run_undoable_changes now called from insdel.fix/segfault-undoable-change-prepare-for-buffer

The original calls from inside undo.c are not always at a safe position
to call lisp, as they originate in varied positions within insdel.c.
Calling them directly from prepare_to_modify_buffer_1 ensures that they
are always run at the same point.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/insdel.c b/src/insdel.c
index 24807b1e8f4..0b1b0c234d3 100644
--- a/src/insdel.c
+++ b/src/insdel.c
@@ -30,6 +30,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "window.h"
 #include "region-cache.h"
 
+
 static void insert_from_string_1 (Lisp_Object, ptrdiff_t, ptrdiff_t, ptrdiff_t,
 				  ptrdiff_t, bool, bool);
 static void insert_from_buffer_1 (struct buffer *, ptrdiff_t, ptrdiff_t, bool);
@@ -1765,6 +1766,15 @@ modify_text (ptrdiff_t start, ptrdiff_t end)
   bset_point_before_scroll (current_buffer, Qnil);
 }
 
+static void
+run_undoable_change (void)
+{
+  if (EQ (BVAR (current_buffer, undo_list), Qt))
+    return;
+
+  call0 (Qundo_auto__undoable_change);
+}
+
 /* Check that it is okay to modify the buffer between START and END,
    which are char positions.
 
@@ -1786,6 +1796,8 @@ prepare_to_modify_buffer_1 (ptrdiff_t start, ptrdiff_t end,
   if (!NILP (BVAR (current_buffer, read_only)))
     Fbarf_if_buffer_read_only (temp);
 
+  run_undoable_change();
+
   bset_redisplay (current_buffer);
 
   if (buffer_intervals (current_buffer))
@@ -2187,6 +2199,8 @@ syms_of_insdel (void)
   combine_after_change_list = Qnil;
   combine_after_change_buffer = Qnil;
 
+  DEFSYM (Qundo_auto__undoable_change, "undo-auto--undoable-change");
+
   DEFVAR_LISP ("combine-after-change-calls", Vcombine_after_change_calls,
 	       doc: /* Used internally by the function `combine-after-change-calls' macro.  */);
   Vcombine_after_change_calls = Qnil;