/*
 * Copyright (c) 2011, 2018, 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.
 *
 * 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
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 * questions.
 */


package org.graalvm.compiler.replacements.test.classfile;

import static org.graalvm.compiler.test.SubprocessUtil.getVMCommandLine;
import static org.graalvm.compiler.test.SubprocessUtil.java;
import static org.graalvm.compiler.test.SubprocessUtil.withoutDebuggerArguments;
import static org.junit.Assume.assumeTrue;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.instrument.Instrumentation;
import java.lang.management.ManagementFactory;
import java.lang.reflect.Method;
import java.nio.file.Files;
import java.nio.file.Path;
import java.security.ProtectionDomain;
import java.util.List;
import java.util.jar.Attributes;
import java.util.jar.JarEntry;
import java.util.jar.JarOutputStream;
import java.util.jar.Manifest;

import javax.tools.ToolProvider;

import org.graalvm.compiler.api.replacements.ClassSubstitution;
import org.graalvm.compiler.api.replacements.MethodSubstitution;
import org.graalvm.compiler.bytecode.BytecodeProvider;
import org.graalvm.compiler.nodes.graphbuilderconf.InvocationPlugins;
import org.graalvm.compiler.nodes.graphbuilderconf.InvocationPlugins.Registration;
import org.graalvm.compiler.replacements.test.ReplacementsTest;
import org.graalvm.compiler.test.SubprocessUtil.Subprocess;
import org.junit.Assert;
import org.junit.Test;

import jdk.vm.ci.meta.ResolvedJavaMethod;

Tests that intrinsics (and snippets) are isolated from bytecode instrumentation.
/**
 * Tests that intrinsics (and snippets) are isolated from bytecode instrumentation.
 */
public class RedefineIntrinsicTest extends ReplacementsTest {

    public static class Original {

        // Intrinsified by Intrinsic.getValue
        public static String getValue() {
            return "original";
        }
    }

    @ClassSubstitution(Original.class)
    private static class Intrinsic {

        @MethodSubstitution
        public static String getValue() {
            return "intrinsic";
        }
    }

    @Override
    protected void registerInvocationPlugins(InvocationPlugins invocationPlugins) {
        BytecodeProvider replacementBytecodeProvider = getSystemClassLoaderBytecodeProvider();
        Registration r = new Registration(invocationPlugins, Original.class, replacementBytecodeProvider);
        r.registerMethodSubstitution(Intrinsic.class, "getValue");
        super.registerInvocationPlugins(invocationPlugins);
    }

    public static String callOriginalGetValue() {
        // This call will be intrinsified when compiled by Graal
        return Original.getValue();
    }

    public static String callIntrinsicGetValue() {
        // This call will *not* be intrinsified when compiled by Graal
        return Intrinsic.getValue();
    }

    @Test
    public void test() throws Throwable {
        assumeManagementLibraryIsLoadable();
        try {
            Class.forName("java.lang.instrument.Instrumentation");
        } catch (ClassNotFoundException ex) {
            // skip this test if java.instrument JDK9 module is missing
            return;
        }
        String recursionPropName = getClass().getName() + ".recursion";
        if (Java8OrEarlier || Boolean.getBoolean(recursionPropName)) {
            testHelper();
        } else {
            List<String> vmArgs = withoutDebuggerArguments(getVMCommandLine());
            vmArgs.add("-D" + recursionPropName + "=true");
            vmArgs.add("-Djdk.attach.allowAttachSelf=true");
            Subprocess proc = java(vmArgs, "com.oracle.mxtool.junit.MxJUnitWrapper", getClass().getName());
            if (proc.exitCode != 0) {
                Assert.fail(String.format("non-zero exit code %d for command:%n%s", proc.exitCode, proc));
            }
        }
    }

    public void testHelper() throws Throwable {

        Object receiver = null;
        Object[] args = {};

        // Prior to redefinition, both Original and Intrinsic
        // should behave as per their Java source code
        Assert.assertEquals("original", Original.getValue());
        Assert.assertEquals("intrinsic", Intrinsic.getValue());

        ResolvedJavaMethod callOriginalGetValue = getResolvedJavaMethod("callOriginalGetValue");
        ResolvedJavaMethod callIntrinsicGetValue = getResolvedJavaMethod("callIntrinsicGetValue");

        // Expect intrinsification to change "original" to "intrinsic"
        testAgainstExpected(callOriginalGetValue, new Result("intrinsic", null), receiver, args);

        // Expect no intrinsification
        testAgainstExpected(callIntrinsicGetValue, new Result("intrinsic", null), receiver, args);

        // Apply redefinition of intrinsic bytecode
        if (!redefineIntrinsic()) {
            // running on JDK9 without agent
            return;
        }

        // Expect redefinition to have no effect
        Assert.assertEquals("original", Original.getValue());

