Fix auto-save and locking for indirect buffers.

* lisp/simple.el (undo): Handle indirect buffers.

* buffer.c (Fset_buffer_modified_p): Handle indirect buffers.

Fixes: debbugs:8207

lisp/ChangeLog

@@ -1,3 +1,7 @@
+2012-09-22  Chong Yidong  <cyd@gnu.org>
+
+	* simple.el (undo): Handle indirect buffers (Bug#8207).
+
 2012-09-21  Leo Liu  <sdl.web@gmail.com>
 
 	IDO: Disable match re-ordering for buffer switching.

lisp/simple.el

@@ -1855,9 +1855,13 @@ as an argument limits undo to changes within the current region."
   ;; another undo command will find the undo history empty
   ;; and will get another error.  To begin undoing the undos,
   ;; you must type some other command.
-  (let ((modified (buffer-modified-p))
-	(recent-save (recent-auto-save-p))
-	message)
+  (let* ((modified (buffer-modified-p))
+	 ;; For an indirect buffer, look in the base buffer for the
+	 ;; auto-save data.
+	 (base-buffer (or (buffer-base-buffer) (current-buffer)))
+	 (recent-save (with-current-buffer base-buffer
+			(recent-auto-save-p)))
+	 message)
     ;; If we get an error in undo-start,
     ;; the next command should not be a "consecutive undo".
     ;; So set `this-command' to something other than `undo'.
@@ -1935,7 +1939,8 @@ as an argument limits undo to changes within the current region."
     ;; Record what the current undo list says,
     ;; so the next command can tell if the buffer was modified in between.
     (and modified (not (buffer-modified-p))
-	 (delete-auto-save-file-if-necessary recent-save))
+	 (with-current-buffer base-buffer
+	   (delete-auto-save-file-if-necessary recent-save)))
     ;; Display a message announcing success.
     (if message
 	(message "%s" message))))

src/ChangeLog

@@ -1,3 +1,8 @@
+2012-09-22  Chong Yidong  <cyd@gnu.org>
+
+	* buffer.c (Fset_buffer_modified_p): Handle indirect buffers
+	(Bug#8207).
+
 2012-09-22  Kenichi Handa  <handa@gnu.org>
 
 	* composite.c (composition_reseat_it): Handle the case that a

src/buffer.c

@@ -1341,9 +1341,13 @@ A non-nil FLAG means mark the buffer modified.  */)
   /* If buffer becoming modified, lock the file.
      If buffer becoming unmodified, unlock the file.  */
 
-  fn = BVAR (current_buffer, file_truename);
+  struct buffer *b = current_buffer->base_buffer
+    ? current_buffer->base_buffer
+    : current_buffer;
+
+  fn = BVAR (b, file_truename);
   /* Test buffer-file-name so that binding it to nil is effective.  */
-  if (!NILP (fn) && ! NILP (BVAR (current_buffer, filename)))
+  if (!NILP (fn) && ! NILP (BVAR (b, filename)))
     {
       bool already = SAVE_MODIFF < MODIFF;
       if (!already && !NILP (flag))