author | alanb |
Fri, 02 Nov 2012 15:50:11 +0000 | |
changeset 14342 | 8435a30053c1 |
parent 10342 | ca0984bc9d32 |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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package sun.reflect; |
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import java.security.AccessController; |
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import java.security.PrivilegedAction; |
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import sun.misc.Unsafe; |
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/** Utility class which assists in calling Unsafe.defineClass() by |
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creating a new class loader which delegates to the one needed in |
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order for proper resolution of the given bytecodes to occur. */ |
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class ClassDefiner { |
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static final Unsafe unsafe = Unsafe.getUnsafe(); |
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/** <P> We define generated code into a new class loader which |
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delegates to the defining loader of the target class. It is |
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necessary for the VM to be able to resolve references to the |
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target class from the generated bytecodes, which could not occur |
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if the generated code was loaded into the bootstrap class |
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loader. </P> |
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<P> There are two primary reasons for creating a new loader |
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instead of defining these bytecodes directly into the defining |
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loader of the target class: first, it avoids any possible |
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security risk of having these bytecodes in the same loader. |
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Second, it allows the generated bytecodes to be unloaded earlier |
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than would otherwise be possible, decreasing run-time |
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footprint. </P> |
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*/ |
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static Class<?> defineClass(String name, byte[] bytes, int off, int len, |
ca0984bc9d32
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final ClassLoader parentClassLoader) |
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{ |
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ClassLoader newLoader = AccessController.doPrivileged( |
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new PrivilegedAction<ClassLoader>() { |
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public ClassLoader run() { |
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return new DelegatingClassLoader(parentClassLoader); |
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} |
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}); |
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return unsafe.defineClass(name, bytes, off, len, newLoader, null); |
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} |
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} |
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// NOTE: this class's name and presence are known to the virtual |
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// machine as of the fix for 4474172. |
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class DelegatingClassLoader extends ClassLoader { |
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DelegatingClassLoader(ClassLoader parent) { |
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super(parent); |
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} |
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} |