Append = fun(Str, Flag) ->
    string:join(sets:to_list(sets:add_element(Flag,
                    sets:from_list(string:tokens(Str, " ")))), " ")
end,

Setenv = fun(_Key, "") ->
                true;
            (Key, Val) ->
                Cur = os:getenv(Key, ""),
                os:putenv(Key, Append(Cur, Val))
end,

EnvEnableDS = fun() ->
    case os:getenv("EWPCAP_DISABLE_DIRTY_SCHEDULER") of
        false ->
            true;
        _ ->
            false
    end
end,

VmEnableDS = fun() ->
    try erlang:system_info(dirty_io_schedulers) of
        _ ->
            true
    catch
        _:_ ->
            false
    end
end,

%%
%% Tests
%%

% Enable support for dirty schedulers
DirtySched = fun(Config) ->
    Env = EnvEnableDS(),
    VM = VmEnableDS(),

    Enable = Env and VM,

    true = case Enable of
        true ->
            true;
        false ->
            Setenv("CFLAGS", "-DEWPCAP_DISABLE_DIRTY_SCHEDULER")
    end,
    Config
end,

lists:foldl(fun(Fun, Cfg) ->
        Fun(Cfg)
    end,
    CONFIG,
    [DirtySched]
).