From fe74caa85e57c8bc1e545a9b02f881edc5db1ee0 Mon Sep 17 00:00:00 2001
From: SukkoPera <software@sukkology.net>
Date: Fri, 14 Nov 2014 00:15:43 +0100
Subject: [PATCH] Try to autodetect systemd and only use it if present.

---
 Makefile       | 10 ++++++++--
 dbus-session.c |  4 ++++
 lightum.c      | 12 ++++++++++++
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index e668c32..94b5555 100644
--- a/Makefile
+++ b/Makefile
@@ -2,11 +2,17 @@ DESTDIR?=/
 SHELL = /bin/sh
 CC?=gcc
 CDEBUGFLAGS= -g -O2
-CFLAGS = `pkg-config --cflags dbus-1 --cflags glib-2.0 --cflags gio-2.0 --cflags libsystemd-login` -Wall -Wextra -Wwrite-strings $(CDEBUGFLAGS)
-LDFLAGS= `pkg-config --libs dbus-1 --libs glib-2.0 --libs gio-2.0 --libs libsystemd-login` $(CDEBUGFLAGS) -lX11 -lXext -lXss -lm
+CFLAGS = `pkg-config --cflags dbus-1 --cflags glib-2.0 --cflags gio-2.0` -Wall -Wextra -Wwrite-strings $(CDEBUGFLAGS)
+LDFLAGS= `pkg-config --libs dbus-1 --libs glib-2.0 --libs gio-2.0` $(CDEBUGFLAGS) -lX11 -lXext -lXss -lm
 INSTALL = /usr/bin/install -c
 INSTALLDATA = /usr/bin/install -c -m 644
 
+SYSTEMD_FOUND := $(shell pkg-config --exists libsystemd-login; echo $$?)
+ifeq ($(SYSTEMD_FOUND),0)
+	CFLAGS += `pkg-config --cflags libsystemd-login` -DHAVE_SYSTEMD
+	LDFLAGS += `pkg-config --libs libsystemd-login`
+endif
+
 srcdir = .
 prefix = $(DESTDIR)
 bindir = $(prefix)/usr/bin
diff --git a/dbus-session.c b/dbus-session.c
index b64df0a..0ffa9a0 100644
--- a/dbus-session.c
+++ b/dbus-session.c
@@ -12,6 +12,8 @@
  *
  */
 
+#ifdef HAVE_SYSTEMD
+
 #include <stdlib.h>
 #include <gio/gio.h>
 #include <systemd/sd-login.h>
@@ -144,3 +146,5 @@ GDBusConnection* get_dbus_connection()
 
 	return connection;
 }
+
+#endif
diff --git a/lightum.c b/lightum.c
index 36efc65..fb78af7 100644
--- a/lightum.c
+++ b/lightum.c
@@ -46,7 +46,9 @@ void usage(const char *error) {
 	fprintf(stderr, "     -x        : manual mode (will honor the brightness value set with Fn keys)\n");
 	fprintf(stderr, "     -l        : fully dim the screen backlight when session is idle\n");
 	fprintf(stderr, "     -u        : do not ignore brightness changes happening outside lightum\n");
+#ifdef HAVE_SYSTEMD
 	fprintf(stderr, "     -U        : ignore session information from systemd\n");
+#endif
 	fprintf(stderr, "     -s        : power off keyboard light when screen saver is active\n");
 	fprintf(stderr, "     -f        : run in foreground (do not daemonize)\n");
 	fprintf(stderr, "     -v        : verbose mode, useful for debugging with -f and -d\n");
@@ -80,9 +82,11 @@ int main(int argc, char *argv[]) {
 	pid_t pid;
 	conf_data conf;
 	Display *display = NULL;
+#ifdef HAVE_SYSTEMD
     GDBusConnection *connection;
     GDBusProxy *proxy_manager;
     GDBusProxy *proxy_session;
+#endif
 	uid_t uid, euid;
 	int light_aux=-1, light_avg=-1;
 	int lightvalues[15] = {0};
@@ -112,9 +116,11 @@ int main(int argc, char *argv[]) {
 			case 'u':
 				conf.ignoreuser=0;
 				break;
+#ifdef HAVE_SYSTEMD
 			case 'U':
 				conf.ignoresession=1;
 				break;
+#endif
 			case 'l':
 				conf.fulldim=1;
 				break;
@@ -162,7 +168,9 @@ int main(int argc, char *argv[]) {
 
 	if (verbose) printf("CONFIG:\n\tmanualmode: %d\n",conf.manualmode);
 	if (verbose) printf("\tignoreuser: %d\n",conf.ignoreuser);
+#ifdef HAVE_SYSTEMD
 	if (verbose) printf("\tignoresession: %d\n",conf.ignoresession);
+#endif
 	if (verbose) printf("\tworkmode: %d\n",conf.workmode);
 	if (verbose) printf("\tqueryscreensaver: %d\n",conf.queryscreensaver);
 	if (verbose) printf("\tmaxbrightness: %d\n",conf.maxbrightness);
@@ -246,6 +254,7 @@ int main(int argc, char *argv[]) {
 
 	signal_installer();
 
+#ifdef HAVE_SYSTEMD
 	connection = 0;
 	proxy_manager = 0;
 	proxy_session = 0;
@@ -254,6 +263,7 @@ int main(int argc, char *argv[]) {
 		proxy_manager = get_dbus_proxy_manager(connection);
 		proxy_session = get_dbus_proxy_session(connection, proxy_manager);
 	}
+#endif
 
 	// initialize the light values array
 	if (!conf.manualmode) {
@@ -275,6 +285,7 @@ int main(int argc, char *argv[]) {
 			reloadconfig=0;
 		}
 
+#ifdef HAVE_SYSTEMD
 		if (!conf.ignoresession) {
 			if (! get_session_active(proxy_session) ) {
 				if (verbose) printf("lightum: user session not active, sleeping %d milliseconds.\nIf you believe this is an error, try running lightum with 'ignoresession=1' or '-U' command line switch.\n", conf.polltime);
@@ -282,6 +293,7 @@ int main(int argc, char *argv[]) {
 				continue;
 			}
 		}
+#endif
 
 		if (!conf.manualmode) {
 			light=get_light_sensor_value();