fff-layer3: Autoconfigure layer3 Router after update

This adds a script to init.d to automatically call
the appropriate configure-layer3 commands after an upgrade,
so the configuration of the device is restored.

The changes are applied if configure-layer3 is successful.
Otherwise, they are reverted. Due to this, no additional checks for
the configuration are necessary: The configure-layer3 script
will fail if the config version is wrong or no configuration exists at all.

After executing the script destroys itself. With START=99,
the execution happens _after_ uci-defaults and configurenetwork,
and no interference is expected.

Signed-off-by: Fabian Bläse <fabian@blaese.de>
[convert to init.d, extend commit message, rebase]
Signed-off-by: Christian Dresel <freifunk@dresel.systems>

src/packages/fff/fff-layer3-config/Makefile

@@ -1,7 +1,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=fff-layer3-config
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_BUILD_DIR:=$(BUILD_DIR)/fff-layer3-config
 

src/packages/fff/fff-layer3-config/files/etc/init.d/fff-layer3-update

@@ -0,0 +1,17 @@
+#!/bin/sh /etc/rc.common
+
+START=99
+
+boot() {
+	# Reapply gateway settings, if configuration succeeds
+	if yes | configure-layer3 -c; then
+		configure-layer3 -a
+	else
+		configure-layer3 -r
+	fi
+
+	# first we disable the init.d
+	/etc/init.d/fff-layer3-update disable
+	# we must delete the symlink manually
+	rm -f /etc/rc.d/S99fff-layer3-update
+}