-module(uds).
-export([listen/1, connect/1, accept/1, send/2, recv/1, close/1,
get_port/1, get_status_counters/1, set_mode/2, controlling_process/2,
tick/1, get_creation/1]).
-define(decode(A,B,C,D), (((A) bsl 24) bor
((B) bsl 16) bor ((C) bsl 8) bor (D))).
-define(encode(N), [(((N) bsr 24) band 16#FF), (((N) bsr 16) band 16#FF),
(((N) bsr 8) band 16#FF), ((N) band 16#FF)]).
-define(check_server(), case whereis(uds_server) of
undefined ->
exit(uds_server_not_started);
_ ->
ok
end).
listen(Name) ->
?check_server(),
command(port(),$L,Name).
connect(Name) ->
?check_server(),
command(port(),$C,Name).
accept(Port) ->
?check_server(),
case control(Port,$N) of
{ok, N} ->
command(port(),$A,N);
Else ->
Else
end.
send(Port,Data) ->
?check_server(),
command(Port, $S, Data).
recv(Port) ->
?check_server(),
command(Port, $R, []).
close(Port) ->
?check_server(),
(catch unlink(Port)), %% Avoids problem with trap exits.
case (catch erlang:port_close(Port)) of
{'EXIT', Reason} ->
{error, closed};
_ ->
ok
end.
get_port(Port) ->
?check_server(),
{ok,Port}.
get_status_counters(Port) ->
?check_server(),
case control(Port, $S) of
{ok, {C0, C1, C2}} ->
{ok, C0, C1, C2};
Other ->
Other
end.
get_creation(Port) ->
?check_server(),
case control(Port, $R) of
{ok, [A]} ->
A;
Else ->
Else
end.
set_mode(Port, command) ->
?check_server(),
control(Port,$C);
set_mode(Port,intermediate) ->
?check_server(),
control(Port,$I);
set_mode(Port,data) ->
?check_server(),
control(Port,$D).
tick(Port) ->
?check_server(),
control(Port,$T).
controlling_process(Port, Pid) ->
?check_server(),
case (catch erlang:port_connect(Port, Pid)) of
true ->
(catch unlink(Port)),
ok;
{'EXIT', {badarg, _}} ->
{error, closed};
Else ->
exit({unexpected_driver_response, Else})
end.
control(Port, Command) ->
case (catch erlang:port_control(Port, Command, [])) of
[0] ->
ok;
[0,A] ->
{ok, [A]};
[0,A,B,C,D] ->
{ok, [A,B,C,D]};
[0,A1,B1,C1,D1,A2,B2,C2,D2,A3,B3,C3,D3] ->
{ok, {?decode(A1,B1,C1,D1),?decode(A2,B2,C2,D2),
?decode(A3,B3,C3,D3)}};
[1|Error] ->
exit({error, list_to_atom(Error)});
{'EXIT', {badarg, _}} ->
{error, closed};
Else ->
exit({unexpected_driver_response, Else})
end.
command(Port, Command, Parameters) ->
SavedTrapExit = process_flag(trap_exit,true),
case (catch erlang:port_command(Port,[Command | Parameters])) of
true ->
receive
{Port, {data, [Command, $o, $k]}} ->
process_flag(trap_exit,SavedTrapExit),
{ok, Port};
{Port, {data, [Command |T]}} ->
process_flag(trap_exit,SavedTrapExit),
{ok, T};
{Port, Else} ->
process_flag(trap_exit,SavedTrapExit),
exit({unexpected_driver_response, Else});
{'EXIT', Port, normal} ->
process_flag(trap_exit,SavedTrapExit),
{error, closed};
{'EXIT', Port, Error} ->
process_flag(trap_exit,SavedTrapExit),
exit(Error)
end;
{'EXIT', {badarg, _}} ->
process_flag(trap_exit,SavedTrapExit),
{error, closed};
Unexpected ->
process_flag(trap_exit,SavedTrapExit),
exit({unexpected_driver_response, Unexpected})
end.
port() ->
SavedTrapExit = process_flag(trap_exit,true),
case open_port({spawn, "uds_drv"},[]) of
P when port(P) ->
process_flag(trap_exit,SavedTrapExit),
P;
{'EXIT',Error} ->
process_flag(trap_exit,SavedTrapExit),
exit(Error);
Else ->
process_flag(trap_exit,SavedTrapExit),
exit({unexpected_driver_response, Else})
end.
