sane-backends: add systemd support

The content of the saned.socket and saned@.service files is based on the
instructions of the sane-backends manual.

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Reviewed-by: "Maxime Hadjinlian" <maxime.hadjinlian@gmail.com>
Tested-by: "Maxime Hadjinlian" <maxime.hadjinlian@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/sane-backends/sane-backends.mk

@@ -14,6 +14,13 @@ SANE_BACKENDS_INSTALL_STAGING = YES
 SANE_BACKENDS_CONF_OPTS = \
 	$(if $(BR2_TOOLCHAIN_HAS_THREADS),--enable-pthread,--disable-pthread)
 
+ifeq ($(BR2_INIT_SYSTEMD),y)
+SANE_BACKENDS_CONF_OPTS += --with-systemd
+SANE_BACKENDS_DEPENDENCIES += systemd
+else
+SANE_BACKENDS_CONF_OPTS += --without-systemd
+endif
+
 ifeq ($(BR2_PACKAGE_LIBUSB),y)
 SANE_BACKENDS_DEPENDENCIES += libusb
 SANE_BACKENDS_CONF_OPTS += --enable-libusb_1_0
@@ -51,4 +58,21 @@ endef
 
 SANE_BACKENDS_POST_CONFIGURE_HOOKS += SANE_BACKENDS_DISABLE_DOCS
 
+define SANE_BACKENDS_USERS
+	saned -1 saned -1 * /etc/sane.d - - Saned User
+endef
+
+define SANE_BACKENDS_INSTALL_INIT_SYSTEMD
+	$(INSTALL) -m 0644 -D package/sane-backends/saned.socket \
+		$(TARGET_DIR)/usr/lib/systemd/system/saned.socket
+	mkdir -p $(TARGET_DIR)/etc/systemd/system/socket.target.wants
+	ln -sf ../../../../usr/lib/systemd/system/saned.socket \
+		$(TARGET_DIR)/etc/systemd/system/socket.target.wants/saned.socket
+	$(INSTALL) -m 0644 -D package/sane-backends/saned@.service \
+		$(TARGET_DIR)/usr/lib/systemd/system/saned@.service
+	mkdir -p $(TARGET_DIR)/etc/systemd/system/multi-user.target.wants
+	ln -sf ../../../../usr/lib/systemd/system/saned@.service \
+		$(TARGET_DIR)/etc/systemd/system/multi-user.target.wants/saned@.service
+endef
+
 $(eval $(autotools-package))

package/sane-backends/saned.socket

@@ -0,0 +1,10 @@
+[Unit]
+Description=saned incoming socket
+
+[Socket]
+ListenStream=6566
+Accept=yes
+MaxConnections=1
+
+[Install]
+WantedBy=sockets.target

package/sane-backends/saned@.service

@@ -0,0 +1,18 @@
+[Unit]
+Description=Scanner Service
+Requires=saned.socket
+
+[Service]
+ExecStart=/usr/sbin/saned
+User=saned
+Group=saned
+StandardInput=null
+StandardOutput=syslog
+StandardError=syslog
+Environment=SANE_CONFIG_DIR=/etc/sane.d
+# If you need to debug your configuration uncomment the next line and
+# change it as appropriate to set the desired debug options
+# Environment=SANE_DEBUG_DLL=255 SANE_DEBUG_BJNP=5
+
+[Install]
+Also=saned.socket