Back to index...

	/*
	* 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.
	*/

	/*
	* This file is available under and governed by the GNU General Public
	* License version 2 only, as published by the Free Software Foundation.
	* However, the following notice accompanied the original version of this
	* file:
	*
	* ASM: a very small and fast Java bytecode manipulation framework
	* Copyright (c) 2000-2011 INRIA, France Telecom
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. Neither the name of the copyright holders nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
	* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
	* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
	* THE POSSIBILITY OF SUCH DAMAGE.
	*/
	package jdk.internal.org.objectweb.asm.commons;

	import java.io.ByteArrayOutputStream;
	import java.io.DataOutput;
	import java.io.DataOutputStream;
	import java.io.IOException;
	import java.security.MessageDigest;
	import java.security.NoSuchAlgorithmException;
	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.Collection;
	import jdk.internal.org.objectweb.asm.ClassVisitor;
	import jdk.internal.org.objectweb.asm.FieldVisitor;
	import jdk.internal.org.objectweb.asm.MethodVisitor;
	import jdk.internal.org.objectweb.asm.Opcodes;

	/**
	* A {@link ClassVisitor} that adds a serial version unique identifier to a class if missing. A
	* typical usage of this class is:
	*
	* <pre>
	* ClassWriter classWriter = new ClassWriter(...);
	* ClassVisitor svuidAdder = new SerialVersionUIDAdder(classWriter);
	* ClassVisitor classVisitor = new MyClassAdapter(svuidAdder);
	* new ClassReader(orginalClass).accept(classVisitor, 0);
	* </pre>
	*
	* <p>The SVUID algorithm can be found at <a href=
	* "https://docs.oracle.com/javase/10/docs/specs/serialization/class.html#stream-unique-identifiers"
	* >https://docs.oracle.com/javase/10/docs/specs/serialization/class.html#stream-unique-identifiers</a>:
	*
	* <p>The serialVersionUID is computed using the signature of a stream of bytes that reflect the
	* class definition. The National Institute of Standards and Technology (NIST) Secure Hash Algorithm
	* (SHA-1) is used to compute a signature for the stream. The first two 32-bit quantities are used
	* to form a 64-bit hash. A java.lang.DataOutputStream is used to convert primitive data types to a
	* sequence of bytes. The values input to the stream are defined by the Java Virtual Machine (VM)
	* specification for classes.
	*
	* <p>The sequence of items in the stream is as follows:
	*
	* <ol>
	* <li>The class name written using UTF encoding.
	* <li>The class modifiers written as a 32-bit integer.
	* <li>The name of each interface sorted by name written using UTF encoding.
	* <li>For each field of the class sorted by field name (except private static and private
	* transient fields):
	* <ol>
	* <li>The name of the field in UTF encoding.
	* <li>The modifiers of the field written as a 32-bit integer.
	* <li>The descriptor of the field in UTF encoding
	* </ol>
	* <li>If a class initializer exists, write out the following:
	* <ol>
	* <li>The name of the method, <clinit>, in UTF encoding.
	* <li>The modifier of the method, STATIC, written as a 32-bit integer.
	* <li>The descriptor of the method, ()V, in UTF encoding.
	* </ol>
	* <li>For each non-private constructor sorted by method name and signature:
	* <ol>
	* <li>The name of the method, <init>, in UTF encoding.
	* <li>The modifiers of the method written as a 32-bit integer.
	* <li>The descriptor of the method in UTF encoding.
	* </ol>
	* <li>For each non-private method sorted by method name and signature:
	* <ol>
	* <li>The name of the method in UTF encoding.
	* <li>The modifiers of the method written as a 32-bit integer.
	* <li>The descriptor of the method in UTF encoding.
	* </ol>
	* <li>The SHA-1 algorithm is executed on the stream of bytes produced by DataOutputStream and
	* produces five 32-bit values sha[0..4].
	* <li>The hash value is assembled from the first and second 32-bit values of the SHA-1 message
	* digest. If the result of the message digest, the five 32-bit words H0 H1 H2 H3 H4, is in an
	* array of five int values named sha, the hash value would be computed as follows: long hash
	* = ((sha[0] >>> 24) & 0xFF) \| ((sha[0] >>> 16) & 0xFF) << 8
	* \| ((sha[0] >>> 8) & 0xFF) << 16 \| ((sha[0] >>> 0) & 0xFF)
	* << 24 \| ((sha[1] >>> 24) & 0xFF) << 32 \| ((sha[1] >>> 16)
	* & 0xFF) << 40 \| ((sha[1] >>> 8) & 0xFF) << 48 \| ((sha[1]
	* >>> 0) & 0xFF) << 56;
	* </ol>
	*
	* @author Rajendra Inamdar, Vishal Vishnoi
	*/
	// DontCheck(AbbreviationAsWordInName): can't be renamed (for backward binary compatibility).
	public class SerialVersionUIDAdder extends ClassVisitor {

