nbd: add nbd-client init script

Adds init.d and config files for nbd-client. Each section holds
parameters of one block device, where section name (eg. nbd0) is NBD
device name.

Signed-off-by: Marcin Jurkowski <marcin1j@gmail.com>

net/nbd/files/nbd-client.init

@@ -0,0 +1,69 @@
+#!/bin/sh /etc/rc.common
+# Copyright (C) 2015 OpenWrt.org
+
+START=90
+STOP=10
+USE_PROCD=1
+
+append_arg() {
+	local cfg="$1"
+	local var="$2"
+	local opt="$3"
+	local def="$4"
+	local val
+
+	config_get val "$cfg" "$var"
+	[ -n "$val" -o -n "$def" ] && procd_append_param command $opt "${val:-$def}"
+}
+
+append_bool() {
+	local cfg="$1"
+	local var="$2"
+	local opt="$3"
+	local def="$4"
+	local val
+
+	config_get_bool val "$cfg" "$var" "$def"
+	[ "$val" = 1 ] && procd_append_param command "$opt"
+}
+
+start_instance() {
+	local cfg="$1"
+	local enabled
+
+	config_get_bool enabled "$cfg" 'enabled' '0'
+	[ "$enabled" = 0 ] && return 1
+
+	procd_open_instance
+
+	procd_set_param command /usr/sbin/nbd-client
+
+	append_arg "$cfg" server
+	append_arg "$cfg" port
+	# device path
+	procd_append_param command "/dev/$cfg"
+	procd_append_param command -nofork
+	append_bool "$cfg" sdp "-sdp"
+	append_bool "$cfg" swap "-swap"
+	append_bool "$cfg" persist "-persist"
+	append_arg "$cfg" blocksize "-block-size"
+	append_arg "$cfg" timeout "-timeout"
+	append_arg "$cfg" exportname "-name"
+
+	procd_close_instance
+}
+
+service_triggers() {
+	procd_add_reload_trigger "nbd-client"
+}
+
+start_service() {
+	config_load nbd-client
+	config_foreach start_instance nbd-client
+}
+
+stop_service() {
+	for dev in /dev/nbd*; do
+		nbd-client -d $dev 1>/dev/null 2>&1
+	done
+}