When cgroup creation failed we reset container_cgroup to NULL to avoid
issues with __cleanup__. Fix that logic:
- add steal_ptr() based on take_ptr()
- move stealing the pointer out of the loop

lxc ctImport 20190210050705.858 DEBUG    network - network.c:instantiate_veth:202 - Instantiated veth "vethGQMH7I/vethSPXNL3", index is "272"
lxc ctImport 20190210050705.858 ERROR    cgfsng - cgroups/cgfsng.c:mkdir_eexist_on_last:1262 - File exists - Failed to create directory "/sys/fs/cgroup/unified//lxc.payload/ctImport-0"
lxc ctImport 20190210050705.858 ERROR    cgfsng - cgroups/cgfsng.c:container_create_path_for_hierarchy:1302 - Failed to create cgroup "/sys/fs/cgroup/unified//lxc.payload/ctImport-0"
lxc ctImport 20190210050705.858 ERROR    cgfsng - cgroups/cgfsng.c:cgfsng_payload_create:1431 - Failed to create cgroup "/sys/fs/cgroup/unified//lxc.payload/ctImport-0"
lxc ctImport 20190210050705.858 INFO     cgfsng - cgroups/cgfsng.c:cgfsng_payload_create:1441 - The container uses "lxc.payload/ctImport-0" as cgroup
lxc ctImport 20190210050705.858 ERROR    cgfsng - cgroups/cgfsng.c:mkdir_eexist_on_last:1262 - File exists - Failed to create directory "/sys/fs/cgroup/unified/"
lxc ctImport 20190210050705.858 ERROR    cgfsng - cgroups/cgfsng.c:container_create_path_for_hierarchy:1302 - Failed to create cgroup "/sys/fs/cgroup/unified/"
lxc ctImport 20190210050705.858 ERROR    cgfsng - cgroups/cgfsng.c:cgfsng_payload_create:1431 - Failed to create cgroup "/sys/fs/cgroup/unified/"
lxc ctImport 20190210050705.858 INFO     cgfsng - cgroups/cgfsng.c:cgfsng_payload_create:1441 - The container uses "(null)" as cgroup

Fixes: d97919ab ("cgroups: partially switch to cleanup macros")
Reported-by: Stéphane Graber <stgraber@ubuntu.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

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

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

bugfixes

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

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

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

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

cgroups: partially switch to cleanup macros

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

README: add LGTM

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

tree-wide: wipe alloca() from the codebase

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

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

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

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

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

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

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

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

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

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

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

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

Switch to a static stack instead of allocating a new one. There's really
no point in doing all of the dance to get the current pagesize.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

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

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

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

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

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

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

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

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

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

The header defines a simple wrapper for free() that can be used with
gcc's and clang's __attribute__((__cleanup__(<cleanup-fun>))) macro.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

compiler: hardening

Warn if an extern declaration is encountered within a function.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Warn when macros __TIME__, __DATE__ or __TIMESTAMP__ are encountered as
they might prevent bit-wise-identical reproducible compilations.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Warn about left shift overflows. This warning is enabled by default in
C99 and C++11 modes (and newer).

-Wshift-overflow=2
This warning level also warns about left-shifting 1 into the sign bit,
unless C++14 mode (or newer) is active.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>