(vc-mode-line): If user is root, verify file really has user-writable bit.

1 files changed, 12 insertions, 3 deletions

diff --git a/lisp/vc-hooks.el b/lisp/vc-hooks.el
index 5005c30383a..86e53116583 100644
--- a/lisp/vc-hooks.el
+++ b/lisp/vc-hooks.el
@@ -878,14 +878,23 @@ control system name."
           (and vc-type
                (concat " " (or label (symbol-name vc-type)) 
                        (and vc-display-status (vc-status file)))))
+    ;; If the file is locked by some other user, make
+    ;; the buffer read-only.  Like this, even root
+    ;; cannot modify a file without locking it first.
     (and vc-type 
          (equal file (buffer-file-name))
          (vc-locking-user file)
-         ;; If the file is locked by some other user, make
-         ;; the buffer read-only.  Like this, even root
-         ;; cannot modify a file without locking it first.
          (not (string= (user-login-name) (vc-locking-user file)))
          (setq buffer-read-only t))
+    ;; If the user is root, and the file is not owner-readable,
+    ;; then pretend that we can't read it
+    ;; even though we can (because root can read anything).
+    (and vc-type
+         (equal file (buffer-file-name))
+         (not buffer-read-only)
+         (zerop (user-real-uid))
+         (zerop (logand (file-modes (buffer-file-name)) 128))
+         (setq buffer-read-only t))
     (force-mode-line-update)
     ;;(set-buffer-modified-p (buffer-modified-p)) ;;use this if Emacs 18
     vc-type))