[libvirt] How does virsh lxc-enter-namespace work? Does it?

[Richard Weinberger]

Hi!

I'm facing the issue that "virsh lxc-enter-namespace ..." does not work for me.
setns() always fails with EINVAL.

Reading the code confused me a bit, maybe you can help me. :D

virsh itself calls:
cmdLxcEnterNamespace()
  virDomainLxcOpenNamespace()
   conn->driver->domainLxcOpenNamespace()

Here comes the first thing that is not clear to me.
conn->driver seems to be the remote driver and therefore
->domainLxcOpenNamespace is remoteDomainLxcOpenNamespace()
Why is lxc:/// a remote connection?

remoteDomainLxcOpenNamespace() does a rpc call to libvirtd.

On the remote side libvirtd does:

lxcDispatchDomainOpenNamespace(), which opens the namespace fds,
and sends them back as result.
How can this work? Does it somewhere magic file descriptor passing
on AF_UNIX?

virsh then receives the fd's (pure numbers) and setns() failed badly.

Wouldn't it make much more sense to do the open(/proc/XXX/ns/{mnt, user, ...}) and setns()
calls directly on the local side? IOW directly in virsh?
driver->domainLxcOpenNamespace() should only report the process id of the container's
init process.

Thanks,
//richard