start: Fix print_top_failing_dir for /var/lib/lxc

In the case where /var/lib/lxc itself was not accessible,
print_top_failing_dir would fail to print the error message.

This fixes it and also change the initial access check for X_OK instead
of R_OK (to match what we actually need and print_top_failing_dir's own
check).

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Fix unprivileged containers started by root

This change makes it possible to create unprivileged containers as root.
They will be stored in the usual system wide location, use the usual
system wide cache but will be running using a uid/gid map.

This also updates lxc_usernsexec to use the same function as the rest of
LXC, centralizing all the userns switch in a single function.

That function now detects the presence of newuidmap and newgidmap on the
system, if they are present, they will be used for containers created as
either user or root. If they're not and the user isn't root, an error is
shown. If they're not and the user is root, LXC will directly set the
uid_map and gid_map values.

All that should allow for a consistent experience as well as supporting
distributions that don't yet ship newuidmap/newgidmap.

To make things simpler in the future, an helper function "on_path" is
also introduced and used to detect the presence of newuidmap and
newgidmap.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
on_path: use strtok_r consistently

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
lxc-download: Fix in_userns again

The use of a subshell was causing various failures, re-arrange not to
use one.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
removed shebang from bash_completion-file

Signed-off-by: Johannes Kastl <git@ojkastl.de>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
cgmanager: don't stay connected

There are only a few times when we need to be connected to the
cgroup manager:

* when starting a container, from cgm_init until we've set cgroup limits
* when changing a cgroup setting (while running)
* when cleaning up (when shutting down)
* around the cgroup entering at attach

So only connect/disconnect the cgmanager socket on-demand as
needed.  This should have a few benefits.

1. Reduce the # open fds when many containers are running
2. if cgmanager is stopped and restarted, the container
   doesn't have to deal with the disconnection.

This is currently RFC.  There are a few issues outstanding:

1. the cgm_set and cgm_get may need to be made thread-safe.
2. a non-daemonized start which fails while cgm is connected,
will not disconnected.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
use btrfs snapshot feature to restore snapshots

fixes #131

changes since v1;
* uses btrfs snapshot feature only if src and dest are on same fs

Signed-off-by: S.Çağlar Onur <caglar@10ur.org>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
clone: don't ever mark the clone's rootfs as being the old, on disk

Otherwise an interrupted clone can lead to the original rootfs
being delete.

There is a period during lxcapi_clone during which we have written down
a temporary configuration file on disk, for the new container, using the
old rootfs. Interruption of clone doesn't allow us to do the cleanup we
do in error paths, so a subsequent lxc-destroy removes the old rootfs.

Fix this by doing the copy_storage as early as possible, and not
writing down the rootfs when we write down the temporary configuration
file.

(note - I tested this by putting a series of
'if (strcmp(newname, "u%d") == 0) exit(1)' inline to trigger
interruption between most blocks.  If someone has a good idea
for a generic way to regression-test this henceforth that'd be
great)

See https://bugs.launchpad.net/lxc/+bug/1285850

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

Only do the funky chroot_into_slave if / is in fact the rootfs.
Rootfs is a special blacklisted case for pivot_root.

If / is not rootfs but is shared, just mount / rslave.  We're
already in our own namespace.

This appears to solve the extra /proc/$$/mount entries in
containers and the host directories in lxc-attach which have
been plagueing at least fedora and arch.

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