nixos/weechat: add setuid wrapper for `screen' to ensure true multius…

…er capabilities

Previously you either had to set the setuid bit yourself or workaround
`isSystemUser = true` (for a loginable shell) to access the weechat
screen.

`programs.screen` shouldn't do this by default to avoid taking too much
assumptions about the setup, however `services.weechat` explicitly
requires tihs.

See NixOS#45728

nixos/modules/services/misc/weechat.nix

@@ -46,10 +46,12 @@ in
         Group = "weechat";
         RemainAfterExit = "yes";
       };
-      script = "exec ${pkgs.screen}/bin/screen -Dm -S ${cfg.sessionName} ${cfg.binary}";
+      script = "exec ${config.security.wrapperDir}/screen -Dm -S ${cfg.sessionName} ${cfg.binary}";
       wantedBy = [ "multi-user.target" ];
       wants = [ "network.target" ];
     };
+
+    security.wrappers.screen.source = "${pkgs.screen}/bin/screen";
   };
 
   meta.doc = ./weechat.xml;

nixos/modules/services/misc/weechat.xml

@@ -54,7 +54,7 @@
 </programlisting>
    Now, the session can be re-attached like this:
 <programlisting>
-screen -r weechat-screen
+screen -x weechat/weechat-screen
 </programlisting>
   </para>