-module(portc).
-vsn(2).
-behaviour(gen_server).

-export([get_data/0]).
-export([init/1, handle_call/3, handle_info/2, code_change/3]).

-record(state, {port, data}).

get_data() -> gen_server:call(portc, get_data).

init([]) ->
    PortProg = code:priv_dir(foo) ++ "/bin/portc",
    Port = open_port({spawn, PortProg}, [binary, {packet, 2}]),
    {ok, #state{port = Port}}.

handle_call(get_data, _From, State) ->
    {reply, {ok, State#state.data}, State}.

handle_info({Port, Cmd}, State) ->
    NewState = do_cmd(Cmd, State),
    {noreply, NewState}.

code_change(_, State, change_port_only) ->
    State#state.port ! close,
    receive
	{Port, closed} -> true
    end,
    NPortProg = code:priv_dir(foo) ++ "/bin/portc",   % get new version
    NPort = open_port({spawn, NPortProg}, [binary, {packet, 2}]),
    {ok, State#state{port = NPort}};
code_change(1, State, change_erl_only) ->
    NState = transform_state(State),
    {ok, NState}.