runsc fsgofer: Support dynamic serving of filesystems.

When multiple containers run inside a sentry, each container has its own root
filesystem and set of mounts. Containers are also added after sentry boot rather
than all configured and known at boot time.

The fsgofer needs to be able to serve the root filesystem of each container.
Thus, it must be possible to add filesystems after the fsgofer has already
started.

This change:
* Creates a URPC endpoint within the gofer process that listens for requests to
  serve new content.
* Enables the sentry, when starting a new container, to add the new container's
  filesystem.
* Mounts those new filesystems at separate roots within the sentry.

PiperOrigin-RevId: 208903248
Change-Id: Ifa91ec9c8caf5f2f0a9eead83c4a57090ce92068

0 files changed, 0 insertions, 0 deletions