Merge pull request erlang#7627 from frazze-jobb/frazze/ssh/dumb_terminal

ssh: support dumb terminals in ssh client
OTP-18861

lib/kernel/src/group.erl

@@ -49,7 +49,10 @@ server(Ancestors, Drv, Shell, Options) ->
     put(user_drv, Drv),
     ExpandFun = normalize_expand_fun(Options, fun edlin_expand:expand/2),
     put(expand_fun, ExpandFun),
-    put(echo, proplists:get_value(echo, Options, true)),
+    Echo = proplists:get_value(echo, Options, true),
+    put(echo, Echo),
+    Dumb = proplists:get_value(dumb, Options, false),
+    put(dumb, Dumb),
     put(expand_below, proplists:get_value(expand_below, Options, true)),
 
     server_loop(Drv, start_shell(Shell), []).
@@ -490,7 +493,7 @@ get_chars_line(Prompt, M, F, Xa, Drv, Shell, Buf, Encoding) ->
     get_chars_loop(Pbs, M, F, Xa, Drv, Shell, Buf, start, [], Encoding).
 
 get_chars_loop(Pbs, M, F, Xa, Drv, Shell, Buf0, State, LineCont0, Encoding) ->
-    Result = case get(echo) of
+    Result = case not(get(dumb)) andalso get(echo) of
                  true ->
                      get_line(Buf0, Pbs, LineCont0, Drv, Shell, Encoding);
                  false ->
@@ -513,7 +516,7 @@ get_chars_loop(Pbs, M, F, Xa, Drv, Shell, Buf0, State, LineCont0, Encoding) ->
 get_chars_apply(Pbs, M, F, Xa, Drv, Shell, Buf, State0, LineCont, Encoding) ->
     %% multi line support means that we should not keep the state
     %% but we need to keep it for oldshell mode
-    {State, Line} = case get(echo) of
+    {State, Line} = case not(get(dumb)) andalso get(echo) of
                         true -> {start, edlin:current_line(LineCont)};
                         false -> {State0, LineCont}
                     end,
@@ -836,19 +839,23 @@ get_line_echo_off(Chars, ToEnc, Pbs, Drv, Shell) ->
             Res
     end.
 
