Re: [PATCH] kvmtool: don't rely on $HOME

[Will Deacon <will.deacon@arm.com>]

On Thu, Sep 17, 2015 at 03:03:15PM +0100, Alban Crequy wrote:
> kvm__set_dir() called in main() and kvm__get_dir() rely on $HOME. But in
> some environments (such as starting lkvm through systemd-run), $HOME is
> undefined. This causes bind() to use a socket path containing "(null)"
> and this fails. The current code does not check errors returned by
> realpath().
> 
> Symptoms:
> 
> | bind: No such file or directory
> |   Error: Failed adding socket to epoll
> |  Warning: Failed init: kvm_ipc__init
> |
> |  Fatal: Initialisation failed
> 
> This bug was first reported on https://github.com/coreos/rkt/issues/1393
> 
> Instead of using "$HOME/.lkvm/" (i.e. "/root/.lkvm/"), this patch uses
> "/var/lib/lkvm/". This also improve the error reporting by printing the
> socket filename.

Hmm, but that requires lkvm to be run with sufficient privileges to
write to /var/lib, which I don't think is generally the case. I think we
have a few options:

  (1) Try /var/lib/lkvm if $HOME is NULL
  (2) Use an alternative environment variable for the pid prefix
  (3) Add a --pid command line option for the pidfile
  (4) ???

Any preferences? What do other projects do?

Will