Merge - deprecated daemon() call

Reimplementing the daemon() call for OSX targets and to support older
setups. Daemonization today is deprecated altogether since the init
system (systemd,rc,upstart,...) should take care of process
daemonization themselves. This just mutes the warning.

src/knot/main.c

@@ -53,6 +53,59 @@ static void init_signal_started(void)
 #endif
 }
 
+static int make_daemon(int nochdir, int noclose)
+{
+	int fd, ret;
+
+	switch (fork()) {
+	case -1:
+		/* Error */
+		return -1;
+	case 0:
+		/* Forked */
+		break;
+	default:
+		/* Exit the main process */
+		_exit(0);
+	}
+
+	if (setsid() == -1) {
+		return -1;
+	}
+
+	if (!nochdir) {
+		ret = chdir("/");
+		if (ret == -1)
+			return errno;
+	}
+
+	if (!noclose) {
+		ret  = close(STDIN_FILENO);
+		ret += close(STDOUT_FILENO);
+		ret += close(STDERR_FILENO);
+		if (ret < 0) {
+			return errno;
+		}
+
+		fd = open("/dev/null", O_RDWR);
+		if (fd == -1) {
+			return errno;
+		}
+
+		if (dup2(fd, STDIN_FILENO) < 0) {
+			return errno;
+		}
+		if (dup2(fd, STDOUT_FILENO) < 0) {
+			return errno;
+		}
+		if (dup2(fd, STDERR_FILENO) < 0) {
+			return errno;
+		}
+	}
+
+	return 0;
+}
+
 /*! \brief PID file cleanup handler. */
 static void pid_cleanup(char *pidfile)
 {
@@ -256,7 +309,7 @@ int main(int argc, char **argv)
 
 	/* Now check if we want to daemonize. */
 	if (daemonize) {
-		if (daemon(1, 0) != 0) {
+		if (make_daemon(1, 0) != 0) {
 			fprintf(stderr, "Daemonization failed, shutting down...\n");
 			return EXIT_FAILURE;
 		}