From b455826db2e64fb0e48e763939c1278f5d89f6a7 Mon Sep 17 00:00:00 2001
From: Ian Gulliver <flamingcow@gmail.com>
Date: Tue, 8 Mar 2016 23:04:20 -0800
Subject: [PATCH] Switch to signalfd for SIGHUP

---
 adsbus/adsbus.c |  4 +++-
 adsbus/log.c    | 34 ++++++++++++++++------------------
 adsbus/log.h    |  3 ++-
 3 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/adsbus/adsbus.c b/adsbus/adsbus.c
index d50207f..a7b1960 100644
--- a/adsbus/adsbus.c
+++ b/adsbus/adsbus.c
@@ -58,7 +58,7 @@ int main(int argc, char *argv[]) {
 	wakeup_init();
 	peer_init();
 
-	log_init2();
+	log_init_peer();
 
 	receive_init();
 	send_init();
@@ -96,6 +96,8 @@ int main(int argc, char *argv[]) {
 	rand_cleanup();
 	wakeup_cleanup();
 
+	log_cleanup_peer();
+
 	peer_cleanup();
 
 	log_cleanup();
diff --git a/adsbus/log.c b/adsbus/log.c
index 40fb95a..279cf7b 100644
--- a/adsbus/log.c
+++ b/adsbus/log.c
@@ -6,6 +6,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/signalfd.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -22,7 +23,6 @@
 static FILE *log_stream = NULL;
 static char *log_path = NULL;
 static uint8_t log_id[UUID_LEN];
-static int log_rotate_fd;
 static struct peer log_rotate_peer;
 static bool log_timestamps = false;
 static opts_group log_opts;
@@ -31,7 +31,7 @@ static char log_module = 'L';
 
 static void log_rotate() {
 	if (!log_path) {
-		LOG(log_id, "Received SIGHUP but logging to stderr; ignoring");
+		LOG(log_id, "Asked to rotate logs but not logging to a file; ignoring");
 		return;
 	}
 
@@ -48,16 +48,12 @@ static void log_rotate() {
 }
 
 static void log_rotate_handler(struct peer *peer) {
-	char buf[1];
-	assert(read(peer->fd, buf, 1) == 1);
-	assert(buf[0] == 'L');
+	struct signalfd_siginfo siginfo;
+	assert(read(peer->fd, &siginfo, sizeof(siginfo)) == sizeof(siginfo));
+	LOG(log_id, "Received signal %u; rotating logs", siginfo.ssi_signo);
 	log_rotate();
 }
 
-static void log_rotate_signal(int __attribute__ ((unused)) signum) {
-	assert(write(log_rotate_fd, "L", 1) == 1);
-}
-
 static bool log_set_path(const char *path) {
 	if (log_path) {
 		return false;
@@ -93,23 +89,25 @@ void log_init() {
 	LOG(log_id, "Log start");
 }
 
-void log_init2() {
-	int rotate_fds[2];
-	assert(!socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, rotate_fds));
-	log_rotate_peer.fd = rotate_fds[0];
-	assert(!shutdown(log_rotate_peer.fd, SHUT_WR));
+void log_init_peer() {
+	sigset_t sigmask;
+	assert(!sigemptyset(&sigmask));
+	assert(!sigaddset(&sigmask, SIGHUP));
+	log_rotate_peer.fd = signalfd(-1, &sigmask, SFD_NONBLOCK | SFD_CLOEXEC);
+	assert(log_rotate_peer.fd >= 0);
 	log_rotate_peer.event_handler = log_rotate_handler;
 	peer_epoll_add(&log_rotate_peer, EPOLLIN);
 
-	log_rotate_fd = rotate_fds[1];
-	signal(SIGHUP, log_rotate_signal);
+	assert(!sigprocmask(SIG_BLOCK, &sigmask, NULL));
+}
+
+void log_cleanup_peer() {
+	peer_close(&log_rotate_peer);
 }
 
 void log_cleanup() {
 	LOG(log_id, "Log end");
 	assert(!fclose(log_stream));
-	assert(!close(log_rotate_fd));
-	assert(!close(log_rotate_peer.fd));
 	if (log_path) {
 		free(log_path);
 		log_path = NULL;
diff --git a/adsbus/log.h b/adsbus/log.h
index 34f2778..6494eb6 100644
--- a/adsbus/log.h
+++ b/adsbus/log.h
@@ -9,7 +9,8 @@
 
 void log_opts_add(void);
 void log_init(void);
-void log_init2(void);
 void log_cleanup(void);
+void log_init_peer(void);
+void log_cleanup_peer(void);
 void log_write(char, const char *, const uint8_t *, const char *, ...)
 		__attribute__ ((__format__ (__printf__, 4, 5)));