-get_line_echo_off1({Chars,[]}, Drv, Shell) ->
+get_line_echo_off1({Chars,[],Rs}, Drv, Shell) ->
+    case get(echo) of
+        true -> send_drv_reqs(Drv, Rs);
+        false -> skip
+    end,
     receive
 	{Drv,{data,Cs}} ->
 	    get_line_echo_off1(edit_line(cast(Cs, list), Chars), Drv, Shell);
 	{Drv,eof} ->
 	    get_line_echo_off1(edit_line(eof, Chars), Drv, Shell);
 	{io_request,From,ReplyAs,Req} when is_pid(From) ->
 	    io_request(Req, From, ReplyAs, Drv, Shell, []),
-	    get_line_echo_off1({Chars,[]}, Drv, Shell);
+	    get_line_echo_off1({Chars,[],[]}, Drv, Shell);
         {reply,{From,ReplyAs},Reply} when From =/= undefined ->
             %% We take care of replies from puts here as well
             io_reply(From, ReplyAs, Reply),
-            get_line_echo_off1({Chars,[]},Drv, Shell);
+            get_line_echo_off1({Chars,[],[]},Drv, Shell);
 	{'EXIT',Drv,interrupt} ->
 	    interrupted;
 	{'EXIT',Drv,_} ->
@@ -858,9 +865,12 @@ get_line_echo_off1({Chars,[]}, Drv, Shell) ->
     end;
 get_line_echo_off1(eof, _Drv, _Shell) ->
     {done,eof,eof};
-get_line_echo_off1({Chars,Rest}, _Drv, _Shell) ->
+get_line_echo_off1({Chars,Rest,Rs}, Drv, _Shell) ->
+    case get(echo) of
+        true -> send_drv_reqs(Drv, Rs);
+        false -> skip
+    end,
     {done,lists:reverse(Chars),case Rest of done -> []; _ -> Rest end}.
-
 get_chars_echo_off(Pbs, Drv, Shell) ->
     send_drv_reqs(Drv, [{insert_chars, unicode,Pbs}]),
     get_chars_echo_off1(Drv, Shell).
@@ -895,22 +905,26 @@ get_chars_echo_off1(Drv, Shell) ->
 %% - ^d in posix/icanon mode: eof, delete-forward in edlin
 %% - ^r in posix/icanon mode: reprint (silly in echo-off mode :-))
 %% - ^w in posix/icanon mode: word-erase (produces a beep in edlin)
-edit_line(eof, []) ->
+edit_line(Input, State) ->
+    edit_line(Input, State, []).
+edit_line(eof, [], _) ->
     eof;
-edit_line(eof, Chars) ->
-    {Chars,eof};
-edit_line([],Chars) ->
-    {Chars,[]};
-edit_line([$\r,$\n|Cs],Chars) ->
-    {[$\n | Chars], remainder_after_nl(Cs)};
-edit_line([NL|Cs],Chars) when NL =:= $\r; NL =:= $\n ->
-    {[$\n | Chars], remainder_after_nl(Cs)};
-edit_line([Erase|Cs],[]) when Erase =:= $\177; Erase =:= $\^H ->
-    edit_line(Cs,[]);
-edit_line([Erase|Cs],[_|Chars]) when Erase =:= $\177; Erase =:= $\^H ->
-    edit_line(Cs,Chars);
-edit_line([Char|Cs],Chars) ->
-    edit_line(Cs,[Char|Chars]).
+edit_line(eof, Chars, Rs) ->
+    {Chars,eof, lists:reverse(Rs)};
+edit_line([],Chars, Rs) ->
+    {Chars,[],lists:reverse(Rs)};
+edit_line([$\r,$\n|Cs],Chars, Rs) ->
+    {[$\n | Chars], remainder_after_nl(Cs), lists:reverse([{put_chars, unicode, "\n"}|Rs])};
+edit_line([NL|Cs],Chars, Rs) when NL =:= $\r; NL =:= $\n ->
+    {[$\n | Chars], remainder_after_nl(Cs), lists:reverse([{put_chars, unicode, "\n"}|Rs])};
+edit_line([Erase|Cs],[], Rs) when Erase =:= $\177; Erase =:= $\^H ->
+    edit_line(Cs,[], Rs);
+edit_line([Erase|Cs],[_|Chars], Rs) when Erase =:= $\177; Erase =:= $\^H ->
+    edit_line(Cs,Chars, [{delete_chars, -1}|Rs]);
+edit_line([CtrlChar|Cs],Chars, Rs) when CtrlChar < 32 ->
+    edit_line(Cs,Chars,Rs);
+edit_line([Char|Cs],Chars, Rs) ->
+    edit_line(Cs,[Char|Chars], [{put_chars, unicode, [Char]}|Rs]).
 
 remainder_after_nl("") -> done;
 remainder_after_nl(Cs) -> Cs.

lib/ssh/src/ssh_cli.erl

@@ -79,7 +79,7 @@ handle_ssh_msg({ssh_cm, _ConnectionHandler,
 	       #state{group = Group} = State0) ->
     {Enc, State} = guess_encoding(Data, State0),
     List = unicode:characters_to_list(Data, Enc),
-    to_group(List, Group),
+    to_group(List, Group, get_dumb(State#state.pty)),
     {ok, State};
 
 handle_ssh_msg({ssh_cm, ConnectionHandler,
@@ -393,21 +393,28 @@ out_enc(#state{encoding = PeerEnc,
 
 %%--------------------------------------------------------------------
 
-to_group([], _Group) ->
+to_group([], _Group, _Dumb) ->
     ok;
-to_group([$\^C | Tail], Group) ->
+to_group([$\^C | Tail], Group, Dumb) ->
     exit(Group, interrupt),
-    to_group(Tail, Group);
-to_group(Data, Group) ->
+    to_group(Tail, Group, Dumb);
+to_group(Data, Group, Dumb) ->
     Func = fun(C) -> C /= $\^C end,
     Tail = case lists:splitwith(Func, Data) of
         {[], Right} ->
             Right;
         {Left, Right} ->
-            Group ! {self(), {data, Left}},
+            %% Filter out escape sequences, only support Ctrl sequences
+            Left1 = if Dumb -> replace_escapes(Left); true -> Left end,
+            Group ! {self(), {data, Left1}},
             Right
     end,
-    to_group(Tail, Group).
+    to_group(Tail, Group, Dumb).
+replace_escapes(Data) ->
+    lists:flatten([ if C =:= 27 ->
+        [$^,C+64];
+         true -> C
+    end || C <- Data]).
 
 %%--------------------------------------------------------------------
 %%% io_request, handle io requests from the user process,
@@ -511,10 +518,10 @@ get_tty_command(left, N, _TerminalType) ->
 -define(TABWIDTH, 8).
 
