python3: Export get_global_config_item

get_global_config_item was added in _lxc but not mapped into lxc itself,
this resolves this oversight.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
lxc-ls: Fix support of --nesting for unpriv

This reworks the way lxc-ls works in nesting mode. In the past it'd use
attach_wait's subprocess function to call itself in the container's
namespace, carefully only attaching to the namespaces it needed.

This works great for system containers but not so much as soon as you
also need to attach to userns. Instead this fix moves all of the
container listing code into a get_containers function (hence the massive
diff, sorry), this function is then called recursively.

For running containers, the function is called through attach_wait
inside the container's namespace, for stopped container, the function is
simply called recursively with a base path (container's rootfs) in an
attempt to find containers that way.
Communication between the parent lxc-ls and the child lxc-ls is done
through a temporary fd and serialized state using json (similar to what
was done using stdout in the previous implementation).

As get_global_config_item unfortunately caches the values, there's no
easy way to figure out what the lxcpath should be for a root container
when running as non-root, so just use @LXCPATH@ for now and have
python do the parsing itself.

As a result, the following things now work as expected:
 - listing nested unprivileged containers (root containers inside unpriv)
 - listing nested containers when they're not running
 - filtering containers in nesting mode (only the first level is filtered)
 - copy with invalid config (used to traceback)

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
cgmanager updates

1. remove the cgm_dbus_disconnected handler.  We're using a proxy
   anyway, and not keeping it around.

2. comment most of the cgm functions to describe when they are called, to
   ease locking review

3. the cgmanager mutex is now held for the duration of a connection, from
   cgm_dbus_connect to cgm_dbus_disconnect.

3b. so remove the mutex lock/unlock from functions which are called during
   container startup with the cgmanager connection already up

4. remove the cgroup_restart().  It's no longer needed since we don't
   daemonize while we have the cgmanager socket open.

5. report errors and return early if cgm_dbus_connect() fails

6. don't keep the cgm connection open after cgm_ops_init.  I'm a bit torn
   on this one as it means that things like lxc-start will always connect
   twice.  But if we do this there is no good answer, given threaded API
   users, on when to drop that initial connection.

7. cgm_unfreeze and nrtasks: grab the dbus connection, as we'll never
   have it at that point.  (technically i doubt anyone will use
   cgmanager and utmp helper on the same host :)

8. lxc_spawn: make sure we only disconnect cgroups if they were already
   connected.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
cgmanager: switch to TLS

Drop the thread mutex.  Set a (TLS) boolean at container start to
indicate that the connection should be kept open;  set it back to false
only when container start is complete.  Every cgm_ method opens the
connection if not already open, and closes it if cgm_keep_connection
is false.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
Update gitignore for lxc-ls

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
snapshot: fix overlayfs restore

And add a testcase to catch regressions.

Without this patch, restoring a snapshot of an overlayfs based
container fails, because we do not pass in LXC_CLONE_SNAPSHOT,
and overlayfs does not support clone without snapshot.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>