Apply commit e0e6958aa074a7714cd7c4aa779a1dfede3a03b1 from upstream.

- Avoid deadlock when activating signals.  Fixes bug 3048812.
  Based on patch by Nicholas Marriott.
The deadlock was ultimately fixed in a different way (by disabling
reinit - see event.c r1.25).  Add it now for consistency but without
the Windows compatibility code.  Convert the fnctl() calls to
SOCK_CLOEXEC | SOCK_NONBLOCK to simplify the code.
OK nicm@

diff --git a/lib/libevent/signal.c b/lib/libevent/signal.c
index c87e6c9..b2091d6 100644 (file)
--- a/lib/libevent/signal.c
+++ b/lib/libevent/signal.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: signal.c,v 1.24 2014/10/30 16:45:37 bluhm Exp $       */
+/*     $OpenBSD: signal.c,v 1.25 2015/01/06 11:42:37 bluhm Exp $       */
 
 /*
  * Copyright 2000-2002 Niels Provos <provos@citi.umich.edu>
@@ -58,30 +58,28 @@ evsignal_cb(int fd, short what, void *arg)
        ssize_t n;
 
        n = recv(fd, signals, sizeof(signals), 0);
-       if (n == -1)
-               event_err(1, "%s: read", __func__);
+       if (n == -1) {
+               if (errno != EAGAIN)
+                       event_err(1, "%s: read", __func__);
+       }
 }
 
 int
 evsignal_init(struct event_base *base)
 {
-       int i, flags;
+       int i;
 
        /*
         * Our signal handler is going to write to one end of the socket
         * pair to wake up our event loop.  The event loop then scans for
         * signals that got delivered.
         */
-       if (socketpair(
-                   AF_UNIX, SOCK_STREAM, 0, base->sig.ev_signal_pair) == -1) {
+       if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
+           0, base->sig.ev_signal_pair) == -1) {
                event_err(1, "%s: socketpair", __func__);
                return -1;
        }
 
-       if (fcntl(base->sig.ev_signal_pair[0], F_SETFD, FD_CLOEXEC) == -1)
-               event_warn("fcntl(signal_pair[0], FD_CLOEXEC)");
-       if (fcntl(base->sig.ev_signal_pair[1], F_SETFD, FD_CLOEXEC) == -1)
-               event_warn("fcntl(signal_pair[1], FD_CLOEXEC)");
        base->sig.sh_old = NULL;
        base->sig.sh_old_max = 0;
        base->sig.evsignal_caught = 0;
@@ -90,10 +88,6 @@ evsignal_init(struct event_base *base)
        for (i = 0; i < NSIG; ++i)
                TAILQ_INIT(&base->sig.evsigevents[i]);
 
-       if ((flags = fcntl(base->sig.ev_signal_pair[0], F_GETFL, NULL)) == -1 ||
-           fcntl(base->sig.ev_signal_pair[0], F_SETFL, flags|O_NONBLOCK) == -1)
-               event_warn("fcntl(signal_pair[0], O_NONBLOCK)");
-
        event_set(&base->sig.ev_signal, base->sig.ev_signal_pair[1],
                EV_READ | EV_PERSIST, evsignal_cb, &base->sig.ev_signal);
        base->sig.ev_signal.ev_base = base;