[socket-nif] Add support for otp option fd

Add a way to *get* the file descriptor (fd) of a socket.
Useful mostly for debugging.

OTP-15528

5 files changed, 55 insertions, 62 deletions

diff --git a/erts/doc/src/socket_usage.xml b/erts/doc/src/socket_usage.xml
index 1ea29097c3..401a70992f 100644
--- a/erts/doc/src/socket_usage.xml
+++ b/erts/doc/src/socket_usage.xml
@@ -4,7 +4,7 @@
 <chapter>
   <header>
     <copyright>
-      <year>2018</year><year>2018</year>
+      <year>2018</year><year>2019</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -102,6 +102,13 @@
 	<cell>yes</cell>
 	<cell>default only valid for set</cell>
       </row>
+      <row>
+	<cell>fd</cell>
+	<cell>integer()</cell>
+	<cell>no</cell>
+	<cell>yes</cell>
+	<cell>none</cell>
+      </row>
     </table>
     
     <p>Options for level <c>socket</c>: </p>
diff --git a/erts/emulator/nifs/common/socket_nif.c b/erts/emulator/nifs/common/socket_nif.c
index 6dcd4ae623..44aa44f5fc 100644
--- a/erts/emulator/nifs/common/socket_nif.c
+++ b/erts/emulator/nifs/common/socket_nif.c
@@ -1,7 +1,7 @@
 /*
  * %CopyrightBegin%
  *
- * Copyright Ericsson AB 2018-2018. All Rights Reserved.
+ * Copyright Ericsson AB 2018-2019. All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -519,6 +519,7 @@ typedef union {
 #define SOCKET_OPT_OTP_RCVBUF       4
 #define SOCKET_OPT_OTP_RCVCTRLBUF   6
 #define SOCKET_OPT_OTP_SNDCTRLBUF   7
+#define SOCKET_OPT_OTP_FD           8
 #define SOCKET_OPT_OTP_DOMAIN       0xFF01 // INTERNAL AND ONLY GET
 #define SOCKET_OPT_OTP_TYPE         0xFF02 // INTERNAL AND ONLY GET
 #define SOCKET_OPT_OTP_PROTOCOL     0xFF03 // INTERNAL AND ONLY GET
@@ -1561,6 +1562,8 @@ static ERL_NIF_TERM ngetopt_otp_rcvctrlbuf(ErlNifEnv*        env,
                                            SocketDescriptor* descP);
 static ERL_NIF_TERM ngetopt_otp_sndctrlbuf(ErlNifEnv*        env,
                                            SocketDescriptor* descP);
+static ERL_NIF_TERM ngetopt_otp_fd(ErlNifEnv*        env,
+                                   SocketDescriptor* descP);
 static ERL_NIF_TERM ngetopt_otp_domain(ErlNifEnv*        env,
                                        SocketDescriptor* descP);
 static ERL_NIF_TERM ngetopt_otp_type(ErlNifEnv*        env,
@@ -10031,6 +10034,10 @@ ERL_NIF_TERM ngetopt_otp(ErlNifEnv*        env,
         result = ngetopt_otp_sndctrlbuf(env, descP);
         break;
 
+    case SOCKET_OPT_OTP_FD:
+        result = ngetopt_otp_fd(env, descP);
+        break;
+
         /* *** INTERNAL *** */
     case SOCKET_OPT_OTP_DOMAIN:
         result = ngetopt_otp_domain(env, descP);
@@ -10058,7 +10065,7 @@ ERL_NIF_TERM ngetopt_otp(ErlNifEnv*        env,
 }
 
 
-/* ngetopt_otp_debug - Handle the OTP (level) debug options
+/* ngetopt_otp_debug - Handle the OTP (level) debug option
  */
 static
 ERL_NIF_TERM ngetopt_otp_debug(ErlNifEnv*        env,
@@ -10070,7 +10077,7 @@ ERL_NIF_TERM ngetopt_otp_debug(ErlNifEnv*        env,
 }
 
 
-/* ngetopt_otp_iow - Handle the OTP (level) iow options
+/* ngetopt_otp_iow - Handle the OTP (level) iow option
  */
 static
 ERL_NIF_TERM ngetopt_otp_iow(ErlNifEnv*        env,
@@ -10082,7 +10089,7 @@ ERL_NIF_TERM ngetopt_otp_iow(ErlNifEnv*        env,
 }
 
 
-/* ngetopt_otp_ctrl_proc - Handle the OTP (level) controlling_process options
+/* ngetopt_otp_ctrl_proc - Handle the OTP (level) controlling_process option
  */
 static
 ERL_NIF_TERM ngetopt_otp_ctrl_proc(ErlNifEnv*        env,
@@ -10095,7 +10102,7 @@ ERL_NIF_TERM ngetopt_otp_ctrl_proc(ErlNifEnv*        env,
 
 
 
-/* ngetopt_otp_rcvbuf - Handle the OTP (level) rcvbuf options
+/* ngetopt_otp_rcvbuf - Handle the OTP (level) rcvbuf option
  */
 static
 ERL_NIF_TERM ngetopt_otp_rcvbuf(ErlNifEnv*        env,
@@ -10107,7 +10114,7 @@ ERL_NIF_TERM ngetopt_otp_rcvbuf(ErlNifEnv*        env,
 }
 