	/** The JVM name of static initializer methods. */
	private static final String CLINIT = "<clinit>";

	/** A flag that indicates if we need to compute SVUID. */
	private boolean computeSvuid;

	/** Whether the class already has a SVUID. */
	private boolean hasSvuid;

	/** The class access flags. */
	private int access;

	/** The internal name of the class. */
	private String name;

	/** The interfaces implemented by the class. */
	private String[] interfaces;

	/** The fields of the class that are needed to compute the SVUID. */
	private Collection<Item> svuidFields;

	/** Whether the class has a static initializer. */
	private boolean hasStaticInitializer;

	/** The constructors of the class that are needed to compute the SVUID. */
	private Collection<Item> svuidConstructors;

	/** The methods of the class that are needed to compute the SVUID. */
	private Collection<Item> svuidMethods;

	/**
	* Constructs a new {@link SerialVersionUIDAdder}. <i>Subclasses must not use this
	* constructor</i>. Instead, they must use the {@link #SerialVersionUIDAdder(int, ClassVisitor)}
	* version.
	*
	* @param classVisitor a {@link ClassVisitor} to which this visitor will delegate calls.
	* @throws IllegalStateException If a subclass calls this constructor.
	*/
	public SerialVersionUIDAdder(final ClassVisitor classVisitor) {
	this(/* latest api = */ Opcodes.ASM8, classVisitor);
	if (getClass() != SerialVersionUIDAdder.class) {
	throw new IllegalStateException();
	}
	}

	/**
	* Constructs a new {@link SerialVersionUIDAdder}.
	*
	* @param api the ASM API version implemented by this visitor. Must be one of {@link
	* Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6}, {@link Opcodes#ASM7} or {@link
	* Opcodes#ASM8}.
	* @param classVisitor a {@link ClassVisitor} to which this visitor will delegate calls.
	*/
	protected SerialVersionUIDAdder(final int api, final ClassVisitor classVisitor) {
	super(api, classVisitor);
	}

	// -----------------------------------------------------------------------------------------------
	// Overridden methods
	// -----------------------------------------------------------------------------------------------

	@Override
	public void visit(
	final int version,
	final int access,
	final String name,
	final String signature,
	final String superName,
	final String[] interfaces) {
	// Get the class name, access flags, and interfaces information (step 1, 2 and 3) for SVUID
	// computation.
	computeSvuid = (access & Opcodes.ACC_ENUM) == 0;

	if (computeSvuid) {
	this.name = name;
	this.access = access;
	this.interfaces = interfaces.clone();
	this.svuidFields = new ArrayList<>();
	this.svuidConstructors = new ArrayList<>();
	this.svuidMethods = new ArrayList<>();
	}

	super.visit(version, access, name, signature, superName, interfaces);
	}

	@Override
	public MethodVisitor visitMethod(
	final int access,
	final String name,
	final String descriptor,
	final String signature,
	final String[] exceptions) {
	// Get constructor and method information (step 5 and 7). Also determine if there is a class
	// initializer (step 6).
	if (computeSvuid) {
	if (CLINIT.equals(name)) {
	hasStaticInitializer = true;
	}
	// Collect the non private constructors and methods. Only the ACC_PUBLIC, ACC_PRIVATE,
	// ACC_PROTECTED, ACC_STATIC, ACC_FINAL, ACC_SYNCHRONIZED, ACC_NATIVE, ACC_ABSTRACT and
	// ACC_STRICT flags are used.
	int mods =
	access
	& (Opcodes.ACC_PUBLIC
	\| Opcodes.ACC_PRIVATE
	\| Opcodes.ACC_PROTECTED
	\| Opcodes.ACC_STATIC
	\| Opcodes.ACC_FINAL
	\| Opcodes.ACC_SYNCHRONIZED
	\| Opcodes.ACC_NATIVE
	\| Opcodes.ACC_ABSTRACT
	\| Opcodes.ACC_STRICT);

	if ((access & Opcodes.ACC_PRIVATE) == 0) {
	if ("<init>".equals(name)) {
	svuidConstructors.add(new Item(name, mods, descriptor));
	} else if (!CLINIT.equals(name)) {
	svuidMethods.add(new Item(name, mods, descriptor));
	}
	}
	}

