILP (all), the_limit, false))
     {
       TSNode node = ts_tree_cursor_current_node (&cursor);
       return_value = make_treesit_node (parser, node);
     }
+
+  unbind_to (count, Qnil);
+
   ts_tree_cursor_delete (&cursor);
   return return_value;
 }
@@ -3254,12 +3266,18 @@ always traverse leaf nodes first, then upwards.  */)
   if (!treesit_cursor_helper (&cursor, XTS_NODE (start)->node, parser))
     return return_value;
 
+  specpdl_ref count = SPECPDL_INDEX ();
+  record_unwind_protect_ptr (treesit_traverse_cleanup_cursor, &cursor);
+
   if (treesit_search_forward (&cursor, predicate, parser,
 			      NILP (backward), NILP (all)))
     {
       TSNode node = ts_tree_cursor_current_node (&cursor);
       return_value = make_treesit_node (parser, node);
     }
+
+  unbind_to (count, Qnil);
+
   ts_tree_cursor_delete (&cursor);
   return return_value;
 }
@@ -3376,8 +3394,14 @@ a regexp.  */)
      to use treesit_cursor_helper.  */
   TSTreeCursor cursor = ts_tree_cursor_new (XTS_NODE (root)->node);
 
+  specpdl_ref count = SPECPDL_INDEX ();
+  record_unwind_protect_ptr (treesit_traverse_cleanup_cursor, &cursor);
+
   treesit_build_sparse_tree (&cursor, parent, predicate, process_fn,
 			     the_limit, parser);
+
+  unbind_to (count, Qnil);
+
   ts_tree_cursor_delete (&cursor);
   Fsetcdr (parent, Fnreverse (Fcdr (parent)));
   if (NILP (Fcdr (parent)))