cgroups: use semantically clean check in cpuset1_cpus_initialize()

The variable is a pointer not a integer.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

cgroups: fix cpumask handling

Link: https://discuss.linuxcontainers.org/t/lxc-4-0-9-lxc-start-sigabrt-on-systems-with-defined-offline-cpus-and-a-total-number-of-cpus-divisible-by-32
Signed-off-by: Jim Ferrigno <jim.ferrigno@oracle.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

cgroups: fix comments in cpuset1_initialize()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Revert "cgroups: fix cpu bitmasks"

This reverts commit e0f7296a6d537f0d2eb5fbc6d7f9e007d11d516a.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

cgroups: s/calloc/zalloc/g

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

cgroups: fix cpu bitmasks

Link: https://discuss.linuxcontainers.org/t/lxc-4-0-9-lxc-start-sigabrt-on-systems-with-defined-offline-cpus-and-a-total-number-of-cpus-divisible-by-32
Signed-off-by: Jim Ferrigno <jim.ferrigno@oracle.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

mainloop: disable IORING_SETUP_SQPOLL for now

It's a bit more complicated to use then I envisioned here.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

mainloop: add comments about multishot and oneshot cleanup

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

mainloop: s/handler_name/name/g

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

mainloop: move variables into tighter scope

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

memory_utils: make cleanup handler as unused

They are sometimes used to just clean something up automatically at end
of scope but the variables themselves might not be actually used.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

mainloop: fix io_uring cleanup handling

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

mainloop: remove CANCEL_RAISE flag

This is really not needed since we're not checking it anywhere anyway.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

mainloop: minor fixes

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

mainloop: s,sys/poll,poll

I get the following warning (which then fails the build because of
-Werror):

In file included from mainloop.c:11:
/usr/include/sys/poll.h:1:2: error: #warning redirecting incorrect #include <sys/poll.h> to <poll.h> [-Werror=cpp]
    1 | #warning redirecting incorrect #include <sys/poll.h> to <poll.h>
      |  ^~~~~~~

Signed-off-by: Tycho Andersen <tycho@tycho.pizza>

lxc-download: add LXC version/compat level to user-agent

Signed-off-by: Simon Deziel <simon.deziel@canonical.com>

mainloop: add io_uring support

Users can choose to compile liblxc with io_uring support. This will
cause LXC to use io_uring instead of epoll.
We're using both, io_uring's one-shot and multi-shot poll mode depending
on the type of handler.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

doc: Adds mention of ability to specify manual IPv4 broadcast address

See also https://github.com/lxc/lxd/pull/9103

Signed-off-by: Thomas Parrott <thomas.parrott@canonical.com>

tree-wide: s/lxc_epoll_descr/lxc_async_descr/g

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: log session keyring failure on WARN level

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

cgroups: log at warning instead of error level

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Improve bash completion.

Use as much as possible from each command `--help` for completion.

Some options require a long list of completions that should be dumped by
some command option. These are not added here yet.

Examples of those are: `lxc-info --config`, `lxc-execute --define` and
`lxc-start --define`.

Signed-off-by: Edenis Freindorfer Azevedo <edenisfa@gmail.com>

Create rules to add/remove symlinks for bash completion.

By default, there is no out-of-the-box bash completion for lxc tools.
This is due to dynamic loading of completions, that requires the
completion filename to be the same as the command (e.g. `lxc-start`
expects a completion filename `lxc-start`). But all commands are in file
`lxc`, which is not read.

Signed-off-by: Edenis Freindorfer Azevedo <edenisfa@gmail.com>

Fix typo on documentation for `lxc-{attach,execute}`.

According to `[1]`, `lxc-attach` uses `-u,-g` instead of `--u,--g`.
According to `[2]`, `lxc-execute` uses `-u,-g` instead of `--u,--g`.

- [1] https://github.com/lxc/lxc/blob/stable-4.0/src/lxc/tools/lxc_attach.c#L131-L132
- [2] https://github.com/lxc/lxc/blob/stable-4.0/src/lxc/tools/lxc_execute.c#L59-L60

Signed-off-by: Edenis Freindorfer Azevedo <edenisfa@gmail.com>

Fix typo on documentation for `lxc-autostart`.