        // Expect redefinition to change "intrinsic" to "redefined"
        Assert.assertEquals("redefined", Intrinsic.getValue());

        // Expect redefinition to have no effect on intrinsification (i.e.,
        // "original" is still changed to "intrinsic", not "redefined"
        testAgainstExpected(callOriginalGetValue, new Result("intrinsic", null), receiver, args);
    }

    
Adds the class file bytes for a given class to a JAR stream.
/**
     * Adds the class file bytes for a given class to a JAR stream.
     */
    static void add(JarOutputStream jar, Class<?> c) throws IOException {
        String name = c.getName();
        String classAsPath = name.replace('.', '/') + ".class";
        jar.putNextEntry(new JarEntry(classAsPath));

        InputStream stream = c.getClassLoader().getResourceAsStream(classAsPath);

        int nRead;
        byte[] buf = new byte[1024];
        while ((nRead = stream.read(buf, 0, buf.length)) != -1) {
            jar.write(buf, 0, nRead);
        }

        jar.closeEntry();
    }

    static boolean redefineIntrinsic() throws Exception {
        Manifest manifest = new Manifest();
        manifest.getMainAttributes().put(Attributes.Name.MANIFEST_VERSION, "1.0");
        Attributes mainAttrs = manifest.getMainAttributes();
        mainAttrs.putValue("Agent-Class", RedefinerAgent.class.getName());
        mainAttrs.putValue("Can-Redefine-Classes", "true");
        mainAttrs.putValue("Can-Retransform-Classes", "true");

        Path jar = Files.createTempFile("myagent", ".jar");
        try {
            JarOutputStream jarStream = new JarOutputStream(new FileOutputStream(jar.toFile()), manifest);
            add(jarStream, RedefinerAgent.class);
            add(jarStream, Redefiner.class);
            jarStream.close();

            return loadAgent(jar);
        } finally {
            Files.deleteIfExists(jar);
        }
    }

    @SuppressWarnings({"deprecation", "unused"})
    public static boolean loadAgent(Path agent) throws Exception {
        String vmName = ManagementFactory.getRuntimeMXBean().getName();
        int p = vmName.indexOf('@');
        assumeTrue("VM name not in <pid>@<host> format: " + vmName, p != -1);
        String pid = vmName.substring(0, p);
        Class<?> c;
        if (Java8OrEarlier) {
            ClassLoader cl = ToolProvider.getSystemToolClassLoader();
            c = Class.forName("com.sun.tools.attach.VirtualMachine", true, cl);
        } else {
            try {
                // I don't know what changed to make this necessary...
                c = Class.forName("com.sun.tools.attach.VirtualMachine", true, RedefineIntrinsicTest.class.getClassLoader());
            } catch (ClassNotFoundException ex) {
                try {
                    Class.forName("javax.naming.Reference");
                } catch (ClassNotFoundException coreNamingMissing) {
                    // if core JDK classes aren't found, we are probably running in a
                    // JDK9 java.base environment and then missing class is OK
                    return false;
                }
                throw ex;
            }
        }
        Method attach = c.getDeclaredMethod("attach", String.class);
        Method loadAgent = c.getDeclaredMethod("loadAgent", String.class, String.class);
        Method detach = c.getDeclaredMethod("detach");
        Object vm = attach.invoke(null, pid);
        loadAgent.invoke(vm, agent.toString(), "");
        detach.invoke(vm);
        return true;
    }

    public static class RedefinerAgent {

        public static void agentmain(@SuppressWarnings("unused") String args, Instrumentation inst) throws Exception {
            if (inst.isRedefineClassesSupported() && inst.isRetransformClassesSupported()) {
                inst.addTransformer(new Redefiner(), true);
                Class<?>[] allClasses = inst.getAllLoadedClasses();
                for (int i = 0; i < allClasses.length; i++) {
                    Class<?> c = allClasses[i];
                    if (c == Intrinsic.class) {
                        inst.retransformClasses(new Class<?>[]{c});
                    }
                }
            }
        }
    }

    
This transformer replaces the first instance of the constant "intrinsic" in the class file for Intrinsic with "redefined". /**
     * This transformer replaces the first instance of the constant "intrinsic" in the class file
     * for {@link Intrinsic} with "redefined".
     */
    static class Redefiner implements ClassFileTransformer {

        @Override
        public byte[] transform(ClassLoader cl, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
            if (Intrinsic.class.equals(classBeingRedefined)) {
                String cf = new String(classfileBuffer);
                int i = cf.indexOf("intrinsic");
                Assert.assertTrue("cannot find \"intrinsic\" constant in " + Intrinsic.class.getSimpleName() + "'s class file", i > 0);
                System.arraycopy("redefined".getBytes(), 0, classfileBuffer, i, "redefined".length());
            }
            return classfileBuffer;
        }
    }
}