Add systemd .service file for redshift

Add a systemd user .service file to allow users to run redshift as a
daemon using systemd. Also adds a new configure option,
`--with-systemduserunitdir`, which gives the install path.

If set to `no`, systemd support is disabled.
If not set, we use `pkg-config` to find the path.

HACKING

@@ -8,9 +8,17 @@ The bootstrap script will use autotools to set up the build environment
 and create the `configure` script.
 
 Use `./configure --help' for options. Use `--prefix' to make an install in
-your home directory. This is necessary to test python scripts. Example:
+your home directory. This is necessary to test python scripts. The systemd
+user unit directory should be set to avoid writing to the system location.
 
- $ ./configure --prefix=$HOME/redshift/root
+Systemd will look for the unit files in `~/.config/systemd/user` so this
+directory can be used as a target if the unit files will be used. Otherwise
+the location can be set to `no` to disable the systemd files.
+
+Example:
+
+ $ ./configure --prefix=$HOME/redshift/root \
+   --with-systemduserunitdir=$HOME/.config/systemd/user
 
 Now, build the files:
 

Makefile.am

@@ -2,6 +2,10 @@
 SUBDIRS = src po
 ACLOCAL_AMFLAGS = -I m4
 
+# Install systemd user unit files locally for distcheck
+DISTCHECK_CONFIGURE_FLAGS = \
+	--with-systemduserunitdir=$$dc_install_base/$(systemduserunitdir)
+
 UPDATE_ICON_CACHE = gtk-update-icon-cache -f -t $(datadir)/icons/hicolor || :
 
 EXTRA_ROOTDOC_FILES = \
@@ -25,6 +29,9 @@ _UBUNTU_MONO_LIGHT_FILES = \
 _DESKTOP_FILES = \
 	data/applications/redshift-gtk.desktop
 
+SYSTEMD_USER_UNIT_IN_FILES = \
+	data/systemd/redshift.service.in
+
 
 # Icons
 if ENABLE_GUI
@@ -55,15 +62,32 @@ uninstall-hook:
 	$(UPDATE_ICON_CACHE);
 endif
 
+
 # man page
 dist_man1_MANS = redshift.1
 
+
+# Systemd service files
+if ENABLE_SYSTEMD
+systemduserunit_DATA = $(SYSTEMD_USER_UNIT_IN_FILES:.service.in=.service)
+endif
+
+$(systemduserunit_DATA): $(SYSTEMD_USER_UNIT_IN_FILES) Makefile
+	$(AM_V_GEN)$(MKDIR_P) $(@D) && \
+		sed -e "s|\@bindir\@|$(bindir)|g" $< > $@
+
+
+
 EXTRA_DIST = \
 	$(EXTRA_ROOTDOC_FILES) \
 	$(_HICOLOR_FILES) \
 	$(_UBUNTU_MONO_DARK_FILES) \
 	$(_UBUNTU_MONO_LIGHT_FILES) \
-	$(_DESKTOP_FILES)
+	$(_DESKTOP_FILES) \
+	$(SYSTEMD_USER_UNIT_IN_FILES)
+
+CLEANFILES = $(systemduserunit_DATA)
+
 
 # Update PO translations
 .PHONY: update-po

configure.ac

@@ -161,6 +161,25 @@ AS_IF([test "x$enable_ubuntu" != xno], [
 ])
 AM_CONDITIONAL([ENABLE_UBUNTU], [test "x$enable_ubuntu" != xno])
 
+
+# Check for systemd
+PKG_PROG_PKG_CONFIG
+AC_MSG_CHECKING([Directory to install systemd user unit files])
+AC_ARG_WITH([systemduserunitdir],
+            [AS_HELP_STRING([--with-systemduserunitdir=<dir>],
+                            [Directory for systemd user unit files])],
+            [], [with_systemduserunitdir=$($PKG_CONFIG --variable=systemduserunitdir systemd)])
+AS_IF([test -n "$with_systemduserunitdir" -a "x$with_systemduserunitdir" != xno], [
+	AC_SUBST([systemduserunitdir], [$with_systemduserunitdir])
+	AC_MSG_RESULT([$systemduserunitdir])
+	enable_systemd=yes
+], [
+	AC_MSG_RESULT([not enabled])
+	enable_systemd=no
+])
+AM_CONDITIONAL([ENABLE_SYSTEMD], [test "x$enable_systemd" != xno])
+
+
 # Checks for header files.
 AC_CHECK_HEADERS([locale.h stdint.h stdlib.h string.h unistd.h signal.h])
 
@@ -200,4 +219,5 @@ echo "
 
     GUI:		${enable_gui}
     Ubuntu icons:	${enable_ubuntu}
+    systemd units:	${enable_systemd} ${systemduserunitdir}
 "

data/systemd/redshift.service.in

@@ -0,0 +1,11 @@
+[Unit]
+Description=Redshift display colour temperature adjustment
+Documentation=http://jonls.dk/redshift/
+After=display-manager.service
+
+[Service]
+ExecStart=@bindir@/redshift
+Restart=always
+
+[Install]
+WantedBy=default.target