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A Java Optimization Framework
package soot;
/*-
* #%L
* Soot - a J*va Optimization Framework
* %%
* Copyright (C) 2002 Ondrej Lhotak
* %%
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 2.1 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 Lesser Public License for more details.
*
* You should have received a copy of the GNU General Lesser Public
* License along with this program. If not, see
* .
* #L%
*/
import java.util.ArrayDeque;
import java.util.Collection;
import java.util.Collections;
import java.util.Deque;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import soot.jimple.SpecialInvokeExpr;
import soot.util.ConcurrentHashMultiMap;
import soot.util.MultiMap;
/**
* Represents the class hierarchy. It is closely linked to a Scene, and must be recreated if the Scene changes.
*
* This version supercedes the old soot.Hierarchy class.
*
* @author Ondrej Lhotak
*/
public class FastHierarchy {
/**
* This map holds all key,value pairs such that value.getSuperclass() == key. This is one of the three maps that hold the
* inverse of the relationships given by the getSuperclass and getInterfaces methods of SootClass.
*/
protected MultiMap classToSubclasses = new ConcurrentHashMultiMap();
/**
* This map holds all key,value pairs such that value is an interface and key is in value.getInterfaces(). This is one of
* the three maps that hold the inverse of the relationships given by the getSuperclass and getInterfaces methods of
* SootClass.
*/
protected MultiMap interfaceToSubinterfaces = new ConcurrentHashMultiMap();
/**
* This map holds all key,value pairs such that value is a class (NOT an interface) and key is in value.getInterfaces().
* This is one of the three maps that hold the inverse of the relationships given by the getSuperclass and getInterfaces
* methods of SootClass.
*/
protected MultiMap interfaceToImplementers = new ConcurrentHashMultiMap();
/**
* This map is a transitive closure of interfaceToSubinterfaces, and each set contains its superinterface itself.
*/
protected MultiMap interfaceToAllSubinterfaces = new ConcurrentHashMultiMap();
/**
* This map gives, for an interface, all concrete classes that implement that interface and all its subinterfaces, but NOT
* their subclasses.
*/
protected MultiMap interfaceToAllImplementers = new ConcurrentHashMultiMap();
/**
* For each class (NOT interface), this map contains a Interval, which is a pair of numbers giving a preorder and postorder
* ordering of classes in the inheritance tree.
*/
protected Map classToInterval = new HashMap();
protected Scene sc;
protected final RefType rtObject;
protected final RefType rtSerializable;
protected final RefType rtCloneable;
protected class Interval {
int lower;
int upper;
public boolean isSubrange(Interval potentialSubrange) {
if (potentialSubrange == null) {
return false;
}
if (lower > potentialSubrange.lower) {
return false;
}
if (upper < potentialSubrange.upper) {
return false;
}
return true;
}
}
protected int dfsVisit(int start, SootClass c) {
Interval r = new Interval();
r.lower = start++;
Collection col = classToSubclasses.get(c);
if (col != null) {
for (SootClass sc : col) {
// For some awful reason, Soot thinks interface are subclasses
// of java.lang.Object
if (sc.isInterface()) {
continue;
}
start = dfsVisit(start, sc);
}
}
r.upper = start++;
if (c.isInterface()) {
throw new RuntimeException("Attempt to dfs visit interface " + c);
}
if (!classToInterval.containsKey(c)) {
classToInterval.put(c, r);
}
return start;
}
/** Constructs a hierarchy from the current scene. */
public FastHierarchy() {
this.sc = Scene.v();
this.rtObject = Scene.v().getObjectType();
this.rtSerializable = RefType.v("java.io.Serializable");
this.rtCloneable = RefType.v("java.lang.Cloneable");
/* First build the inverse maps. */
for (SootClass cl : sc.getClasses().getElementsUnsorted()) {
if (cl.resolvingLevel() < SootClass.HIERARCHY) {
continue;
}
if (!cl.isInterface()) {
