Currently the coding style guide does not mention that we use kernel
coding style as a base style for LXC.  We have just linked to
CODING_STLYE.md from CONTRIBUTING (which mentions use of kernel coding
style).  We can increase documentation congruence and completeness by
mentioning kernel coding style guide in the introduction to our style
guide.

Add heading and introduction to coding style guide informing readers
that we follow kernel coding style as a base before explaining our style
additions.
Signed-off-by: Tobin C. Harding <me@tobin.cc>

Currently the 'Coding Style' section mentions only the kernel coding
style.  We have additions on top on this outlined in CODING_STYLE.md.
We should direct readers to this document as well as the kernel docs.

Direct readers to CODING_STLYE.md in the 'Coding Style' section.
Signed-off-by: Tobin C. Harding <me@tobin.cc>

Currently we link to a URL for v4.10 of the kernel docs.  Since we
already mention the kernel tree we should link to the _latest_ kernel
docs online instead of a fixed past version.

Link to latest online kernel docs tracking the mainline instead of past
fixed version.
Signed-off-by: Tobin C. Harding <me@tobin.cc>

Kernel coding style guide filename is stale, this file has been renamed
in the kernel tree.  While this file still exists we should use the new
filename.

Update reference to kernel coding style guide to use the new file name.
Signed-off-by: Tobin C. Harding <me@tobin.cc>

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

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

Add a thread-safe and uniform way to retrieve errno values in programs that are
shipped as part of LXC but are not expected to have access to the logging
system.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Add a thread-safe and uniform way to retrieve errno values in programs that are
shipped as part of LXC but are not expected to have access to the logging
system.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

checkpatch.pl emits error

    ERROR: do not use assignment in if condition

Move assignment out of if statement.
Signed-off-by: Tobin C. Harding <me@tobin.cc>

checkpatch.pl emits a bunch of warnings about various whitespace
issues.  Fix all these as a single patch since they are all whitespace
only changes.

Fix whitespace issues found by checkpatch.pl
Signed-off-by: Tobin C. Harding <me@tobin.cc>

checkpatch.pl emits error

    ERROR: do not initialise statics to 0

Do not initialise statics to 0.
Signed-off-by: Tobin C. Harding <me@tobin.cc>

checkpatch.pl emits error

    ERROR: do not use assignment in if condition

Correctly indent switch statement.
Signed-off-by: Tobin C. Harding <me@tobin.cc>

Currently if lxc-usernsexec is run on a kernel without user namespaces
enabled the error message is

	unshare: Invalid argument
	read pipe: Success

This error message 'Invalid argument' does not point at the root cause
of the error.  We can help the user out by giving a more detailed error
message and also not using perror() if errno==0.

Improve error message by
 - Printing unshare flags
 - Printing suggested cause of failure (user namespace not enabled)
 - Print error message with fprintf() if errno==0 (EOF)
Signed-off-by: Tobin C. Harding <me@tobin.cc>

Current we have a few minor grammatical errors in the documentation for
lxc container configuration.

Fix minor grammatical errors.
Signed-off-by: Tobin C. Harding <me@tobin.cc>

sleep() is not thread-safe but nanosleep() is. Since no resources are allocated
in lxc_wait() it is safe to call nanosleep() without cancellation handlers.
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>

When we check whether an open file description lock has been taken on a file we
need to set the l_pid field to 0 otherwise the kernel will send back EINVAL.
Additionally, the kernel will not do pid translation and simply set the l_pid
value to -1.

Fixes https://discuss.linuxcontainers.org/t/container-deleted-or-stopped-when-lxc-ls-executed-concurrently/2439Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Dereference before null check
Signed-off-by: 2xsec <dh48.jeong@samsung.com>

Signed-off-by: 2xsec <dh48.jeong@samsung.com>

Signed-off-by: 2xsec <dh48.jeong@samsung.com>

These allow to pass a struct nlmsghdr directly and are used in the higher level
netlink_{send,rcv,transaction}.
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: 2xsec <dh48.jeong@samsung.com>

Signed-off-by: 2xsec <dh48.jeong@samsung.com>

Signed-off-by: 2xsec <dh48.jeong@samsung.com>

The kernel expects a __s32 for NETNSA_NSID and a __u32 for NETNSA_FD.
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>

Start to allocate a new network namespace id for each container.

Relates to https://github.com/lxc/lxd/issues/4831.
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>

Closes #2512.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Failure to restore non-local value
Signed-off-by: 2xsec <dh48.jeong@samsung.com>

Signed-off-by: 2xsec <dh48.jeong@samsung.com>

Dereference after null check
Signed-off-by: 2xsec <dh48.jeong@samsung.com>