/*

 * Copyright (c) 2003, 2016, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.instrument;

import java.lang.reflect.Method;

import java.lang.reflect.Module;

import java.lang.reflect.AccessibleObject;

import java.lang.instrument.ClassFileTransformer;

import java.lang.instrument.ClassDefinition;

import java.lang.instrument.Instrumentation;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.security.ProtectionDomain;

import java.util.Objects;

import java.util.jar.JarFile;

/*

 * Copyright 2003 Wily Technology, Inc.

 */

/**

 * The Java side of the JPLIS implementation. Works in concert with a native JVMTI agent

 * to implement the JPLIS API set. Provides both the Java API implementation of

 * the Instrumentation interface and utility Java routines to support the native code.

 * Keeps a pointer to the native data structure in a scalar field to allow native

 * processing behind native methods.

 */

public class InstrumentationImpl implements Instrumentation {

    private final     TransformerManager      mTransformerManager;

    private           TransformerManager      mRetransfomableTransformerManager;

    // needs to store a native pointer, so use 64 bits

    private final     long                    mNativeAgent;

    private final     boolean                 mEnvironmentSupportsRedefineClasses;

    private volatile  boolean                 mEnvironmentSupportsRetransformClassesKnown;

    private volatile  boolean                 mEnvironmentSupportsRetransformClasses;

    private final     boolean                 mEnvironmentSupportsNativeMethodPrefix;

    private

    InstrumentationImpl(long    nativeAgent,

                        boolean environmentSupportsRedefineClasses,

                        boolean environmentSupportsNativeMethodPrefix) {

        mTransformerManager                    = new TransformerManager(false);

        mRetransfomableTransformerManager      = null;

        mNativeAgent                           = nativeAgent;

        mEnvironmentSupportsRedefineClasses    = environmentSupportsRedefineClasses;

        mEnvironmentSupportsRetransformClassesKnown = false; // false = need to ask

        mEnvironmentSupportsRetransformClasses = false;      // don't know yet

        mEnvironmentSupportsNativeMethodPrefix = environmentSupportsNativeMethodPrefix;

    }

    public void

    addTransformer(ClassFileTransformer transformer) {

        addTransformer(transformer, false);

    }

    public synchronized void

    addTransformer(ClassFileTransformer transformer, boolean canRetransform) {

        if (transformer == null) {

            throw new NullPointerException("null passed as 'transformer' in addTransformer");

        }

        if (canRetransform) {

            if (!isRetransformClassesSupported()) {

                throw new UnsupportedOperationException(

                  "adding retransformable transformers is not supported in this environment");

            }

            if (mRetransfomableTransformerManager == null) {

                mRetransfomableTransformerManager = new TransformerManager(true);

            }

            mRetransfomableTransformerManager.addTransformer(transformer);

            if (mRetransfomableTransformerManager.getTransformerCount() == 1) {

                setHasRetransformableTransformers(mNativeAgent, true);

            }

        } else {

            mTransformerManager.addTransformer(transformer);

        }

    }

    public synchronized boolean

    removeTransformer(ClassFileTransformer transformer) {

        if (transformer == null) {

            throw new NullPointerException("null passed as 'transformer' in removeTransformer");

        }

        TransformerManager mgr = findTransformerManager(transformer);

        if (mgr != null) {

            mgr.removeTransformer(transformer);

            if (mgr.isRetransformable() && mgr.getTransformerCount() == 0) {

                setHasRetransformableTransformers(mNativeAgent, false);

            }

            return true;

        }

        return false;

    }

    public boolean

    isModifiableClass(Class<?> theClass) {

        if (theClass == null) {

            throw new NullPointerException(

                         "null passed as 'theClass' in isModifiableClass");

        }

        return isModifiableClass0(mNativeAgent, theClass);

    }

    public boolean

    isRetransformClassesSupported() {

        // ask lazily since there is some overhead

        if (!mEnvironmentSupportsRetransformClassesKnown) {

            mEnvironmentSupportsRetransformClasses = isRetransformClassesSupported0(mNativeAgent);

            mEnvironmentSupportsRetransformClassesKnown = true;

        }

        return mEnvironmentSupportsRetransformClasses;

    }

    public void

    retransformClasses(Class<?>... classes) {

        if (!isRetransformClassesSupported()) {

            throw new UnsupportedOperationException(

              "retransformClasses is not supported in this environment");

        }

        retransformClasses0(mNativeAgent, classes);

    }

    public boolean

    isRedefineClassesSupported() {

        return mEnvironmentSupportsRedefineClasses;

