TMPDIR = os:getenv("TMPDIR", "/tmp"),

Compile = fun(Name0, Prog) ->
                  Name = filename:join(TMPDIR, Name0),
                  ok = file:write_file(Name, Prog, [write, exclusive]),
                  Cmd = erlang:open_port({spawn, ["${CC-cc} -o /dev/null ", Name, " -lpcap"]},
                                         [stream, exit_status]),
                  Status = receive
                               {Cmd, {exit_status, 0}} ->
                                   true;
                               {Cmd, {exit_status, _}} ->
                                   false
                           end,
                  ok = file:delete(Name),
                  Status
          end,

Test = fun(Name, Prog, Supported, Unsupported) ->
               case Compile(Name, Prog) of
                   true ->
                       Supported;
                   false ->
                       Unsupported
               end
       end,

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

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

%%
%% Tests
%%

PFRING = fun(Config) -> case os:getenv("PFRING") of
                            false ->
                                ok;
                            Value ->
                                case filelib:is_dir(Value) of
                                    true ->
                                        LDFLAGS = os:getenv("EPCAP_LDFLAGS", ""),
                                        true = Setenv("EPCAP_LDFLAGS", "-L" ++ Value);
                                    _ ->
                                        ok
                                end
                        end,
                        Config
         end,

Pcap_create = fun(Config) ->
                      Check = "
#include <pcap.h>
                          int main(int argc, char *argv[])
                          {
                           char errbuf[PCAP_ERRBUF_SIZE];
                               (void)pcap_create(NULL, errbuf);
                               return 0;
                          }",

    Flag = Test("test_pcap_create.c", Check, "-DHAVE_PCAP_CREATE", ""),
                      true = Setenv("EPCAP_DEFINE", Flag),
                      Config
              end,

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