 
-/* ngetopt_otp_rcvctrlbuf - Handle the OTP (level) rcvctrlbuf options
+/* ngetopt_otp_rcvctrlbuf - Handle the OTP (level) rcvctrlbuf option
  */
 static
 ERL_NIF_TERM ngetopt_otp_rcvctrlbuf(ErlNifEnv*        env,
@@ -10119,7 +10126,7 @@ ERL_NIF_TERM ngetopt_otp_rcvctrlbuf(ErlNifEnv*        env,
 }
 
 
-/* ngetopt_otp_sndctrlbuf - Handle the OTP (level) sndctrlbuf options
+/* ngetopt_otp_sndctrlbuf - Handle the OTP (level) sndctrlbuf option
  */
 static
 ERL_NIF_TERM ngetopt_otp_sndctrlbuf(ErlNifEnv*        env,
@@ -10131,7 +10138,19 @@ ERL_NIF_TERM ngetopt_otp_sndctrlbuf(ErlNifEnv*        env,
 }
 
 
-/* ngetopt_otp_domain - Handle the OTP (level) domain options.
+/* ngetopt_otp_fd - Handle the OTP (level) fd option
+ */
+static
+ERL_NIF_TERM ngetopt_otp_fd(ErlNifEnv*        env,
+                            SocketDescriptor* descP)
+{
+    ERL_NIF_TERM eVal = MKI(env, descP->sock);
+
+    return esock_make_ok2(env, eVal);
+}
+
+
+/* ngetopt_otp_domain - Handle the OTP (level) domain option
  */
 static
 ERL_NIF_TERM ngetopt_otp_domain(ErlNifEnv*        env,
diff --git a/erts/emulator/test/socket_SUITE.erl b/erts/emulator/test/socket_SUITE.erl
index 6d44a245e4..2fbc0dddad 100644
--- a/erts/emulator/test/socket_SUITE.erl
+++ b/erts/emulator/test/socket_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %% 
-%% Copyright Ericsson AB 2018-2018. All Rights Reserved.
+%% Copyright Ericsson AB 2018-2019. All Rights Reserved.
 %% 
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -3112,37 +3112,6 @@ api_to_connect_tcp_await_timeout3([Sock|Socka]) ->
     (catch socket:close(Sock)),
     api_to_connect_tcp_await_timeout3(Socka).
 
-%% api_to_connect_tcp_await_timeout(Socks, To, ServerSA) ->
-%%     api_to_connect_tcp_await_timeout(Socks, To, ServerSA, 1).
-
-%% api_to_connect_tcp_await_timeout([], _To, _ServerSA, _ID) ->
-%%     ?FAIL(unexpected_success);
-%% api_to_connect_tcp_await_timeout([Sock|Socks], To, ServerSA, ID) ->
-%%     ?SEV_IPRINT("~w: try connect", [ID]),
-%%     Start = t(),
-%%     case socket:connect(Sock, ServerSA, To) of
-%%         {error, timeout} ->
-%%             ?SEV_IPRINT("expected timeout (~w)", [ID]),
-%%             Stop  = t(),
-%%             TDiff = tdiff(Start, Stop),
-%%             if
-%%                 (TDiff >= To) ->
-%%                     ok;
-%%                 true ->
-%%                     {error, {unexpected_timeout, TDiff, To}}
-%%             end;
-%%         {error, econnreset = Reason} ->
-%%             ?SEV_IPRINT("failed connecting: ~p - giving up", [Reason]),
-%%             ok;
-%%         {error, Reason} ->
-%%             ?SEV_EPRINT("failed connecting: ~p", [Reason]),
-%%             ?FAIL({connect, Reason});
-%%         ok ->
-%%             ?SEV_IPRINT("unexpected success (~w) - try next", [ID]),
-%%             api_to_connect_tcp_await_timeout(Socks, To, ServerSA, ID+1)
-%%     end.
-        
-
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
@@ -6866,6 +6835,12 @@ sc_rc_tcp_client_create(Domain) ->
     i("sc_rc_tcp_client_create -> entry"),
     case socket:open(Domain, stream, tcp) of
         {ok, Sock} ->
+            case socket:getopt(Sock, otp, fd) of
+                {ok, FD} ->
+                    put(sname, f("rclient-~w", [FD])); % Update SName
+                _ ->
+                    ok
+            end,
             Sock;
         {error, Reason} ->
             exit({open_failed, Reason})
@@ -6884,10 +6859,11 @@ sc_rc_tcp_client_bind(Sock, Domain) ->
     end.
 
 sc_rc_tcp_client_announce_ready(Parent, Slogan) ->
+    ?SEV_IPRINT("ready ~w", [Slogan]),
     ?SEV_ANNOUNCE_READY(Parent, Slogan).
 