    }

    public void

    redefineClasses(ClassDefinition...  definitions)

            throws  ClassNotFoundException {

        if (!isRedefineClassesSupported()) {

            throw new UnsupportedOperationException("redefineClasses is not supported in this environment");

        }

        if (definitions == null) {

            throw new NullPointerException("null passed as 'definitions' in redefineClasses");

        }

        for (int i = 0; i < definitions.length; ++i) {

            if (definitions[i] == null) {

                throw new NullPointerException("element of 'definitions' is null in redefineClasses");

            }

        }

        if (definitions.length == 0) {

            return; // short-circuit if there are no changes requested

        }

        redefineClasses0(mNativeAgent, definitions);

    }

    @SuppressWarnings("rawtypes")

    public Class[]

    getAllLoadedClasses() {

        return getAllLoadedClasses0(mNativeAgent);

    }

    @SuppressWarnings("rawtypes")

    public Class[]

    getInitiatedClasses(ClassLoader loader) {

        return getInitiatedClasses0(mNativeAgent, loader);

    }

    public long

    getObjectSize(Object objectToSize) {

        if (objectToSize == null) {

            throw new NullPointerException("null passed as 'objectToSize' in getObjectSize");

        }

        return getObjectSize0(mNativeAgent, objectToSize);

    }

    public void

    appendToBootstrapClassLoaderSearch(JarFile jarfile) {

        appendToClassLoaderSearch0(mNativeAgent, jarfile.getName(), true);

    }

    public void

    appendToSystemClassLoaderSearch(JarFile jarfile) {

        appendToClassLoaderSearch0(mNativeAgent, jarfile.getName(), false);

    }

    public boolean

    isNativeMethodPrefixSupported() {

        return mEnvironmentSupportsNativeMethodPrefix;

    }

    public synchronized void

    setNativeMethodPrefix(ClassFileTransformer transformer, String prefix) {

        if (!isNativeMethodPrefixSupported()) {

            throw new UnsupportedOperationException(

                   "setNativeMethodPrefix is not supported in this environment");

        }

        if (transformer == null) {

            throw new NullPointerException(

                       "null passed as 'transformer' in setNativeMethodPrefix");

        }

        TransformerManager mgr = findTransformerManager(transformer);

        if (mgr == null) {

            throw new IllegalArgumentException(

                       "transformer not registered in setNativeMethodPrefix");

        }

        mgr.setNativeMethodPrefix(transformer, prefix);

        String[] prefixes = mgr.getNativeMethodPrefixes();

        setNativeMethodPrefixes(mNativeAgent, prefixes, mgr.isRetransformable());

    }

    @Override

    public void addModuleReads(Module module, Module other) {

        Objects.requireNonNull(module);

        Objects.requireNonNull(other);

        jdk.internal.module.Modules.addReads(module, other);

    }

    private TransformerManager

    findTransformerManager(ClassFileTransformer transformer) {

        if (mTransformerManager.includesTransformer(transformer)) {

            return mTransformerManager;

        }

        if (mRetransfomableTransformerManager != null &&

                mRetransfomableTransformerManager.includesTransformer(transformer)) {

            return mRetransfomableTransformerManager;

        }

        return null;

    }

    /*

     *  Natives

     */

    private native boolean

    isModifiableClass0(long nativeAgent, Class<?> theClass);

    private native boolean

    isRetransformClassesSupported0(long nativeAgent);

    private native void

    setHasRetransformableTransformers(long nativeAgent, boolean has);

    private native void

    retransformClasses0(long nativeAgent, Class<?>[] classes);

    private native void

    redefineClasses0(long nativeAgent, ClassDefinition[]  definitions)

        throws  ClassNotFoundException;

    @SuppressWarnings("rawtypes")

    private native Class[]

    getAllLoadedClasses0(long nativeAgent);

    @SuppressWarnings("rawtypes")

    private native Class[]

    getInitiatedClasses0(long nativeAgent, ClassLoader loader);

    private native long

    getObjectSize0(long nativeAgent, Object objectToSize);

    private native void

    appendToClassLoaderSearch0(long nativeAgent, String jarfile, boolean bootLoader);

    private native void

    setNativeMethodPrefixes(long nativeAgent, String[] prefixes, boolean isRetransformable);

    static {

        System.loadLibrary("instrument");

    }

    /*

     *  Internals

     */

    // Enable or disable Java programming language access checks on a

    // reflected object (for example, a method)

    private static void setAccessible(final AccessibleObject ao, final boolean accessible) {

