Subject: bug#41628: [PATCH] Allow emacsclient to connect to other user's socket when using -s

From: Eli Zaretskii <[email-masked]>
Date: Sun, 31 May 2020 18:44:50 +0300

> Date: Sun, 31 May 2020 15:51:02 +0200
> From: rabite <[email-masked]>
> 
> Since commit 5c0d8bb95bbd5354e6b2cd2e56a91afe4e780759 emacsclient won't 
> connect to my usual emacs session when run as root. I use this all the 
> time to edit files, combined with "-T /sudo:root@localhost" to handle 
> permissions. Using a separate emacs process would be unpractical as it 
> would require setting up a whole new emacs configuration and keeping it 
> in sync with my main one. I think this is a common use-case for those 
> who have an emacs-server running all the time and supporting it makes a 
> lot of sense. In principle I see no reason emacsclient should refuse a 
> connection that is possible in theory.
> 
> It looks like this "feature" has been explicitly disabled, maybe because 
> it might triggered unintentionally if running su doesn't set USER or 
> something?

The discussion which led to that change is here:

  https://lists.gnu.org/r/emacs-devel/2018-11/msg00019.html