%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1996-2013. 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_drv).
%% Basic interface to a port.
-export([start/0,start/1,start/2,start/3,server/2,server/3]).
-export([interfaces/1]).
-define(OP_PUTC,0).
-define(OP_MOVE,1).
-define(OP_INSC,2).
-define(OP_DELC,3).
-define(OP_BEEP,4).
-define(OP_PUTC_SYNC,5).
% Control op
-define(CTRL_OP_GET_WINSIZE,100).
-define(CTRL_OP_GET_UNICODE_STATE,101).
-define(CTRL_OP_SET_UNICODE_STATE,102).
%% start()
%% start(ArgumentList)
%% start(PortName, Shell)
%% start(InPortName, OutPortName, Shell)
%% Start the user driver server. The arguments to start/1 are slightly
%% strange as this may be called both at start up from the command line
%% and explicitly from other code.
-spec start() -> pid().
start() -> %Default line editing shell
spawn(user_drv, server, ['tty_sl -c -e',{shell,start,[init]}]).
start([Pname]) ->
spawn(user_drv, server, [Pname,{shell,start,[init]}]);
start([Pname|Args]) ->
spawn(user_drv, server, [Pname|Args]);
start(Pname) ->
spawn(user_drv, server, [Pname,{shell,start,[init]}]).
start(Pname, Shell) ->
spawn(user_drv, server, [Pname,Shell]).
start(Iname, Oname, Shell) ->
spawn(user_drv, server, [Iname,Oname,Shell]).
%% Return the pid of the active group process.
%% Note: We can't ask the user_drv process for this info since it
%% may be busy waiting for data from the port.
-spec interfaces(pid()) -> [{'current_group', pid()}].
interfaces(UserDrv) ->
case process_info(UserDrv, dictionary) of
{dictionary,Dict} ->
case lists:keysearch(current_group, 1, Dict) of
{value,Gr={_,Group}} when is_pid(Group) ->
[Gr];
_ ->
[]
end;
_ ->
[]
end.
%% server(Pid, Shell)
%% server(Pname, Shell)
%% server(Iname, Oname, Shell)
%% The initial calls to run the user driver. These start the port(s)
%% then call server1/3 to set everything else up.
server(Pid, Shell) when is_pid(Pid) ->
server1(Pid, Pid, Shell);
server(Pname, Shell) ->
process_flag(trap_exit, true),
case catch open_port({spawn,Pname}, [eof]) of
{'EXIT', _} ->
%% Let's try a dumb user instead
user:start();
Port ->
server1(Port, Port, Shell)
end.
server(Iname, Oname, Shell) ->
process_flag(trap_exit, true),
case catch open_port({spawn,Iname}, [eof]) of
{'EXIT', _} -> %% It might be a dumb terminal lets start dumb user
user:start();
Iport ->
Oport = open_port({spawn,Oname}, [eof]),
server1(Iport, Oport, Shell)
end.
server1(Iport, Oport, Shell) ->
put(eof, false),
%% Start user and initial shell.
User = start_user(),
Gr1 = gr_add_cur(gr_new(), User, {}),
{Curr,Shell1} =
case init:get_argument(remsh) of
{ok,[[Node]]} ->
ANode = list_to_atom(Node),
RShell = {ANode,shell,start,[]},
RGr = group:start(self(), RShell, rem_sh_opts(ANode)),
{RGr,RShell};
E when E =:= error ; E =:= {ok,[[]]} ->
{group:start(self(), Shell),Shell}
end,
put(current_group, Curr),
Gr = gr_add_cur(Gr1, Curr, Shell1),
%% Print some information.
io_request({put_chars, unicode,
flatten(io_lib:format("~ts\n",
[erlang:system_info(system_version)]))},
Iport, Oport),
%% Enter the server loop.
server_loop(Iport, Oport, Curr, User, Gr, queue:new()).
rem_sh_opts(Node) ->
[{expand_fun,fun(B)-> rpc:call(Node,edlin_expand,expand,[B]) end}].
