[Emacs-diffs] emacs-26 7669bf7: Avoid assertion violations in set_text_properties_1

[Eli Zaretskii]

branch: emacs-26
commit 7669bf7880e54aae7036a1b62db3693c2f627649
Author: Eli Zaretskii <address@hidden>
Commit: Eli Zaretskii <address@hidden>

    Avoid assertion violations in set_text_properties_1
    
    * src/textprop.c (set_text_properties): If the call to
    modify_text_properties modifies the interval tree as side effect,
    recalculate the correct interval for START and END.  (Bug#32265)
---
 src/textprop.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/textprop.c b/src/textprop.c
index 984f2e6..904e226 100644
--- a/src/textprop.c
+++ b/src/textprop.c
@@ -1350,6 +1350,7 @@ set_text_properties (Lisp_Object start, Lisp_Object end, 
Lisp_Object properties,
 {
   register INTERVAL i;
   Lisp_Object ostart, oend;
+  bool first_time = true;
 
   ostart = start;
   oend = end;
@@ -1372,6 +1373,7 @@ set_text_properties (Lisp_Object start, Lisp_Object end, 
Lisp_Object properties,
       return Qt;
     }
 
+ retry:
   i = validate_interval_range (object, &start, &end, soft);
 
   if (!i)
@@ -1391,8 +1393,22 @@ set_text_properties (Lisp_Object start, Lisp_Object end, 
Lisp_Object properties,
        return Qnil;
     }
 
-  if (BUFFERP (object) && !NILP (coherent_change_p))
-    modify_text_properties (object, start, end);
+  if (BUFFERP (object) && !NILP (coherent_change_p) && first_time)
+    {
+      ptrdiff_t prev_length = LENGTH (i);
+      ptrdiff_t prev_pos = i->position;
+
+      modify_text_properties (object, start, end);
+      /* If someone called us recursively as a side effect of
+        modify_text_properties, and changed the intervals behind our
+        back, we cannot continue with I, because its data changed.
+        So we restart the interval analysis anew.  */
+      if (LENGTH (i) != prev_length || i->position != prev_pos)
+       {
+         first_time = false;
+         goto retry;
+       }
+    }
 
   set_text_properties_1 (start, end, properties, object, i);