proguard.evaluation

Class ExecutingInvocationUnit

java.lang.Object

proguard.evaluation.SimplifiedInvocationUnit

proguard.evaluation.BasicInvocationUnit

proguard.evaluation.ExecutingInvocationUnit

All Implemented Interfaces:

ConstantVisitor, MemberVisitor, ParameterVisitor, InvocationUnit

public class ExecutingInvocationUnit
extends BasicInvocationUnit

This ExecutingInvocationUnit reflectively executes the method calls it visits on a given ParticularReferenceValue.

After the (reflective) execution of method, it also takes care to replace values on stack/variables if needed. This needs to be done, as the PartialEvaluator treats all entries on stack/variables as immutable, and assumes that every change creates a new object.

Before a method call, the stack/variables can contain multiple references to the same object. If the method call then creates a new Variable (representing an updated object), we need to update all references to this new Variable.

There are some methods which always return a new object when the method is actually executed in the JVM (e.g. StringBuilder.toString). For such method calls, we never update the stack/variables (Denylist, Case 1)

For certain methods (e.g. the Constructor), we always need to replace the value on stack/variables (Allowlist, Case 3)

In all other cases, we assume the underlying object was changed if the returned value is of the same type as the called upon instance. This is an approximation, which works well for Strings, StringBuffer, StringBuilder (Approximation, Case 3)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ExecutingInvocationUnit.Builder Builds an ExecutingInvocationUnit.

Field Summary

Fields

Modifier and Type	Field and Description
static boolean	DEBUG

Fields inherited from class proguard.evaluation.BasicInvocationUnit

valueFactory

Fields inherited from class proguard.evaluation.SimplifiedInvocationUnit

isLoad, isStatic, method, stack, variables

Constructor Summary

Constructors

Modifier	Constructor and Description
	ExecutingInvocationUnit(ValueFactory valueFactory) Deprecated.
protected	ExecutingInvocationUnit(ValueFactory valueFactory, java.util.Map<java.lang.String,java.util.Set<java.lang.String>> alwaysReturnsNewInstance, java.util.Map<java.lang.String,java.util.Set<java.lang.String>> alwaysModifiesInstance, boolean enableSameInstanceIdApproximation) Creates an invocation unit resolving the methods from the specified classes via reflection.

Method Summary

Modifier and Type	Method and Description
boolean	alwaysReturnsNewInstance(java.lang.String internalClassName, java.lang.String methodName) Returns true, if a call to internalClassName.methodName should return a new (i.e.
Value	executeMethod(Clazz callingClass, Method callingMethod, int callingOffset, Clazz clazz, Method method, Value... parameters) Executes a method, by reflectively trying to call it with the given parameters.
Value	executeMethod(ConcreteCall call, Value... parameters) Executes a method, by reflectively trying to call the method represented by the given Call.
Value	getFieldValue(Clazz clazz, FieldrefConstant fieldrefConstant, java.lang.String type) Returns the value of the specified field.
Value	getMethodReturnValue(Clazz clazz, AnyMethodrefConstant anyMethodrefConstant, java.lang.String returnType) Returns the return value of the specified method.
boolean	isSupportedClass(java.lang.String internalClassName) Returns true if the class is supported by the invocation unit.
boolean	isSupportedMethodCall(java.lang.String internalClassName, java.lang.String methodName) Returns true if a method call can be called reflectively.
boolean	methodMayHaveSideEffects(Clazz clazz, AnyMethodrefConstant anyMethodrefConstant, java.lang.String returnType) Returns true if the method itself can modify the stack/variables and therefore needs to be executed even if it returns void.
boolean	returnsOwnInstance(Clazz clazz, Method method, Value instance) Determines if the stack/variables need to be updated.
void	setMethodParameterValue(Clazz clazz, AnyMethodrefConstant anyMethodrefConstant, int parameterIndex, Value value) Sets the value of the specified method parameter.
void	visitAnyMethodrefConstant(Clazz clazz, AnyMethodrefConstant anyMethodrefConstant) Visits any RefConstant instance.

Methods inherited from class proguard.evaluation.BasicInvocationUnit

getExceptionValue, getFieldClassValue, getMethodParameterValue, getMethodReturnValue, setFieldClassValue, setFieldValue, setMethodReturnValue, visitLibraryField, visitLibraryMethod, visitProgramField, visitProgramMethod

Methods inherited from class proguard.evaluation.SimplifiedInvocationUnit

enterExceptionHandler, enterMethod, exitMethod, invokeMember, visitFieldrefConstant, visitInvokeDynamicConstant, visitParameter

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface proguard.evaluation.InvocationUnit

enterExceptionHandler, enterMethod, exitMethod, invokeMember

Methods inherited from interface proguard.classfile.visitor.MemberVisitor

visitAnyMember, visitLibraryMember, visitProgramMember

Methods inherited from interface proguard.classfile.constant.visitor.ConstantVisitor

visitAnyConstant, visitAnyRefConstant, visitClassConstant, visitDoubleConstant, visitDynamicConstant, visitFloatConstant, visitIntegerConstant, visitInterfaceMethodrefConstant, visitLongConstant, visitMethodHandleConstant, visitMethodrefConstant, visitMethodTypeConstant, visitModuleConstant, visitNameAndTypeConstant, visitPackageConstant, visitPrimitiveArrayConstant, visitStringConstant, visitUtf8Constant

Field Detail

DEBUG

public static boolean DEBUG

Constructor Detail

ExecutingInvocationUnit

protected ExecutingInvocationUnit(ValueFactory valueFactory,
                                  java.util.Map<java.lang.String,java.util.Set<java.lang.String>> alwaysReturnsNewInstance,
                                  java.util.Map<java.lang.String,java.util.Set<java.lang.String>> alwaysModifiesInstance,
                                  boolean enableSameInstanceIdApproximation)

Creates an invocation unit resolving the methods from the specified classes via reflection.