%% start_user()
%% Start a group leader process and register it as 'user', unless,
%% of course, a 'user' already exists.
start_user() ->
case whereis(user_drv) of
undefined ->
register(user_drv, self());
_ ->
ok
end,
case whereis(user) of
undefined ->
User = group:start(self(), {}),
register(user, User),
User;
User ->
User
end.
server_loop(Iport, Oport, User, Gr, IOQueue) ->
Curr = gr_cur_pid(Gr),
put(current_group, Curr),
server_loop(Iport, Oport, Curr, User, Gr, IOQueue).
server_loop(Iport, Oport, Curr, User, Gr, IOQueue) ->
receive
{Iport,{data,Bs}} ->
BsBin = list_to_binary(Bs),
Unicode = unicode:characters_to_list(BsBin,utf8),
port_bytes(Unicode, Iport, Oport, Curr, User, Gr, IOQueue);
{Iport,eof} ->
Curr ! {self(),eof},
server_loop(Iport, Oport, Curr, User, Gr, IOQueue);
Req when element(1,Req) =:= User orelse element(1,Req) =:= Curr,
tuple_size(Req) =:= 2 orelse tuple_size(Req) =:= 3 ->
%% We match {User|Curr,_}|{User|Curr,_,_}
NewQ = handle_req(Req, Iport, Oport, IOQueue),
server_loop(Iport, Oport, Curr, User, Gr, NewQ);
{Oport,ok} ->
%% We get this ok from the port, in io_request we store
%% info about where to send reply at head of queue
{{value,{Origin,Reply}},ReplyQ} = queue:out(IOQueue),
Origin ! {reply,Reply},
NewQ = handle_req(next, Iport, Oport, ReplyQ),
server_loop(Iport, Oport, Curr, User, Gr, NewQ);
{'EXIT',Iport,_R} ->
server_loop(Iport, Oport, Curr, User, Gr, IOQueue);
{'EXIT',Oport,_R} ->
server_loop(Iport, Oport, Curr, User, Gr, IOQueue);
{'EXIT',User,shutdown} -> % force data to port
server_loop(Iport, Oport, Curr, User, Gr, IOQueue);
{'EXIT',User,_R} -> % keep 'user' alive
NewU = start_user(),
server_loop(Iport, Oport, Curr, NewU, gr_set_num(Gr, 1, NewU, {}), IOQueue);
{'EXIT',Pid,R} -> % shell and group leader exit
case gr_cur_pid(Gr) of
Pid when R =/= die ,
R =/= terminated -> % current shell exited
if R =/= normal ->
io_requests([{put_chars,unicode,"*** ERROR: "}], Iport, Oport);
true -> % exit not caused by error
io_requests([{put_chars,unicode,"*** "}], Iport, Oport)
end,
io_requests([{put_chars,unicode,"Shell process terminated! "}], Iport, Oport),
Gr1 = gr_del_pid(Gr, Pid),
case gr_get_info(Gr, Pid) of
{Ix,{shell,start,Params}} -> % 3-tuple == local shell
io_requests([{put_chars,unicode,"***\n"}], Iport, Oport),
%% restart group leader and shell, same index
Pid1 = group:start(self(), {shell,start,Params}),
{ok,Gr2} = gr_set_cur(gr_set_num(Gr1, Ix, Pid1,
{shell,start,Params}), Ix),
put(current_group, Pid1),
server_loop(Iport, Oport, Pid1, User, Gr2, IOQueue);
_ -> % remote shell
io_requests([{put_chars,unicode,"(^G to start new job) ***\n"}],
Iport, Oport),
server_loop(Iport, Oport, Curr, User, Gr1, IOQueue)
end;
_ -> % not current, just remove it
server_loop(Iport, Oport, Curr, User, gr_del_pid(Gr, Pid), IOQueue)
end;
_X ->
%% Ignore unknown messages.
server_loop(Iport, Oport, Curr, User, Gr, IOQueue)
end.
%% We always handle geometry and unicode requests
handle_req({Curr,tty_geometry},Iport,_Oport,IOQueue) ->
Curr ! {self(),tty_geometry,get_tty_geometry(Iport)},
IOQueue;
handle_req({Curr,get_unicode_state},Iport,_Oport,IOQueue) ->
Curr ! {self(),get_unicode_state,get_unicode_state(Iport)},
IOQueue;
handle_req({Curr,set_unicode_state, Bool},Iport,_Oport,IOQueue) ->
Curr ! {self(),set_unicode_state,set_unicode_state(Iport,Bool)},
IOQueue;
handle_req(next,Iport,Oport,IOQueue) ->
case queue:out(IOQueue) of
{{value,Next},ExecQ} ->
NewQ = handle_req(Next,Iport,Oport,queue:new()),
queue:join(NewQ,ExecQ);
{empty,_} ->
IOQueue
end;
handle_req(Msg,Iport,Oport,IOQueue) ->
case queue:peek(IOQueue) of
empty ->
{Origin,Req} = Msg,
case io_request(Req, Iport, Oport) of
ok -> IOQueue;
Reply ->
%% Push reply info to front of queue
queue:in_r({Origin,Reply},IOQueue)
end;
_Else ->
%% All requests are queued when we have outstanding sync put_chars
queue:in(Msg,IOQueue)
end.
