better bookkeeping

README.md

@@ -2,7 +2,7 @@
 
 [![NPM version](https://badge.fury.io/js/socket-pair.svg)](http://badge.fury.io/js/socket-pair)
 
-A pair of coupled sockets.
+A pair of coupled Unix sockets (or Windows pipes).
 
 Similar to `stream-pair`, but with sockets with real fds. A workaround for <https://github.com/nodejs/node/issues/12716>.
 
@@ -11,9 +11,9 @@ Similar to `stream-pair`, but with sockets with real fds. A workaround for <http
 ```javascript
 var socketPair = require('socket-pair');
 
-socketPair.create(function (pair) {
-  var a = pair.client;
-  var b = pair.connection;
+socketPair.create(function (err, pair) {
+  var a = pair.client;      // as in `client = net.connect()`
+  var b = pair.connection;  // as in `server.on('connection', function (conn) { ... })`
 
   a.write('123');
   b.on('data', function (chunk) {
@@ -24,6 +24,10 @@ socketPair.create(function (pair) {
 });
 ```
 
+I named them `client` and `connection`, but their names really have no meaning.
+
+You can call them `a` and `b` or `other` and `one` or `red` and `blue`. It makes no difference.
+
 ## API
 
 ```

lib/socket-pair.js

@@ -4,7 +4,7 @@ var server;
 var listening = false;
 var sock;
 
-function createServer(prefix) {
+function createServer(cb, prefix) {
 	var os = require('os');
 	var net = require('net');
 	var path = require('path');
@@ -18,29 +18,44 @@ function createServer(prefix) {
   }
 
   server = net.createServer();
+  function onServerError(err) {
+    cb(err);
+  }
+  server.once('error', onServerError);
+  server.once('listening', function () {
+    listening = true;
+    server.removeListener('error', onServerError);
+  });
 }
 
 exports.create = function create(cb, prefix) {
 	var net = require('net');
-	var writer;
+	var client;
+
+  function createConnection() {
+    function onClientError(err) {
+      cb(err);
+    }
+    client = net.connect(sock, function () {
+      client.removeListener('error', onClientError);
+    });
+    client.once('error', onClientError);
+  }
 
 	// This server listens on a Unix socket or Windows pipe at 'sock'
   if (!server) {
-    createServer(prefix);
-  }
-  if (!listening) {
-    server.listen(sock, function () {
- 		  writer = net.connect(sock);
-      listening = true;
-    });
+    createServer(cb, prefix);
   }
 
-  server.once('connection', function each(reader) {
-    cb({ reader: reader, writer: writer });
+  server.once('connection', function onEach(connection) {
+    cb(null, { client: client, connection: connection });
   });
 
-  if (listening) {
- 		writer = net.connect(sock);
+  if (!listening) {
+    server.listen(sock, createConnection);
+  }
+  else {
+    createConnection();
   }
 };