%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1996-2010. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
-module(user).
-compile( [ inline, { inline_size, 100 } ] ).
%% Basic standard i/o server for user interface port.
-export([start/0, start/1, start_out/0]).
-export([interfaces/1]).
-define(NAME, user).
%% Defines for control ops
-define(CTRL_OP_GET_WINSIZE,100).
%%
%% The basic server and start-up.
%%
start() ->
start_port([eof,binary]).
start([Mod,Fun|Args]) ->
%% Mod,Fun,Args should return a pid. That process is supposed to act
%% as the io port.
Pid = apply(Mod, Fun, Args), % This better work!
Id = spawn(fun() -> server(Pid) end),
register(?NAME, Id),
Id.
start_out() ->
%% Output-only version of start/0
start_port([out,binary]).
start_port(PortSettings) ->
Id = spawn(fun() -> server({fd,0,1}, PortSettings) end),
register(?NAME, Id),
Id.
%% Return the pid of the shell process.
%% Note: We can't ask the user process for this info since it
%% may be busy waiting for data from the port.
interfaces(User) ->
case process_info(User, dictionary) of
{dictionary,Dict} ->
case lists:keysearch(shell, 1, Dict) of
{value,Sh={shell,Shell}} when is_pid(Shell) ->
[Sh];
_ ->
[]
end;
_ ->
[]
end.
server(Pid) when is_pid(Pid) ->
process_flag(trap_exit, true),
link(Pid),
run(Pid).
server(PortName,PortSettings) ->
process_flag(trap_exit, true),
Port = open_port(PortName,PortSettings),
run(Port).
run(P) ->
put(read_mode,list),
put(unicode,false),
case init:get_argument(noshell) of
%% non-empty list -> noshell
{ok, [_|_]} ->
put(shell, noshell),
server_loop(P, queue:new());
_ ->
group_leader(self(), self()),
catch_loop(P, start_init_shell())
end.
catch_loop(Port, Shell) ->
catch_loop(Port, Shell, queue:new()).
catch_loop(Port, Shell, Q) ->
case catch server_loop(Port, Q) of
new_shell ->
exit(Shell, kill),
catch_loop(Port, start_new_shell());
{unknown_exit,{Shell,Reason},_} -> % shell has exited
case Reason of
normal ->
put_chars("*** ", Port, []);
_ ->
put_chars("*** ERROR: ", Port, [])
end,
put_chars("Shell process terminated! ***\n", Port, []),
catch_loop(Port, start_new_shell());
{unknown_exit,_,Q1} ->
catch_loop(Port, Shell, Q1);
{'EXIT',R} ->
exit(R)
end.
link_and_save_shell(Shell) ->
link(Shell),
put(shell, Shell),
Shell.
start_init_shell() ->
link_and_save_shell(shell:start(init)).
start_new_shell() ->
link_and_save_shell(shell:start()).
server_loop(Port, Q) ->
receive
{io_request,From,ReplyAs,Request} when is_pid(From) ->
server_loop(Port, do_io_request(Request, From, ReplyAs, Port, Q));
{Port,{data,Bytes}} ->
case get(shell) of
noshell ->
server_loop(Port, queue:snoc(Q, Bytes));
_ ->
case contains_ctrl_g_or_ctrl_c(Bytes) of
false ->
server_loop(Port, queue:snoc(Q, Bytes));
_ ->
throw(new_shell)
end
end;
{Port, eof} ->
put(eof, true),
server_loop(Port, Q);
%% Ignore messages from port here.
{'EXIT',Port,badsig} -> % Ignore badsig errors
server_loop(Port, Q);
{'EXIT',Port,What} -> % Port has exited
exit(What);
%% Check if shell has exited
{'EXIT',SomePid,What} ->
case get(shell) of
noshell ->
server_loop(Port, Q); % Ignore
_ ->
throw({unknown_exit,{SomePid,What},Q})
end;
_Other -> % Ignore other messages
server_loop(Port, Q)
end.
get_fd_geometry(Port) ->
case (catch port_control(Port,?CTRL_OP_GET_WINSIZE,[])) of
List when length(List) =:= 8 ->
<<W:32/native,H:32/native>> = list_to_binary(List),
{W,H};
_ ->
error
end.
