Re: vc-mode-line ancient, root-specific code for buffer-read-only

[Glenn Morris <rgm@gnu.org>]

Paul Eggert wrote:

> On the other hand I don't follow the comment "root cannot 'write
> anything'". Traditionally, root can write any file that is writable to
> any user (and even some files that no other users can write to), so in
> that sense roote can "write anything".

This vc code is only relevant to files that are not writable by their owner.
The most normal example would be a file with mode 444.
If you visit such a file with Emacs as root, it is marked read-only anyway.
(That is what I meant by root not being able to "write anything";
obviously root can change the permissions and then do whatever.)

The vc-mode line code would only make a difference to files with odd
modes like 466. But RCS (for example) changes file modes to 444 when it
locks a file, so AFAICS the vc-mode code serves no purpose even for RCS.