%% port_bytes(Bytes, InPort, OutPort, CurrentProcess, UserProcess, Group)
%% Check the Bytes from the port to see if it contains a ^G. If so,
%% either escape to switch_loop or restart the shell. Otherwise send
%% the bytes to Curr.
port_bytes([$\^G|_Bs], Iport, Oport, _Curr, User, Gr, IOQueue) ->
handle_escape(Iport, Oport, User, Gr, IOQueue);
port_bytes([$\^C|_Bs], Iport, Oport, Curr, User, Gr, IOQueue) ->
interrupt_shell(Iport, Oport, Curr, User, Gr, IOQueue);
port_bytes([B], Iport, Oport, Curr, User, Gr, IOQueue) ->
Curr ! {self(),{data,[B]}},
server_loop(Iport, Oport, Curr, User, Gr, IOQueue);
port_bytes(Bs, Iport, Oport, Curr, User, Gr, IOQueue) ->
case member($\^G, Bs) of
true ->
handle_escape(Iport, Oport, User, Gr, IOQueue);
false ->
Curr ! {self(),{data,Bs}},
server_loop(Iport, Oport, Curr, User, Gr, IOQueue)
end.
interrupt_shell(Iport, Oport, Curr, User, Gr, IOQueue) ->
case gr_get_info(Gr, Curr) of
undefined ->
ok; % unknown
_ ->
exit(Curr, interrupt)
end,
server_loop(Iport, Oport, Curr, User, Gr, IOQueue).
handle_escape(Iport, Oport, User, Gr, IOQueue) ->
case application:get_env(stdlib, shell_esc) of
{ok,abort} ->
Pid = gr_cur_pid(Gr),
exit(Pid, die),
Gr1 =
case gr_get_info(Gr, Pid) of
{_Ix,{}} -> % no shell
Gr;
_ ->
receive {'EXIT',Pid,_} ->
gr_del_pid(Gr, Pid)
after 1000 ->
Gr
end
end,
Pid1 = group:start(self(), {shell,start,[]}),
io_request({put_chars,unicode,"\n"}, Iport, Oport),
server_loop(Iport, Oport, User,
gr_add_cur(Gr1, Pid1, {shell,start,[]}), IOQueue);
_ -> % {ok,jcl} | undefined
io_request({put_chars,unicode,"\nUser switch command\n"}, Iport, Oport),
%% init edlin used by switch command and have it copy the
%% text buffer from current group process
edlin:init(gr_cur_pid(Gr)),
server_loop(Iport, Oport, User, switch_loop(Iport, Oport, Gr), IOQueue)
end.
switch_loop(Iport, Oport, Gr) ->
Line = get_line(edlin:start(" --> "), Iport, Oport),
switch_cmd(erl_scan:string(Line), Iport, Oport, Gr).