%% NewSaveBuffer = io_request(Request, FromPid, ReplyAs, Port, SaveBuffer)
do_io_request(Req, From, ReplyAs, Port, Q0) ->
case io_request(Req, Port, Q0) of
{_Status,Reply,Q1} ->
io_reply(From, ReplyAs, Reply),
Q1;
{exit,What} ->
send_port(Port, close),
exit(What)
end.
%% New in R13B
%% Encoding option (unicode/latin1)
io_request({put_chars,unicode,Chars}, Port, Q) -> % Binary new in R9C
put_chars(wrap_characters_to_binary(Chars,unicode,
case get(unicode) of
true -> unicode;
_ -> latin1
end), Port, Q);
io_request({put_chars,unicode,Mod,Func,Args}, Port, Q) ->
Result = case catch apply(Mod,Func,Args) of
Data when is_list(Data); is_binary(Data) ->
wrap_characters_to_binary(Data,unicode,
case get(unicode) of
true -> unicode;
_ -> latin1
end);
Undef ->
Undef
end,
put_chars(Result, Port, Q);
io_request({put_chars,latin1,Chars}, Port, Q) -> % Binary new in R9C
Data = case get(unicode) of
true ->
unicode:characters_to_binary(Chars,latin1,unicode);
false ->
erlang:iolist_to_binary(Chars)
end,
put_chars(Data, Port, Q);
io_request({put_chars,latin1,Mod,Func,Args}, Port, Q) ->
Result = case catch apply(Mod,Func,Args) of
Data when is_list(Data); is_binary(Data) ->
unicode:characters_to_binary(Data,latin1,
case get(unicode) of
true -> unicode;
_ -> latin1
end);
Undef ->
Undef
end,
put_chars(Result, Port, Q);
io_request({get_chars,Enc,Prompt,N}, Port, Q) -> % New in R9C
get_chars(Prompt, io_lib, collect_chars, N, Port, Q, Enc);
io_request({get_line,Enc,Prompt}, Port, Q) ->
case get(read_mode) of
binary ->
get_line_bin(Prompt,Port,Q,Enc);
_ ->
get_chars(Prompt, io_lib, collect_line, [], Port, Q, Enc)
end;
io_request({get_until,Enc,Prompt,M,F,As}, Port, Q) ->
get_chars(Prompt, io_lib, get_until, {M,F,As}, Port, Q, Enc);
%% End New in R13B
io_request(getopts, Port, Q) ->
getopts(Port, Q);
io_request({setopts,Opts}, Port, Q) when is_list(Opts) ->
setopts(Opts, Port, Q);
io_request({requests,Reqs}, Port, Q) ->
io_requests(Reqs, {ok,ok,Q}, Port);
%% New in R12
io_request({get_geometry,columns},Port,Q) ->
case get_fd_geometry(Port) of
{W,_H} ->
{ok,W,Q};
_ ->
{error,{error,enotsup},Q}
end;
io_request({get_geometry,rows},Port,Q) ->
case get_fd_geometry(Port) of
{_W,H} ->
{ok,H,Q};
_ ->
{error,{error,enotsup},Q}
end;
%% BC with pre-R13 nodes
io_request({put_chars,Chars}, Port, Q) ->
io_request({put_chars,latin1,Chars}, Port, Q);
io_request({put_chars,Mod,Func,Args}, Port, Q) ->
io_request({put_chars,latin1,Mod,Func,Args}, Port, Q);
io_request({get_chars,Prompt,N}, Port, Q) ->
io_request({get_chars,latin1,Prompt,N}, Port, Q);
io_request({get_line,Prompt}, Port, Q) ->
io_request({get_line,latin1,Prompt}, Port, Q);
io_request({get_until,Prompt,M,F,As}, Port, Q) ->
io_request({get_until,latin1,Prompt,M,F,As}, Port, Q);
io_request(R, _Port, Q) -> %Unknown request
{error,{error,{request,R}},Q}. %Ignore but give error (?)
%% Status = io_requests(RequestList, PrevStat, Port)
%% Process a list of output requests as long as the previous status is 'ok'.
io_requests([R|Rs], {ok,_Res,Q}, Port) ->
io_requests(Rs, io_request(R, Port, Q), Port);
io_requests([_|_], Error, _) ->
Error;
io_requests([], Stat, _) ->
Stat.
