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/*
* Javassist, a Java-bytecode translator toolkit.
* Copyright (C) 1999- Shigeru Chiba. All Rights Reserved.
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. Alternatively, the contents of this file may be used under
* the terms of the GNU Lesser General Public License Version 2.1 or later,
* or the Apache License Version 2.0.
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*/
package javassist.util.proxy;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodHandles.Lookup;
import java.lang.reflect.Method;
import java.security.ProtectionDomain;
import java.util.List;
import javassist.CannotCompileException;
import javassist.bytecode.ClassFile;
/**
* Helper class for invoking {@link ClassLoader#defineClass(String,byte[],int,int)}.
*
* @since 3.22
*/
public class DefineClassHelper {
private static abstract class Helper {
abstract Class defineClass(String name, byte[] b, int off, int len, Class neighbor,
ClassLoader loader, ProtectionDomain protectionDomain)
throws ClassFormatError, CannotCompileException;
}
private static class Java11 extends JavaOther {
Class defineClass(String name, byte[] bcode, int off, int len, Class neighbor,
ClassLoader loader, ProtectionDomain protectionDomain)
throws ClassFormatError, CannotCompileException
{
if (neighbor != null)
return toClass(neighbor, bcode);
else {
// Lookup#defineClass() is not available. So fallback to invoking defineClass on
// ClassLoader, which causes a warning message.
return super.defineClass(name, bcode, off, len, neighbor, loader, protectionDomain);
}
}
}
private static class Java9 extends Helper {
final class ReferencedUnsafe {
private final SecurityActions.TheUnsafe sunMiscUnsafeTheUnsafe;
private final MethodHandle defineClass;
ReferencedUnsafe(SecurityActions.TheUnsafe usf, MethodHandle meth) {
this.sunMiscUnsafeTheUnsafe = usf;
this.defineClass = meth;
}
Class defineClass(String name, byte[] b, int off, int len,
ClassLoader loader, ProtectionDomain protectionDomain)
throws ClassFormatError
{
try {
if (getCallerClass.invoke(stack) != Java9.class)
throw new IllegalAccessError("Access denied for caller.");
} catch (Exception e) {
throw new RuntimeException("cannot initialize", e);
}
try {
return (Class) defineClass.invokeWithArguments(
sunMiscUnsafeTheUnsafe.theUnsafe,
name, b, off, len, loader, protectionDomain);
} catch (Throwable e) {
if (e instanceof RuntimeException) throw (RuntimeException) e;
if (e instanceof ClassFormatError) throw (ClassFormatError) e;
throw new ClassFormatError(e.getMessage());
}
}
}
private final Object stack;
private final Method getCallerClass;
private final ReferencedUnsafe sunMiscUnsafe = getReferencedUnsafe();
Java9 () {
Class stackWalkerClass = null;
try {
stackWalkerClass = Class.forName("java.lang.StackWalker");
} catch (ClassNotFoundException e) {
// Skip initialization when the class doesn't exist i.e. we are on JDK < 9
}
if (stackWalkerClass != null) {
try {
Class optionClass = Class.forName("java.lang.StackWalker$Option");
stack = stackWalkerClass.getMethod("getInstance", optionClass)
// The first one is RETAIN_CLASS_REFERENCE
.invoke(null, optionClass.getEnumConstants()[0]);
getCallerClass = stackWalkerClass.getMethod("getCallerClass");
} catch (Throwable e) {
throw new RuntimeException("cannot initialize", e);
}
} else {
stack = null;
getCallerClass = null;
}
}
private final ReferencedUnsafe getReferencedUnsafe() {
try {
if (privileged != null && getCallerClass.invoke(stack) != this.getClass())
throw new IllegalAccessError("Access denied for caller.");
} catch (Exception e) {
throw new RuntimeException("cannot initialize", e);
}
try {
SecurityActions.TheUnsafe usf = SecurityActions.getSunMiscUnsafeAnonymously();
List defineClassMethod = usf.methods.get("defineClass");
// On Java 11+ the defineClass method does not exist anymore
if (null == defineClassMethod)
return null;
MethodHandle meth = MethodHandles.lookup().unreflect(defineClassMethod.get(0));
return new ReferencedUnsafe(usf, meth);
} catch (Throwable e) {
throw new RuntimeException("cannot initialize", e);
}
}
@Override
Class defineClass(String name, byte[] b, int off, int len, Class neighbor,
ClassLoader loader, ProtectionDomain protectionDomain)
throws ClassFormatError
{
try {
if (getCallerClass.invoke(stack) != DefineClassHelper.class)
throw new IllegalAccessError("Access denied for caller.");
} catch (Exception e) {
throw new RuntimeException("cannot initialize", e);
}
return sunMiscUnsafe.defineClass(name, b, off, len, loader,
protectionDomain);
}
}
private static class Java7 extends Helper {
private final SecurityActions stack = SecurityActions.stack;
private final MethodHandle defineClass = getDefineClassMethodHandle();
private final MethodHandle getDefineClassMethodHandle() {
if (privileged != null && stack.getCallerClass() != this.getClass())
throw new IllegalAccessError("Access denied for caller.");
try {
return SecurityActions.getMethodHandle(ClassLoader.class, "defineClass",
new Class[] {
String.class, byte[].class, int.class, int.class,
ProtectionDomain.class
});
} catch (NoSuchMethodException e) {
throw new RuntimeException("cannot initialize", e);
}
}
@Override
Class defineClass(String name, byte[] b, int off, int len, Class neighbor,
ClassLoader loader, ProtectionDomain protectionDomain)
throws ClassFormatError
{