switch_cmd({ok,[{atom,_,c},{integer,_,I}],_}, Iport, Oport, Gr0) ->
case gr_set_cur(Gr0, I) of
{ok,Gr} -> Gr;
undefined -> unknown_group(Iport, Oport, Gr0)
end;
switch_cmd({ok,[{atom,_,c}],_}, Iport, Oport, Gr) ->
case gr_get_info(Gr, gr_cur_pid(Gr)) of
undefined ->
unknown_group(Iport, Oport, Gr);
_ ->
Gr
end;
switch_cmd({ok,[{atom,_,i},{integer,_,I}],_}, Iport, Oport, Gr) ->
case gr_get_num(Gr, I) of
{pid,Pid} ->
exit(Pid, interrupt),
switch_loop(Iport, Oport, Gr);
undefined ->
unknown_group(Iport, Oport, Gr)
end;
switch_cmd({ok,[{atom,_,i}],_}, Iport, Oport, Gr) ->
Pid = gr_cur_pid(Gr),
case gr_get_info(Gr, Pid) of
undefined ->
unknown_group(Iport, Oport, Gr);
_ ->
exit(Pid, interrupt),
switch_loop(Iport, Oport, Gr)
end;
switch_cmd({ok,[{atom,_,k},{integer,_,I}],_}, Iport, Oport, Gr) ->
case gr_get_num(Gr, I) of
{pid,Pid} ->
exit(Pid, die),
case gr_get_info(Gr, Pid) of
{_Ix,{}} -> % no shell
switch_loop(Iport, Oport, Gr);
_ ->
Gr1 =
receive {'EXIT',Pid,_} ->
gr_del_pid(Gr, Pid)
after 1000 ->
Gr
end,
switch_loop(Iport, Oport, Gr1)
end;
undefined ->
unknown_group(Iport, Oport, Gr)
end;
switch_cmd({ok,[{atom,_,k}],_}, Iport, Oport, Gr) ->
Pid = gr_cur_pid(Gr),
Info = gr_get_info(Gr, Pid),
case Info of
undefined ->
unknown_group(Iport, Oport, Gr);
{_Ix,{}} -> % no shell
switch_loop(Iport, Oport, Gr);
_ ->
exit(Pid, die),
Gr1 =
receive {'EXIT',Pid,_} ->
gr_del_pid(Gr, Pid)
after 1000 ->
Gr
end,
switch_loop(Iport, Oport, Gr1)
end;
switch_cmd({ok,[{atom,_,j}],_}, Iport, Oport, Gr) ->
io_requests(gr_list(Gr), Iport, Oport),
switch_loop(Iport, Oport, Gr);
switch_cmd({ok,[{atom,_,s},{atom,_,Shell}],_}, Iport, Oport, Gr0) ->
Pid = group:start(self(), {Shell,start,[]}),
Gr = gr_add_cur(Gr0, Pid, {Shell,start,[]}),
switch_loop(Iport, Oport, Gr);
switch_cmd({ok,[{atom,_,s}],_}, Iport, Oport, Gr0) ->
Pid = group:start(self(), {shell,start,[]}),
Gr = gr_add_cur(Gr0, Pid, {shell,start,[]}),
switch_loop(Iport, Oport, Gr);
switch_cmd({ok,[{atom,_,r}],_}, Iport, Oport, Gr0) ->
case is_alive() of
true ->
Node = pool:get_node(),
Pid = group:start(self(), {Node,shell,start,[]}),
Gr = gr_add_cur(Gr0, Pid, {Node,shell,start,[]}),
switch_loop(Iport, Oport, Gr);
false ->
io_request({put_chars,unicode,"Not alive\n"}, Iport, Oport),
switch_loop(Iport, Oport, Gr0)
end;
switch_cmd({ok,[{atom,_,r},{atom,_,Node}],_}, Iport, Oport, Gr0) ->
Pid = group:start(self(), {Node,shell,start,[]}),
Gr = gr_add_cur(Gr0, Pid, {Node,shell,start,[]}),
switch_loop(Iport, Oport, Gr);
switch_cmd({ok,[{atom,_,r},{atom,_,Node},{atom,_,Shell}],_},
Iport, Oport, Gr0) ->
Pid = group:start(self(), {Node,Shell,start,[]}),
Gr = gr_add_cur(Gr0, Pid, {Node,Shell,start,[]}),
switch_loop(Iport, Oport, Gr);
switch_cmd({ok,[{atom,_,q}],_}, Iport, Oport, Gr) ->
case erlang:system_info(break_ignored) of
true -> % noop
io_request({put_chars,unicode,"Unknown command\n"}, Iport, Oport),
switch_loop(Iport, Oport, Gr);
false ->
halt()
end;
switch_cmd({ok,[{atom,_,h}],_}, Iport, Oport, Gr) ->
list_commands(Iport, Oport),
switch_loop(Iport, Oport, Gr);
switch_cmd({ok,[{'?',_}],_}, Iport, Oport, Gr) ->
list_commands(Iport, Oport),
switch_loop(Iport, Oport, Gr);
switch_cmd({ok,[],_}, Iport, Oport, Gr) ->
switch_loop(Iport, Oport, Gr);
switch_cmd({ok,_Ts,_}, Iport, Oport, Gr) ->
io_request({put_chars,unicode,"Unknown command\n"}, Iport, Oport),
switch_loop(Iport, Oport, Gr);
switch_cmd(_Ts, Iport, Oport, Gr) ->
io_request({put_chars,unicode,"Illegal input\n"}, Iport, Oport),
switch_loop(Iport, Oport, Gr).
