%%%----------------------------------------------------------------------
%%% File : uds_server.erl
%%% Purpose : Holder for the uds_drv ddll driver.
%%% Created : 15 Mar 2000
%%%----------------------------------------------------------------------
-module(uds_server).
-behaviour(gen_server).
%% External exports
-export([start_link/0]).
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
-define(DRIVER_NAME,"uds_drv").
%%%----------------------------------------------------------------------
%%% API
%%%----------------------------------------------------------------------
start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
%%%----------------------------------------------------------------------
%%% Callback functions from gen_server
%%%----------------------------------------------------------------------
%%----------------------------------------------------------------------
%% Func: init/1
%% Returns: {ok, State} |
%% {ok, State, Timeout} |
%% ignore |
%% {stop, Reason}
%%----------------------------------------------------------------------
init([]) ->
process_flag(trap_exit,true),
case load_driver() of
ok ->
{ok, []};
{error, already_loaded} ->
{ok, []};
Error ->
exit(Error)
end.
%%----------------------------------------------------------------------
%% Func: handle_call/3
%% Returns: {reply, Reply, State} |
%% {reply, Reply, State, Timeout} |
%% {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, Reply, State} | (terminate/2 is called)
%% {stop, Reason, State} (terminate/2 is called)
%%----------------------------------------------------------------------
handle_call(Request, From, State) ->
Reply = ok,
{reply, Reply, State}.
%%----------------------------------------------------------------------
%% Func: handle_cast/2
%% Returns: {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State} (terminate/2 is called)
%%----------------------------------------------------------------------
handle_cast(Msg, State) ->
{noreply, State}.
%%----------------------------------------------------------------------
%% Func: handle_info/2
%% Returns: {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State} (terminate/2 is called)
%%----------------------------------------------------------------------
handle_info(Info, State) ->
{noreply, State}.
%%----------------------------------------------------------------------
%% Func: terminate/2
%% Purpose: Shutdown the server
%% Returns: any (ignored by gen_server)
%%----------------------------------------------------------------------
terminate(Reason, State) ->
erl_ddll:unload_driver(?DRIVER_NAME),
ok.
%%----------------------------------------------------------------------
%% Func: code_change/3
%% Purpose: Convert process state when code is changed
%% Returns: {ok, NewState}
%%----------------------------------------------------------------------
code_change(OldVsn, State, Extra) ->
{ok, State}.
%%%----------------------------------------------------------------------
%%% Internal functions
%%%----------------------------------------------------------------------
%%
%% Actually load the driver.
%%
load_driver() ->
Dir = find_priv_lib(),
erl_ddll:load_driver(Dir,?DRIVER_NAME).
%%
%% As this server may be started by the distribution, it is not safe to assume
%% a working code server, neither a working file server.
%% I try to utilize the most primitive interfaces available to determine
%% the directory of the port_program.
%%
find_priv_lib() ->
PrivDir = case (catch code:priv_dir(uds_dist)) of
{'EXIT', _} ->
%% Code server probably not startet yet
{ok, P} = erl_prim_loader:get_path(),
ModuleFile = atom_to_list(?MODULE) ++ extension(),
Pd = (catch lists:foldl
(fun(X,Acc) ->
M = filename:join([X, ModuleFile]),
%% The file server probably not started
%% either, has to use raw interface.
case file:raw_read_file_info(M) of
{ok,_} ->
%% Found our own module in the
%% path, lets bail out with
%% the priv_dir of this directory
Y = filename:split(X),
throw(filename:join
(lists:sublist
(Y,length(Y) - 1)
++ ["priv"]));
_ ->
Acc
end
end,
false,P)),
case Pd of
false ->
exit(uds_dist_priv_lib_indeterminate);
_ ->
Pd
end;
Dir ->
Dir
end,
filename:join([PrivDir, "lib"]).
extension() ->
%% erlang:info(machine) returns machine name as text in all uppercase
"." ++ lists:map(fun(X) ->
X + $a - $A
end,
erlang:info(machine)).
