Re: [gdm-list] reauthentication breaks XDMCP

[Ray Strode <halfline gmail com>]

Hey, thanks for investigating this.  Can you make sure there's a
report in bugzilla? I'll have a look.

--Ray

On Mon, Dec 24, 2012 at 6:24 PM, Gordon Messmer <yinyang eburg com> wrote:
> Yesterday I installed Fedora 18's beta and configured it as an XDMCP server
> for an X11 terminal running CentOS 6.  The terminal will display the GDM
> login screen, but entering a username causes the interface to stop working.
> The username will remain displayed, and the buttons will animate when
> clicked, but no login is apparently attempted.
>
> It looks like the problem is caused by the reauthentication support added in
> commit 2853ce5812aa8f03f677516e64d5dcff1e6e01ab.  GDM logs an exception and
> the error "Error getting session ids from systemd: No such file or
> directory".
>
> I think there are three problems here.  First, glib is warning that GError
> isn't being set correctly.  GDM's exception and subsequent unresponsiveness
> may be a result of that, or a bug of it's own.  I'm not sure.  The big
> problem, though, is that as of that commit, GDM seems to require multiseat
> information from the X11 servers.  That requirement doesn't seem to make
> sense in XDMCP mode, but no fallback appears to be present.
>
> Assuming that is the case, could someone either implement an alternate path
> for XDMCP so that the greeter doesn't crash, or disable XDMCP support when
> the system is built WITH_SYSTEMD?  If XDMCP isn't going to work, it'd be far
> preferable for GDM to simply log that it cannot enable XDMCP when built
> WITH_SYSTEMD than it is to enable XDMCP and subsequently fail.
>
> Thanks.
>
>
> Version:
> gdm-3.6.2-5.fc18.x86_64
>
> Commit:
> https://mail.gnome.org/archives/commits-list/2012-July/msg04426.html
>
> Logs:
> ==> messages <==
> Dec 23 17:38:05 herald gdm[2173]: gdm-binary[2173]: GLib-WARNING: GError set
> over the top of a previous GError or uninitialized memory.
> Dec 23 17:38:05 herald gdm[2173]: This indicates a bug in someone's code.
> You must ensure an error is NULL before it's set.
> Dec 23 17:38:05 herald gdm[2173]: The overwriting error message was: Error
> getting session ids from systemd: No such file or directory
> Dec 23 17:38:05 herald gdm-binary[2173]: GLib-WARNING: GError set over the
> top of a previous GError or uninitialized memory.
>
> ==> gdm/192.168.89.1:0-greeter.log <==
>     JS ERROR: !!!   Exception was: TypeError: Object 0x7fdf06b41ec8 is not a
> subclass of (null), it's a GLib_Error
>     JS ERROR: !!!     message = '"Object 0x7fdf06b41ec8 is not a subclass of
> (null), it's a GLib_Error"'
>     JS ERROR: !!!     fileName = '"/usr/share/gnome-shell/js/gdm/util.js"'
>     JS ERROR: !!!     lineNumber = '159'
>     JS ERROR: !!!     stack = '"([object _private_Gdm_Client],[object
> _private_Gio_SimpleAsyncResult])@/usr/share/gnome-shell/js/gdm/util.js:159
> wrapper([object _private_Gdm_Client],[object
> _private_Gio_SimpleAsyncResult])@/usr/share/gjs-1.0/lang.js:204"'
>
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