laminard: ignore SIGHUP

Many daemons reload config file on SIGHUP; laminar don't have config file, so
signal is ignored (with informative message on stdout). Previously, default
handler for SIGHUP was used that terminates process.

Closes: #166

src/main.cpp

@@ -26,6 +26,7 @@
 #include <kj/async-unix.h>
 #include <kj/filesystem.h>
 #include <signal.h>
+#include <unistd.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 
@@ -53,6 +54,13 @@ static void usage(std::ostream& out) {
     out << "  -v              enable verbose output\n";
 }
 
+static void on_sighup(int)
+{
+	constexpr const char msg[] = "Laminar received and ignored SIGHUP\n";
+	// write(2) is safe to call inside signal handler.
+	write(STDERR_FILENO, msg, sizeof(msg) - 1);
+}
+
 int main(int argc, char** argv) {
     if(argv[0][0] == '{')
         return leader_main();
@@ -92,6 +100,7 @@ int main(int argc, char** argv) {
 
     signal(SIGINT, &laminar_quit);
     signal(SIGTERM, &laminar_quit);
+    signal(SIGHUP, &on_sighup);
 
     printf("laminard version %s started\n", laminar_version());