[626] in athena10
GDM Greeter Custom Commands
daemon@ATHENA.MIT.EDU (Quentin Smith)
Tue Dec 2 01:07:49 2008
Date: Tue, 2 Dec 2008 01:06:12 -0500 (EST)
From: Quentin Smith <quentin@MIT.EDU>
To: athena10@mit.edu
cc: Geoffrey G Thomas <geofft@mit.edu>
Message-ID: <Pine.LNX.4.64L.0812020100090.19068@vinegar-pot.mit.edu>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
Hey-
I investigated the feasibility of adding custom buttons to the GDM greeter
UI for performing actions such as registration. Unfortunately, this is not
possible in the version of gdm we're running. It has functionality for
running custom commands and associating those with buttons, but the
DISPLAY environment variable is not set for those commands.
gdm 2.20, which ships with Intrepid, is the last in this gdm series. The
gdm code base has been forked for a complete rewrite, and the custom
command functionality doesn't appear to exist in the (unfinished) new
version (but the distros still seem to be using the old branch).
Custom commands don't have DISPLAY set because the button on the greeter
signals the gdm slave which signals the gdm daemon to run the command.
Following along in the gdm package's daemon/gdm.c, the GDM_SOP_CUSTOM_CMD
message is received. gdm looks up the display associated with the slave
that sent the request, then promptly discards that information and calls
the custom_cmd function with the requested custom command. gdm runs as a
daemon and can be associated with multiple displays, so it doesn't have
DISPLAY set.
It would probably be a 5-10 line patch to set the DISPLAY environment
variable before running the custom command, but I don't think we want to
patch a package like gdm for trivial functionality such as this.
--Quentin
