anchor.diff:  
   t_shutdown_async(Config) when is_list(Config) ->
       {OS, _} = os:type(),
  -    {ok, L} = gen_tcp:listen(0, [{sndbuf, 4096}]),
  +    {ok, L} = gen_tcp:listen(0, ?INET_BACKEND_OPTS(Config) ++ [{sndbuf, 4096}]),
       {ok, Port} = inet:port(L),
       {ok, Client} = gen_tcp:connect(localhost, Port,
  -				   [{recbuf, 4096},
  -				    {active, false}]),
  +				   ?INET_BACKEND_OPTS(Config) ++
  +                                       [{recbuf, 4096},
  +                                        {active, false}]),
       {ok, S} = gen_tcp:accept(L),
       PayloadSize = 1024 * 1024,
       Payload = lists:duplicate(PayloadSize, $.),
  
positive.code: %%% gen_tcp:shutdown/2
  
  t_shutdown_write(Config) when is_list(Config) ->
      {ok, L} = gen_tcp:listen(0, []),
      {ok, Port} = inet:port(L),
      {ok, Client} = gen_tcp:connect(localhost, Port, [{active, false}]),
      {ok, A} = gen_tcp:accept(L),
      ok = gen_tcp:shutdown(A, write),
      {error, closed} = gen_tcp:recv(Client, 0),
      ok.
  
  t_shutdown_both(Config) when is_list(Config) ->
      {ok, L} = gen_tcp:listen(0, []),
      {ok, Port} = inet:port(L),
      {ok, Client} = gen_tcp:connect(localhost, Port, [{active, false}]),
      {ok, A} = gen_tcp:accept(L),
      ok = gen_tcp:shutdown(A, read_write),
      {error, closed} = gen_tcp:recv(Client, 0),
      ok.
  
  t_shutdown_error(Config) when is_list(Config) ->
      {ok, L} = gen_tcp:listen(0, []),
      {error, enotconn} = gen_tcp:shutdown(L, read_write),
      ok = gen_tcp:close(L),
      {error, closed} = gen_tcp:shutdown(L, read_write),
  
negative.code:     ok = file:delete(SFile),
      ok.
  
  t_local_fdopen_connect_unbound(Config) ->
      SFile = local_filename(server),
      SAddr = {local,bin_filename(SFile)},
      _ = file:delete(SFile),
      InetBackendOpts = ?INET_BACKEND_OPTS(Config),
      L = ok(gen_tcp:listen(0, InetBackendOpts ++ [{ifaddr,SAddr},{active,false}])),
      P = ok(prim_inet:open(tcp, local, stream)),
      Fd = ok(prim_inet:getfd(P)),
      C =	ok(gen_tcp:connect(SAddr, 0, InetBackendOpts ++ [{fd,Fd},{active,false}])),
      S = ok(gen_tcp:accept(L)),
      SAddr = ok(inet:sockname(L)),
      {error,enotconn} = inet:peername(L),
  