p910nd: Fix init script and make use use append_bool() and appand_string() functions

git-svn-id: svn://svn.openwrt.org/openwrt/packages@9179 3c298f89-4303-0410-b956-a3cf2f4a3e73

net/p910nd/files/p910nd.conf

@@ -2,3 +2,4 @@ config p910nd
 	option device        "/dev/usb/lp0"
 	option port          0
 	option bidirectional 1
+	option enabled       0

net/p910nd/files/p910nd.init

@@ -2,21 +2,33 @@
 # Copyright (C) 2007 OpenWrt.org
 START=50
 
-BIN=p910nd
+append_bool() {
+	local section="$1"
+	local option="$2"
+	local value="$3"
+	local _val
+	config_get_bool _val "$section" "$option" '0'
+	[ "$_val" -gt 0 ] && append args "$3"
+}
+
+append_string() {
+	local section="$1"
+	local option="$2"
+	local value="$3"
+	local _val
+	config_get _val "$section" "$option"
+	[ -n "$_val" ] && append args "$3$_val"
+}
 
 start_service() {
 	local section="$1"
-	config_get      port          "$section" port
-	config_get      device        "$section" device
-	config_get_bool bidirectional "$section" bidirectional
+	args=""
 
-	options=""
-	[ $bidirectional -eq 1 ] && {
-		options="$options -b"
-	}
-	options="$options -f $device $port"
-
-	$BIN $options
+	append_bool "$section" bidirectional "-b"
+	append_string "$section" device "-f "
+	append_string "$section" port ""
+	config_get_bool "enabled" "$section" "enabled" '1'
+	[ "$enabled" -gt 0 ] && /usr/sbin/p910nd $args
 }
 
 stop_service() {