--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.naming/share/classes/com/sun/jndi/ldap/VersionHelper.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 1999, 2014, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+
+package com.sun.jndi.ldap;
+
+import jdk.internal.misc.SharedSecrets;
+
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.security.AccessControlContext;
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+
+public final class VersionHelper {
+
+    private static final VersionHelper helper = new VersionHelper();
+
+    /**
+     * Determines whether classes may be loaded from an arbitrary URL code base.
+     */
+    private static final boolean trustURLCodebase;
+
+    static {
+        // System property to control whether classes may be loaded from an
+        // arbitrary URL code base
+        PrivilegedAction<String> act =
+                () -> System.getProperty("com.sun.jndi.ldap.object.trustURLCodebase", "false");
+        String trust = AccessController.doPrivileged(act);
+        trustURLCodebase = "true".equalsIgnoreCase(trust);
+    }
+
+    private VersionHelper() { }
+
+    static VersionHelper getVersionHelper() {
+        return helper;
+    }
+
+    ClassLoader getURLClassLoader(String[] url) throws MalformedURLException {
+        ClassLoader parent = getContextClassLoader();
+        /*
+         * Classes may only be loaded from an arbitrary URL code base when
+         * the system property com.sun.jndi.ldap.object.trustURLCodebase
+         * has been set to "true".
+         */
+        if (url != null && trustURLCodebase) {
+            return URLClassLoader.newInstance(getUrlArray(url), parent);
+        } else {
+            return parent;
+        }
+    }
+
+    Class<?> loadClass(String className) throws ClassNotFoundException {
+        return Class.forName(className, true, getContextClassLoader());
+    }
+
+    Thread createThread(Runnable r) {
+        AccessControlContext acc = AccessController.getContext();
+        // 4290486: doPrivileged is needed to create a thread in
+        // an environment that restricts "modifyThreadGroup".
+        PrivilegedAction<Thread> act =
+                () -> SharedSecrets.getJavaLangAccess().newThreadWithAcc(r, acc);
+        return AccessController.doPrivileged(act);
+    }
+
+    private ClassLoader getContextClassLoader() {
+        PrivilegedAction<ClassLoader> act =
+                Thread.currentThread()::getContextClassLoader;
+        return AccessController.doPrivileged(act);
+    }
+
+    private static URL[] getUrlArray(String[] url) throws MalformedURLException {
+        URL[] urlArray = new URL[url.length];
+        for (int i = 0; i < urlArray.length; i++) {
+            urlArray[i] = new URL(url[i]);
+        }
+        return urlArray;
+    }
+}