Hang on login caused by 'df'

[gcorrall]

In debian/patches/04_language_handling.patch, a 'df' is run, to check if lightdm is running in a 'live session':

if (system ("df | grep -q ^/cow") != 0)
    session_set_env (session, "LANGUAGE", language);

(from this commit: 'Only set LANGUAGE if not in a live session'; 3b11df7).

This can cause lightdm to hang when the 'df' hangs - such as when an NFS mount becomes unresponsive. I have encountered this on a machine where remote SSH users had mounted an NFS share, which later became stuck, and I was unable to login via lightdm.

Perhaps some other way of checking for the mount could be used ( grep -q "^/cow / " /proc/mounts ? ), or a timeout could be added to the 'df':

timeout 5 df | grep -q ^/cow