Plug some large error_logger message holes with trunc_io

src/error_logger_lager_h.erl

@@ -80,7 +80,7 @@ handle_event(Event, State) ->
                         [ID, Name, format_reason(Reason)]);
                 _ ->
                     ?CRASH_LOG(Event),
-                    ?LOG(error, Pid, Fmt, Args)
+                    ?LOG(error, Pid, lager_trunc_io:format(Fmt, Args, 4096))
             end;
         {error_report, _GL, {Pid, std_error, D}} ->
             ?CRASH_LOG(Event),
@@ -98,11 +98,11 @@ handle_event(Event, State) ->
             ?CRASH_LOG(Event),
             ?LOG(error, Pid, ["CRASH REPORT ", format_crash_report(Self, Neighbours)]);
         {warning_msg, _GL, {Pid, Fmt, Args}} ->
-            ?LOG(warning, Pid, Fmt, Args);
+            ?LOG(warning, Pid, lager_trunc_io:format(Fmt, Args, 4096));
         {warning_report, _GL, {Pid, std_warning, Report}} ->
             ?LOG(warning, Pid, print_silly_list(Report));
         {info_msg, _GL, {Pid, Fmt, Args}} ->
-            ?LOG(info, Pid, Fmt, Args);
+            ?LOG(info, Pid, lager_trunc_io:format(Fmt, Args, 4096));
         {info_report, _GL, {Pid, std_info, D}} when is_list(D) ->
             Details = lists:sort(D),
             case Details of
@@ -235,14 +235,18 @@ format_args([_|T], Acc) ->
 
 print_silly_list(L) when is_list(L) ->
     case lager_stdlib:string_p(L) of
-        true -> L;
-        _ -> print_silly_list(L, [], [])
+        true ->
+            lager_trunc_io:format("~s", [L], 4096);
+        _ ->
+            print_silly_list(L, [], [])
     end;
 print_silly_list(L) ->
-    io_lib:format("~w", [L]).
+    {Str, _} = lager_trunc_io:print(L, 4096),
+    Str.
 
 print_silly_list([], Fmt, Acc) ->
-    io_lib:format(string:join(lists:reverse(Fmt), ", "), lists:reverse(Acc));
+    lager_trunc_io:format(string:join(lists:reverse(Fmt), ", "),
+        lists:reverse(Acc), 4096);
 print_silly_list([{K,V}|T], Fmt, Acc) ->
     print_silly_list(T, ["~w: ~w" | Fmt], [V, K | Acc]);
 print_silly_list([H|T], Fmt, Acc) ->

test/lager_test_backend.erl

@@ -386,6 +386,14 @@ error_logger_redirect_test_() ->
                         ?assertEqual(Expected, lists:flatten(Msg))
                 end
             },
+            {"error messages are truncated at 4096 characters",
+                fun() ->
+                        error_logger:error_msg("doom, doom has come upon you all ~p", [string:copies("doom", 10000)]),
+                        timer:sleep(100),
+                        {_, _, Msg} = pop(),
+                        ?assert(length(lists:flatten(Msg)) < 5100)
+                end
+            },
             {"info reports are printed",
                 fun() ->
                         error_logger:info_report([{this, is}, a, {silly, format}]),
@@ -395,6 +403,14 @@ error_logger_redirect_test_() ->
                         ?assertEqual(Expected, lists:flatten(Msg))
                 end
             },
+            {"info reports are truncated at 4096 characters",
+                fun() ->
+                        error_logger:info_report([[{this, is}, a, {silly, format}] || _ <- lists:seq(0, 600)]),
+                        timer:sleep(1000),
+                        {_, _, Msg} = pop(),
+                        ?assert(length(lists:flatten(Msg)) < 5000)
+                end
+            },
             {"single term info reports are printed",
                 fun() ->
                         error_logger:info_report({foolish, bees}),
@@ -422,6 +438,15 @@ error_logger_redirect_test_() ->
                         ?assertEqual(Expected, lists:flatten(Msg))
                 end
             },
+            {"string info reports are truncated at 4096 characters",
+                fun() ->
+                        error_logger:info_report(string:copies("this is less silly", 1000)),
+                        timer:sleep(100),
+                        {_, _, Msg} = pop(),
+                        ?assert(length(lists:flatten(Msg)) < 5100)
+                end
+            },
+
             {"info messages are printed",
                 fun() ->
                         error_logger:info_msg("doom, doom has come upon you all"),
@@ -431,6 +456,15 @@ error_logger_redirect_test_() ->
                         ?assertEqual(Expected, lists:flatten(Msg))
                 end
             },
+            {"info messages are truncated at 4096 characters",
+                fun() ->
+                        error_logger:info_msg("doom, doom has come upon you all ~p", [string:copies("doom", 10000)]),
+                        timer:sleep(100),
+                        {_, _, Msg} = pop(),
+                        ?assert(length(lists:flatten(Msg)) < 5100)
+                end
+            },
+
             {"warning messages are printed at the correct level",
                 fun() ->
                         error_logger:warning_msg("doom, doom has come upon you all"),
@@ -571,7 +605,15 @@ error_logger_redirect_test_() ->
                         ?assertEqual(Expected, lists:flatten(Msg))
                 end
             },
-
+            {"crash report for unknown system limit should be truncated at 500 characters",
+                fun() ->
+                        error_logger:error_report(crash_report, [[{pid, self()}, {error_info, {error, {system_limit,[{wtf,boom,[string:copies("aaaa", 4096)]}]}, []}}], []]),
+                        timer:sleep(100),
+                        {_, _, Msg} = pop(),
+                        ?assert(length(lists:flatten(Msg)) > 500),
+                        ?assert(length(lists:flatten(Msg)) < 700)
+                end
+            },
             {"messages should not be generated if they don't satisfy the threshold",
                 fun() ->
                         lager:set_loglevel(?MODULE, error),