unknown_group(Iport, Oport, Gr) ->
io_request({put_chars,unicode,"Unknown job\n"}, Iport, Oport),
switch_loop(Iport, Oport, Gr).
list_commands(Iport, Oport) ->
QuitReq = case erlang:system_info(break_ignored) of
true ->
[];
false ->
[{put_chars, unicode," q - quit erlang\n"}]
end,
io_requests([{put_chars, unicode," c [nn] - connect to job\n"},
{put_chars, unicode," i [nn] - interrupt job\n"},
{put_chars, unicode," k [nn] - kill job\n"},
{put_chars, unicode," j - list all jobs\n"},
{put_chars, unicode," s [shell] - start local shell\n"},
{put_chars, unicode," r [node [shell]] - start remote shell\n"}] ++
QuitReq ++
[{put_chars, unicode," ? | h - this message\n"}],
Iport, Oport).
get_line({done,Line,_Rest,Rs}, Iport, Oport) ->
io_requests(Rs, Iport, Oport),
Line;
get_line({undefined,_Char,Cs,Cont,Rs}, Iport, Oport) ->
io_requests(Rs, Iport, Oport),
io_request(beep, Iport, Oport),
get_line(edlin:edit_line(Cs, Cont), Iport, Oport);
get_line({What,Cont0,Rs}, Iport, Oport) ->
io_requests(Rs, Iport, Oport),
receive
{Iport,{data,Cs}} ->
get_line(edlin:edit_line(Cs, Cont0), Iport, Oport);
{Iport,eof} ->
get_line(edlin:edit_line(eof, Cont0), Iport, Oport)
after
get_line_timeout(What) ->
get_line(edlin:edit_line([], Cont0), Iport, Oport)
end.
get_line_timeout(blink) -> 1000;
get_line_timeout(more_chars) -> infinity.
% Let driver report window geometry,
% definitely outside of the common interface
get_tty_geometry(Iport) ->
case (catch port_control(Iport,?CTRL_OP_GET_WINSIZE,[])) of
List when length(List) =:= 8 ->
<<W:32/native,H:32/native>> = list_to_binary(List),
{W,H};
_ ->
error
end.
get_unicode_state(Iport) ->
case (catch port_control(Iport,?CTRL_OP_GET_UNICODE_STATE,[])) of
[Int] when Int > 0 ->
true;
[Int] when Int =:= 0 ->
false;
_ ->
error
end.
set_unicode_state(Iport, Bool) ->
Data = case Bool of
true -> [1];
false -> [0]
end,
case (catch port_control(Iport,?CTRL_OP_SET_UNICODE_STATE,Data)) of
[Int] when Int > 0 ->
{unicode, utf8};
[Int] when Int =:= 0 ->
{unicode, false};
_ ->
error
end.
%% io_request(Request, InPort, OutPort)
%% io_requests(Requests, InPort, OutPort)
%% Note: InPort is unused.
io_request(Request, Iport, Oport) ->
try io_command(Request) of
{command,_} = Command ->
Oport ! {self(),Command},
ok;
{Command,Reply} ->
Oport ! {self(),Command},
Reply
catch
{requests,Rs} ->
io_requests(Rs, Iport, Oport);
_ ->
ok
end.
io_requests([R|Rs], Iport, Oport) ->
io_request(R, Iport, Oport),
io_requests(Rs, Iport, Oport);
io_requests([], _Iport, _Oport) ->
ok.
put_int16(N, Tail) ->
[(N bsr 8)band 255,N band 255|Tail].
%% When a put_chars_sync command is used, user_drv guarantees that
%% the bytes have been put in the buffer of the port before an acknowledgement
%% is sent back to the process sending the request. This command was added in
%% OTP 18 to make sure that data sent from io:format is actually printed
%% to the console before the vm stops when calling erlang:halt(integer()).
io_command({put_chars_sync, unicode,Cs,Reply}) ->
{{command,[?OP_PUTC_SYNC|unicode:characters_to_binary(Cs,utf8)]},Reply};
io_command({put_chars, unicode,Cs}) ->
{command,[?OP_PUTC|unicode:characters_to_binary(Cs,utf8)]};
io_command({move_rel,N}) ->
{command,[?OP_MOVE|put_int16(N, [])]};
io_command({insert_chars,unicode,Cs}) ->
{command,[?OP_INSC|unicode:characters_to_binary(Cs,utf8)]};
io_command({delete_chars,N}) ->
{command,[?OP_DELC|put_int16(N, [])]};
io_command(beep) ->
{command,[?OP_BEEP]};
io_command(Else) ->
throw(Else).
