Signed-off-by: John Howard <jhoward@microsoft.com>
Also fixes https://github.com/moby/moby/issues/22874
This commit is a pre-requisite to moving moby/moby on Windows to using
Containerd for its runtime.
The reason for this is that the interface between moby and containerd
for the runtime is an OCI spec which must be unambigious.
It is the responsibility of the runtime (runhcs in the case of
containerd on Windows) to ensure that arguments are escaped prior
to calling into HCS and onwards to the Win32 CreateProcess call.
Previously, the builder was always escaping arguments which has
led to several bugs in moby. Because the local runtime in
libcontainerd had context of whether or not arguments were escaped,
it was possible to hack around in daemon/oci_windows.go with
knowledge of the context of the call (from builder or not).
With a remote runtime, this is not possible as there's rightly
no context of the caller passed across in the OCI spec. Put another
way, as I put above, the OCI spec must be unambigious.
The other previous limitation (which leads to various subtle bugs)
is that moby is coded entirely from a Linux-centric point of view.
Unfortunately, Windows != Linux. Windows CreateProcess uses a
command line, not an array of arguments. And it has very specific
rules about how to escape a command line. Some interesting reading
links about this are:
https://blogs.msdn.microsoft.com/twistylittlepassagesallalike/2011/04/23/everyone-quotes-command-line-arguments-the-wrong-way/https://stackoverflow.com/questions/31838469/how-do-i-convert-argv-to-lpcommandline-parameter-of-createprocesshttps://docs.microsoft.com/en-us/cpp/cpp/parsing-cpp-command-line-arguments?view=vs-2017
For this reason, the OCI spec has recently been updated to cater
for more natural syntax by including a CommandLine option in
Process.
What does this commit do?
Primary objective is to ensure that the built OCI spec is unambigious.
It changes the builder so that `ArgsEscaped` as commited in a
layer is only controlled by the use of CMD or ENTRYPOINT.
Subsequently, when calling in to create a container from the builder,
if follows a different path to both `docker run` and `docker create`
using the added `ContainerCreateIgnoreImagesArgsEscaped`. This allows
a RUN from the builder to control how to escape in the OCI spec.
It changes the builder so that when shell form is used for RUN,
CMD or ENTRYPOINT, it builds (for WCOW) a more natural command line
using the original as put by the user in the dockerfile, not
the parsed version as a set of args which loses fidelity.
This command line is put into args[0] and `ArgsEscaped` is set
to true for CMD or ENTRYPOINT. A RUN statement does not commit
`ArgsEscaped` to the commited layer regardless or whether shell
or exec form were used.
