More signal handling fixes

1 files changed, 20 insertions, 17 deletions

diff --git a/src/poll.c b/src/poll.c
index f05a345..a74d249 100644
--- a/src/poll.c
+++ b/src/poll.c
@@ -133,23 +133,19 @@ void fastd_poll_handle(void) {
 	if (timeout < 0 || timeout > maintenance_timeout)
 		timeout = maintenance_timeout;
 
-	sigset_t set, oldset;
+	sigset_t set;
 	sigemptyset(&set);
-	pthread_sigmask(SIG_SETMASK, &set, &oldset);
 
 	struct epoll_event events[16];
-	int ret = epoll_wait(ctx.epoll_fd, events, 16, timeout);
-	if (ret < 0) {
-		if (errno == EINTR)
-			return;
-
+	int ret = epoll_pwait(ctx.epoll_fd, events, 16, timeout, &set);
+	if (ret < 0 && errno != EINTR)
 		exit_errno("epoll_wait");
-	}
-
-	pthread_sigmask(SIG_SETMASK, &oldset, NULL);
 
 	fastd_update_time();
 
+	if (ret < 0)
+		return;
+
 	size_t i;
 	for (i = 0; i < (size_t)ret; i++) {
 		if (events[i].data.ptr == &ctx.tunfd) {
@@ -257,18 +253,25 @@ void fastd_poll_handle(void) {
 	sigemptyset(&set);
 	pthread_sigmask(SIG_SETMASK, &set, &oldset);
 
-	int ret = poll(VECTOR_DATA(ctx.pollfds), VECTOR_LEN(ctx.pollfds), timeout);
-	if (ret < 0) {
-		if (errno == EINTR)
-			return;
-
-		exit_errno("poll");
+	int ret = -1;
+
+	if (!fastd_signalled()) {
+		/*
+		  There is a race condition here: if a signal occurs after the fastd_signalled() check, but before the poll
+		  call, poll() will be called with its normal timeout, potentially delaying the actual signal handling. On
+		  OpenBSD we could use ppoll() to fix this, but on FreeBSD we're out of luck.
+		 */
+		ret = poll(VECTOR_DATA(ctx.pollfds), VECTOR_LEN(ctx.pollfds), timeout);
+		if (ret < 0 && errno != EINTR)
+			exit_errno("poll");
 	}
 
 	pthread_sigmask(SIG_SETMASK, &oldset, NULL);
-
 	fastd_update_time();
 
+	if (ret < 0)
+		return;
+
 	if (VECTOR_INDEX(ctx.pollfds, 0).revents & POLLIN)
 		fastd_tuntap_handle();
 	if (VECTOR_INDEX(ctx.pollfds, 1).revents & POLLIN)