Teach error_logger_tty_h to truncate big messages

Add the possibility to truncate big messages to avoid running out
of memory.

2 files changed, 70 insertions, 15 deletions

diff --git a/lib/stdlib/src/error_logger_tty_h.erl b/lib/stdlib/src/error_logger_tty_h.erl
index 5dd8b0caa0..d2df6681e3 100644
--- a/lib/stdlib/src/error_logger_tty_h.erl
+++ b/lib/stdlib/src/error_logger_tty_h.erl
@@ -33,17 +33,19 @@
 	 handle_event/2, handle_call/2, handle_info/2,
 	 terminate/2, code_change/3]).
 
--export([write_event/2]).
+-export([write_event/2,write_event/3]).
 
 -record(st,
 	{user,
 	 prev_handler,
-	 io_mod=io}).
+	 io_mod=io,
+	 depth=unlimited}).
 
 %% This one is used when we takeover from the simple error_logger.
 init({[], {error_logger, Buf}}) ->
     User = set_group_leader(),
-    State = #st{user=User,prev_handler=error_logger},
+    Depth = get_depth(),
+    State = #st{user=User,prev_handler=error_logger,depth=Depth},
     write_events(State, Buf),
     {ok, State};
 %% This one is used if someone took over from us, and now wants to
@@ -54,7 +56,16 @@ init({[], {error_logger_tty_h, PrevHandler}}) ->
 %% This one is used when we are started directly.
 init([]) ->
     User = set_group_leader(),
-    {ok, #st{user=User,prev_handler=[]}}.
+    Depth = get_depth(),
+    {ok, #st{user=User,prev_handler=[],depth=Depth}}.
+
+get_depth() ->
+    case application:get_env(kernel, error_logger_format_depth) of
+	{ok, Depth} when is_integer(Depth) ->
+	    max(10, Depth);
+	undefined ->
+	    unlimited
+    end.
     
 handle_event({_Type, GL, _Msg}, State) when node(GL) =/= node() ->
     {ok, State};
@@ -88,6 +99,9 @@ code_change(_OldVsn, State, _Extra) ->
 write_event(Event, IoMod) ->
     do_write_event(#st{io_mod=IoMod}, Event).
 
+write_event(Event, IoMod, Depth) ->
+    do_write_event(#st{io_mod=IoMod,depth=Depth}, Event).
+
 
 %%% ------------------------------------------------------
 %%% Misc. functions.
@@ -140,17 +154,35 @@ do_write_event(_, _) ->
     ok.
 
 format_body(State, [{Format,Args}|T]) ->
-    S = try io_lib:format(Format, Args) of
+    S = try format(State, Format, Args) of
 	    S0 ->
 		S0
 	catch
 	    _:_ ->
-		io_lib:format("ERROR: ~p - ~p\n", [Format,Args])
+		format(State, "ERROR: ~p - ~p\n", [Format,Args])
 	end,
     [S|format_body(State, T)];
 format_body(_State, []) ->
     [].
 
+format(#st{depth=unlimited}, Format, Args) ->
+    io_lib:format(Format, Args);
+format(#st{depth=Depth}, Format0, Args) ->
+    Format1 = io_lib:scan_format(Format0, Args),
+    Format = limit_format(Format1, Depth),
+    io_lib:build_text(Format).
+
+limit_format([#{control_char:=C0}=M0|T], Depth) when C0 =:= $p;
+						     C0 =:= $w ->
+    C = C0 - ($a - $A),				%To uppercase.
+    #{args:=Args} = M0,
+    M = M0#{control_char:=C,args:=Args++[Depth]},
+    [M|limit_format(T, Depth)];
+limit_format([H|T], Depth) ->
+    [H|limit_format(T, Depth)];
+limit_format([], _) ->
+    [].
+
 parse_event({error, _GL, {Pid, Format, Args}}) ->
     {"ERROR REPORT",Pid,[{Format,Args}]};
 parse_event({info_msg, _GL, {Pid, Format, Args}}) ->
diff --git a/lib/stdlib/test/error_logger_h_SUITE.erl b/lib/stdlib/test/error_logger_h_SUITE.erl
index 7cde659b9f..b0b9c717a1 100644
--- a/lib/stdlib/test/error_logger_h_SUITE.erl
+++ b/lib/stdlib/test/error_logger_h_SUITE.erl
@@ -20,7 +20,7 @@
 -module(error_logger_h_SUITE).
 -export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1,
 	 init_per_group/2,end_per_group/2]).
--export([logfile/1,logfile_truncated/1,tty/1]).
+-export([logfile/1,logfile_truncated/1,tty/1,tty_truncated/1]).
 
 %% Event handler exports.
 -export([init/1,handle_event/2,terminate/2]).
@@ -30,7 +30,7 @@
 suite() -> [{ct_hooks,[ts_install_cth]}].
 
 all() ->
-    [logfile,logfile_truncated,tty].
+    [logfile,logfile_truncated,tty,tty_truncated].
 
 groups() ->
     [].
@@ -118,6 +118,25 @@ tty(Config) ->
     cleanup(Log),
     ok.
 
+tty_truncated(Config) ->
+    PrivDir = ?config(priv_dir, Config),
+    LogDir = filename:join(PrivDir, ?MODULE),
+    Log = filename:join(LogDir, "tty_truncated.log"),
+    ok = filelib:ensure_dir(Log),
+
+    Ev = event_templates(),
+
+    Depth = 20,
+    application:set_env(kernel, error_logger_format_depth, Depth),
+    try
+       do_one_tty(Log, Ev, Depth)
+    after
+	application:unset_env(kernel, error_logger_format_depth)
+    end,
+
+    cleanup(Log),
+    ok.
+
 do_one_tty(Log, Ev, Depth) ->
     tty_log_open(Log),
     gen_events(Ev),
@@ -126,7 +145,11 @@ do_one_tty(Log, Ev, Depth) ->
 
 tty_log_open(Log) ->
     {ok,Fd} = file:open(Log, [write]),
-    error_logger:add_report_handler(?MODULE, Fd),
+    Depth = case application:get_env(kernel, error_logger_format_depth) of
+		{ok,D} -> D;
+		_ -> unlimited
+	    end,
+    error_logger:add_report_handler(?MODULE, {Fd,Depth}),
     Fd.
 
 tty_log_close() ->
@@ -357,19 +380,19 @@ dl_format_1([], [], _, Facc, Aacc) ->
 %%% calling error_logger_tty_h:write_event/2.
 %%%
 
-init(Fd) ->
-    {ok,Fd}.
+init({_,_}=St) ->
+    {ok,St}.
 
-handle_event(Event, Fd) ->
-    case error_logger_tty_h:write_event(tag_event(Event), io_lib) of
+handle_event(Event, {Fd,Depth}=St) ->
+    case error_logger_tty_h:write_event(tag_event(Event), io_lib, Depth) of
 	ok ->
 	    ok;
 	Str when is_list(Str) ->
 	    io:put_chars(Fd, Str)
     end,
-    {ok,Fd}.
+    {ok,St}.
 
-terminate(_Reason, Fd) ->
+terminate(_Reason, {Fd,_}) ->
     ok = file:close(Fd),
     [].