[diff] usr.sbin/smtpd: fix event handling upon exit

[GILLES CHEHADE]

Hello,

Upon termination, the parent process will call parent_shutdown() which will in 
turn call mproc_clear() to properly terminate IPC with child processes.

In mproc_clear(), event_del() is called but a check is lacking to ensure 
event_add() was called prior to this.

On OpenBSD, this doesn’t seem to cause any issue but on other systems with a 
different libevent, calling event_del() without a matching event_add() either 
causes a runtime warning or a crash upon exit.

Gilles


diff --git a/usr.sbin/smtpd/mproc.c b/usr.sbin/smtpd/mproc.c
index bde229e1..dac38af2 100644
--- a/usr.sbin/smtpd/mproc.c
+++ b/usr.sbin/smtpd/mproc.c
@@ -90,7 +90,8 @@ mproc_clear(struct mproc *p)
{
        log_debug("debug: clearing p=%s, fd=%d, pid=%d", p->name, 
p->imsgbuf.fd, p->pid);

-       event_del(&p->ev);
+       if (p->events)
+               event_del(&p->ev);
        close(p->imsgbuf.fd);
        imsg_clear(&p->imsgbuf);
}