	return super.visitMethod(access, name, descriptor, signature, exceptions);
	}

	@Override
	public FieldVisitor visitField(
	final int access,
	final String name,
	final String desc,
	final String signature,
	final Object value) {
	// Get the class field information for step 4 of the algorithm. Also determine if the class
	// already has a SVUID.
	if (computeSvuid) {
	if ("serialVersionUID".equals(name)) {
	// Since the class already has SVUID, we won't be computing it.
	computeSvuid = false;
	hasSvuid = true;
	}
	// Collect the non private fields. Only the ACC_PUBLIC, ACC_PRIVATE, ACC_PROTECTED,
	// ACC_STATIC, ACC_FINAL, ACC_VOLATILE, and ACC_TRANSIENT flags are used when computing
	// serialVersionUID values.
	if ((access & Opcodes.ACC_PRIVATE) == 0
	\|\| (access & (Opcodes.ACC_STATIC \| Opcodes.ACC_TRANSIENT)) == 0) {
	int mods =
	access
	& (Opcodes.ACC_PUBLIC
	\| Opcodes.ACC_PRIVATE
	\| Opcodes.ACC_PROTECTED
	\| Opcodes.ACC_STATIC
	\| Opcodes.ACC_FINAL
	\| Opcodes.ACC_VOLATILE
	\| Opcodes.ACC_TRANSIENT);
	svuidFields.add(new Item(name, mods, desc));
	}
	}

	return super.visitField(access, name, desc, signature, value);
	}

	@Override
	public void visitInnerClass(
	final String innerClassName,
	final String outerName,
	final String innerName,
	final int innerClassAccess) {
	// Handles a bizarre special case. Nested classes (static classes declared inside another class)
	// that are protected have their access bit set to public in their class files to deal with some
	// odd reflection situation. Our SVUID computation must do as the JVM does and ignore access
	// bits in the class file in favor of the access bits of the InnerClass attribute.
	if ((name != null) && name.equals(innerClassName)) {
	this.access = innerClassAccess;
	}
	super.visitInnerClass(innerClassName, outerName, innerName, innerClassAccess);
	}

	@Override
	public void visitEnd() {
	// Add the SVUID field to the class if it doesn't have one.
	if (computeSvuid && !hasSvuid) {
	try {
	addSVUID(computeSVUID());
	} catch (IOException e) {
	throw new IllegalStateException("Error while computing SVUID for " + name, e);
	}
	}

	super.visitEnd();
	}

	// -----------------------------------------------------------------------------------------------
	// Utility methods
	// -----------------------------------------------------------------------------------------------

	/**
	* Returns true if the class already has a SVUID field. The result of this method is only valid
	* when visitEnd has been called.
	*
	* @return true if the class already has a SVUID field.
	*/
	// DontCheck(AbbreviationAsWordInName): can't be renamed (for backward binary compatibility).
	public boolean hasSVUID() {
	return hasSvuid;
	}

	/**
	* Adds a static final serialVersionUID field to the class, with the given value.
	*
	* @param svuid the serialVersionUID field value.
	*/
	// DontCheck(AbbreviationAsWordInName): can't be renamed (for backward binary compatibility).
	protected void addSVUID(final long svuid) {
	FieldVisitor fieldVisitor =
	super.visitField(
	Opcodes.ACC_FINAL + Opcodes.ACC_STATIC, "serialVersionUID", "J", null, svuid);
	if (fieldVisitor != null) {
	fieldVisitor.visitEnd();
	}
	}

	/**
	* Computes and returns the value of SVUID.
	*
	* @return the serial version UID.
	* @throws IOException if an I/O error occurs.
	*/
	// DontCheck(AbbreviationAsWordInName): can't be renamed (for backward binary compatibility).
	protected long computeSVUID() throws IOException {
	long svuid = 0;

	try (ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
	DataOutputStream dataOutputStream = new DataOutputStream(byteArrayOutputStream)) {

	// 1. The class name written using UTF encoding.
	dataOutputStream.writeUTF(name.replace('/', '.'));

	// 2. The class modifiers written as a 32-bit integer.
	int mods = access;
	if ((mods & Opcodes.ACC_INTERFACE) != 0) {
	mods =
	svuidMethods.isEmpty() ? (mods & ~Opcodes.ACC_ABSTRACT) : (mods \| Opcodes.ACC_ABSTRACT);
	}
	dataOutputStream.writeInt(
	mods
	& (Opcodes.ACC_PUBLIC
	\| Opcodes.ACC_FINAL
	\| Opcodes.ACC_INTERFACE
	\| Opcodes.ACC_ABSTRACT));

