/*
* ProGuard -- shrinking, optimization, obfuscation, and preverification
* of Java bytecode.
*
* Copyright (c) 2002-2010 Eric Lafortune (eric@graphics.cornell.edu)
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program 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 for
* more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package proguard.classfile.editor;
import proguard.classfile.*;
import proguard.classfile.attribute.*;
import proguard.classfile.attribute.visitor.AttributeVisitor;
import proguard.classfile.constant.*;
import proguard.classfile.constant.visitor.ConstantVisitor;
import proguard.classfile.instruction.*;
import proguard.classfile.instruction.visitor.InstructionVisitor;
import proguard.classfile.util.*;
import proguard.classfile.visitor.*;
/**
* This AttributeVisitor fixes all inappropriate special/virtual/static/interface
* invocations of the code attributes that it visits.
*
* @author Eric Lafortune
*/
public class MethodInvocationFixer
extends SimplifiedVisitor
implements AttributeVisitor,
InstructionVisitor,
ConstantVisitor,
ClassVisitor,
MemberVisitor
{
private static final boolean DEBUG = false;
private final CodeAttributeEditor codeAttributeEditor = new CodeAttributeEditor();
// Return values for the visitor methods.
private Clazz referencedClass;
private Clazz referencedMethodClass;
private Member referencedMethod;
// Implementations for AttributeVisitor.
public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute)
{
// Reset the code attribute editor.
codeAttributeEditor.reset(codeAttribute.u4codeLength);
// Remap the variables of the instructions.
codeAttribute.instructionsAccept(clazz, method, this);
// Apply the code atribute editor.
codeAttributeEditor.visitCodeAttribute(clazz, method, codeAttribute);
}
// Implementations for InstructionVisitor.
public void visitAnyInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, Instruction instruction) {}
public void visitConstantInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, ConstantInstruction constantInstruction)
{
int constantIndex = constantInstruction.constantIndex;
// Get information on the called class and method, if present.
referencedMethod = null;
clazz.constantPoolEntryAccept(constantIndex, this);
// Did we find the called class and method?
if (referencedMethod != null)
{
// Do we need to update the opcode?
byte opcode = constantInstruction.opcode;
// Is the method static?
if ((referencedMethod.getAccessFlags() & ClassConstants.INTERNAL_ACC_STATIC) != 0)
{
// But is it not a static invocation?
if (opcode != InstructionConstants.OP_INVOKESTATIC)
{
// Replace the invocation by an invokestatic instruction.
Instruction replacementInstruction =
new ConstantInstruction(InstructionConstants.OP_INVOKESTATIC,
constantIndex).shrink();
codeAttributeEditor.replaceInstruction(offset, replacementInstruction);
if (DEBUG)
{
debug(clazz, method, offset, constantInstruction, replacementInstruction);
}
}
}
// Is the method private, or an instance initializer?
else if ((referencedMethod.getAccessFlags() & ClassConstants.INTERNAL_ACC_PRIVATE) != 0 ||
referencedMethod.getName(referencedMethodClass).equals(ClassConstants.INTERNAL_METHOD_NAME_INIT))
{
// But is it not a special invocation?
if (opcode != InstructionConstants.OP_INVOKESPECIAL)
{
// Replace the invocation by an invokespecial instruction.
Instruction replacementInstruction =
new ConstantInstruction(InstructionConstants.OP_INVOKESPECIAL,
constantIndex).shrink();
codeAttributeEditor.replaceInstruction(offset, replacementInstruction);
if (DEBUG)
{
debug(clazz, method, offset, constantInstruction, replacementInstruction);
}
}
}
// Is the method an interface method?
else if ((referencedClass.getAccessFlags() & ClassConstants.INTERNAL_ACC_INTERFACE) != 0)
{
int invokeinterfaceConstant =
(ClassUtil.internalMethodParameterSize(referencedMethod.getDescriptor(referencedMethodClass), false)) << 8;
// But is it not an interface invocation, or is the parameter
// size incorrect?
if (opcode != InstructionConstants.OP_INVOKEINTERFACE ||
constantInstruction.constant != invokeinterfaceConstant)
{
// Fix the parameter size of the interface invocation.
Instruction replacementInstruction =
new ConstantInstruction(InstructionConstants.OP_INVOKEINTERFACE,
constantIndex,
invokeinterfaceConstant).shrink();
codeAttributeEditor.replaceInstruction(offset, replacementInstruction);
if (DEBUG)
{
debug(clazz, method, offset, constantInstruction, replacementInstruction);
}
}
}
// The method is not static, private, an instance initializer, or
// an interface method.
else
{
// But is it not a virtual invocation (or a special invocation,
// but not a super call)?
if (opcode != InstructionConstants.OP_INVOKEVIRTUAL &&
(opcode != InstructionConstants.OP_INVOKESPECIAL ||
clazz.equals(referencedClass) ||
!clazz.extends_(referencedClass)))
{
// Replace the invocation by an invokevirtual instruction.
Instruction replacementInstruction =
new ConstantInstruction(InstructionConstants.OP_INVOKEVIRTUAL,
constantIndex).shrink();
codeAttributeEditor.replaceInstruction(offset, replacementInstruction);
if (DEBUG)
{
debug(clazz, method, offset, constantInstruction, replacementInstruction);
}
}
}
}
}
// Implementations for ConstantVisitor.
public void visitAnyConstant(Clazz clazz, Constant constant) {}
public void visitAnyMethodrefConstant(Clazz clazz, RefConstant refConstant)
{
// Check if this is an interface method. Note that we're interested in
// the class of the method reference, not in the class in which the
// method was actually found.
//refConstant.referencedClassAccept(this);
clazz.constantPoolEntryAccept(refConstant.u2classIndex, this);
// Get the referenced access flags and names.
refConstant.referencedMemberAccept(this);
}
public void visitClassConstant(Clazz clazz, ClassConstant classConstant)
{
// Check if this is an interface class.
classConstant.referencedClassAccept(this);
}
// Implementations for ClassVisitor.
public void visitAnyClass(Clazz clazz)
{
// Remember the referenced class.
referencedClass = clazz;
}
// Implementations for MemberVisitor.
public void visitAnyMember(Clazz clazz, Member member)
{
// Remember the referenced method.
referencedMethodClass = clazz;
referencedMethod = member;
}
// Small utility methods.
private void debug(Clazz clazz,
Method method,
int offset,
ConstantInstruction constantInstruction,
Instruction replacementInstruction)
{
System.out.println("MethodInvocationFixer:");
System.out.println(" Class = "+clazz.getName());
System.out.println(" Method = "+method.getName(clazz)+method.getDescriptor(clazz));
System.out.println(" Instruction = "+constantInstruction.toString(offset));
System.out.println(" -> Class = "+referencedClass);
System.out.println(" Method = "+referencedMethod);
if ((referencedClass.getAccessFlags() & ClassConstants.INTERNAL_ACC_INTERFACE) != 0)
{
System.out.println(" Parameter size = "+(ClassUtil.internalMethodParameterSize(referencedMethod.getDescriptor(referencedMethodClass), false)));
}
System.out.println(" Replacement instruction = "+replacementInstruction.toString(offset));
}
}