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Fix treesit crash (bug#71681)

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To reproduce the problem:

0. emacs -Q
1. eval: (add-to-list 'major-mode-remap-alist '(c-mode . c-ts-mode))
2. C-x v L
3. in the *vc-change-log* buffer move point to the commit 20af58d3a1
4. type D
5. crash caused by diff-font-lock-syntax fontification that uses treesit

Emacs: 6f2036243f (2024-06-23, latest master)
Tree-sitter: 3da7deed (2024-06-08, version 0.22.6)

The immediate cause of the crash is that tree-sitter accessed a node's
tree, but the tree is already deleted.  Commenting out the
ts_tree_delete line in treesit_ensure_parsed can "fix" the crash.

What happended, I think, is this:

1. Buffer modified, parser->need_reparse set to true,
parser->timestamp incremented.
2. A node is created from the parser, this node has the old tree but
the new timestamp (bad!).
3. Parser re-parses (treesit_ensure_parsed), new tree created, old
tree deleted.
4. Ftreesit_query_capture accessed the old node, and the old tree,
crash.

We shouldn't bump the parser timestamp when we set
parser->need_reparse to true; instead, we should bump the timestamp
when we actually reparsed and created a new tree.

* src/treesit.c (treesit_record_change): Don't bump parser timestamp.
(treesit_sync_visible_region): Don't bump parser timestamp.
(Ftreesit_parser_set_included_ranges): Don't bump parser timestamp.
(treesit_ensure_parsed): Bump parser timestamp.
(Ftreesit_query_capture): Add node check.
This commit is contained in:
Yuan Fu 2024-06-29 00:16:36 -07:00
parent eaf2dc96c1
commit 8819e5a45d
No known key found for this signature in database
GPG key ID: 56E19BC57664A442
1 changed files with 14 additions and 14 deletions
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28
src/treesit.c
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@ -846,7 +846,6 @@ treesit_record_change (ptrdiff_t start_byte, ptrdiff_t old_end_byte,
treesit_tree_edit_1 (tree, start_offset, old_end_offset,
new_end_offset);
XTS_PARSER (lisp_parser)->need_reparse = true;
XTS_PARSER (lisp_parser)->timestamp++;
/* VISIBLE_BEG/END records tree-sitter's range of view in
the buffer. We need to adjust them when tree-sitter's
@ -948,10 +947,7 @@ treesit_sync_visible_region (Lisp_Object parser)
this function is called), we need to reparse. */
if (visible_beg != BUF_BEGV_BYTE (buffer)
|| visible_end != BUF_ZV_BYTE (buffer))
{
XTS_PARSER (parser)->need_reparse = true;
XTS_PARSER (parser)->timestamp++;
}
XTS_PARSER (parser)->need_reparse = true;
/* Before we parse or set ranges, catch up with the narrowing
situation. We change visible_beg and visible_end to match
@ -1090,6 +1086,7 @@ treesit_ensure_parsed (Lisp_Object parser)
XTS_PARSER (parser)->tree = new_tree;
XTS_PARSER (parser)->need_reparse = false;
XTS_PARSER (parser)->timestamp++;
/* After-change functions should run at the very end, most crucially
after need_reparse is set to false, this way if the function
@ -1725,7 +1722,6 @@ buffer. */)
ranges);
XTS_PARSER (parser)->need_reparse = true;
XTS_PARSER (parser)->timestamp++;
return Qnil;
}
@ -2923,11 +2919,10 @@ be completely in the region.
If NODE-ONLY is non-nil, return a list of nodes.
Besides a node, NODE can also be a parser, in which case the root node
of that parser is used.
NODE can also be a language symbol, in which case the root node of a
parser for that language is used. If such a parser doesn't exist, it
is created.
Besides a node, NODE can be a parser, in which case the root node of
that parser is used. NODE can also be a language symbol, in which case
the root node of a parser for that language is used. If such a parser
doesn't exist, it is created.
Signal `treesit-query-error' if QUERY is malformed or something else
goes wrong. You can use `treesit-query-validate' to validate and debug
@ -2941,8 +2936,13 @@ the query. */)
treesit_initialize ();
/* Resolve NODE into an actual node. */
/* Resolve NODE into an actual node, signals if node not
up-to-date. */
Lisp_Object lisp_node = treesit_resolve_node (node);
/* As of right now, the node returned by treesit_resolve_node always
passes treesit_check_node; but it might not be true in the future,
so adding the line below just to be safe. */
treesit_check_node (node);
/* Extract C values from Lisp objects. */
TSNode treesit_node = XTS_NODE (lisp_node)->node;
@ -2970,8 +2970,8 @@ the query. */)
&signal_symbol, &signal_data))
xsignal (signal_symbol, signal_data);
/* WARN: After this point, free TREESIT_QUERY and CURSOR before every
signal and return if NEEDS_TO_FREE_QUERY_AND_CURSOR is true. */
/* WARN: After this point, if NEEDS_TO_FREE_QUERY_AND_CURSOR is true,
free TREESIT_QUERY and CURSOR before every signal and return. */
/* Set query range. */
if (!NILP (beg) && !NILP (end))