According to `[1,2]`, this command has `--groups` instead of `--group`.

- [1] https://github.com/lxc/lxc/blob/stable-4.0/src/lxc/tools/lxc_autostart.c#L64
- [2] https://github.com/lxc/lxc/blob/stable-4.0/src/lxc/tools/lxc_autostart.c#L84

Signed-off-by: Edenis Freindorfer Azevedo <edenisfa@gmail.com>

Merge pull request #3969 from brauner/2021-09-03.fixes.stable

tests: fix config file tests

tests: fix config file tests

Link: https://bugs.launchpad.net/bugs/1943441
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

doc/api-extensions: Grammar fix

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>

lsm/apparmor: use cleanup macro

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

lsm/apparmor: log failure to write AppArmor profile

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

network: fix container with empty network namespaces

Fixes: #3922
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

tests: add test for rootfs mount options

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: allow mount options for rootfs when using new mount api

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

mount_utils: make some mount helpers static inline

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: let parse_vfs_attr() handle legacy mount flags as well

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: log failure to create tty mountpoint

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: refactor lxc_recv_ttys_from_child()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: fix logging in lxc_idmapped_mounts_child()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

mount_utils: introduce mount_at()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

terminal: fail on unknown error during TIOCGPTPEER

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

terminal: move native terminal allocation from error logging to info

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: handle kernels without TIOCGPTPEER

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

start: allow containers to use a native console

After all of the previous rework we can make it possible for a container
to use a console allocated from the container's devpts instance.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

terminal: remove unused argument from lxc_devpts_terminal()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: rework console setup

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

file_utils: add open_at_same()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: use mount_fd() during console mounting

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: use mount_fd() in lxc_setup_dev_console()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: use mount_fd() helper when mounting ttys

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

mount_utils: add mount_fd()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: stash pty_nr in struct lxc_terminal

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: move lxc_create_ttys() before pivot root

This is the last setup step that occured after pivot root.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

terminal: split out lxc_devpts_terminal() helper

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

string_utils: cast __s64 to long long signed int

Link: https://launchpadlibrarian.net/550723147/buildlog_snap_ubuntu_focal_ppc64el_lxd-latest-edge_BUILDING.txt.gz
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: merge devpts setup and move before pivot root

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

terminal: don't use ttyname_r() for native terminal allocation

Since we can call that function from another mount namespace we need to
do this manually.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: add and use mount_beneath_fd()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: update comment

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: use a relative path in symlinkat()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: s/lxc_setup_devpts_parent/lxc_recv_devpts_from_child/g

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: attach devpts mount directly when new mount api can be used

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: set source property for devpts

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: surface failures to setup console

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Fix typos

This fixes all typos identified by lintian.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>

conf: ensure devpts_fd is set to -EBADF

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

terminal: ttyname_r() returns an error number on failure

In other words, how inconsistent can an API be?

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: use new mount api for devpts setup

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

bpf: bpf_devices_cgroup_supported() should check if bpf() is available

bpf_devices_cgroup_supported() tries to load a simple BPF program to
test if BPF works. This is problematic because the function used to load
the program - bpf_program_load_kernel() - emits an error to the log if
BPF is not enabled in the kernel although device controller is not
requested in the configuration. Users could interpret that as a problem.

Make bpf_devices_cgroup_supported() check if the BPF syscall is available
before calling bpf_program_load_kernel(). We can do it by passing a NULL
pointer instead of the syscall argument as the kernel returns either
ENOSYS, when the syscall is not implemented or EFAULT, when it is
implemented.

Signed-off-by: Petr Malat <oss@malat.biz>

lxc_setup_ttys: Handle existing ttyN file without underlying device

If a device file is opened and there isn't the underlying device,
the open call fails with ENXIO, but the path can be opened with
O_PATH, which is enough for mounting over the device file.

