Function defaultPath always parses /proc/self/cgroup, but
the resulting value is not always used.

Avoid unnecessary reading/parsing by moving the code
to just before its use.

Modify the test case accordingly.

[v2: test: use UnifiedMountpoint, skip test if not on v2]

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

cgroups/fs2: don't always parse /proc/self/cgroup

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

...just to test the new package.

This complexity is temporary: once criu-3.14 will be moved from testing
to stable, this will be removed.

Also remove criu build deps as we're no longer building it from source.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

1. Disable updating the kernel (we're not going to reboot into it
   anyway)

2. Disable weak dependencies (that includes git, svn and a ton of perl
   modules).

3. Add git-core to list of packages since it is used from Makefile.

Before:

    default: Transaction Summary
    default: ================================================================================
    default: Install  123 Packages
    default: Upgrade   63 Packages
    default: Total size: 326 M
    default: Total download size: 326 M

After:

    default: Transaction Summary
    default: ================================================================================
    default: Install  53 Packages
    default: Upgrade  63 Packages
    default: Total size: 181 M
    default: Total download size: 180 M

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

genericError.Error() was formatting the underlying error using `%q`; as a
result, quotes in underlying errors were escaped multiple times, which
caused the output to become hard to read, for example (wrapped for readability):

```
container_linux.go:345: starting container process caused "process_linux.go:430:
container init caused \"rootfs_linux.go:58: mounting \\\"/foo.txt\\\"
to rootfs \\\"/var/lib/docker/overlay2/f49a0ae0ec6646c818dcf05dbcbbdd79fc7c42561f3684fbb1fc5d2b9d3ad192/merged\\\"
at \\\"/var/lib/docker/overlay2/f49a0ae0ec6646c818dcf05dbcbbdd79fc7c42561f3684fbb1fc5d2b9d3ad192/merged/usr/share/nginx/html\\\"
caused \\\"not a directory\\\"\"": unknown
```

With this patch applied:

```
container_linux.go:348: starting container process caused: process_linux.go:438:
container init caused: rootfs_linux.go:58: mounting "/foo.txt"
to rootfs "/var/lib/docker/overlay2/de506d67da606b807009e23b548fec60d72359c77eec88785d8c7ecd54a6e4b2/merged"
at "/var/lib/docker/overlay2/de506d67da606b807009e23b548fec60d72359c77eec88785d8c7ecd54a6e4b2/merged/usr/share/nginx/html"
caused: not a directory: unknown
```

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

The error message was including both the rootfs path, and the full
mount path, which also includes the path of the rootfs.

This patch removes the rootfs path from the error message, as it
was redundant, and made the error message overly verbose

Before this patch (errors wrapped for readability):

```
container_linux.go:348: starting container process caused: process_linux.go:438:
container init caused: rootfs_linux.go:58: mounting "/foo.txt"
to rootfs "/var/lib/docker/overlay2/de506d67da606b807009e23b548fec60d72359c77eec88785d8c7ecd54a6e4b2/merged"
at "/var/lib/docker/overlay2/de506d67da606b807009e23b548fec60d72359c77eec88785d8c7ecd54a6e4b2/merged/usr/share/nginx/html"
caused: not a directory: unknown
```

With this patch applied:

```
container_linux.go:348: starting container process caused: process_linux.go:438:
container init caused: rootfs_linux.go:58: mounting "/foo.txt"
to rootfs at "/var/lib/docker/overlay2/de506d67da606b807009e23b548fec60d72359c77eec88785d8c7ecd54a6e4b2/merged/usr/share/nginx/html"
caused: not a directory: unknown
```

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Improve readability of errors

Signed-off-by: Ted Yu <yuzhihong@gmail.com>

Close fd in case fd.Write() returns error

Use criu 3.14

Tested with both Podman (master) and Moby (master), on Ubuntu 19.10 .

$ podman --cgroup-manager=systemd run -it --rm --runtime=runc \
  --cgroupns=host --memory 42m --cpus 0.42 --pids-limit 42 alpine
/ # cat /proc/self/cgroup
0::/user.slice/user-1001.slice/user@1001.service/user.slice/libpod-132ff0d72245e6f13a3bbc6cdc5376886897b60ac59eaa8dea1df7ab959cbf1c.scope
/ # cat /sys/fs/cgroup/user.slice/user-1001.slice/user@1001.service/user.slice/libpod-132ff0d72245e6f13a3bbc6cdc5376886897b60ac59eaa8dea1df7ab959cbf1c.scope/memory.max
44040192
/ # cat /sys/fs/cgroup/user.slice/user-1001.slice/user@1001.service/user.slice/libpod-132ff0d72245e6f13a3bbc6cdc5376886897b60ac59eaa8dea1df7ab959cbf1c.scope/cpu.max
42000 100000
/ # cat /sys/fs/cgroup/user.slice/user-1001.slice/user@1001.service/user.slice/libpod-132ff0d72245e6f13a3bbc6cdc5376886897b60ac59eaa8dea1df7ab959cbf1c.scope/pids.max
42

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>