Fix bounds checking for text properties in `format' (Bug#5306).

* intervals.h, textprop.c (extend_property_ranges): Return value
and args changed.  Discard properties that begin at or after the
new end (Bug#5306).

* editfns.c (Fformat): Caller changed.

1 files changed, 26 insertions, 9 deletions

diff --git a/src/textprop.c b/src/textprop.c
index 3df5cc9204d..afeaa2b1040 100644
--- a/src/textprop.c
+++ b/src/textprop.c
@@ -2028,24 +2028,41 @@ add_text_properties_from_list (object, list, delta)
 
 
 
-/* Modify end-points of ranges in LIST destructively.  LIST is a list
-   as returned from text_property_list.  Change end-points equal to
-   OLD_END to NEW_END.  */
+/* Modify end-points of ranges in LIST destructively, and return the
+   new list.  LIST is a list as returned from text_property_list.
+   Discard properties that begin at or after NEW_END, and limit
+   end-points to NEW_END.  */
 
-void
-extend_property_ranges (list, old_end, new_end)
-     Lisp_Object list, old_end, new_end;
+Lisp_Object
+extend_property_ranges (list, new_end)
+     Lisp_Object list, new_end;
 {
-  for (; CONSP (list); list = XCDR (list))
+  Lisp_Object prev = Qnil, head = list;
+  int max = XINT (new_end);
+
+  for (; CONSP (list); prev = list, list = XCDR (list))
     {
-      Lisp_Object item, end;
+      Lisp_Object item, beg, end;
 
       item = XCAR (list);
+      beg = XCAR (item);
       end = XCAR (XCDR (item));
 
-      if (EQ (end, old_end))
+      if (XINT (beg) >= max)
+        {
+          /* The start-point is past the end of the new string.
+             Discard this property.  */
+          if (EQ (head, list))
+            head = XCDR (list);
+          else
+            XSETCDR (prev, XCDR (list));
+        }
+      else if (XINT (end) > max)
+        /* The end-point is past the end of the new string.  */
         XSETCAR (XCDR (item), new_end);
     }
+
+  return head;
 }