Generalize this idea and use O_PATH for all cases when the file
is there. One still must check for both ENXIO and EEXIST as it's
unspecified what error is reported if multiple error conditions
occur at the same time.

Signed-off-by: Petr Malat <oss@malat.biz>

cgroups: remove unneeded variables from cgroup_tree_create

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>

cgroups: populate hierarchy for device cgroup

With the changes introduced in:
b7b1e3a34ce28b01206c48227930ff83d399e7b6
the hierarchy-struct did not have the path_lim set anymore, which is
needed by setup_limits_legacy (->cg_legacy_set_data->lxc_write_openat)
to actually access the cgroup directory.

The issue can be reproduced with a container config having
```
lxc.cgroup.devices.deny = a
```
(or any lxc.cgroup.devices entry) set on a system booted with
systemd.unified_cgroup_hierarchy=0.

This affects all privileged containers on PVE (due to the default
devices.deny entry).

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>

Release LXC 4.0.10

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>

terminal: fix error handling

Fixes: f382bcc6d820 ("terminal: log TIOCGPTPEER failure less alarmingly")
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

af_unix: report error when no fd is to be sent

Fixes: #3624
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

terminal: log TIOCGPTPEER failure less alarmingly

This is not a fatal error and the fallback codepath is equally safe.
When we use TIOCGPTPEER we're using a stashed fd to the container's
devpts mount's ptmx device and allocating a new fd non-path based
through this ioctl. If this ioctl can't be used we're falling back to
allocating a pts device from the host's devpts mount's ptmx device which
is path-based but is not under control of the container and so that's
safe. The difference is just that the first method gets you a nice
native terminal with all the pleasantries of having tty and friends
working whereas the latter method does not.

Fixes: #3625
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

sync: fix log message

Fixes: #3875
Suggested-by: Hank.shi <shk242673@163.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

start: fix logging message

Fixes: #3875
Suggested-by: Hank.shi <shk242673@163.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

initutils: include pthread.h

Otherwise we might end up with implicit function declaration warnings.

Link: https://jenkins.linuxcontainers.org/job/lxc-build-android/8915/console
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

doc/common_options: add trace and alert loglevels

Signed-off-by: Serge Hallyn <serge@hallyn.com>

file_utils: surface ENOENT when falling back to openat()

Link: https://discuss.linuxcontainers.org/t/error-failed-to-retrieve-pid-of-executing-child-process
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

lxc_unshare: fix network device handling

We were passing the wrong PID. Fix this!

Link: https://discuss.linuxcontainers.org/t/problem-with-moving-interface-new-network-namespace-in-lxc-unshare
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

lxc_unshare: make mount table private

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

confile: allow including nonexisting directories

If an include directive ends with a trailing slash, we now
always assume it is a directory and do not treat the
non-existence as an error.

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

conf: userns.conf: include userns.conf.d

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

doc: Fix typo in English lxc.container.conf(5)

Signed-off-by: KATOH Yasufumi <karma@jazz.email.ne.jp>

doc: Add new idmap= option to Japanese lxc.container.conf(5)

Update for commit 1852be904823e3532af38efc5ef55d3fb931e616

Signed-off-by: KATOH Yasufumi <karma@jazz.email.ne.jp>

doc: Append description of net type field

Update for commit 320061b34fea7d7f280b0a421dddeac7dac7f1bf

Signed-off-by: KATOH Yasufumi <karma@jazz.email.ne.jp>

doc: Add eBPF-based device controller semantics to Japanese man page

Update for commit 5025f3a69053bbddbe6c76ffb55b4bbd5759dcc8

Signed-off-by: KATOH Yasufumi <karma@jazz.email.ne.jp>

cmd/lxc-checkconfig: list cgroup namespaces and rename confusing ns_cgroup entry

Link: https://discuss.linuxcontainers.org/t/cgroup-namespace-required-in-lxc-checkconfig-and-config-cgroup-ns
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

terminal: ensure newlines are turned into newlines+carriage return for terminal output