%% put_port(DeepList, Port)
%% Take a deep list of characters, flatten and output them to the
%% port.
put_port(List, Port) ->
send_port(Port, {command, List}).
%% send_port(Port, Command)
send_port(Port, Command) ->
Port ! {self(),Command}.
%% io_reply(From, ReplyAs, Reply)
%% The function for sending i/o command acknowledgement.
%% The ACK contains the return value.
io_reply(From, ReplyAs, Reply) ->
From ! {io_reply,ReplyAs,Reply}.
%% put_chars
put_chars(Chars, Port, Q) when is_binary(Chars) ->
put_port(Chars, Port),
{ok,ok,Q};
put_chars(Chars, Port, Q) ->
case catch list_to_binary(Chars) of
Binary when is_binary(Binary) ->
put_chars(Binary, Port, Q);
_ ->
{error,{error,put_chars},Q}
end.
expand_encoding([]) ->
[];
expand_encoding([latin1 | T]) ->
[{encoding,latin1} | expand_encoding(T)];
expand_encoding([unicode | T]) ->
[{encoding,unicode} | expand_encoding(T)];
expand_encoding([H|T]) ->
[H|expand_encoding(T)].
%% setopts
setopts(Opts0,Port,Q) ->
Opts = proplists:unfold(
proplists:substitute_negations(
[{list,binary}],
expand_encoding(Opts0))),
case check_valid_opts(Opts) of
true ->
do_setopts(Opts,Port,Q);
false ->
{error,{error,enotsup},Q}
end.
check_valid_opts([]) ->
true;
check_valid_opts([{binary,_}|T]) ->
check_valid_opts(T);
check_valid_opts([{encoding,Valid}|T]) when Valid =:= latin1; Valid =:= utf8; Valid =:= unicode ->
check_valid_opts(T);
check_valid_opts(_) ->
false.
do_setopts(Opts, _Port, Q) ->
case proplists:get_value(encoding,Opts) of
Valid when Valid =:= unicode; Valid =:= utf8 ->
put(unicode,true);
latin1 ->
put(unicode,false);
undefined ->
ok
end,
case proplists:get_value(binary, Opts) of
true ->
put(read_mode,binary),
{ok,ok,Q};
false ->
put(read_mode,list),
{ok,ok,Q};
_ ->
{ok,ok,Q}
end.
getopts(_Port,Q) ->
Bin = {binary, get(read_mode) =:= binary},
Uni = {encoding, case get(unicode) of
true ->
unicode;
_ ->
latin1
end},
{ok,[Bin,Uni],Q}.
get_line_bin(Prompt,Port,Q, Enc) ->
prompt(Port, Prompt),
case {get(eof),queue:is_empty(Q)} of
{true,true} ->
{ok,eof,Q};
_ ->
get_line(Prompt,Port, Q, [], Enc)
end.
get_line(Prompt, Port, Q, Acc, Enc) ->
case queue:is_empty(Q) of
true ->
receive
{Port,{data,Bytes}} ->
get_line_bytes(Prompt, Port, Q, Acc, Bytes, Enc);
{Port, eof} ->
put(eof, true),
{ok, eof, []};
{io_request,From,ReplyAs,{get_geometry,_}=Req} when is_pid(From) ->
do_io_request(Req, From, ReplyAs, Port,
queue:new()),
%% No prompt.
get_line(Prompt, Port, Q, Acc, Enc);
{io_request,From,ReplyAs,Request} when is_pid(From) ->
do_io_request(Request, From, ReplyAs, Port, queue:new()),
prompt(Port, Prompt),
get_line(Prompt, Port, Q, Acc, Enc);
{'EXIT',From,What} when node(From) =:= node() ->
{exit,What}
end;
false ->
get_line_doit(Prompt, Port, Q, Acc, Enc)
end.
get_line_bytes(Prompt, Port, Q, Acc, Bytes, Enc) ->
case get(shell) of
noshell ->
get_line_doit(Prompt, Port, queue:snoc(Q, Bytes),Acc,Enc);
_ ->
case contains_ctrl_g_or_ctrl_c(Bytes) of
false ->
get_line_doit(Prompt, Port, queue:snoc(Q, Bytes), Acc, Enc);
_ ->
throw(new_shell)
end
end.