%% gr_new()
%% gr_get_num(Group, Index)
%% gr_get_info(Group, Pid)
%% gr_add_cur(Group, Pid, Shell)
%% gr_set_cur(Group, Index)
%% gr_cur_pid(Group)
%% gr_del_pid(Group, Pid)
%% Manage the group list. The group structure has the form:
%% {NextIndex,CurrIndex,CurrPid,GroupList}
%%
%% where each element in the group list is:
%% {Index,GroupPid,Shell}
gr_new() ->
{0,0,none,[]}.
gr_get_num({_Next,_CurI,_CurP,Gs}, I) ->
gr_get_num1(Gs, I).
gr_get_num1([{I,_Pid,{}}|_Gs], I) ->
undefined;
gr_get_num1([{I,Pid,_S}|_Gs], I) ->
{pid,Pid};
gr_get_num1([_G|Gs], I) ->
gr_get_num1(Gs, I);
gr_get_num1([], _I) ->
undefined.
gr_get_info({_Next,_CurI,_CurP,Gs}, Pid) ->
gr_get_info1(Gs, Pid).
gr_get_info1([{I,Pid,S}|_Gs], Pid) ->
{I,S};
gr_get_info1([_G|Gs], I) ->
gr_get_info1(Gs, I);
gr_get_info1([], _I) ->
undefined.
gr_add_cur({Next,_CurI,_CurP,Gs}, Pid, Shell) ->
{Next+1,Next,Pid,append(Gs, [{Next,Pid,Shell}])}.
gr_set_cur({Next,_CurI,_CurP,Gs}, I) ->
case gr_get_num1(Gs, I) of
{pid,Pid} -> {ok,{Next,I,Pid,Gs}};
undefined -> undefined
end.
gr_set_num({Next,CurI,CurP,Gs}, I, Pid, Shell) ->
{Next,CurI,CurP,gr_set_num1(Gs, I, Pid, Shell)}.
gr_set_num1([{I,_Pid,_Shell}|Gs], I, NewPid, NewShell) ->
[{I,NewPid,NewShell}|Gs];
gr_set_num1([{I,Pid,Shell}|Gs], NewI, NewPid, NewShell) when NewI > I ->
[{I,Pid,Shell}|gr_set_num1(Gs, NewI, NewPid, NewShell)];
gr_set_num1(Gs, NewI, NewPid, NewShell) ->
[{NewI,NewPid,NewShell}|Gs].
gr_del_pid({Next,CurI,CurP,Gs}, Pid) ->
{Next,CurI,CurP,gr_del_pid1(Gs, Pid)}.
gr_del_pid1([{_I,Pid,_S}|Gs], Pid) ->
Gs;
gr_del_pid1([G|Gs], Pid) ->
[G|gr_del_pid1(Gs, Pid)];
gr_del_pid1([], _Pid) ->
[].
gr_cur_pid({_Next,_CurI,CurP,_Gs}) ->
CurP.
gr_list({_Next,CurI,_CurP,Gs}) ->
gr_list(Gs, CurI, []).
gr_list([{_I,_Pid,{}}|Gs], Cur, Jobs) ->
gr_list(Gs, Cur, Jobs);
gr_list([{Cur,_Pid,Shell}|Gs], Cur, Jobs) ->
gr_list(Gs, Cur, [{put_chars, unicode,flatten(io_lib:format("~4w* ~w\n", [Cur,Shell]))}|Jobs]);
gr_list([{I,_Pid,Shell}|Gs], Cur, Jobs) ->
gr_list(Gs, Cur, [{put_chars, unicode,flatten(io_lib:format("~4w ~w\n", [I,Shell]))}|Jobs]);
gr_list([], _Cur, Jobs) ->
lists:reverse(Jobs).
append([H|T], X) ->
[H|append(T, X)];
append([], X) ->
X.
member(X, [X|_Rest]) -> true;
member(X, [_H|Rest]) ->
member(X, Rest);
member(_X, []) -> false.
flatten(List) ->
flatten(List, [], []).
flatten([H|T], Cont, Tail) when is_list(H) ->
flatten(H, [T|Cont], Tail);
flatten([H|T], Cont, Tail) ->
[H|flatten(T, Cont, Tail)];
flatten([], [H|Cont], Tail) ->
flatten(H, Cont, Tail);
flatten([], [], Tail) ->
Tail.
