com.sun.ejb.codegen.ClassGenerator Maven / Gradle / Ivy
/*
* Copyright (c) 2022, 2023 Eclipse Foundation and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package com.sun.ejb.codegen;
import com.sun.enterprise.loader.ASURLClassLoader;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodHandles.Lookup;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedExceptionAction;
import java.security.ProtectionDomain;
import java.util.Objects;
import java.util.logging.Logger;
import static java.util.logging.Level.CONFIG;
/**
* This class serves to generate classes, because ...
*
* {@link java.lang.invoke.MethodHandles.Lookup} class restricts the generated class to use
* an already existing class as a source of the package and {@link ProtectionDomain}.
*
* {@link Proxy#newProxyInstance(ClassLoader, Class[], java.lang.reflect.InvocationHandler)}
* has another requirements, ie. all referred classes must be loadable by used classloader.
*
* @author David Matejcek
*/
public final class ClassGenerator {
private static final Logger LOG = Logger.getLogger(ClassGenerator.class.getName());
private static Method defineClassMethod;
private static Method defineClassMethodSM;
static {
try {
final PrivilegedExceptionAction action = () -> {
final Class cl = Class.forName("java.lang.ClassLoader");
final String name = "defineClass";
defineClassMethod = cl.getDeclaredMethod(name, String.class, byte[].class, int.class, int.class);
defineClassMethod.setAccessible(true);
defineClassMethodSM = cl.getDeclaredMethod(
name, String.class, byte[].class, int.class, int.class, ProtectionDomain.class);
defineClassMethodSM.setAccessible(true);
return null;
};
AccessController.doPrivileged(action);
LOG.config("ClassLoader methods capable of generating classes were successfully detected.");
} catch (final Exception e) {
throw new Error("Could not initialize access to ClassLoader.defineClass method.", e);
}
}
private ClassGenerator() {
// hidden
}
/**
* Decides which method is suitable to define the new class and then uses it.
*
* @param loader the classloader instance used to generate the class
* @param anchorClass the class used as an "orientation" class. See the {@link Lookup} class for
* more info.
* @param targetPackageName the name is used in decision logic; if the anchor class is from
* a different package, the {@link Lookup}'s method is not usable.
* @param className expected binary name or null
* @param classData the valid bytes that make up the class data.
* @return the new generated class
* @throws ClassDefinitionException invalid data, missing dependency, or another error related
* to the class generation
*/
public static Class defineClass(final ClassLoader loader, final Class anchorClass,
final String targetPackageName, final String className, final byte[] classData) {
if (useMethodHandles(loader, anchorClass, targetPackageName)) {
return defineClass(anchorClass, className, classData);
}
return defineClass(loader, className, classData, anchorClass.getProtectionDomain());
}
/**
* Calls the {@link Lookup}'s defineClass method to create a new class.
*
* @param anchorClass the class used as an "orientation" class. See the {@link Lookup} class for more info.
* @param className expected binary name or null
* @param classData the valid bytes that make up the class data.
* @return the new generated class
* @throws ClassDefinitionException invalid data, missing dependency, or another error related
* to the class generation
*/
public static Class defineClass(final Class anchorClass, final String className, final byte[] classData) {
LOG.log(CONFIG, "Defining class: {0} with anchorClass: {1}", new Object[] {className, anchorClass});
final PrivilegedAction> action = () -> {
try {
final Lookup lookup = MethodHandles.privateLookupIn(anchorClass, MethodHandles.lookup());
return lookup.defineClass(classData);
} catch (IllegalAccessException e) {
throw new ClassDefinitionException(className,anchorClass, e);
}
};
return AccessController.doPrivileged(action);
}
/**
* Calls the {@link ClassLoader}'s protected defineClass method to create a new class.
*
* @param loader the classloader instance used to generate the class
* @param className expected binary name or null
* @param classData the valid bytes that make up the class data.
