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An unofficial backport of the JDK Classfile API to Java 17
/*
* Copyright (c) 2022, 2024, 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 io.github.dmlloyd.classfile.impl;
import io.github.dmlloyd.classfile.CodeBuilder;
import io.github.dmlloyd.classfile.CustomAttribute;
import io.github.dmlloyd.classfile.FieldBuilder;
import io.github.dmlloyd.classfile.MethodBuilder;
import io.github.dmlloyd.classfile.PseudoInstruction;
import io.github.dmlloyd.classfile.constantpool.PoolEntry;
import java.lang.constant.ClassDesc;
import java.lang.constant.MethodTypeDesc;
import java.util.AbstractList;
import java.util.Collection;
import java.util.List;
import java.util.function.Function;
import io.github.dmlloyd.classfile.Attribute;
import io.github.dmlloyd.classfile.AttributeMapper;
import io.github.dmlloyd.classfile.Attributes;
import io.github.dmlloyd.classfile.BufWriter;
import io.github.dmlloyd.classfile.ClassFile;
import io.github.dmlloyd.classfile.extras.constant.ExtraClassDesc;
import io.github.dmlloyd.classfile.Opcode;
import io.github.dmlloyd.classfile.constantpool.ClassEntry;
import io.github.dmlloyd.classfile.constantpool.ModuleEntry;
import io.github.dmlloyd.classfile.constantpool.NameAndTypeEntry;
import io.github.dmlloyd.classfile.extras.constant.ModuleDesc;
import io.github.dmlloyd.classfile.extras.reflect.AccessFlag;
import static io.github.dmlloyd.classfile.ClassFile.ACC_STATIC;
import io.github.dmlloyd.classfile.attribute.CodeAttribute;
import io.github.dmlloyd.classfile.components.ClassPrinter;
import java.nio.ByteBuffer;
import java.util.function.Consumer;
/**
* Helper to create and manipulate type descriptors, where type descriptors are
* represented as JVM type descriptor strings and symbols are represented as
* name strings
*/
public class Util {
private Util() {
}
public static Consumer> writingAll(Iterable container) {
record ForEachConsumer(Iterable container) implements Consumer> {
@Override
public void accept(Consumer consumer) {
container.forEach(consumer);
}
}
return new ForEachConsumer<>(container);
}
public static Consumer buildingCode(Consumer codeHandler) {
record WithCodeMethodHandler(Consumer codeHandler) implements Consumer {
@Override
public void accept(MethodBuilder builder) {
builder.withCode(codeHandler);
}
}
return new WithCodeMethodHandler(codeHandler);
}
public static Consumer buildingFlags(int flags) {
record WithFlagFieldHandler(int flags) implements Consumer {
@Override
public void accept(FieldBuilder builder) {
builder.withFlags(flags);
}
}
return new WithFlagFieldHandler(flags);
}
private static final int ATTRIBUTE_STABILITY_COUNT = AttributeMapper.AttributeStability.values().length;
public static boolean isAttributeAllowed(final Attribute attr,
final ClassFile.AttributesProcessingOption processingOption) {
return attr instanceof BoundAttribute
? ATTRIBUTE_STABILITY_COUNT - attr.attributeMapper().stability().ordinal() > processingOption.ordinal()
: true;
}
public static int parameterSlots(MethodTypeDesc mDesc) {
int count = 0;
for (int i = 0; i < mDesc.parameterCount(); i++) {
count += slotSize(mDesc.parameterType(i));
}
return count;
}
public static int[] parseParameterSlots(int flags, MethodTypeDesc mDesc) {
int[] result = new int[mDesc.parameterCount()];
int count = ((flags & ACC_STATIC) != 0) ? 0 : 1;
for (int i = 0; i < result.length; i++) {
result[i] = count;
count += slotSize(mDesc.parameterType(i));
}
return result;
}
public static int maxLocals(int flags, MethodTypeDesc mDesc) {
int count = ((flags & ACC_STATIC) != 0) ? 0 : 1;
for (int i = 0; i < mDesc.parameterCount(); i++) {
count += slotSize(mDesc.parameterType(i));
}
return count;
}
/**
* Converts a descriptor of classes or interfaces into
* a binary name. Rejects primitive types or arrays.
* This is an inverse of {@link ClassDesc#of(String)}.