is_cr_at(Pos,Bin) ->
case Bin of
<<_:Pos/binary,$\r,_/binary>> ->
true;
_ ->
false
end.
srch(<<>>,_,_) ->
nomatch;
srch(<<X:8,_/binary>>,X,N) ->
{match,[{N,1}]};
srch(<<_:8,T/binary>>,X,N) ->
srch(T,X,N+1).
get_line_doit(Prompt, Port, Q, Accu, Enc) ->
case queue:is_empty(Q) of
true ->
case get(eof) of
true ->
case Accu of
[] ->
{ok,eof,Q};
_ ->
{ok,binrev(Accu,[]),Q}
end;
_ ->
get_line(Prompt, Port, Q, Accu, Enc)
end;
false ->
Bin = queue:head(Q),
case srch(Bin,$\n,0) of
nomatch ->
X = byte_size(Bin)-1,
case is_cr_at(X,Bin) of
true ->
<<D:X/binary,_/binary>> = Bin,
get_line_doit(Prompt, Port, queue:tail(Q),
[<<$\r>>,D|Accu], Enc);
false ->
get_line_doit(Prompt, Port, queue:tail(Q),
[Bin|Accu], Enc)
end;
{match,[{Pos,1}]} ->
%% We are done
PosPlus = Pos + 1,
case Accu of
[] ->
{Head,Tail} =
case is_cr_at(Pos - 1,Bin) of
false ->
<<H:PosPlus/binary,
T/binary>> = Bin,
{H,T};
true ->
PosMinus = Pos - 1,
<<H:PosMinus/binary,
_,_,T/binary>> = Bin,
{binrev([],[H,$\n]),T}
end,
case Tail of
<<>> ->
{ok, cast(Head,Enc), queue:tail(Q)};
_ ->
{ok, cast(Head,Enc),
queue:cons(Tail, queue:tail(Q))}
end;
[<<$\r>>|Stack1] when Pos =:= 0 ->
<<_:PosPlus/binary,Tail/binary>> = Bin,
case Tail of
<<>> ->
{ok, cast(binrev(Stack1, [$\n]),Enc),
queue:tail(Q)};
_ ->
{ok, cast(binrev(Stack1, [$\n]),Enc),
queue:cons(Tail, queue:tail(Q))}
end;
_ ->
{Head,Tail} =
case is_cr_at(Pos - 1,Bin) of
false ->
<<H:PosPlus/binary,
T/binary>> = Bin,
{H,T};
true ->
PosMinus = Pos - 1,
<<H:PosMinus/binary,
_,_,T/binary>> = Bin,
{[H,$\n],T}
end,
case Tail of
<<>> ->
{ok, cast(binrev(Accu,[Head]),Enc),
queue:tail(Q)};
_ ->
{ok, cast(binrev(Accu,[Head]),Enc),
queue:cons(Tail, queue:tail(Q))}
end
end
end
end.
binrev(L, T) ->
list_to_binary(lists:reverse(L, T)).
%% is_cr_at(Pos,Bin) ->
%% case Bin of
%% <<_:Pos/binary,$\r,_/binary>> ->
%% true;
%% _ ->
%% false
%% end.
%% collect_line_bin_re(Bin,_Data,Stack,_) ->
%% case re:run(Bin,<<"\n">>) of
%% nomatch ->
%% X = byte_size(Bin)-1,
%% case is_cr_at(X,Bin) of
%% true ->
%% <<D:X/binary,_/binary>> = Bin,
%% [<<$\r>>,D|Stack];
%% false ->
%% [Bin|Stack]
%% end;
%% {match,[{Pos,1}]} ->
%% PosPlus = Pos + 1,
%% case Stack of
%% [] ->
%% case is_cr_at(Pos - 1,Bin) of
%% false ->
%% <<Head:PosPlus/binary,Tail/binary>> = Bin,
%% {stop, Head, Tail};
%% true ->
%% PosMinus = Pos - 1,
%% <<Head:PosMinus/binary,_,_,Tail/binary>> = Bin,
%% {stop, binrev([],[Head,$\n]),Tail}
%% end;
%% [<<$\r>>|Stack1] when Pos =:= 0 ->
%% <<_:PosPlus/binary,Tail/binary>> = Bin,
%% {stop,binrev(Stack1, [$\n]),Tail};
%% _ ->
%% case is_cr_at(Pos - 1,Bin) of
%% false ->
%% <<Head:PosPlus/binary,Tail/binary>> = Bin,
%% {stop,binrev(Stack, [Head]),Tail};
%% true ->
%% PosMinus = Pos - 1,
%% <<Head:PosMinus/binary,_,_,Tail/binary>> = Bin,
%% {stop, binrev(Stack,[Head,$\n]),Tail}
%% end
%% end
%% end.