 %% convert input characters to buffer and to writeout
-%% Note that the buf is reversed but the buftail is not
+%% Note that Bef is reversed but Aft is not
 %% (this is handy; the head is always next to the cursor)
 conv_buf([], {LB, {Bef, Aft}, LA, Col}, AccWrite, _Tty) ->
-    {{LB, {Bef, Aft}, LA}, lists:reverse(AccWrite), Col};
+    {{LB, {Bef, Aft}, LA, Col}, lists:reverse(AccWrite)};
 conv_buf([13, 10 | Rest], {LB, {Bef, Aft}, LA, Col}, AccWrite, Tty = #ssh_pty{width = W}) ->
     conv_buf(Rest, {[lists:reverse(Bef)|LB], {[], tl2(Aft)}, LA, Col+(W-(Col rem W))}, [10, 13 | AccWrite], Tty);
 conv_buf([13 | Rest], {LB, {Bef, Aft}, LA, Col}, AccWrite, Tty = #ssh_pty{width = W}) ->
@@ -532,21 +539,28 @@ conv_buf([C | Rest], {LB, {Bef, Aft}, LA, Col}, AccWrite, Tty) ->
 
 %%% put characters before the prompt
 put_chars(Chars, Buf, Tty) ->
+    Dumb = get_dumb(Tty),
     case Buf of
-        {[],{[],[]},[],_} -> {_, WriteBuf, _} = conv_buf(Chars, Buf, [], Tty),
+        {[],{[],[]},[],_} -> {_, WriteBuf} = conv_buf(Chars, Buf, [], Tty),
             {WriteBuf, Buf};
-        _ ->
+        _ when Dumb =:= false ->
             {Delete, DeletedState} = io_request(delete_line, Buf, Tty, []),
-            {_, PutBuffer, _} = conv_buf(Chars, DeletedState, [], Tty),
+            {_, PutBuffer} = conv_buf(Chars, DeletedState, [], Tty),
             {Redraw, _} = io_request(redraw_prompt_pre_deleted, Buf, Tty, []),
-            {[Delete, PutBuffer, Redraw], Buf}
+            {[Delete, PutBuffer, Redraw], Buf};
+        _ ->
+            %% When we have a dumb terminal, we get messages via put_chars requests
+            %% so state should be empty {[],{[],[]},[],_},
+            %% but if we end up here its not, so keep the state
+            {_, WriteBuf} = conv_buf(Chars, Buf, [], Tty),
+            {WriteBuf, Buf}
     end.
 
 %%% insert character at current position
 insert_chars([], Buf, _Tty) ->
     {[], Buf};
 insert_chars(Chars, {_LB,{_Bef, Aft},LA, _Col}=Buf, Tty) ->
-    {{NewLB, {NewBef, _NewAft}, _NewLA}, WriteBuf, NewCol} = conv_buf(Chars, Buf, [], Tty),
+    {{NewLB, {NewBef, _NewAft}, _NewLA, NewCol}, WriteBuf} = conv_buf(Chars, Buf, [], Tty),
     M = move_cursor(special_at_width(NewCol+length(Aft), Tty), NewCol, Tty),
     {[WriteBuf, Aft | M], {NewLB,{NewBef, Aft},LA, NewCol}}.
 
@@ -725,7 +739,7 @@ start_shell(ConnectionHandler, State) ->
                 Shell
         end,
     State#state{group = group:start(self(), ShellSpawner,
-                                    [{expand_below, false},
+                                    [{dumb, get_dumb(State#state.pty)},{expand_below, false},
                                      {echo, get_echo(State#state.pty)}]),
                 buf = empty_buf()}.
 
@@ -842,6 +856,13 @@ t2str(T) -> try io_lib:format("~s",[T])
             end.
 
 %%--------------------------------------------------------------------
+get_dumb(Tty) ->
+    try
+        Tty#ssh_pty.term =:= "dumb"
+    catch
+        _:_ -> false
+    end.
+
 % Pty can be undefined if the client never sets any pty options before
 % starting the shell.
 get_echo(Tty) ->

lib/stdlib/src/edlin.erl

@@ -74,7 +74,7 @@ start(Pbs) ->
 
 %% Only two modes used: 'none' and 'search'. Other modes can be
 %% handled inline through specific character handling.
-start(Pbs, {_,{_,_},[]}=Cont) ->
+start(Pbs, {_,{_,[]},[]}=Cont) ->
     %% Skip redraw if the cursor is at the end.
     {more_chars,{line,Pbs,Cont,{normal,none}},[{insert_chars,unicode,multi_line_prompt(Pbs)}]};