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/*
* Copyright (c) 2014, 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.
*
* 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 asmlib;
import java.lang.classfile.AccessFlags;
import java.lang.classfile.ClassBuilder;
import java.lang.classfile.ClassElement;
import java.lang.classfile.ClassModel;
import java.lang.classfile.ClassTransform;
import java.lang.classfile.ClassFile;
import java.lang.classfile.CodeBuilder;
import java.lang.classfile.CodeElement;
import java.lang.classfile.CodeModel;
import java.lang.classfile.CodeTransform;
import java.lang.classfile.MethodBuilder;
import java.lang.classfile.MethodElement;
import java.lang.classfile.MethodModel;
import java.lang.classfile.MethodTransform;
import java.lang.classfile.Opcode;
import java.lang.classfile.TypeKind;
import java.lang.constant.MethodTypeDesc;
import java.lang.reflect.AccessFlag;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.function.BiConsumer;
import java.util.function.Consumer;
import static java.lang.classfile.ClassFile.ACC_NATIVE;
public class Instrumentor {
public static Instrumentor instrFor(byte[] classData) {
return new Instrumentor(classData);
}
private final ClassModel model;
private ClassTransform transform = ClassTransform.ACCEPT_ALL;
private final AtomicBoolean dirty = new AtomicBoolean(false);
private Instrumentor(byte[] classData) {
model = ClassFile.of().parse(classData);
}
public synchronized Instrumentor addMethodEntryInjection(String methodName, Consumer<CodeBuilder> injector) {
transform = transform.andThen(ClassTransform.transformingMethodBodies(mm -> {
if (mm.methodName().equalsString(methodName)) {
dirty.set(true);
return true;
}
return false;
}, new CodeTransform() {
@Override
public void atStart(CodeBuilder builder) {
injector.accept(builder);
}
@Override
public void accept(CodeBuilder builder, CodeElement element) {
builder.accept(element);
}
}));
return this;
}
public synchronized Instrumentor addNativeMethodTrackingInjection(String prefix, BiConsumer<String, CodeBuilder> injector) {
transform = transform.andThen(ClassTransform.ofStateful(() -> new ClassTransform() {
private final Set<Consumer<ClassBuilder>> wmGenerators = new HashSet<>();
@Override
public void accept(ClassBuilder builder, ClassElement element) {
if (element instanceof MethodModel mm && mm.flags().has(AccessFlag.NATIVE)) {
dirty.set(true);
String name = mm.methodName().stringValue();
String newName = prefix + name;
MethodTypeDesc mt = mm.methodTypeSymbol();
wmGenerators.add(clb -> clb.transformMethod(mm, new MethodTransform() {
@Override
public void accept(MethodBuilder mb, MethodElement me) {
if (me instanceof AccessFlags flags) {
mb.withFlags(flags.flagsMask() & ~ACC_NATIVE);
} else if (!(me instanceof CodeModel)) {
mb.with(me);
}
}
@Override
public void atEnd(MethodBuilder mb) {
Consumer<CodeBuilder> injection = cb -> injector.accept(name, cb);
mb.withCode(injection.andThen(cb -> {
int ptr;
boolean isStatic = mm.flags().has(AccessFlag.STATIC);
if (!isStatic) {
cb.aload(0); // load "this"
ptr = 1;
} else {
ptr = 0;
}
// load method parameters
for (int i = 0; i < mt.parameterCount(); i++) {
TypeKind kind = TypeKind.from(mt.parameterType(i));
cb.loadLocal(kind, ptr);
ptr += kind.slotSize();
}
cb.invoke(isStatic ? Opcode.INVOKESTATIC : Opcode.INVOKESPECIAL,
model.thisClass().asSymbol(), newName, mt, false);
cb.return_(TypeKind.from(mt.returnType()));
}));
}
}));
builder.withMethod(newName, mt, mm.flags().flagsMask(), mm::forEach);
} else {
builder.accept(element);
}
}
@Override
public void atEnd(ClassBuilder builder) {
wmGenerators.forEach(e -> e.accept(builder));
}
}));
return this;
}
public synchronized byte[] apply() {
var bytes = ClassFile.of().transformClass(model, transform);
return dirty.get() ? bytes : null;
}
}
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