[Libguestfs] collectd leaks SIGCHLD == SIG_IGN into plugins

Peter Dimitrov and myself were debugging a very peculiar bug when libguestfs is run as a plugin from collectd: https://www.redhat.com/archives/libguestfs/2018-November/thread.html#00023 The long story short is that collectd leaks SIGCHLD == SIG_IGN setting into plugins: https://www.redhat.com/archives/libguestfs/2018-November/msg00095.html This means that any plugin that does the usual pattern of: pid = fork (); ... if (waitpid (pid, NULL, 0) == -1) { perror ("waitpid"); exit (EXIT_FAILURE); } will fail, because the forked subprocess is automatically reaped before waitpid is called, resulting in the wait failing with errno == ECHILD. It is possible to work around this by adding: signal (SIGCHLD, SIG_DFL); to the plugin. However I believe this is a bug in collectd, and it should sanitize signals (and maybe other things) before running plugins. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top