[GitHub] eiri commented on a change in pull request #1754: Do not use [] in feature_flags configuration

[GitBox <gi...@apache.org>]

eiri commented on a change in pull request #1754: Do not use [] in feature_flags configuration
URL: https://github.com/apache/couchdb/pull/1754#discussion_r235944452
 
 

 ##########
 File path: src/couch/src/couch_flags_config.erl
 ##########
 @@ -120,16 +121,29 @@ parse_flags(_Tokens, _) ->
     [flag_id()] | {error, Reason :: term()}.
 
 parse_flags_term(FlagsBin) ->
-    case couch_util:parse_term(FlagsBin) of
-        {ok, Flags} when is_list(Flags) ->
-            lists:usort(Flags);
-        Term ->
-            {error, {
-                "Flags should be list of atoms (got \"~s\"): ~p",
-                [FlagsBin, Term]
-            }}
+    {Flags, Errors} = lists:splitwith(fun erlang:is_atom/1,
+        [parse_flag(F) || F <- split_by_comma(FlagsBin)]),
+    case Errors of
+       [] ->
+           lists:usort(Flags);
+       _ ->
+           {error, {
+               "Cannot parse list of tags: ~n~p",
+               Errors
+           }}
     end.
 
+split_by_comma(Binary) ->
+    case binary:split(Binary, <<",">>, [global]) of
+       [<<>>] -> [];
+       Tokens -> Tokens
+    end.
+
+parse_flag(FlagName) when size(FlagName) > ?MAX_FLAG_NAME_LENGTH ->
+	{too_long, FlagName};
+parse_flag(FlagName) ->
+	list_to_atom(string:strip(binary_to_list(FlagName))).
 
 Review comment:
   How about changing this into `list_to_existing_atom/1`, just to be super safe? If I understand correctly a flag should be defined by this time, so that should work. It can even act as a poor man's validator, if we wrap it in something like `try ... catch _:_ -> {invalid_flag, FlagName}`

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