%% get_chars(Prompt, Module, Function, XtraArg, Port, Queue)
%% Gets characters from the input port until the applied function
%% returns {stop,Result,RestBuf}. Does not block output until input
%% has been received.
%% Returns:
%% {Status,Result,NewQueue}
%% {exit,Reason}
%% Entry function.
get_chars(Prompt, M, F, Xa, Port, Q, Fmt) ->
prompt(Port, Prompt),
case {get(eof),queue:is_empty(Q)} of
{true,true} ->
{ok,eof,Q};
_ ->
get_chars(Prompt, M, F, Xa, Port, Q, start, Fmt)
end.
%% First loop. Wait for port data. Respond to output requests.
get_chars(Prompt, M, F, Xa, Port, Q, State, Fmt) ->
case queue:is_empty(Q) of
true ->
receive
{Port,{data,Bytes}} ->
get_chars_bytes(State, M, F, Xa, Port, Q, Bytes, Fmt);
{Port, eof} ->
put(eof, true),
{ok, eof, []};
%%{io_request,From,ReplyAs,Request} when is_pid(From) ->
%% get_chars_req(Prompt, M, F, Xa, Port, queue:new(), State,
%% Request, From, ReplyAs);
{io_request,From,ReplyAs,{get_geometry,_}=Req} when is_pid(From) ->
do_io_request(Req, From, ReplyAs, Port,
queue:new()), %Keep Q over this call
%% No prompt.
get_chars(Prompt, M, F, Xa, Port, Q, State, Fmt);
{io_request,From,ReplyAs,Request} when is_pid(From) ->
get_chars_req(Prompt, M, F, Xa, Port, Q, State,
Request, From, ReplyAs, Fmt);
{'EXIT',From,What} when node(From) =:= node() ->
{exit,What}
end;
false ->
get_chars_apply(State, M, F, Xa, Port, Q, Fmt)
end.
get_chars_req(Prompt, M, F, XtraArg, Port, Q, State,
Req, From, ReplyAs, Fmt) ->
do_io_request(Req, From, ReplyAs, Port, queue:new()), %Keep Q over this call
prompt(Port, Prompt),
get_chars(Prompt, M, F, XtraArg, Port, Q, State, Fmt).
%% Second loop. Pass data to client as long as it wants more.
%% A ^G in data interrupts loop if 'noshell' is not undefined.
get_chars_bytes(State, M, F, Xa, Port, Q, Bytes, Fmt) ->
case get(shell) of
noshell ->
get_chars_apply(State, M, F, Xa, Port, queue:snoc(Q, Bytes),Fmt);
_ ->
case contains_ctrl_g_or_ctrl_c(Bytes) of
false ->
get_chars_apply(State, M, F, Xa, Port,
queue:snoc(Q, Bytes),Fmt);
_ ->
throw(new_shell)
end
end.
get_chars_apply(State0, M, F, Xa, Port, Q, Fmt) ->
case catch M:F(State0, cast(queue:head(Q),Fmt), Fmt, Xa) of
{stop,Result,<<>>} ->
{ok,Result,queue:tail(Q)};
{stop,Result,[]} ->
{ok,Result,queue:tail(Q)};
{stop,Result,eof} ->
{ok,Result,queue:tail(Q)};
{stop,Result,Buf} ->
{ok,Result,queue:cons(Buf, queue:tail(Q))};
{'EXIT',_} ->
{error,{error,err_func(M, F, Xa)},queue:new()};
State1 ->
get_chars_more(State1, M, F, Xa, Port, queue:tail(Q), Fmt)
end.