 sc_rc_tcp_client_await_continue(Parent, Slogan) ->
-    i("sc_rc_tcp_client_await_continue -> entry"),
+    ?SEV_IPRINT("await ~w continue", [Slogan]),
     ?SEV_AWAIT_CONTINUE(Parent, parent, Slogan).
 
 sc_rc_tcp_client_connect(Sock, ServerSA) ->
@@ -6927,15 +6903,15 @@ sc_rc_tcp_handler_start(ID, Recv, Sock) ->
     Pid.
 
 sc_rc_tcp_handler(ID, Parent, Recv, Sock) ->
-    sc_rc_tcp_handler_init(ID, Parent),
+    sc_rc_tcp_handler_init(ID, socket:getopt(Sock, otp, fd), Parent),
     sc_rc_tcp_handler_await(Parent, recv),
     RecvRes = sc_rc_tcp_handler_recv(Recv, Sock),
     sc_rc_tcp_handler_announce_ready(Parent, recv, RecvRes),
     Reason = sc_rc_tcp_handler_await(Parent, terminate),
     exit(Reason).
 
-sc_rc_tcp_handler_init(ID, Parent) ->
-    put(sname, f("handler-~w", [ID])),
+sc_rc_tcp_handler_init(ID, {ok, FD}, Parent) ->
+    put(sname, f("handler-~w:~w", [ID, FD])),
     _MRef = erlang:monitor(process, Parent),
     ?SEV_IPRINT("started"),
     ?SEV_ANNOUNCE_READY(Parent, init),
diff --git a/erts/preloaded/ebin/socket.beam b/erts/preloaded/ebin/socket.beam
index ddd50fdefa..06e7c2910d 100644
--- a/erts/preloaded/ebin/socket.beam
+++ b/erts/preloaded/ebin/socket.beam
diff --git a/erts/preloaded/src/socket.erl b/erts/preloaded/src/socket.erl
index 2e295a91ae..839087ef2a 100644
--- a/erts/preloaded/src/socket.erl
+++ b/erts/preloaded/src/socket.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2018-2018. All Rights Reserved.
+%% Copyright Ericsson AB 2018-2019. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -41,12 +41,10 @@
          send/2, send/3, send/4,
          sendto/3, sendto/4, sendto/5,
          sendmsg/2, sendmsg/3, sendmsg/4,
-         %% writev/4, OR SENDV? It will be strange for recv then: recvv (instead of readv)
 
          recv/1, recv/2, recv/3, recv/4,
          recvfrom/1, recvfrom/2, recvfrom/3, recvfrom/4,
          recvmsg/1, recvmsg/2, recvmsg/3, recvmsg/5,
-         %% readv/3,
 
          close/1,
          shutdown/2,
@@ -164,16 +162,6 @@
             0..65535,
             0..65535}.
 
-%% <KOLLA>
-%%
-%% Should we do these as maps instead?
-%% If we do we may need to include the family (domain) in the
-%% map (as the native type do. See struct sockaddr_in6).
-%%
-%% What about default values? Such as for port (=0) and addr (=any)?
-%%
-%% </KOLLA>
-
 -type timeval() :: #{sec  := integer(),
                      usec := integer()}.
 
@@ -183,7 +171,7 @@
                         addr     := ip4_address()      % Header Destination address
                        }.
 
-%% If the integer value is used its up to the caller to ensure its valid!
+%% If the integer value is used, its up to the caller to ensure its valid!
 -type ip_tos() :: lowdeley |
                   throughput |
                   reliability |
@@ -326,10 +314,10 @@
 -type otp_socket_option() :: debug |
                              iow |
                              controlling_process |
-                             rcvbuf |
-                             sndbuf |
+                             rcvbuf | % sndbuf |
                              rcvctrlbuf |
-                             sndctrlbuf.
+                             sndctrlbuf |
+                             fd.
 %% Shall we have special treatment of linger??
 %% read-only options:
 %% domain | protocol | type.
@@ -653,6 +641,7 @@
 %%-define(SOCKET_OPT_OTP_SNDBUF,           5).
 -define(SOCKET_OPT_OTP_RCVCTRLBUF,       6).
 -define(SOCKET_OPT_OTP_SNDCTRLBUF,       7).
+-define(SOCKET_OPT_OTP_FD,               8).
 -define(SOCKET_OPT_OTP_DOMAIN,           16#FF01). % INTERNAL
 -define(SOCKET_OPT_OTP_TYPE,             16#FF02). % INTERNAL
 -define(SOCKET_OPT_OTP_PROTOCOL,         16#FF03). % INTERNAL
@@ -3051,6 +3040,8 @@ enc_sockopt_key(otp, rcvctrlbuf, _, _, _, _) ->
     ?SOCKET_OPT_OTP_RCVCTRLBUF;
 enc_sockopt_key(otp, sndctrlbuf, _, _, _, _) ->
     ?SOCKET_OPT_OTP_SNDCTRLBUF;
+enc_sockopt_key(otp, fd, get = _Dir, _, _, _) ->
+    ?SOCKET_OPT_OTP_FD;
 enc_sockopt_key(otp = L, Opt, _, _, _, _) ->
     not_supported({L, Opt});