* @return the new generated class
* @throws ClassDefinitionException invalid data, missing dependency, or another error related
* to the class generation
*/
public static Class defineClass(final ClassLoader loader, final String className, final byte[] classData)
throws ClassDefinitionException {
return defineClass(loader, className, classData, 0, classData.length);
}
/**
* Calls the {@link ClassLoader}'s protected defineClass method to create a new class.
*
* @param loader the classloader instance used to generate the class
* @param className expected binary name or null
* @param classData the valid bytes that make up the class data.
* @param offset The start offset in {@code b} of the class data
* @param length The length of the class data
* @return the new generated class
* @throws ClassDefinitionException invalid data, missing dependency, or another error related
* to the class generation
*/
public static Class defineClass(final ClassLoader loader, final String className, final byte[] classData,
final int offset, final int length) throws ClassDefinitionException {
LOG.log(CONFIG, "Defining class: {0} by loader: {1}", new Object[] {className, loader});
final PrivilegedAction> action = () -> {
try {
return (Class) defineClassMethod.invoke(loader, className, classData, 0, length);
} catch (final Exception | NoClassDefFoundError | ClassFormatError e) {
throw new ClassDefinitionException(className, loader, e);
}
};
return AccessController.doPrivileged(action);
}
/**
* Calls the {@link ClassLoader}'s protected defineClass method to create a new class.
*
* @param loader the classloader instance used to generate the class
* @param className expected binary name or null
* @param classData the valid bytes that make up the class data.
* @param protectionDomain The {@code ProtectionDomain} of the class
* @return the new generated class
* @throws ClassDefinitionException invalid data, missing dependency, or another error related
* to the class generation
*/
public static Class defineClass(final ClassLoader loader, final String className, final byte[] classData,
final ProtectionDomain protectionDomain) throws ClassDefinitionException {
return defineClass(loader, className, classData, 0, classData.length, protectionDomain);
}
/**
* Calls the {@link ClassLoader}'s protected defineClass method to create a new class.
*
* @param loader the classloader instance used to generate the class
* @param className expected binary name or null
* @param classData the valid bytes that make up the class data.
* @param offset The start offset in {@code b} of the class data
* @param length The length of the class data
* @param protectionDomain The {@code ProtectionDomain} of the class
* @return the new generated class
* @throws ClassDefinitionException invalid data, missing dependency, or another error related
* to the class generation
*/
public static Class defineClass(
final ClassLoader loader, final String className,
final byte[] classData, final int offset, final int length,
final ProtectionDomain protectionDomain) throws ClassDefinitionException {
LOG.log(CONFIG, "Defining class: {0} by loader: {1}", new Object[] {className, loader});
final PrivilegedAction> action = () -> {
try {
return (Class) defineClassMethodSM.invoke(loader, className, classData, 0, length, protectionDomain);
} catch (final Exception | NoClassDefFoundError | ClassFormatError e) {
throw new ClassDefinitionException(className, loader, e);
}
};
return AccessController.doPrivileged(action);
}
/**
* The class wasn't generated. See the message and cause to see what happened.
*/
public static class ClassDefinitionException extends RuntimeException {
private static final long serialVersionUID = -8955780830818904365L;
ClassDefinitionException(final String className, final ClassLoader loader, final Throwable cause) {
super("Could not define class '" + className + "' by the class loader: " + loader, cause);
}
ClassDefinitionException(final String className, final Class anchorClass, final Throwable cause) {
super("Could not define class '" + className + "' using the anchor " + anchorClass, cause);
}
}
private static boolean useMethodHandles(final ClassLoader loader, final Class anchorClass,
final String targetPackageName) {
if (loader == null) {
return true;
}
// The bootstrap CL used by embedded glassfish doesn't remember generated classes
// Further ClassLoader.findClass calls will fail.
if (anchorClass == null || loader.getParent() == null || loader.getClass() == ASURLClassLoader.class) {
return false;
}
// Use MethodHandles.Lookup only if the anchor run-time Package defined by CL.
return Objects.equals(anchorClass.getPackage(), loader.getDefinedPackage(targetPackageName));
}
}