get_chars_more(State, M, F, Xa, Port, Q, Fmt) ->
case queue:is_empty(Q) of
true ->
case get(eof) of
undefined ->
receive
{Port,{data,Bytes}} ->
get_chars_bytes(State, M, F, Xa, Port, Q, Bytes, Fmt);
{Port,eof} ->
put(eof, true),
get_chars_apply(State, M, F, Xa, Port,
queue:snoc(Q, eof), Fmt);
{'EXIT',From,What} when node(From) =:= node() ->
{exit,What}
end;
_ ->
get_chars_apply(State, M, F, Xa, Port, queue:snoc(Q, eof), Fmt)
end;
false ->
get_chars_apply(State, M, F, Xa, Port, Q, Fmt)
end.
%% prompt(Port, Prompt)
%% Print Prompt onto Port
%% common case, reduces execution time by 20%
prompt(_Port, '') -> ok;
prompt(Port, Prompt) ->
put_port(wrap_characters_to_binary(io_lib:format_prompt(Prompt),unicode,
case get(unicode) of
true -> unicode;
_ -> latin1
end), Port).
%% Convert error code to make it look as before
err_func(io_lib, get_until, {_,F,_}) ->
F;
err_func(_, F, _) ->
F.
%% using regexp reduces execution time by >50% compared to old code
%% running two regexps in sequence is much faster than \\x03|\\x07
contains_ctrl_g_or_ctrl_c(BinOrList)->
case {re:run(BinOrList, <<3>>),re:run(BinOrList, <<7>>)} of
{nomatch, nomatch} -> false;
_ -> true
end.
%% Convert a buffer between list and binary
cast(Data, _Format) when is_atom(Data) ->
Data;
cast(Data, Format) ->
cast(Data, get(read_mode), Format, get(unicode)).
cast(B, binary, latin1, false) when is_binary(B) ->
B;
cast(B, binary, latin1, true) when is_binary(B) ->
unicode:characters_to_binary(B, unicode, latin1);
cast(L, binary, latin1, false) ->
erlang:iolist_to_binary(L);
cast(L, binary, latin1, true) ->
case unicode:characters_to_binary(
erlang:iolist_to_binary(L),unicode,latin1) of % may fail
{error,_,_} -> exit({no_translation, unicode, latin1});
Else -> Else
end;
cast(B, binary, unicode, true) when is_binary(B) ->
B;
cast(B, binary, unicode, false) when is_binary(B) ->
unicode:characters_to_binary(B,latin1,unicode);
cast(L, binary, unicode, true) ->
% possibly a list containing UTF-8 encoded characters
unicode:characters_to_binary(erlang:iolist_to_binary(L));
cast(L, binary, unicode, false) ->
unicode:characters_to_binary(L, latin1, unicode);
cast(L, list, latin1, UniTerm) ->
case UniTerm of
true -> % Convert input characters to protocol format (i.e latin1)
case unicode:characters_to_list(
erlang:iolist_to_binary(L),unicode) of % may fail
{error,_,_} -> exit({no_translation, unicode, latin1});
Else -> [ case X of
High when High > 255 ->
exit({no_translation, unicode, latin1});
Low ->
Low
end || X <- Else ]
end;
_ ->
binary_to_list(erlang:iolist_to_binary(L))
end;
cast(L, list, unicode, UniTerm) ->
unicode:characters_to_list(erlang:iolist_to_binary(L),
case UniTerm of
true -> unicode;
_ -> latin1
end);
cast(Other, _, _,_) ->
Other.
wrap_characters_to_binary(Chars,unicode,latin1) ->
case unicode:characters_to_binary(Chars,unicode,latin1) of
{error,_,_} ->
list_to_binary(
[ case X of
High when High > 255 ->
["\\x{",erlang:integer_to_list(X, 16),$}];
Low ->
Low
end || X <- unicode:characters_to_list(Chars,unicode) ]);
Bin ->
Bin
end;
wrap_characters_to_binary(Bin,From,From) when is_binary(Bin) ->
Bin;
wrap_characters_to_binary(Chars,From,To) ->
unicode:characters_to_binary(Chars,From,To).
