Enable network namespace sharing in lxc-start

Right now lxc-start always does one of two things: it creates
a new namespace or inherits it from the parent environment.
This patch adds a third option: share a namespace with another
container (actually: a process).

In some situations this is handy. For example by sharing a network
namespace it is possible to migrate services between containers
without (or with little) downtime.

This patch creates an infrastructure for inheriting any type
of namespace, but only the network namespace is supported for now.
Allow specifying a container by name or pid in --share-net option.
Cosmetic - clean up error message
Describe --share-net in the lxc-start manual
Cosmetic.
Create --share-ipc option
Merge remote-tracking branch 'lxc/master' into share-namespaces
Fix memory leak in pid_from_lxcname and use ns_proc_name in open_ns.
Refactoring - make the option parsing code generic
Make it possible to share UTS namespace
Cosmetic: shorten the options summary in documentation
remove HAVE_NEWUIDMAP and NEWUIDMAP

Always build lxc-usernsexec.  Else we require having uidmap
installed on the build host for no good reason.  And we never
actually used the NEWUIDMAP path we detected.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
add lxc-usernsexec to .gitignore

Signed-off-by: S.Çağlar Onur <caglar@10ur.org>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Add lxc.service to extra_DIST

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
lxcapi_destroy: run in a namespace if we are unprivileged

This is necessary to have the rights to remove files owned by our subuids.

Also update lxc_rmdir_onedev to return 0 on success, -1 on failure.
Callers were not consistent in using it correctly, and this is more
in keeping with the rest of our code.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
don't fail lxc-init if we couldn't mount proc

In general proc gets mounted ahead of time, so init shouldn't
have to do it.  Without this patch, you cannot

	lxc-execute -n x1 -s lxc.cap.drop=sys_admin /bin/bash

(See https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/1253669 for
a bug about this)

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
doc: Update Japanese lxc-attach(1)

Update for commit 4d69b2939ce09fbe624636dc01734a542e050ef9

Signed-off-by: KATOH Yasufumi <karma@jazz.email.ne.jp>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
use awk, instead of 'grep | awk'

Signed-off-by: Elan Ruusamäe <glen@delfi.ee>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
lxc-ubuntu: Add extra options

This adds support for "packages", "user" and "password"

Signed-off-by: Guilhem Lettron <guilhem.lettron@optiflows.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
lxc-ubuntu: Move package install to post-process

Signed-off-by: Guilhem Lettron <guilhem.lettron@optiflows.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>