feat: set printable characters range to unicode

Fixes https://emqx.atlassian.net/browse/EMQX-13115

See also: emqx/rebar3#20

apps/emqx/etc/vm.args.cloud

@@ -128,3 +128,6 @@
 
 ## Disable os_mon's disksup by default
 -os_mon start_disksup false
+
+## Sets unicode as the printable character range when formatting binaries
++pc unicode

apps/emqx_utils/src/emqx_utils.erl

@@ -569,7 +569,7 @@ tcp_keepalive_opts(OS, _Idle, _Interval, _Probes) ->
     {error, {unsupported_os, OS}}.
 
 format(Term) ->
-    unicode:characters_to_binary(io_lib:format("~0p", [Term])).
+    unicode:characters_to_binary(io_lib:format("~0tp", [Term])).
 
 format(Fmt, Args) ->
     unicode:characters_to_binary(io_lib:format(Fmt, Args)).

apps/emqx_utils/test/emqx_utils_tests.erl

@@ -50,3 +50,30 @@ foldl_while_test_() ->
             )
         )
     ].
+
+to_binary_representation(Bin) when is_binary(Bin) ->
+    Bytes = binary_to_list(Bin),
+    iolist_to_binary([
+                      [$<, $<],
+                      lists:join($,, [ integer_to_binary(B)
+                      || B <- Bytes
+                     ]),
+                      [$>, $>]
+                     ]).
+
+readable_error_msg_test_() ->
+    [
+     { "binary in nested structure with non-latin1 characters"
+     , ?_assert(begin
+         %% An unexpected error that could occur and be returned via HTTP API.
+         Text = <<"test中文"/utf8>>,
+         Error = {badmatch, #{description => Text}},
+         %% Output shouldn't contain the "exploded" bytes
+         Exploded = to_binary_representation(Text),
+         Formatted = emqx_utils:readable_error_msg(Error),
+         %% Precondition: `+pc unicode' must be set on the VM.
+         ?assertEqual(unicode, io:printable_range()),
+         nomatch =:= re:run(Formatted, Exploded, [{capture, all, binary}])
+       end)
+     }
+    ].