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ProGuardCORE is a free library to read, analyze, modify, and write Java class files.
/*
* ProGuardCORE -- library to process Java bytecode.
*
* Copyright (c) 2002-2020 Guardsquare NV
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package proguard.evaluation;
import proguard.classfile.*;
import proguard.classfile.attribute.CodeAttribute;
import proguard.classfile.constant.*;
import proguard.classfile.constant.visitor.ConstantVisitor;
import proguard.classfile.instruction.*;
import proguard.classfile.util.*;
import proguard.classfile.visitor.*;
import proguard.evaluation.value.*;
/**
* This {@link InvocationUnit} sets up the variables for entering a method,
* and it updates the stack for the invocation of a class member,
* using simple values.
*
* @author Eric Lafortune
*/
public abstract class SimplifiedInvocationUnit
implements InvocationUnit,
ParameterVisitor,
ConstantVisitor
{
private final MemberVisitor parameterInitializer = new AllParameterVisitor(true, this);
// Fields acting as parameters between the visitor methods.
protected Variables variables;
protected boolean isStatic;
protected boolean isLoad;
protected Stack stack;
protected Method method;
// Implementations for InvocationUnit.
public void enterMethod(Clazz clazz, Method method, Variables variables)
{
// Count the number of parameters, taking into account their categories.
int parameterSize =
ClassUtil.internalMethodParameterSize(method.getDescriptor(clazz),
method.getAccessFlags());
// Reuse the existing parameters object, ensuring the right size.
variables.reset(parameterSize);
// Initialize the parameters.
this.variables = variables;
method.accept(clazz, parameterInitializer);
this.variables = null;
}
// Implementation for ParameterVisitor.
public void visitParameter(Clazz clazz, Member member, int parameterIndex, int parameterCount, int parameterOffset, int parameterSize, String parameterType, Clazz referencedClass)
{
Method method = (Method)member;
// Get the parameter value.
Value value = getMethodParameterValue(clazz,
method,
parameterIndex,
parameterType,
referencedClass);
// Store the value in the corresponding variable.
variables.store(parameterOffset, value);
}
public void exitMethod(Clazz clazz, Method method, Value returnValue)
{
setMethodReturnValue(clazz, method, returnValue);
}
public void enterExceptionHandler(Clazz clazz,
Method method,
CodeAttribute codeAttribute,
int offset,
int catchType,
Stack stack)
{
ClassConstant exceptionClassConstant =
(ClassConstant)((ProgramClass)clazz).getConstant(catchType);
stack.push(getExceptionValue(clazz, exceptionClassConstant));
}
public void invokeMember(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, ConstantInstruction constantInstruction, Stack stack, Variables variables)
{
int constantIndex = constantInstruction.constantIndex;
switch (constantInstruction.opcode)
{
case Instruction.OP_GETSTATIC:
isStatic = true;
isLoad = true;
break;
case Instruction.OP_PUTSTATIC:
isStatic = true;
isLoad = false;
break;
case Instruction.OP_GETFIELD:
isStatic = false;
isLoad = true;
break;
case Instruction.OP_PUTFIELD:
isStatic = false;
isLoad = false;
break;
case Instruction.OP_INVOKESTATIC:
case Instruction.OP_INVOKEDYNAMIC:
isStatic = true;
break;
case Instruction.OP_INVOKEVIRTUAL:
case Instruction.OP_INVOKESPECIAL:
case Instruction.OP_INVOKEINTERFACE:
isStatic = false;
break;
}
// Pop the parameters and push the return value.
this.stack = stack;
this.variables = variables;
this.method = method;
clazz.constantPoolEntryAccept(constantIndex, this);
this.method = null;
this.variables = null;
this.stack = null;
}
// Implementations for ConstantVisitor.
public void visitFieldrefConstant(Clazz clazz, FieldrefConstant fieldrefConstant)
{
// Pop the field value, if applicable.
if (!isLoad)
{
setFieldValue(clazz, fieldrefConstant, stack.pop());
}
// Pop the reference value, if applicable.
if (!isStatic)
{
setFieldClassValue(clazz, fieldrefConstant, stack.apop());
}
// Push the field value, if applicable.
