| /* |
| * Copyright (c) 2001, 2008, 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 sun.reflect; |
| |
| import java.security.AccessController; |
| import java.security.PrivilegedAction; |
| import sun.misc.Unsafe; |
| |
| /** Utility class which assists in calling Unsafe.defineClass() by |
| creating a new class loader which delegates to the one needed in |
| order for proper resolution of the given bytecodes to occur. */ |
| |
| class ClassDefiner { |
| static final Unsafe unsafe = Unsafe.getUnsafe(); |
| |
| /** <P> We define generated code into a new class loader which |
| delegates to the defining loader of the target class. It is |
| necessary for the VM to be able to resolve references to the |
| target class from the generated bytecodes, which could not occur |
| if the generated code was loaded into the bootstrap class |
| loader. </P> |
| |
| <P> There are two primary reasons for creating a new loader |
| instead of defining these bytecodes directly into the defining |
| loader of the target class: first, it avoids any possible |
| security risk of having these bytecodes in the same loader. |
| Second, it allows the generated bytecodes to be unloaded earlier |
| than would otherwise be possible, decreasing run-time |
| footprint. </P> |
| */ |
| static Class defineClass(String name, byte[] bytes, int off, int len, |
| final ClassLoader parentClassLoader) |
| { |
| ClassLoader newLoader = AccessController.doPrivileged( |
| new PrivilegedAction<ClassLoader>() { |
| public ClassLoader run() { |
| return new DelegatingClassLoader(parentClassLoader); |
| } |
| }); |
| return unsafe.defineClass(name, bytes, off, len, newLoader, null); |
| } |
| } |
| |
| |
| // NOTE: this class's name and presence are known to the virtual |
| // machine as of the fix for 4474172. |
| class DelegatingClassLoader extends ClassLoader { |
| DelegatingClassLoader(ClassLoader parent) { |
| super(parent); |
| } |
| } |