| /* |
| * Copyright (c) 2013, 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 jdk.internal.misc; |
| |
| import java.security.AccessControlContext; |
| import java.security.AccessController; |
| import java.security.ProtectionDomain; |
| import java.security.PrivilegedAction; |
| import java.util.concurrent.atomic.AtomicInteger; |
| |
| /** |
| * A thread that has no permissions, is not a member of any user-defined |
| * ThreadGroup and supports the ability to erase ThreadLocals. |
| */ |
| public final class InnocuousThread extends Thread { |
| private static final jdk.internal.misc.Unsafe UNSAFE; |
| private static final long THREAD_LOCALS; |
| private static final long INHERITABLE_THREAD_LOCALS; |
| private static final ThreadGroup INNOCUOUSTHREADGROUP; |
| private static final AccessControlContext ACC; |
| private static final long INHERITEDACCESSCONTROLCONTEXT; |
| private static final long CONTEXTCLASSLOADER; |
| |
| private static final AtomicInteger threadNumber = new AtomicInteger(1); |
| private static String newName() { |
| return "InnocuousThread-" + threadNumber.getAndIncrement(); |
| } |
| |
| /** |
| * Returns a new InnocuousThread with an auto-generated thread name |
| * and its context class loader is set to the system class loader. |
| */ |
| public static Thread newThread(Runnable target) { |
| return newThread(newName(), target); |
| } |
| |
| /** |
| * Returns a new InnocuousThread with its context class loader |
| * set to the system class loader. |
| */ |
| public static Thread newThread(String name, Runnable target) { |
| return AccessController.doPrivileged( |
| new PrivilegedAction<Thread>() { |
| @Override |
| public Thread run() { |
| return new InnocuousThread(INNOCUOUSTHREADGROUP, |
| target, |
| name, |
| ClassLoader.getSystemClassLoader()); |
| } |
| }); |
| } |
| |
| /** |
| * Returns a new InnocuousThread with an auto-generated thread name. |
| * Its context class loader is set to null. |
| */ |
| public static Thread newSystemThread(Runnable target) { |
| return newSystemThread(newName(), target); |
| } |
| |
| /** |
| * Returns a new InnocuousThread with null context class loader. |
| */ |
| public static Thread newSystemThread(String name, Runnable target) { |
| return AccessController.doPrivileged( |
| new PrivilegedAction<Thread>() { |
| @Override |
| public Thread run() { |
| return new InnocuousThread(INNOCUOUSTHREADGROUP, |
| target, name, null); |
| } |
| }); |
| } |
| |
| private InnocuousThread(ThreadGroup group, Runnable target, String name, ClassLoader tccl) { |
| super(group, target, name, 0L, false); |
| UNSAFE.putObjectRelease(this, INHERITEDACCESSCONTROLCONTEXT, ACC); |
| UNSAFE.putObjectRelease(this, CONTEXTCLASSLOADER, tccl); |
| } |
| |
| @Override |
| public void setUncaughtExceptionHandler(UncaughtExceptionHandler x) { |
| // silently fail |
| } |
| |
| @Override |
| public void setContextClassLoader(ClassLoader cl) { |
| // Allow clearing of the TCCL to remove the reference to the system classloader. |
| if (cl == null) |
| super.setContextClassLoader(null); |
| else |
| throw new SecurityException("setContextClassLoader"); |
| } |
| |
| /** |
| * Drops all thread locals (and inherited thread locals). |
| */ |
| public final void eraseThreadLocals() { |
| UNSAFE.putObject(this, THREAD_LOCALS, null); |
| UNSAFE.putObject(this, INHERITABLE_THREAD_LOCALS, null); |
| } |
| |
| // ensure run method is run only once |
| private volatile boolean hasRun; |
| |
| @Override |
| public void run() { |
| if (Thread.currentThread() == this && !hasRun) { |
| hasRun = true; |
| super.run(); |
| } |
| } |
| |
| // Use Unsafe to access Thread group and ThreadGroup parent fields |
| static { |
| try { |
| ACC = new AccessControlContext(new ProtectionDomain[] { |
| new ProtectionDomain(null, null) |
| }); |
| |
| // Find and use topmost ThreadGroup as parent of new group |
| UNSAFE = jdk.internal.misc.Unsafe.getUnsafe(); |
| Class<?> tk = Thread.class; |
| Class<?> gk = ThreadGroup.class; |
| |
| THREAD_LOCALS = UNSAFE.objectFieldOffset(tk, "threadLocals"); |
| INHERITABLE_THREAD_LOCALS = UNSAFE.objectFieldOffset |
| (tk, "inheritableThreadLocals"); |
| INHERITEDACCESSCONTROLCONTEXT = UNSAFE.objectFieldOffset |
| (tk, "inheritedAccessControlContext"); |
| CONTEXTCLASSLOADER = UNSAFE.objectFieldOffset |
| (tk, "contextClassLoader"); |
| |
| long tg = UNSAFE.objectFieldOffset(tk, "group"); |
| long gp = UNSAFE.objectFieldOffset(gk, "parent"); |
| ThreadGroup group = (ThreadGroup) |
| UNSAFE.getObject(Thread.currentThread(), tg); |
| |
| while (group != null) { |
| ThreadGroup parent = (ThreadGroup)UNSAFE.getObject(group, gp); |
| if (parent == null) |
| break; |
| group = parent; |
| } |
| final ThreadGroup root = group; |
| INNOCUOUSTHREADGROUP = AccessController.doPrivileged( |
| new PrivilegedAction<ThreadGroup>() { |
| @Override |
| public ThreadGroup run() { |
| return new ThreadGroup(root, "InnocuousThreadGroup"); |
| } |
| }); |
| } catch (Exception e) { |
| throw new Error(e); |
| } |
| } |
| } |