Merge branch 'legoscia/erts/epmd-module-option/OTP-13627'

* legoscia/erts/epmd-module-option/OTP-13627:
  Add tests for -start_epmd and -epmd_module options
  Use the -epmd_module flag consistently
  Add -start_epmd command line option

4 files changed, 109 insertions, 4 deletions

diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index 1bbde7f1e0..e63928ddb0 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -338,7 +338,8 @@
           <seealso marker="kernel:net_kernel">net_kernel(3)</seealso>.
           It is also ensured that <c><![CDATA[epmd]]></c> runs on the current host
           before Erlang is started. See
-          <seealso marker="epmd">epmd(1)</seealso>.</p>
+          <seealso marker="epmd">epmd(1)</seealso> and the
+          <seealso marker="#start_epmd"><c>-start_epmd</c></seealso> option.</p>
         <p>The name of the node will be <c><![CDATA[Name@Host]]></c>, where
           <c><![CDATA[Host]]></c> is the fully qualified host name of the current
           host. For short names, use the <c><![CDATA[-sname]]></c> flag instead.</p>
@@ -463,6 +464,21 @@
           flag and those running with the <c><![CDATA[-name]]></c> flag, as node
           names must be unique in distributed Erlang systems.</p>
       </item>
+      <tag><marker id="start_epmd"/><c>-start_epmd true | false</c></tag>
+      <item>
+
+        <p>Specifies whether Erlang should start
+          <seealso marker="epmd">epmd</seealso> on startup. By default
+          this is <c>true</c>, but if you prefer to start epmd
+          manually, set this to <c>false</c>.</p>
+
+        <p>This only applies if Erlang is started as a distributed node,
+          i.e. if <c>-name</c> or <c>-sname</c> is specified. Otherwise,
+          epmd is not started even if <c>-start_epmd true</c> is given.</p>
+
+        <p>Note that a distributed node will fail to start if epmd is
+          not running.</p>
+      </item>
       <tag><marker id="smp"/><c><![CDATA[-smp [enable|auto|disable]]]></c></tag>
       <item>
         <p><c>-smp enable</c> and <c>-smp</c> starts the Erlang runtime
diff --git a/erts/doc/src/init.xml b/erts/doc/src/init.xml
index 84a5aea335..878a33c9ca 100644
--- a/erts/doc/src/init.xml
+++ b/erts/doc/src/init.xml
@@ -241,6 +241,11 @@
          marker="kernel:code">code(3)</seealso>.</p>
 	 
       </item>
+      <tag><c>-epmd_module Module</c></tag>
+      <item>
+        <p>Specifies the module to use for registration and lookup of
+          node names.  Defaults to <c>erl_epmd</c>.</p>
+      </item>
       <tag><c>-eval Expr</c></tag>
       <item>
         <p>Scans, parses and evaluates an arbitrary expression
diff --git a/erts/emulator/test/distribution_SUITE.erl b/erts/emulator/test/distribution_SUITE.erl
index d0096fb1bc..26780f6017 100644
--- a/erts/emulator/test/distribution_SUITE.erl
+++ b/erts/emulator/test/distribution_SUITE.erl
@@ -55,7 +55,8 @@
          bad_dist_ext_receive/1,
          bad_dist_ext_process_info/1,
          bad_dist_ext_control/1,
-         bad_dist_ext_connection_id/1]).
+         bad_dist_ext_connection_id/1,
+	 start_epmd_false/1, epmd_module/1]).
 
 %% Internal exports.
 -export([sender/3, receiver2/2, dummy_waiter/0, dead_process/0,
@@ -64,6 +65,9 @@
          dist_evil_parallel_receiver/0,
          sendersender/4, sendersender2/4]).
 
+%% epmd_module exports
+-export([start_link/0, register_node/2, port_please/2]).
+
 suite() ->
     [{ct_hooks,[ts_install_cth]},
      {timetrap, {minutes, 4}}].
@@ -76,7 +80,8 @@ all() ->
      {group, trap_bif}, {group, dist_auto_connect},
      dist_parallel_send, atom_roundtrip, unicode_atom_roundtrip, atom_roundtrip_r15b,
      contended_atom_cache_entry, contended_unicode_atom_cache_entry,
-     bad_dist_structure, {group, bad_dist_ext}].
+     bad_dist_structure, {group, bad_dist_ext},
+     start_epmd_false, epmd_module].
 
 groups() -> 
     [{bulk_send, [], [bulk_send_small, bulk_send_big, bulk_send_bigbig]},
@@ -1881,6 +1886,66 @@ dmsg_ext(Term) ->
 dmsg_bad_atom_cache_ref() ->
     [$R, 137].
 
