[Qemu-devel] [PATCH 0/2] Couple of qemu-pr-helper fixes

[Michal Privoznik]

The first one is trivial.

The second is slightly trickier. Libvirt has this virCommand subsystem
(found under src/util/vircommand.c) which it uses to spawn commands. The
subsystem allows libvirt to both daemonize a process and learn its PID.
The latter of course does not work if command daemonizes itself (hence
libvirt will not use qemu-pr-helper --daemon). BUT, we still need
qemu-pr-helper to lock the pidfile (so that when libvirt tries to lock
it it is denied). NB, libvirt uses fnctl(cmd = F_SETLK) to lock
pidfiles. So leaking locked FD into qemu-pr-helper is not an option
because that doesn't survive fork().

Another, trivial reason might be that if I run:

  qemu-pr-helper --pidfile /tmp/pr.pid

(without --daemon), I'd still expect qemu-pr-helper to write pidfile
because I told it to.

Michal Privoznik (2):
  qemu-pr-helper: Daemonize before dropping privileges
  qemu-pr-helper: Write pidfile more often

 scsi/qemu-pr-helper.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

-- 
2.16.1