On Mon, Jun 22, 2015 at 04:40:37PM +0200, Richard Weinberger wrote:
Hi!
Why is libvirt-lxc issuing a setsid() in lxcContainerSetupFDs()? To me it seems like a hack to have a controlling TTY if PID 1 is /bin/bash.
I honestly can't remember the reason. It might have been to ensure we have separation from the libvirt_lxc session.
If one runs a sysv init style distro (like Debian) in libvirt-lxc the setsid() has a major downside, when getty spawns a login shell on /dev/tty1 it cannot become the controlling tty. Hence, if one presses ctrl-c in such a session, the container will reboot.
Is that problem due to the fact we call setsid(), or due to use calling ioctl(TIOCSCTTY) ?
Interestingly it does not happen when a systemd distro is used. Maybe because systemd completely closes and reopens the TTY?
I have a feeling it does close & reopen the tty, but i dunno if that has an impact on the ability to set the controlling tty ? Also note systemd uses the device via /dev/console, not /dev/tty1 and with 'container_ttys' we've told it not to use /dev/tty1 for gettys. So maybe it deals with /dev/console in a different way than it would if it were /dev/tty1 Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|