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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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/*

 * @test

 * @bug 8232613

 * @summary Ensure Object natives stay registered after redefinition

 * @library /test/lib

 * @modules java.base/jdk.internal.misc

 *          java.base/jdk.internal.org.objectweb.asm

 *          java.compiler

 *          java.instrument

 *          jdk.jartool/sun.tools.jar

 * @run main RedefineObject buildagent

 * @run main/othervm -javaagent:redefineagent.jar RedefineObject

 */

import static jdk.test.lib.Asserts.assertTrue;

import java.io.FileNotFoundException;

import java.io.PrintWriter;

import java.lang.RuntimeException;

import java.lang.instrument.ClassFileTransformer;

import java.lang.instrument.IllegalClassFormatException;

import java.lang.instrument.Instrumentation;

import java.lang.instrument.UnmodifiableClassException;

import java.security.ProtectionDomain;

import java.util.Arrays;

import jdk.internal.org.objectweb.asm.ClassReader;

import jdk.internal.org.objectweb.asm.ClassVisitor;

import jdk.internal.org.objectweb.asm.ClassWriter;

import static jdk.internal.org.objectweb.asm.Opcodes.ASM6;

import static jdk.internal.org.objectweb.asm.Opcodes.V1_8;

public class RedefineObject {

    static Instrumentation inst;

    public static void premain(String agentArgs, Instrumentation inst) {

        RedefineObject.inst = inst;

    }

    static class Transformer implements ClassFileTransformer {

        public byte[] asm(ClassLoader loader, String className,

                          Class<?> classBeingRedefined,

                          ProtectionDomain protectionDomain, byte[] classfileBuffer)

                throws IllegalClassFormatException {

            ClassWriter cw = new ClassWriter(0);

            // Force an older ASM to force a bytecode update

            ClassVisitor cv = new DummyClassVisitor(ASM6, cw) { };

            ClassReader cr = new ClassReader(classfileBuffer);

            cr.accept(cv, 0);

            byte[] bytes = cw.toByteArray();

            return bytes;

        }

        public class DummyClassVisitor extends ClassVisitor {

            public DummyClassVisitor(int api, ClassVisitor cv) {

                super(api, cv);

            }

            public void visit(

                    final int version,

                    final int access,

                    final String name,

                    final String signature,

                    final String superName,

                    final String[] interfaces) {

                // Artificially lower to JDK 8 version to force a redefine

                cv.visit(V1_8, access, name, signature, superName, interfaces);

            }

        }

        @Override public byte[] transform(ClassLoader loader, String className,

                                          Class<?> classBeingRedefined,

                                          ProtectionDomain protectionDomain, byte[] classfileBuffer)

                throws IllegalClassFormatException {

            if (className.contains("java/lang/Object")) {

                try {

                    // Here we remove and re-add the dummy fields. This shuffles the constant pool

                    return asm(loader, className, classBeingRedefined, protectionDomain, classfileBuffer);

                } catch (Throwable e) {

                    // The retransform native code that called this method does not propagate

                    // exceptions. Instead of getting an uninformative generic error, catch

                    // problems here and print it, then exit.

                    e.printStackTrace();

                    System.exit(1);

                }

            }

            return null;

        }

    }

    private static void buildAgent() {

        try {

            ClassFileInstaller.main("RedefineObject");

        } catch (Exception e) {

            throw new RuntimeException("Could not write agent classfile", e);

        }

        try {

            PrintWriter pw = new PrintWriter("MANIFEST.MF");

            pw.println("Premain-Class: RedefineObject");

            pw.println("Agent-Class: RedefineObject");

            pw.println("Can-Retransform-Classes: true");

            pw.close();

        } catch (FileNotFoundException e) {

            throw new RuntimeException("Could not write manifest file for the agent", e);

        }

        sun.tools.jar.Main jarTool = new sun.tools.jar.Main(System.out, System.err, "jar");

        if (!jarTool.run(new String[] { "-cmf", "MANIFEST.MF", "redefineagent.jar", "RedefineObject.class" })) {

            throw new RuntimeException("Could not write the agent jar file");

        }

    }

    public static void main(String[] args) throws Exception {

        int objHash = System.identityHashCode(Object.class);

        System.out.println("Object hashCode: " + objHash);

        if (args.length == 1 && args[0].equals("buildagent")) {

            buildAgent();

            return;

        }

        if (inst == null) {

            throw new RuntimeException("Instrumentation object was null");

        }

        try {

            inst.addTransformer(new RedefineObject.Transformer(), true);

            inst.retransformClasses(Object.class);

        } catch (UnmodifiableClassException e) {

            throw new RuntimeException(e);

        }

        // Exercise native methods on Object after transform

        Object b = new Object();

        b.hashCode();

        C c = new C();

        assertTrue(c.hashCode() != c.clone().hashCode() || c != c.clone());

        assertTrue(c.clone() instanceof C);

        c = (C)c.clone(); // native method on new Object

    }

    private static class C implements Cloneable {

        @Override

        protected Object clone() throws CloneNotSupportedException {

            return super.clone();

        }

    }

}