+start_epmd_false(Config) when is_list(Config) ->
+    %% Start a node with the option -start_epmd false.
+    {ok, OtherNode} = start_node(start_epmd_false, "-start_epmd false"),
+    %% We should be able to ping it, as epmd was started by us:
+    pong = net_adm:ping(OtherNode),
+    stop_node(OtherNode),
+
+    ok.
+
+epmd_module(Config) when is_list(Config) ->
+    %% We need a relay node to test this, since the test node uses the
+    %% standard epmd module.
+    Sock1 = start_relay_node(epmd_module_node1, "-epmd_module " ++ ?MODULE_STRING),
+    Node1 = inet_rpc_nodename(Sock1),
+    %% Ask what port it's listening on - it won't have registered with
+    %% epmd.
+    {ok, {ok, Port1}} = do_inet_rpc(Sock1, application, get_env, [kernel, dist_listen_port]),
+
+    %% Start a second node, passing the port number as a secret
+    %% argument.
+    Sock2 = start_relay_node(epmd_module_node2, "-epmd_module " ++ ?MODULE_STRING
+			     ++ " -other_node_port " ++ integer_to_list(Port1)),
+    Node2 = inet_rpc_nodename(Sock2),
+    %% Node 1 can't ping node 2
+    {ok, pang} = do_inet_rpc(Sock1, net_adm, ping, [Node2]),
+    {ok, []} = do_inet_rpc(Sock1, erlang, nodes, []),
+    {ok, []} = do_inet_rpc(Sock2, erlang, nodes, []),
+    %% But node 2 can ping node 1
+    {ok, pong} = do_inet_rpc(Sock2, net_adm, ping, [Node1]),
+    {ok, [Node2]} = do_inet_rpc(Sock1, erlang, nodes, []),
+    {ok, [Node1]} = do_inet_rpc(Sock2, erlang, nodes, []),
+
+    stop_relay_node(Sock2),
+    stop_relay_node(Sock1).
+
+%% epmd_module functions:
+
+start_link() ->
+    ignore.
+
+register_node(_Name, Port) ->
+    %% Save the port number we're listening on.
+    application:set_env(kernel, dist_listen_port, Port),
+    Creation = rand:uniform(3),
+    {ok, Creation}.
+
+port_please(_Name, _Ip) ->
+    case init:get_argument(other_node_port) of
+	error ->
+	    %% None specified.  Default to 42.
+	    Port = 42,
+	    Version = 5,
+	    {port, Port, Version};
+	{ok, [[PortS]]} ->
+	    %% Port number given on command line.
+	    Port = list_to_integer(PortS),
+	    Version = 5,
+	    {port, Port, Version}
+    end.
+
 %%% Utilities
 
 timestamp() ->
diff --git a/erts/etc/common/erlexec.c b/erts/etc/common/erlexec.c
index 42da05b1f7..2b2e0e480a 100644
--- a/erts/etc/common/erlexec.c
+++ b/erts/etc/common/erlexec.c
@@ -195,6 +195,7 @@ static char *plusz_val_switches[] = {
 #endif
 
 void usage(const char *switchname);
+static void usage_format(char *format, ...);
 void start_epmd(char *epmd);
 void error(char* format, ...);
 
@@ -795,6 +796,24 @@ int main(int argc, char **argv)
 			    get_start_erl_data((char *) NULL);
 		    }
 #endif
+		    else if (strcmp(argv[i], "-start_epmd") == 0) {
+			if (i+1 >= argc)
+			    usage("-start_epmd");
+
+			if (strcmp(argv[i+1], "true") == 0) {
+			    /* The default */
+			    no_epmd = 0;
+			}
+			else if (strcmp(argv[i+1], "false") == 0) {
+			    no_epmd = 1;
+			}
+			else
+			    usage_format("Expected boolean argument for \'-start_epmd\'.\n");
+
+			add_arg(argv[i]);
+			add_arg(argv[i+1]);
+			i++;
+		    }
 		    else
 			add_arg(argv[i]);
 		
@@ -1173,7 +1192,7 @@ usage_aux(void)
 	  "]"
 #endif
 	  "] "
-	  "[-make] [-man [manopts] MANPAGE] [-x] [-emu_args] "
+	  "[-make] [-man [manopts] MANPAGE] [-x] [-emu_args] [-start_epmd BOOLEAN] "
 	  "[-args_file FILENAME] [+A THREADS] [+a SIZE] [+B[c|d|i]] [+c [BOOLEAN]] "
 	  "[+C MODE] [+h HEAP_SIZE_OPTION] [+K BOOLEAN] "
 	  "[+l] [+M<SUBSWITCH> <ARGUMENT>] [+P MAX_PROCS] [+Q MAX_PORTS] "