	// 3. The name of each interface sorted by name written using UTF encoding.
	Arrays.sort(interfaces);
	for (String interfaceName : interfaces) {
	dataOutputStream.writeUTF(interfaceName.replace('/', '.'));
	}

	// 4. For each field of the class sorted by field name (except private static and private
	// transient fields):
	// 1. The name of the field in UTF encoding.
	// 2. The modifiers of the field written as a 32-bit integer.
	// 3. The descriptor of the field in UTF encoding.
	// Note that field signatures are not dot separated. Method and constructor signatures are dot
	// separated. Go figure...
	writeItems(svuidFields, dataOutputStream, false);

	// 5. If a class initializer exists, write out the following:
	// 1. The name of the method, <clinit>, in UTF encoding.
	// 2. The modifier of the method, ACC_STATIC, written as a 32-bit integer.
	// 3. The descriptor of the method, ()V, in UTF encoding.
	if (hasStaticInitializer) {
	dataOutputStream.writeUTF(CLINIT);
	dataOutputStream.writeInt(Opcodes.ACC_STATIC);
	dataOutputStream.writeUTF("()V");
	}

	// 6. For each non-private constructor sorted by method name and signature:
	// 1. The name of the method, <init>, in UTF encoding.
	// 2. The modifiers of the method written as a 32-bit integer.
	// 3. The descriptor of the method in UTF encoding.
	writeItems(svuidConstructors, dataOutputStream, true);

	// 7. For each non-private method sorted by method name and signature:
	// 1. The name of the method in UTF encoding.
	// 2. The modifiers of the method written as a 32-bit integer.
	// 3. The descriptor of the method in UTF encoding.
	writeItems(svuidMethods, dataOutputStream, true);

	dataOutputStream.flush();

	// 8. The SHA-1 algorithm is executed on the stream of bytes produced by DataOutputStream and
	// produces five 32-bit values sha[0..4].
	byte[] hashBytes = computeSHAdigest(byteArrayOutputStream.toByteArray());

	// 9. The hash value is assembled from the first and second 32-bit values of the SHA-1 message
	// digest. If the result of the message digest, the five 32-bit words H0 H1 H2 H3 H4, is in an
	// array of five int values named sha, the hash value would be computed as follows:
	for (int i = Math.min(hashBytes.length, 8) - 1; i >= 0; i--) {
	svuid = (svuid << 8) \| (hashBytes[i] & 0xFF);
	}
	}

	return svuid;
	}

	/**
	* Returns the SHA-1 message digest of the given value.
	*
	* @param value the value whose SHA message digest must be computed.
	* @return the SHA-1 message digest of the given value.
	*/
	// DontCheck(AbbreviationAsWordInName): can't be renamed (for backward binary compatibility).
	protected byte[] computeSHAdigest(final byte[] value) {
	try {
	return MessageDigest.getInstance("SHA").digest(value);
	} catch (NoSuchAlgorithmException e) {
	throw new UnsupportedOperationException(e);
	}
	}

	/**
	* Sorts the items in the collection and writes it to the given output stream.
	*
	* @param itemCollection a collection of items.
	* @param dataOutputStream where the items must be written.
	* @param dotted whether package names must use dots, instead of slashes.
	* @exception IOException if an error occurs.
	*/
	private static void writeItems(
	final Collection<Item> itemCollection,
	final DataOutput dataOutputStream,
	final boolean dotted)
	throws IOException {
	Item[] items = itemCollection.toArray(new Item[0]);
	Arrays.sort(items);
	for (Item item : items) {
	dataOutputStream.writeUTF(item.name);
	dataOutputStream.writeInt(item.access);
	dataOutputStream.writeUTF(dotted ? item.descriptor.replace('/', '.') : item.descriptor);
	}
	}

	// -----------------------------------------------------------------------------------------------
	// Inner classes
	// -----------------------------------------------------------------------------------------------

	private static final class Item implements Comparable<Item> {

	final String name;
	final int access;
	final String descriptor;

	Item(final String name, final int access, final String descriptor) {
	this.name = name;
	this.access = access;
	this.descriptor = descriptor;
	}

	@Override
	public int compareTo(final Item item) {
	int result = name.compareTo(item.name);
	if (result == 0) {
	result = descriptor.compareTo(item.descriptor);
	}
	return result;
	}

	@Override
	public boolean equals(final Object other) {
	if (other instanceof Item) {
	return compareTo((Item) other) == 0;
	}
	return false;
	}

	@Override
	public int hashCode() {
	return name.hashCode() ^ descriptor.hashCode();
	}
	}
	}

Back to index...