(verify_interval_modification): For insertion in

middle of an interval, use the same criterion as between intervals
for whether read-only forbids it.

1 files changed, 22 insertions, 11 deletions

diff --git a/src/intervals.c b/src/intervals.c
index 6c7ce7ee898..597fcf07b30 100644
--- a/src/intervals.c
+++ b/src/intervals.c
@@ -1847,8 +1847,7 @@ verify_interval_modification (buf, start, end)
                         error ("Attempt to insert within read-only text");
                     }
                 }
-              else
-                after = Qnil;
+
               if (! NULL_INTERVAL_P (prev))
                 {
                   before = textget (prev->plist, Qread_only);
@@ -1868,18 +1867,30 @@ verify_interval_modification (buf, start, end)
                         error ("Attempt to insert within read-only text");
                     }
                 }
-              else
-                before = Qnil;
             }
           else if (! NULL_INTERVAL_P (i))
-            before = after = textget (i->plist, Qread_only);
-          if (! NULL_INTERVAL_P (i) && ! NULL_INTERVAL_P (prev))
             {
-              /* If I and PREV differ, neither of them has a sticky
-                 read-only property. It only remains to check, whether
-                 they have a common read-only property.  */
-              if (! NILP (before) && EQ (before, after))
-                error ("Attempt to insert within read-only text");
+              after = textget (i->plist, Qread_only);
+                  
+              /* If interval I is read-only and read-only is
+                 front-sticky, inhibit insertion.
+                 Check for read-only as well as category.  */
+              if (! NILP (after) && NILP (Fmemq (after, Vinhibit_read_only)))
+                {
+                  Lisp_Object tem;
+
+                  tem = textget (i->plist, Qfront_sticky);
+                  if (TMEM (Qread_only, tem)
+                      || (NILP (textget_direct (i->plist, Qread_only))
+                          && TMEM (Qcategory, tem)))
+                    error ("Attempt to insert within read-only text");
+
+                  tem = textget (prev->plist, Qrear_nonsticky);
+                  if (! TMEM (Qread_only, tem)
+                      && (! NILP (textget_direct (prev->plist, Qread_only))
+                          || ! TMEM (Qcategory, tem)))
+                    error ("Attempt to insert within read-only text");
+                }
             }
         }