Fixes: #3879
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

cgroups: handle funky cgroup layouts

Old versions of Docker emulate a cgroup namespace by bind-mounting the
container's cgroup over the corresponding controller:

/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod7d4424e6_bb13_42f4_a47a_45a4828bf54d.slice/docker-d0b3604b67ac7930dd34ba3a796627e3e4717d12309e90a4afe3f38b6816ac98.scope /sys/fs/cgroup/systemd rw,nosuid,nodev,noexec,relatime master:11 - cgroup cgroup rw,xattr,name=systemd
/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod7d4424e6_bb13_42f4_a47a_45a4828bf54d.slice/docker-d0b3604b67ac7930dd34ba3a796627e3e4717d12309e90a4afe3f38b6816ac98.scope /sys/fs/cgroup/net_cls,net_prio rw,nosuid,nodev,noexec,relatime master:15 - cgroup cgroup rw,net_cls,net_prio
/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod7d4424e6_bb13_42f4_a47a_45a4828bf54d.slice/docker-d0b3604b67ac7930dd34ba3a796627e3e4717d12309e90a4afe3f38b6816ac98.scope /sys/fs/cgroup/cpu,cpuacct rw,nosuid,nodev,noexec,relatime master:16 - cgroup cgroup rw,cpu,cpuacct
/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod7d4424e6_bb13_42f4_a47a_45a4828bf54d.slice/docker-d0b3604b67ac7930dd34ba3a796627e3e4717d12309e90a4afe3f38b6816ac98.scope /sys/fs/cgroup/memory rw,nosuid,nodev,noexec,relatime master:17 - cgroup cgroup rw,memory
/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod7d4424e6_bb13_42f4_a47a_45a4828bf54d.slice/docker-d0b3604b67ac7930dd34ba3a796627e3e4717d12309e90a4afe3f38b6816ac98.scope /sys/fs/cgroup/devices rw,nosuid,nodev,noexec,relatime master:18 - cgroup cgroup rw,devices
/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod7d4424e6_bb13_42f4_a47a_45a4828bf54d.slice/docker-d0b3604b67ac7930dd34ba3a796627e3e4717d12309e90a4afe3f38b6816ac98.scope /sys/fs/cgroup/hugetlb rw,nosuid,nodev,noexec,relatime master:19 - cgroup cgroup rw,hugetlb
/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod7d4424e6_bb13_42f4_a47a_45a4828bf54d.slice/docker-d0b3604b67ac7930dd34ba3a796627e3e4717d12309e90a4afe3f38b6816ac98.scope /sys/fs/cgroup/perf_event rw,nosuid,nodev,noexec,relatime master:20 - cgroup cgroup rw,perf_event
/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod7d4424e6_bb13_42f4_a47a_45a4828bf54d.slice/docker-d0b3604b67ac7930dd34ba3a796627e3e4717d12309e90a4afe3f38b6816ac98.scope /sys/fs/cgroup/cpuset rw,nosuid,nodev,noexec,relatime master:21 - cgroup cgroup rw,cpuset
/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod7d4424e6_bb13_42f4_a47a_45a4828bf54d.slice/docker-d0b3604b67ac7930dd34ba3a796627e3e4717d12309e90a4afe3f38b6816ac98.scope /sys/fs/cgroup/blkio rw,nosuid,nodev,noexec,relatime master:22 - cgroup cgroup rw,blkio
/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod7d4424e6_bb13_42f4_a47a_45a4828bf54d.slice/docker-d0b3604b67ac7930dd34ba3a796627e3e4717d12309e90a4afe3f38b6816ac98.scope /sys/fs/cgroup/pids rw,nosuid,nodev,noexec,relatime master:23 - cgroup cgroup rw,pids
/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod7d4424e6_bb13_42f4_a47a_45a4828bf54d.slice/docker-d0b3604b67ac7930dd34ba3a796627e3e4717d12309e90a4afe3f38b6816ac98.scope /sys/fs/cgroup/freezer rw,nosuid,nodev,noexec,relatime master:24 - cgroup cgroup rw,freezer

New versions of LXC always stash a file descriptor for the root of the
cgroup mount at /sys/fs/cgroup and then resolve the current cgroup
parsed from /proc/{1,self}/cgroup relative to that file descriptor. This
doesn't work when the caller's cgroup is mouned over the controllers.
Older versions of LXC simply counted such layouts as having no cgroups
available for delegation at all and moved on provided no cgroup limits
were requested. But mainline LXC would fail such layouts. While I would
argue that failing such layouts is the semantically clean approach we
shouldn't regress users so make mainline LXC treat such cgroup layouts
as having no cgroups available for delegation.

