Avoid crashes in PGTK build due to signal in 'note_mouse_highlight'

* src/xdisp.c (string_buffer_position): Make sure the TO argument
of 'string_buffer_position_lim' is always inside [BEGV..ZV].
Otherwise 'string_buffer_position_lim' might call
'get-char-property' and friends with invalid position, which will
just signal an error and do nothing useful.  (Bug#60144)

1 files changed, 7 insertions, 4 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index 45da4966907..06c8b7730cd 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -6281,13 +6281,16 @@ static ptrdiff_t
 string_buffer_position (Lisp_Object string, ptrdiff_t around_charpos)
 {
   const int MAX_DISTANCE = 1000;
+  ptrdiff_t forward_limit = min (around_charpos + MAX_DISTANCE, ZV);
   ptrdiff_t found = string_buffer_position_lim (string, around_charpos,
-                                                around_charpos + MAX_DISTANCE,
-                                                false);
+                                                forward_limit, false);
 
   if (!found)
-    found = string_buffer_position_lim (string, around_charpos,
-                                        around_charpos - MAX_DISTANCE, true);
+    {
+      ptrdiff_t backward_limit = max (around_charpos - MAX_DISTANCE, BEGV);
+      found = string_buffer_position_lim (string, around_charpos,
+                                          backward_limit, true);
+    }
   return found;
 }