Reject invalid format strings more aggressively

src/lager_format.erl

@@ -29,18 +29,29 @@
 format(FmtStr, Args, MaxLen) ->
     format(FmtStr, Args, MaxLen, []).
 
-format(FmtStr, Args, MaxLen, Opts) ->
-    Options = make_options(Opts, #options{}),
-    Cs = collect(FmtStr, Args),
-    {Cs2, MaxLen2} = build(Cs, [], MaxLen, Options),
-    %% count how many terms remain
-    {Count, StrLen} = lists:foldl(
-        fun({_C, _As, _F, _Adj, _P, _Pad, _Enc}, {Terms, Chars}) ->
-                {Terms + 1, Chars};
-            (_, {Terms, Chars}) ->
-                {Terms, Chars + 1}
-        end, {0, 0}, Cs2),
-    build2(Cs2, Count, MaxLen2 - StrLen).
+format(FmtStr, Args, MaxLen, Opts) when is_atom(FmtStr) ->
+    format(atom_to_list(FmtStr), Args, MaxLen, Opts);
+format(FmtStr, Args, MaxLen, Opts) when is_binary(FmtStr) ->
+    format(binary_to_list(FmtStr), Args, MaxLen, Opts);
+format(FmtStr, Args, MaxLen, Opts) when is_list(FmtStr) ->
+    case lager_stdlib:string_p(FmtStr) of
+        true ->
+            Options = make_options(Opts, #options{}),
+            Cs = collect(FmtStr, Args),
+            {Cs2, MaxLen2} = build(Cs, [], MaxLen, Options),
+            %% count how many terms remain
+            {Count, StrLen} = lists:foldl(
+                fun({_C, _As, _F, _Adj, _P, _Pad, _Enc}, {Terms, Chars}) ->
+                        {Terms + 1, Chars};
+                    (_, {Terms, Chars}) ->
+                        {Terms, Chars + 1}
+                end, {0, 0}, Cs2),
+            build2(Cs2, Count, MaxLen2 - StrLen);
+        false ->
+            erlang:error(badarg)
+    end;
+format(_FmtStr, _Args, _MaxLen, _Opts) ->
+    erlang:error(badarg).
 
 collect([$~|Fmt0], Args0) ->
     {C,Fmt1,Args1} = collect_cseq(Fmt0, Args0),

src/lager_trunc_io.erl

@@ -721,4 +721,15 @@ depth_limit_test() ->
 
     ok.
 
+print_terms_without_format_string_test() ->
+    ?assertError(badarg, format({hello, world}, [], 50)),
+    ?assertError(badarg, format([{google, bomb}], [], 50)),
+    ?assertError(badarg, format([$h,$e,$l,$l,$o, 3594], [], 50)),
+    ?assertEqual("helloworld", lists:flatten(format([$h,$e,$l,$l,$o, "world"], [], 50))),
+    ?assertEqual("hello", lists:flatten(format(<<"hello">>, [], 50))),
+    ?assertEqual("hello", lists:flatten(format('hello', [], 50))),
+    ?assertError(badarg, format(<<1, 2, 3, 1:7>>, [], 100)),
+    ?assertError(badarg, format(65535, [], 50)),
+    ok.
+
 -endif.