Fixes: #3890
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

tests: add tests for read-only /sys with read-write /sys/devices/virtual/net

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

conf: improve read-only /sys with read-write /sys/devices/virtual/net

Some tools require /sys/devices/virtual/net to be read-write. At the
same time we want all other parts of /sys to be read-only. To do this we
created a layout where we hade a read-only instance of sysfs mounted on
top of a read-write instance of sysfs:

`-/sys                                  sysfs                                                        sysfs      rw,nosuid,nodev,noexec,relatime
  `-/sys                                sysfs                                                        sysfs      ro,nosuid,nodev,noexec,relatime
    |-/sys/devices/virtual/net          sysfs                                                        sysfs      rw,relatime
    | `-/sys/devices/virtual/net        sysfs[/devices/virtual/net]                                  sysfs      rw,nosuid,nodev,noexec,relatime

This causes issues for systemd services that create a separate mount
namespace as they get confused to what mount options need to be
respected.

Simplify our mounting logic so we end up with a single read-only mount
of sysfs on /sys and a read-write bind-mount of /sys/devices/virtual/net:

├─/sys                                sysfs                                                                                  sysfs         ro,nosuid,nodev,noexec,relatime
│ ├─/sys/devices/virtual/net          sysfs[/devices/virtual/net]                                                            sysfs         rw,nosuid,nodev,noexec,relatime

Link: systemd/systemd#20032
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

initutils: close dirfd in error path

Signed-off-by: Simon Deziel <simon.deziel@canonical.com>

execute: ensure parent is notified about child exec and close all unneeded fds

lxc_container_init() creates the container payload process as it's child
so lxc_container_init() itself never really exits and thus the parent
isn't notified about the child exec'ing since the sync file descriptor
is never closed. Make sure it's closed to notify the parent about the
child's exec.

In addition we're currently leaking all file descriptors associated with
the handler into the stub init. Make sure that all file descriptors
other than stderr are closed.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

network: log network devices while sending

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

initutils: use vfork() in lxc_container_init()

We can let the child finish calling exec before continuing in the
parent.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

execute: don't exec init, call it

Instead of having a statically linked init that we put on the host fs
somewhere via packaging, have to either bind mount in or detect fexecve()
functionality, let's just call it as a library function. This way we don't
have to do any of that.

This also fixes up a bunch of conditions from:

if (quiet)
    fprintf(stderr, "log message");

to

if (!quiet)
    fprintf(stderr, "log message");

:)

and it drops all the code for fexecve() detection and bind mounting our
init in, since we no longer need any of that.

A couple other thoughts:

* I left the lxc-init binary in since we ship it, so someone could be using
  it outside of the internal uses.
* There are lots of unused arguments to lxc-init (including presumably
  --quiet, since nobody noticed the above); those may be part of the API
  though and so we don't want to drop them.

Signed-off-by: Tycho Andersen <tycho@tycho.pizza>

When an item is added to an array, then the array is realloc()ed (to size+1),
and the item is copied (strdup()) to the array.
Thus, when an item is removed from an array, memory allocated for that item
should be freed, successive items should be left-shifted and the array
realloc()ed again (size-1).

Additional changes:
- If strdup() fails in add_to_array(), then an array should be
  realloc()ed again to original size.
- Initialize an array in list_all_containers().

Signed-off-by: Tomasz Blaszczak <tomasz.blaszczak@consult.red>

cgroups: verify that hierarchies are non-empty

Fixes: #3881
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>