--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/java/nio/channels/TestUtil.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/* Test utilities
+ *
+ */
+
+import java.io.*;
+import java.net.*;
+import java.nio.channels.*;
+import java.util.Random;
+
+
+public class TestUtil {
+
+    // Test hosts used by the channels tests - change these when
+    // executing in a different network.
+    public static final String UNRESOLVABLE_HOST = "blah-blah.blah-blah.blah";
+
+    private TestUtil() { }
+
+    // Repeatedly try random ports until we bind to one.  You might be tempted
+    // to do this:
+    //
+    //     ServerSocketChannel ssc = ServerSocketChannel.open();
+    //     ssc.socket().bind(new InetSocketAddress(0));
+    //     SocketAddress sa = ssc.socket().getLocalSocketAddress();
+    //
+    // but unfortunately it doesn't work on NT 4.0.
+    //
+    // Returns the bound port.
+    //
+    static int bind(ServerSocketChannel ssc) throws IOException {
+        InetAddress lh = InetAddress.getLocalHost();
+        Random r = new Random();
+        for (;;) {
+            int p = r.nextInt((1 << 16) - 1024) + 1024;
+            InetSocketAddress isa = new InetSocketAddress(lh, p);
+            try {
+                ssc.socket().bind(isa);
+            } catch (IOException x) {
+                continue;
+            }
+            return p;
+        }
+    }
+
+    // A more convenient form of bind(ServerSocketChannel) that returns a full
+    // socket address.
+    //
+    static InetSocketAddress bindToRandomPort(ServerSocketChannel ssc)
+        throws IOException
+    {
+        int p = bind(ssc);
+        return new InetSocketAddress(InetAddress.getLocalHost(), p);
+    }
+
+    private static String osName = System.getProperty("os.name");
+
+    static boolean onSolaris() {
+        return osName.startsWith("SunOS");
+    }
+
+    static boolean onWindows() {
+        return osName.startsWith("Windows");
+    }
+}