if (stack.getCallerClass() != DefineClassHelper.class)
throw new IllegalAccessError("Access denied for caller.");
try {
return (Class) defineClass.invokeWithArguments(
loader, name, b, off, len, protectionDomain);
} catch (Throwable e) {
if (e instanceof RuntimeException) throw (RuntimeException) e;
if (e instanceof ClassFormatError) throw (ClassFormatError) e;
throw new ClassFormatError(e.getMessage());
}
}
}
private static class JavaOther extends Helper {
private final Method defineClass = getDefineClassMethod();
private final SecurityActions stack = SecurityActions.stack;
private final Method getDefineClassMethod() {
if (privileged != null && stack.getCallerClass() != this.getClass())
throw new IllegalAccessError("Access denied for caller.");
try {
return SecurityActions.getDeclaredMethod(ClassLoader.class, "defineClass",
new Class[] {
String.class, byte[].class, int.class, int.class, ProtectionDomain.class
});
} catch (NoSuchMethodException e) {
throw new RuntimeException("cannot initialize", e);
}
}
@Override
Class defineClass(String name, byte[] b, int off, int len, Class neighbor,
ClassLoader loader, ProtectionDomain protectionDomain)
throws ClassFormatError, CannotCompileException
{
Class klass = stack.getCallerClass();
if (klass != DefineClassHelper.class && klass != this.getClass())
throw new IllegalAccessError("Access denied for caller.");
try {
SecurityActions.setAccessible(defineClass, true);
return (Class) defineClass.invoke(loader, new Object[] {
name, b, off, len, protectionDomain
});
} catch (Throwable e) {
if (e instanceof ClassFormatError) throw (ClassFormatError) e;
if (e instanceof RuntimeException) throw (RuntimeException) e;
throw new CannotCompileException(e);
}
}
}
// Java 11+ removed sun.misc.Unsafe.defineClass, so we fallback to invoking defineClass on
// ClassLoader until we have an implementation that uses MethodHandles.Lookup.defineClass
private static final Helper privileged = ClassFile.MAJOR_VERSION > ClassFile.JAVA_10
? new Java11()
: ClassFile.MAJOR_VERSION >= ClassFile.JAVA_9
? new Java9()
: ClassFile.MAJOR_VERSION >= ClassFile.JAVA_7 ? new Java7() : new JavaOther();
/**
* Loads a class file by a given class loader.
*
* This first tries to use {@code java.lang.invoke.MethodHandle} to load a class.
* Otherwise, or if {@code neighbor} is null,
* this tries to use {@code sun.misc.Unsafe} to load a class.
* Then it tries to use a {@code protected} method in {@code java.lang.ClassLoader}
* via {@code PrivilegedAction}. Since the latter approach is not available
* any longer by default in Java 9 or later, the JVM argument
* {@code --add-opens java.base/java.lang=ALL-UNNAMED} must be given to the JVM.
* If this JVM argument cannot be given, {@link #toPublicClass(String,byte[])}
* should be used instead.
*
*
* @param className the name of the loaded class.
* @param neighbor the class contained in the same package as the loaded class.
* @param loader the class loader. It can be null if {@code neighbor} is not null
* and the JVM is Java 11 or later.
* @param domain if it is null, a default domain is used.
* @param bcode the bytecode for the loaded class.
* @since 3.22
*/
public static Class toClass(String className, Class neighbor, ClassLoader loader,
ProtectionDomain domain, byte[] bcode)
throws CannotCompileException
{
try {
return privileged.defineClass(className, bcode, 0, bcode.length,
neighbor, loader, domain);
}
catch (RuntimeException e) {
throw e;
}
catch (CannotCompileException e) {
throw e;
}
catch (ClassFormatError e) {
Throwable t = e.getCause();
throw new CannotCompileException(t == null ? e : t);
}
catch (Exception e) {
throw new CannotCompileException(e);
}
}
/**
* Loads a class file by {@code java.lang.invoke.MethodHandles.Lookup}.
* It is obtained by using {@code neighbor}.
*
* @param neighbor a class belonging to the same package that the loaded
* class belogns to.
* @param bcode the bytecode.
* @since 3.24
*/
public static Class toClass(Class neighbor, byte[] bcode)
throws CannotCompileException
{
try {
DefineClassHelper.class.getModule().addReads(neighbor.getModule());
Lookup lookup = MethodHandles.lookup();
Lookup prvlookup = MethodHandles.privateLookupIn(neighbor, lookup);
return prvlookup.defineClass(bcode);
} catch (IllegalAccessException | IllegalArgumentException e) {
throw new CannotCompileException(e.getMessage() + ": " + neighbor.getName()
+ " has no permission to define the class");
}
}
/**
* Loads a class file by {@code java.lang.invoke.MethodHandles.Lookup}.
* It can be obtained by {@code MethodHandles.lookup()} called from
* somewhere in the package that the loaded class belongs to.
*
* @param bcode the bytecode.
* @since 3.24
*/
public static Class toClass(Lookup lookup, byte[] bcode)
throws CannotCompileException
{
try {
return lookup.defineClass(bcode);
} catch (IllegalAccessException | IllegalArgumentException e) {
throw new CannotCompileException(e.getMessage());
}
}
/**
* Loads a class file by {@code java.lang.invoke.MethodHandles.Lookup}.
*
* @since 3.22
*/
static Class toPublicClass(String className, byte[] bcode)
throws CannotCompileException
{
try {
Lookup lookup = MethodHandles.lookup();
lookup = lookup.dropLookupMode(java.lang.invoke.MethodHandles.Lookup.PRIVATE);
return lookup.defineClass(bcode);
}
catch (Throwable t) {
throw new CannotCompileException(t);
}
}
private DefineClassHelper() {}
}