[blfs-support] Automounting

David Brodie lfs at aba.eclipse.co.uk
Mon Dec 9 11:52:38 PST 2013

On 09/12/13 18:30, Dan McGhee wrote:
> I discovered in my research that autofs needs discreetly identified
> mount points for removable devices.  This is great for unique devices
> like CD/DVD players, cameras and PDA's, but it's quite cumbersome for
> mass storage devices with multiple partitions on them.  As a result, I
> installed xfce4 and wanted to use udisks.  So far, I have not been able
> to get anything to automount using this combination.  Running 'udisksctl
> status' gives the following output with the first two lines repeating
> four times before the whole thing stops.
>> (process:26376): GLib-GObject-WARNING **: invalid (NULL) pointer instance
>> (process:26376): GLib-GObject-CRITICAL **:
>> g_signal_handlers_disconnect_matched: assertion 'G_TYPE_CHECK_INSTANCE
>> (instance)' failed
>> (process:26376): GLib-GObject-CRITICAL **: g_object_unref: assertion
>> 'G_IS_OBJECT (object)' failed
>> Error connecting to the udisks daemon: Error calling
>> StartServiceByName for org.freedesktop.UDisks2:
>> GDBus.Error:org.freedesktop.DBus.Error.Spawn.PermissionsInvalid: The
>> permission of the setuid helper is not correct
> When I plug my USB drive in, /var/log/daemon.log gives:
>> dbus[644]: [system] Activated service 'org.freedesktop.UDisks2'
>> failed: The permission of the setuid helper is not correct
> When I log out of xfce, I see the following messages--I don't know when
> they occur although I have plugged in and removed one of my USB drives a
> couple of times.  The first long line occurs with each final statement.
> I will include the long line and then the two statements in order of
> their appearance.
>> GVFS--Remote Volume Monitor--Warning remote volume monitor with dbus
>> name org.gtk.Private.UDisks2VolumeMonitor is not supported
>>       thunar-volman: Could not detect the volume corresponding to the
>> device
> I have reviewed my install logs and as far as I can see all the
> permissions of what I have installed are correct.  I could have missed
> something, however.  Additionally, I don't know if there are any of the
> applications and daemons that need to be owned by root. I'm specifically
> thinking of Polkit.  Most of the files are owned by their package names
> for my Package Users system.
> In any event, I do not know where to even start troubleshooting.  I
> tried looking at the different files, but I do not understand the
> syntax, esp Polkit rules.  I've looked in the Arch, Gentoo and Xfce
> wiki's and couldn't find anything that solved the situation.
> I will really appreciate any help.
> Thanks,
> Dan


You need both udisks2 and gvfs - the latter is actually a dependency of 
Thunar itself, not just thunar-volman - plus you need a polkit rules 
file for udisks2, which is written in Javascript format for the latest 
version of Polkit - this is a very simple example:


/* Allow members of group users to do anything with udisks2! */
polkit.addRule(function(action, subject) {
     if (action.id.indexOf("org.freedesktop.udisks2.") == 0 && 
subject.isInGroup("users")) {
         return polkit.Result.YES;

That will allow a member of 'users' to mount local disks, use 
hot-plugging, and optionally browse remote filesystems, I believe, if 
you have the right optional dependencies installed, such as Samba.

The polkit daemon usually has its own user and group.


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