/***
* ASM examples: examples showing how ASM can be used
* Copyright (c) 2000-2007 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.
*/
import org.ow2.asm.FieldVisitor;
import org.ow2.asm.ClassAdapter;
import org.ow2.asm.ClassReader;
import org.ow2.asm.ClassVisitor;
import org.ow2.asm.ClassWriter;
import org.ow2.asm.MethodAdapter;
import org.ow2.asm.MethodVisitor;
import org.ow2.asm.Opcodes;
import org.ow2.asm.Type;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
/**
* @author Eric Bruneton
*/
public class Adapt extends ClassLoader {
@Override
protected synchronized Class<?> loadClass(
final String name,
final boolean resolve) throws ClassNotFoundException
{
if (name.startsWith("java.")) {
System.err.println("Adapt: loading class '" + name
+ "' without on the fly adaptation");
return super.loadClass(name, resolve);
} else {
System.err.println("Adapt: loading class '" + name
+ "' with on the fly adaptation");
}
// gets an input stream to read the bytecode of the class
String resource = name.replace('.', '/') + ".class";
InputStream is = getResourceAsStream(resource);
byte[] b;
// adapts the class on the fly
try {
ClassReader cr = new ClassReader(is);
ClassWriter cw = new ClassWriter(0);
ClassVisitor cv = new TraceFieldClassAdapter(cw);
cr.accept(cv, 0);
b = cw.toByteArray();
} catch (Exception e) {
throw new ClassNotFoundException(name, e);
}
// optional: stores the adapted class on disk
try {
FileOutputStream fos = new FileOutputStream(resource + ".adapted");
fos.write(b);
fos.close();
} catch (IOException e) {
}
// returns the adapted class
return defineClass(name, b, 0, b.length);
}
public static void main(final String args[]) throws Exception {
// loads the application class (in args[0]) with an Adapt class loader
ClassLoader loader = new Adapt();
Class<?> c = loader.loadClass(args[0]);
// calls the 'main' static method of this class with the
// application arguments (in args[1] ... args[n]) as parameter
Method m = c.getMethod("main", new Class<?>[] { String[].class });
String[] applicationArgs = new String[args.length - 1];
System.arraycopy(args, 1, applicationArgs, 0, applicationArgs.length);
m.invoke(null, new Object[] { applicationArgs });
}
}
class TraceFieldClassAdapter extends ClassAdapter implements Opcodes {
private String owner;
public TraceFieldClassAdapter(final ClassVisitor cv) {
super(cv);
}
@Override
public void visit(
final int version,
final int access,
final String name,
final String signature,
final String superName,
final String[] interfaces)
{
owner = name;
super.visit(version, access, name, signature, superName, interfaces);
}
@Override
public FieldVisitor visitField(
final int access,
final String name,
final String desc,
final String signature,
final Object value)
{
FieldVisitor fv = super.visitField(access, name, desc, signature, value);
if ((access & ACC_STATIC) == 0) {
Type t = Type.getType(desc);
int size = t.getSize();
// generates getter method
String gDesc = "()" + desc;
MethodVisitor gv = cv.visitMethod(ACC_PRIVATE,
"_get" + name,
gDesc,
null,
null);
gv.visitFieldInsn(GETSTATIC,
"java/lang/System",
"err",
"Ljava/io/PrintStream;");
gv.visitLdcInsn("_get" + name + " called");
gv.visitMethodInsn(INVOKEVIRTUAL,
"java/io/PrintStream",
"println",
"(Ljava/lang/String;)V");
gv.visitVarInsn(ALOAD, 0);
gv.visitFieldInsn(GETFIELD, owner, name, desc);
gv.visitInsn(t.getOpcode(IRETURN));
gv.visitMaxs(1 + size, 1);
gv.visitEnd();
// generates setter method
String sDesc = "(" + desc + ")V";
MethodVisitor sv = cv.visitMethod(ACC_PRIVATE,
"_set" + name,
sDesc,
null,
null);
sv.visitFieldInsn(GETSTATIC,
"java/lang/System",
"err",
"Ljava/io/PrintStream;");
sv.visitLdcInsn("_set" + name + " called");
sv.visitMethodInsn(INVOKEVIRTUAL,
"java/io/PrintStream",
"println",
"(Ljava/lang/String;)V");
sv.visitVarInsn(ALOAD, 0);
sv.visitVarInsn(t.getOpcode(ILOAD), 1);
sv.visitFieldInsn(PUTFIELD, owner, name, desc);
sv.visitInsn(RETURN);
sv.visitMaxs(1 + size, 1 + size);
sv.visitEnd();
}
return fv;
}
@Override
public MethodVisitor visitMethod(
final int access,
final String name,
final String desc,
final String signature,
final String[] exceptions)
{
MethodVisitor mv = cv.visitMethod(access,
name,
desc,
signature,
exceptions);
return mv == null ? null : new TraceFieldCodeAdapter(mv, owner);
}
}
class TraceFieldCodeAdapter extends MethodAdapter implements Opcodes {
private String owner;
public TraceFieldCodeAdapter(final MethodVisitor mv, final String owner) {
super(mv);
this.owner = owner;
}
@Override
public void visitFieldInsn(
final int opcode,
final String owner,
final String name,
final String desc)
{
if (owner.equals(this.owner)) {
if (opcode == GETFIELD) {
// replaces GETFIELD f by INVOKESPECIAL _getf
String gDesc = "()" + desc;
visitMethodInsn(INVOKESPECIAL, owner, "_get" + name, gDesc);
return;
} else if (opcode == PUTFIELD) {
// replaces PUTFIELD f by INVOKESPECIAL _setf
String sDesc = "(" + desc + ")V";
visitMethodInsn(INVOKESPECIAL, owner, "_set" + name, sDesc);
return;
}
}
super.visitFieldInsn(opcode, owner, name, desc);
}
}