        AccessController.doPrivileged(new PrivilegedAction<Object>() {

                public Object run() {

                    ao.setAccessible(accessible);

                    return null;

                }});

    }

    // Attempt to load and start an agent

    private void

    loadClassAndStartAgent( String  classname,

                            String  methodname,

                            String  optionsString)

            throws Throwable {

        ClassLoader mainAppLoader   = ClassLoader.getSystemClassLoader();

        Class<?>    javaAgentClass  = mainAppLoader.loadClass(classname);

        Method m = null;

        NoSuchMethodException firstExc = null;

        boolean twoArgAgent = false;

        // The agent class must have a premain or agentmain method that

        // has 1 or 2 arguments. We check in the following order:

        //

        // 1) declared with a signature of (String, Instrumentation)

        // 2) declared with a signature of (String)

        // 3) inherited with a signature of (String, Instrumentation)

        // 4) inherited with a signature of (String)

        //

        // So the declared version of either 1-arg or 2-arg always takes

        // primary precedence over an inherited version. After that, the

        // 2-arg version takes precedence over the 1-arg version.

        //

        // If no method is found then we throw the NoSuchMethodException

        // from the first attempt so that the exception text indicates

        // the lookup failed for the 2-arg method (same as JDK5.0).

        try {

            m = javaAgentClass.getDeclaredMethod( methodname,

                                 new Class<?>[] {

                                     String.class,

                                     java.lang.instrument.Instrumentation.class

                                 }

                               );

            twoArgAgent = true;

        } catch (NoSuchMethodException x) {

            // remember the NoSuchMethodException

            firstExc = x;

        }

        if (m == null) {

            // now try the declared 1-arg method

            try {

                m = javaAgentClass.getDeclaredMethod(methodname,

                                                 new Class<?>[] { String.class });

            } catch (NoSuchMethodException x) {

                // ignore this exception because we'll try

                // two arg inheritance next

            }

        }

        if (m == null) {

            // now try the inherited 2-arg method

            try {

                m = javaAgentClass.getMethod( methodname,

                                 new Class<?>[] {

                                     String.class,

                                     java.lang.instrument.Instrumentation.class

                                 }

                               );

                twoArgAgent = true;

            } catch (NoSuchMethodException x) {

                // ignore this exception because we'll try

                // one arg inheritance next

            }

        }

        if (m == null) {

            // finally try the inherited 1-arg method

            try {

                m = javaAgentClass.getMethod(methodname,

                                             new Class<?>[] { String.class });

            } catch (NoSuchMethodException x) {

                // none of the methods exists so we throw the

                // first NoSuchMethodException as per 5.0

                throw firstExc;

            }

        }

        // the premain method should not be required to be public,

        // make it accessible so we can call it

        // Note: The spec says the following:

        //     The agent class must implement a public static premain method...

        setAccessible(m, true);

        // invoke the 1 or 2-arg method

        if (twoArgAgent) {

            m.invoke(null, new Object[] { optionsString, this });

        } else {

            m.invoke(null, new Object[] { optionsString });

        }

    }

    // WARNING: the native code knows the name & signature of this method

    private void

    loadClassAndCallPremain(    String  classname,

                                String  optionsString)

            throws Throwable {

        loadClassAndStartAgent( classname, "premain", optionsString );

    }

    // WARNING: the native code knows the name & signature of this method

    private void

    loadClassAndCallAgentmain(  String  classname,

                                String  optionsString)

            throws Throwable {

        loadClassAndStartAgent( classname, "agentmain", optionsString );

    }

    // WARNING: the native code knows the name & signature of this method

    private byte[]

                String              classname,

                Class<?>            classBeingRedefined,

                ProtectionDomain    protectionDomain,

                byte[]              classfileBuffer,

                boolean             isRetransformer) {

        TransformerManager mgr = isRetransformer?

                                        mRetransfomableTransformerManager :

                                        mTransformerManager;

        // module is null when not a class load or when loading a class in an

        // unnamed module and this is the first type to be loaded in the package.

        if (module == null) {

            if (classBeingRedefined != null) {

                module = classBeingRedefined.getModule();

            } else {

                module = (loader == null) ? jdk.internal.loader.BootLoader.getUnnamedModule()

                                          : loader.getUnnamedModule();

            }

        }

        if (mgr == null) {

            return null; // no manager, no transform

        } else {

            return mgr.transform(   module,

                                    classname,

                                    classBeingRedefined,

                                    protectionDomain,

                                    classfileBuffer);

        }

    }

}