Subject: Re: [X2Go-Dev] Bug#638: broker agent in LOCAL mode cannot find state file

From: Mike Gabriel <[email-masked]>
Date: Fri, 17 Oct 2014 08:46:50 +0000

Control: reassign -1 x2goserver
Control: found -1 4.0.1.18

Hi Stefan,

On  Sa 11 Okt 2014 11:03:48 CEST, Mike Gabriel wrote:

> Package: x2gobroker
> Severity: important
> Version: 0.3.0.0
>
> Since X2Go Server 4.0.1.16, all session relevant files moved to  
> /tmp/.x2go-<user>. In $HOME/.x2go there only is a symlink to the  
> session dir on /tmp.
>
> This change breaks x2gobroker-agent in LOCAL mode (evoked on the  
> broker host itself, assuming all session files are available).
>
> In LOCAL mode, x2gobroker-agent is evoked on the X2Go Broker host  
> itself and assumes that it can access all session files in  
> $HOME/.x2go/C-<session>.
>
> But what it finds is a dangling symlink to a non-existent  
> C-<session> dir in /tmp/.x2go-<user>.
>
> The wanted session dir, of course, can only be found on
>
>   X2Go-Server-node-N:/tmp/.x2go-<user>/C-<session>

This issue should actually be silenced (not really fixed, as it is not  
fixable) in X2Go Server.

Most of the session manipulation happens via the X2Go Server node's  
x2gocleansessions daemon script.

The x2golistsessions command (evoked by x2gobroker-agent), which  
triggers the observed bug, does not necessarily need access to the  
session state file. If it can gain access, it will check the session  
state, and update the session DB, if the DB value differs from the  
actual state in the session state file (the session state file should  
be more up-to-date).

If we omit this DB update in x2golistsessions, we need to rely on a  
working x2gocleansessions daemon, which should still be enough.

Thus, I will test for the existence of the state file in  
x2golistsessions first and then execute the DB update code. If there  
is no session state file, we should be clear, as well (and need to  
rely on x2gocleansessions on the X2Go Server nodes).

Mike

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