On Wed, Oct 16, 2019 at 06:50:33AM -0500, Eric Blake wrote: > On 10/16/19 4:02 AM, Daniel P. Berrangé wrote: > > > > > The challenge here is that we're in between fork + execve and want signal > > handlers back to their defaults at time of execve. > > > > If we set SIGPIPE to SIG_IGN and then execve() will that get reset back > > to SIG_DFL automatically ? > > Sadly, no. execve() does not change whether a signal is ignored or masked > (ignored is more common - a number of CI systems have had issues where the > child inherits SIGPIPE ignored because the parent forgot to reset it, but > the child wasn't expecting it; but inheriting a signal masked is also a real > issue), with the lone exception of SIGCHLD. However, execve() _does_ change > a signal that is being caught in the parent into SIG_DFL post-exec. > > That does mean, however, that it is viable to install a no-op SIGPIPE > handler (SIGPIPE is generated but ignored, I/O gets the EPIPE as desired), > then post-exec the new process will have SIG_DFL. Yeah, that's workable. So we need virFork() to install a dummy SIGPIPE handler function that is a no-op, *before* it unmasks signals. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
