JavaAdapterClassLoader.java revision 953:221a84ef44c0
1/* 2 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26package jdk.nashorn.internal.runtime.linker; 27 28import java.security.AccessControlContext; 29import java.security.AccessController; 30import java.security.PrivilegedAction; 31import java.security.ProtectionDomain; 32import java.security.SecureClassLoader; 33import java.util.Arrays; 34import java.util.Collection; 35import java.util.Collections; 36import java.util.HashSet; 37import jdk.internal.dynalink.beans.StaticClass; 38import jdk.nashorn.internal.codegen.DumpBytecode; 39import jdk.nashorn.internal.runtime.Context; 40import jdk.nashorn.internal.runtime.JSType; 41import jdk.nashorn.internal.runtime.ScriptFunction; 42 43/** 44 * This class encapsulates the bytecode of the adapter class and can be used to load it into the JVM as an actual Class. 45 * It can be invoked repeatedly to create multiple adapter classes from the same bytecode; adapter classes that have 46 * class-level overrides must be re-created for every set of such overrides. Note that while this class is named 47 * "class loader", it does not, in fact, extend {@code ClassLoader}, but rather uses them internally. Instances of this 48 * class are normally created by {@code JavaAdapterBytecodeGenerator}. 49 */ 50final class JavaAdapterClassLoader { 51 private static final AccessControlContext CREATE_LOADER_ACC_CTXT = ClassAndLoader.createPermAccCtxt("createClassLoader"); 52 private static final AccessControlContext GET_CONTEXT_ACC_CTXT = ClassAndLoader.createPermAccCtxt(Context.NASHORN_GET_CONTEXT); 53 private static final Collection<String> VISIBLE_INTERNAL_CLASS_NAMES = Collections.unmodifiableCollection(new HashSet<>( 54 Arrays.asList(JavaAdapterServices.class.getName(), ScriptFunction.class.getName(), JSType.class.getName()))); 55 56 private final String className; 57 private final byte[] classBytes; 58 59 JavaAdapterClassLoader(final String className, final byte[] classBytes) { 60 this.className = className.replace('/', '.'); 61 this.classBytes = classBytes; 62 } 63 64 /** 65 * Loads the generated adapter class into the JVM. 66 * @param parentLoader the parent class loader for the generated class loader 67 * @param protectionDomain the protection domain for the generated class 68 * @return the generated adapter class 69 */ 70 StaticClass generateClass(final ClassLoader parentLoader, final ProtectionDomain protectionDomain) { 71 assert protectionDomain != null; 72 return AccessController.doPrivileged(new PrivilegedAction<StaticClass>() { 73 @Override 74 public StaticClass run() { 75 try { 76 return StaticClass.forClass(Class.forName(className, true, createClassLoader(parentLoader, protectionDomain))); 77 } catch (final ClassNotFoundException e) { 78 throw new AssertionError(e); // cannot happen 79 } 80 } 81 }, CREATE_LOADER_ACC_CTXT); 82 } 83 84 // Note that the adapter class is created in the protection domain of the class/interface being 85 // extended/implemented, and only the privileged global setter action class is generated in the protection domain 86 // of Nashorn itself. Also note that the creation and loading of the global setter is deferred until it is 87 // required by JVM linker, which will only happen on first invocation of any of the adapted method. We could defer 88 // it even more by separating its invocation into a separate static method on the adapter class, but then someone 89 // with ability to introspect on the class and use setAccessible(true) on it could invoke the method. It's a 90 // security tradeoff... 91 private ClassLoader createClassLoader(final ClassLoader parentLoader, final ProtectionDomain protectionDomain) { 92 return new SecureClassLoader(parentLoader) { 93 private final ClassLoader myLoader = getClass().getClassLoader(); 94 95 @Override 96 public Class<?> loadClass(final String name, final boolean resolve) throws ClassNotFoundException { 97 try { 98 Context.checkPackageAccess(name); 99 return super.loadClass(name, resolve); 100 } catch (final SecurityException se) { 101 // we may be implementing an interface or extending a class that was 102 // loaded by a loader that prevents package.access. If so, it'd throw 103 // SecurityException for nashorn's classes!. For adapter's to work, we 104 // should be able to refer to the few classes it needs in its implementation. 105 if(VISIBLE_INTERNAL_CLASS_NAMES.contains(name)) { 106 return myLoader.loadClass(name); 107 } 108 throw se; 109 } 110 } 111 112 @Override 113 protected Class<?> findClass(final String name) throws ClassNotFoundException { 114 if(name.equals(className)) { 115 assert classBytes != null : "what? already cleared .class bytes!!"; 116 117 final Context ctx = AccessController.doPrivileged(new PrivilegedAction<Context>() { 118 @Override 119 public Context run() { 120 return Context.getContext(); 121 } 122 }, GET_CONTEXT_ACC_CTXT); 123 DumpBytecode.dumpBytecode(ctx.getEnv(), ctx.getLogger(jdk.nashorn.internal.codegen.Compiler.class), classBytes, name); 124 return defineClass(name, classBytes, 0, classBytes.length, protectionDomain); 125 } 126 throw new ClassNotFoundException(name); 127 } 128 }; 129 } 130} 131