if (isLoad)
{
String type = fieldrefConstant.getType(clazz);
stack.push(getFieldValue(clazz, fieldrefConstant, type));
}
}
public void visitAnyMethodrefConstant(Clazz clazz, AnyMethodrefConstant anyMethodrefConstant)
{
String type = anyMethodrefConstant.getType(clazz);
// Count the number of parameters.
int parameterCount = ClassUtil.internalMethodParameterCount(type, isStatic);
// Pop the parameters and the class reference, in reverse order.
for (int parameterIndex = parameterCount-1; parameterIndex >= 0; parameterIndex--)
{
setMethodParameterValue(clazz, anyMethodrefConstant, parameterIndex, stack.pop());
}
// Push the return value, if applicable.
String returnType = ClassUtil.internalMethodReturnType(type);
Value returnValue = null;
// Check if the methodReturnValue needs to be calculated, i.e., if the function needs to be executed.
if (returnType.charAt(0) != TypeConstants.VOID
|| methodMayHaveSideEffects(clazz, anyMethodrefConstant, returnType))
{
returnValue = getMethodReturnValue(clazz, anyMethodrefConstant, returnType);
}
// Only push the value on the stack if the method actually returns something.
if (returnType.charAt(0) != TypeConstants.VOID)
{
stack.push(returnValue);
}
}
public void visitInvokeDynamicConstant(Clazz clazz, InvokeDynamicConstant invokeDynamicConstant)
{
String type = invokeDynamicConstant.getType(clazz);
// Count the number of parameters.
int parameterCount = ClassUtil.internalMethodParameterCount(type, isStatic);
// Pop the parameters and the class reference, in reverse order.
for (int parameterIndex = parameterCount-1; parameterIndex >= 0; parameterIndex--)
{
stack.pop();
}
// Push the return value, if applicable.
String returnType = ClassUtil.internalMethodReturnType(type);
if (returnType.charAt(0) != TypeConstants.VOID)
{
stack.push(getMethodReturnValue(clazz, invokeDynamicConstant, returnType));
}
}
/**
* Returns the value of the specified exception.
*/
public abstract Value getExceptionValue(Clazz clazz,
ClassConstant catchClassConstant);
/**
* Sets the class through which the specified field is accessed.
*/
public abstract void setFieldClassValue(Clazz clazz,
FieldrefConstant fieldrefConstant,
ReferenceValue value);
/**
* Returns the class though which the specified field is accessed.
*/
public abstract Value getFieldClassValue(Clazz clazz,
FieldrefConstant fieldrefConstant,
String type);
/**
* Sets the value of the specified field.
*/
public abstract void setFieldValue(Clazz clazz,
FieldrefConstant fieldrefConstant,
Value value);
/**
* Returns the value of the specified field.
*/
public abstract Value getFieldValue(Clazz clazz,
FieldrefConstant fieldrefConstant,
String type);
/**
* Sets the value of the specified method parameter.
*/
public abstract void setMethodParameterValue(Clazz clazz,
AnyMethodrefConstant anyMethodrefConstant,
int parameterIndex,
Value value);
/**
* Returns the value of the specified method parameter.
*/
public abstract Value getMethodParameterValue(Clazz clazz,
Method method,
int parameterIndex,
String type,
Clazz referencedClass);
/**
* Sets the return value of the specified method.
*/
public abstract void setMethodReturnValue(Clazz clazz,
Method method,
Value value);
/**
* Returns the return value of the specified method.
*/
public abstract Value getMethodReturnValue(Clazz clazz,
AnyMethodrefConstant anyMethodrefConstant,
String type);
/**
* Returns the return value of the specified method.
*/
public abstract Value getMethodReturnValue(Clazz clazz,
InvokeDynamicConstant invokeDynamicConstant,
String type);
/**
* Returns true if the method itself can modify the stack/variables and therefore
* needs to be executed even if it returns void.
*/
protected boolean methodMayHaveSideEffects(Clazz clazz,
AnyMethodrefConstant anyMethodrefConstant,
String returnType)
{
return false;
}
}
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