https://github.com/msantos/procket/issues/23

hawk_uds.erl

-module(hawk_uds).

%% API
-export([start_link/1,
         init/1]).
-export([accept/1, handle/1]).

start_link(File) ->
  {ok, spawn_link(?MODULE, init, [File])}.


init(File0) ->
  inert:start(),
  File = iolist_to_binary(File0),
  file:delete(File),
  {ok, Fd} = procket:socket(unix, stream, 0),
  Len = byte_size(File),
  Sun = <<(procket:sockaddr_common(1, Len))/binary, File/binary, 0:((procket:unix_path_max() - Len) * 8)>>,
  ok = procket:bind(Fd, Sun),
  ok = procket:listen(Fd),
  accept(Fd).


accept(Fd) ->
  case inert:poll(Fd) of
    {ok,read} -> ok;
    Error ->
      procket:close(Fd),
      erlang:exit({accept, Error})
  end,
  case procket:accept(Fd) of
    {error, eagain} ->
      ok;
    {ok, ClientFd} ->
      spawn_opt(?MODULE, handle, [ClientFd], [{fullsweep_after, 0}])
  end,
  accept(Fd).


handle(Sock) ->
  {ok, PackLen} = read_packet_len(Sock),
  {ok, Binary} = read_packet(Sock, PackLen),

  BinSize = byte_size(Binary),

  case procket:write(Sock, <<BinSize:32/big-unsigned-integer, Binary/binary>>) of
    {error, _} ->
      procket:close(Sock),
      erlang:exit({reason, connection_refused});
    _ ->
      ok
  end,

  handle(Sock).

read_packet_len(Fd) ->
  case read_packet(Fd, 4, <<>>) of
    {ok, <<Len:32/big-unsigned-integer>>} -> {ok, Len};
    _Error ->
      procket:close(Fd),
      erlang:exit({reason, read_packet_len})
  end.


read_packet(Fd, Len) ->
  read_packet(Fd, Len, <<>>).


read_packet(_Fd, 0, Bin) ->
  {ok, Bin};
read_packet(Fd, Len, Bin) ->
  case procket:read(Fd, Len) of
    {error, eagain} ->
      case inert:poll(Fd) of
        {ok, read} ->
          read_packet(Fd, Len, Bin);
        _ ->
          procket:close(Fd),
          ok
      end;
    {ok, <<>>} ->
      procket:close(Fd),
      erlang:exit({reason, connection_refused});
    {ok, Data} when Len == erlang:byte_size(Data) ->
      {ok, Data};
    {ok, Data} ->
      read_packet(Fd, Len - byte_size(Data), <<Bin/binary, Data/binary>>);
    Error ->
        error_logger:info_report({read_packet, Error}),
        procket:close(Fd)
  end.