Re: [Libguestfs] [p2v PATCH 09/10] rely on Linux for killing nbdkit, when the parent thread exits

So this patch unfortunately isn't correct for a few reasons: (1) Non-Linux/BSD OSes don't support a concept like --exit-with-parent. nbdkit will exit with an error if you try to use this feature on such OSes. You can test if --exit-with-parent is supported before trying to use it by: nbdkit --exit-with-parent --version which will exit with an error if the feature is not supported. However this isn't really a major issue for us. The bigger one is: (2) --exit-with-parent is not reliable. It's best thought of as a best-effort, fallback attempt to kill nbdkit. It requires that nbdkit issues a prctl(2), so any time that the parent (virt-p2v) dies before nbdkit issues the prctl, nbdkit will not get cleaned up. So I would say to implement this you'll have to: - Check if “system ("nbdkit --exit-with-parent --version")” returns 0. - If so, add the --exit-with-parent flag (otherwise, don't). - Keep the PID tracking / kill code that already exists.