(vc-mode-line): Make buffer read-only for root if file is locked.

diff --git a/lisp/vc-hooks.el b/lisp/vc-hooks.el
index 283d2bf56ebcc79dcdada417a63a8519be649629..8f407d5b9d875051927d78d36a50c64075f91a34 100644 (file)
--- a/lisp/vc-hooks.el
+++ b/lisp/vc-hooks.el
@@ -147,6 +147,13 @@ visiting FILE."
               (concat " " (or label (symbol-name vc-type))
                       (if (and vc-rcs-status (eq vc-type 'RCS))
                           (vc-rcs-status file)))))
+    ;; Even root shouldn't modify a registered file without locking it first.
+    (and vc-type
+        (not buffer-read-only)
+        (zerop (user-uid))
+        (require 'vc)
+        (not (string-equal (user-login-name) (vc-locking-user file)))
+        (setq buffer-read-only t))
     ;; force update of mode line
     (set-buffer-modified-p (buffer-modified-p))
     vc-type))