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.
-- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