Parameters:

valueFactory - a value factory

alwaysReturnsNewInstance - a mapping from class name to method name of methods that the invocation unit will assume to always return a new reference

alwaysModifiesInstance - a mapping from class name to method name of methods that the invocation unit will assume to modify the calling instance

enableSameInstanceIdApproximation - whether the invocation unit will assume for classes not supported for execution that they might return the same reference of the calling instance if their types match

ExecutingInvocationUnit

@Deprecated
public ExecutingInvocationUnit(ValueFactory valueFactory)

Deprecated.

Method Detail

setMethodParameterValue

public void setMethodParameterValue(Clazz clazz,
                                    AnyMethodrefConstant anyMethodrefConstant,
                                    int parameterIndex,
                                    Value value)

Description copied from class: SimplifiedInvocationUnit

Sets the value of the specified method parameter.

Overrides:

setMethodParameterValue in class BasicInvocationUnit

methodMayHaveSideEffects

public boolean methodMayHaveSideEffects(Clazz clazz,
                                        AnyMethodrefConstant anyMethodrefConstant,
                                        java.lang.String returnType)

Description copied from class: SimplifiedInvocationUnit

Returns true if the method itself can modify the stack/variables and therefore needs to be executed even if it returns void.

Overrides:

methodMayHaveSideEffects in class SimplifiedInvocationUnit

getMethodReturnValue

public Value getMethodReturnValue(Clazz clazz,
                                  AnyMethodrefConstant anyMethodrefConstant,
                                  java.lang.String returnType)

Description copied from class: SimplifiedInvocationUnit

Returns the return value of the specified method.

Overrides:

getMethodReturnValue in class BasicInvocationUnit

visitAnyMethodrefConstant

public void visitAnyMethodrefConstant(Clazz clazz,
                                      AnyMethodrefConstant anyMethodrefConstant)

Description copied from interface: ConstantVisitor

Visits any RefConstant instance. The more specific default implementations of this interface delegate to this method.

Specified by:

visitAnyMethodrefConstant in interface ConstantVisitor

Overrides:

visitAnyMethodrefConstant in class SimplifiedInvocationUnit

getFieldValue

public Value getFieldValue(Clazz clazz,
                           FieldrefConstant fieldrefConstant,
                           java.lang.String type)

Description copied from class: SimplifiedInvocationUnit

Returns the value of the specified field.

Overrides:

getFieldValue in class BasicInvocationUnit

isSupportedMethodCall

public boolean isSupportedMethodCall(java.lang.String internalClassName,
                                     java.lang.String methodName)

Returns true if a method call can be called reflectively. Currently, supports all methods of String, StringBuilder, StringBuffer.

isSupportedClass

public boolean isSupportedClass(java.lang.String internalClassName)

Returns true if the class is supported by the invocation unit.

executeMethod

public Value executeMethod(ConcreteCall call,
                           Value... parameters)

Executes a method, by reflectively trying to call the method represented by the given Call.

Parameters:

call - The method to call.

parameters - An array containing the parameters values (for a non-static call, parameters[0] is the instance.

Returns:

The return value of the method call. Even for a void method, a created value might be returned, which might need to be replaced on stack/values (e.g. for Constructors).

executeMethod

public Value executeMethod(Clazz callingClass,
                           Method callingMethod,
                           int callingOffset,
                           Clazz clazz,
                           Method method,
                           Value... parameters)

Executes a method, by reflectively trying to call it with the given parameters.

Parameters:

callingClass - The class from where the method is being executed from.

callingMethod - The method from where the method is being executed from.

callingOffset - The offset from where the method is being executed from.

parameters - An array containing the parameters values (for a non-static call, parameters[0] is the instance.

Returns:

The return value of the method call. Even for a void method, a created value might be returned, which might need to be replaced on stack/values (e.g. for Constructors).

alwaysReturnsNewInstance

public boolean alwaysReturnsNewInstance(java.lang.String internalClassName,
                                        java.lang.String methodName)

Returns true, if a call to internalClassName.methodName should return a new (i.e. not-linked) instance.

Parameters:

internalClassName - full class name of the base class of the method (e.g. java/lang/StringBuilder).

methodName - method name.

Returns:

if it should create a new instance.

returnsOwnInstance

public boolean returnsOwnInstance(Clazz clazz,
                                  Method method,
                                  Value instance)

Determines if the stack/variables need to be updated.

Limitations: We are only checking if the instance of the call was modified, i.e. - for static calls, no value should be replaced on stack/variables (since no instance exists), and - the method call assumes that the parameters are not changed.

This is an approximation which works well for StringBuilder/StringBuffer and Strings.