*/
public static String toBinaryName(ClassDesc cd) {
return toInternalName(cd).replace('/', '.');
}
public static String toInternalName(ClassDesc cd) {
var desc = cd.descriptorString();
if (desc.charAt(0) == 'L')
return desc.substring(1, desc.length() - 1);
throw new IllegalArgumentException(desc);
}
public static ClassDesc toClassDesc(String classInternalNameOrArrayDesc) {
return classInternalNameOrArrayDesc.charAt(0) == '['
? ClassDesc.ofDescriptor(classInternalNameOrArrayDesc)
: ExtraClassDesc.ofInternalName(classInternalNameOrArrayDesc);
}
public static List mappedList(List list, Function mapper) {
return new AbstractList<>() {
@Override
public U get(int index) {
return mapper.apply(list.get(index));
}
@Override
public int size() {
return list.size();
}
};
}
public static List entryList(List list) {
var result = new ClassEntry[list.size()]; // null check
for (int i = 0; i < result.length; i++) {
result[i] = TemporaryConstantPool.INSTANCE.classEntry(list.get(i));
}
return List.of(result);
}
public static List moduleEntryList(List list) {
var result = new ModuleEntry[list.size()]; // null check
for (int i = 0; i < result.length; i++) {
result[i] = TemporaryConstantPool.INSTANCE.moduleEntry(TemporaryConstantPool.INSTANCE.utf8Entry(list.get(i).name()));
}
return List.of(result);
}
public static void checkKind(Opcode op, Opcode.Kind k) {
if (op.kind() != k)
throw new IllegalArgumentException(
String.format("Wrong opcode kind specified; found %s(%s), expected %s", op, op.kind(), k));
}
public static int flagsToBits(AccessFlag.Location location, Collection flags) {
int i = 0;
for (AccessFlag f : flags) {
if (!f.locations().contains(location)) {
throw new IllegalArgumentException("unexpected flag: " + f + " use in target location: " + location);
}
i |= f.mask();
}
return i;
}
public static int flagsToBits(AccessFlag.Location location, AccessFlag... flags) {
int i = 0;
for (AccessFlag f : flags) {
if (!f.locations().contains(location)) {
throw new IllegalArgumentException("unexpected flag: " + f + " use in target location: " + location);
}
i |= f.mask();
}
return i;
}
public static boolean has(AccessFlag.Location location, int flagsMask, AccessFlag flag) {
return (flag.mask() & flagsMask) == flag.mask() && flag.locations().contains(location);
}
public static ClassDesc fieldTypeSymbol(NameAndTypeEntry nat) {
return ((AbstractPoolEntry.NameAndTypeEntryImpl)nat).fieldTypeSymbol();
}
public static MethodTypeDesc methodTypeSymbol(NameAndTypeEntry nat) {
return ((AbstractPoolEntry.NameAndTypeEntryImpl)nat).methodTypeSymbol();
}
@SuppressWarnings("unchecked")
private static > void writeAttribute(BufWriterImpl writer, Attribute attr) {
if (attr instanceof CustomAttribute ca) {
var mapper = (AttributeMapper) ca.attributeMapper();
mapper.writeAttribute(writer, (T) ca);
} else {
assert attr instanceof BoundAttribute || attr instanceof UnboundAttribute;
((Writable) attr).writeTo(writer);
}
}
public static void writeAttributes(BufWriterImpl buf, List> list) {
buf.writeU2(list.size());
for (var e : list) {
writeAttribute(buf, e);
}
}
static void writeList(BufWriterImpl buf, List list) {
buf.writeU2(list.size());
for (var e : list) {
e.writeTo(buf);
}
}
public static int slotSize(ClassDesc desc) {
return switch (desc.descriptorString().charAt(0)) {
case 'V' -> 0;
case 'D','J' -> 2;
default -> 1;
};
}
public static boolean isDoubleSlot(ClassDesc desc) {
char ch = desc.descriptorString().charAt(0);
return ch == 'D' || ch == 'J';
}
public static void dumpMethod(SplitConstantPool cp,
ClassDesc cls,
String methodName,
MethodTypeDesc methodDesc,
int acc,
ByteBuffer bytecode,
Consumer dump) {
// try to dump debug info about corrupted bytecode
try {
var cc = ClassFile.of();
var clm = cc.parse(cc.build(cp.classEntry(cls), cp, clb ->
clb.withMethod(methodName, methodDesc, acc, mb ->
((DirectMethodBuilder)mb).writeAttribute(new UnboundAttribute.AdHocAttribute(Attributes.code()) {
@Override
public void writeBody(BufWriterImpl b) {
b.writeU2(-1);//max stack
b.writeU2(-1);//max locals
b.writeInt(bytecode.limit());
b.writeBytes(bytecode.array(), 0, bytecode.limit());
b.writeU2(0);//exception handlers
b.writeU2(0);//attributes
}
}))));
ClassPrinter.toYaml(clm.methods().get(0).code().get(), ClassPrinter.Verbosity.TRACE_ALL, dump);
} catch (Error | Exception __) {
// fallback to bytecode hex dump
bytecode.rewind();
while (bytecode.position() < bytecode.limit()) {
dump.accept("%n%04x:".formatted(bytecode.position()));
for (int i = 0; i < 16 && bytecode.position() < bytecode.limit(); i++) {
dump.accept(" %02x".formatted(bytecode.get()));
}
}
}
}
public static void writeListIndices(BufWriter writer, List list) {
writer.writeU2(list.size());
for (PoolEntry info : list) {
writer.writeIndex(info);
}
}
public static boolean writeLocalVariable(BufWriterImpl buf, PseudoInstruction lvOrLvt) {
return ((WritableLocalVariable) lvOrLvt).writeLocalTo(buf);
}
/**
* A generic interface for objects to write to a
* buf writer. Do not implement unless necessary,
* as this writeTo is public, which can be troublesome.
*/
interface Writable {
void writeTo(BufWriterImpl writer);
}
interface WritableLocalVariable {
boolean writeLocalTo(BufWriterImpl buf);
}
}