SootClass superClass = cl.getSuperclassUnsafe();
if (superClass != null) {
classToSubclasses.put(superClass, cl);
}
}
for (final SootClass supercl : cl.getInterfaces()) {
if (cl.isInterface()) {
interfaceToSubinterfaces.put(supercl, cl);
} else {
interfaceToImplementers.put(supercl, cl);
}
}
}
/* Now do a dfs traversal to get the Interval numbers. */
dfsVisit(0, sc.getSootClass("java.lang.Object"));
/*
* also have to traverse for all phantom classes because they also can be roots of the type hierarchy
*/
for (final Iterator phantomClassIt = sc.getPhantomClasses().snapshotIterator(); phantomClassIt.hasNext();) {
SootClass phantomClass = phantomClassIt.next();
if (!phantomClass.isInterface()) {
dfsVisit(0, phantomClass);
}
}
}
/**
* Return true if class child is a subclass of class parent, neither of them being allowed to be interfaces. If we don't
* know any of the classes, we always return false
*/
public boolean isSubclass(SootClass child, SootClass parent) {
child.checkLevel(SootClass.HIERARCHY);
parent.checkLevel(SootClass.HIERARCHY);
Interval parentInterval = classToInterval.get(parent);
Interval childInterval = classToInterval.get(child);
return parentInterval != null && childInterval != null && parentInterval.isSubrange(childInterval);
}
/**
* For an interface parent (MUST be an interface), returns set of all implementers of it but NOT their subclasses.
*/
public Set getAllImplementersOfInterface(SootClass parent) {
parent.checkLevel(SootClass.HIERARCHY);
if (!interfaceToAllImplementers.containsKey(parent)) {
for (SootClass subinterface : getAllSubinterfaces(parent)) {
if (subinterface == parent) {
continue;
}
interfaceToAllImplementers.putAll(parent, getAllImplementersOfInterface(subinterface));
}
interfaceToAllImplementers.putAll(parent, interfaceToImplementers.get(parent));
}
return interfaceToAllImplementers.get(parent);
}
/**
* For an interface parent (MUST be an interface), returns set of all subinterfaces.
*
* @param parent
* the parent interface.
* @return an set, possibly empty
*/
public Set getAllSubinterfaces(SootClass parent) {
parent.checkLevel(SootClass.HIERARCHY);
if (!parent.isInterface()) {
return Collections.emptySet();
}
if (interfaceToAllSubinterfaces.put(parent, parent)) {
for (SootClass si : interfaceToSubinterfaces.get(parent)) {
interfaceToAllSubinterfaces.putAll(parent, getAllSubinterfaces(si));
}
}
return interfaceToAllSubinterfaces.get(parent);
}
/**
* Given an object of declared type child, returns true if the object can be stored in a variable of type parent. If child
* is an interface that is not a subinterface of parent, this method will return false even though some objects
* implementing the child interface may also implement the parent interface.
*/
public boolean canStoreType(Type child, Type parent) {
if (child == parent || child.equals(parent)) {
return true;
} else if (parent instanceof NullType) {
return false;
} else if (child instanceof NullType) {
return parent instanceof RefLikeType;
} else if (child instanceof RefType) {
if (parent == rtObject) {
return true;
} else if (parent instanceof RefType) {
return canStoreClass(((RefType) child).getSootClass(), ((RefType) parent).getSootClass());
} else {
return false;
}
} else if (child instanceof AnySubType) {
if (!(parent instanceof RefLikeType)) {
throw new RuntimeException("Unhandled type " + parent);
} else if (parent instanceof ArrayType) {
Type base = ((AnySubType) child).getBase();
// From Java Language Spec 2nd ed., Chapter 10, Arrays
return base == rtObject || base == rtSerializable || base == rtCloneable;
} else {
SootClass base = ((AnySubType) child).getBase().getSootClass();
SootClass parentClass = ((RefType) parent).getSootClass();
Deque worklist = new ArrayDeque();
if (base.isInterface()) {
worklist.addAll(getAllImplementersOfInterface(base));
} else {
worklist.add(base);
}
Set workset = new HashSet<>();
while (true) {
SootClass cl = worklist.poll();
if (cl == null) {
break;
} else if (!workset.add(cl)) {
continue;
} else if (cl.isConcrete() && canStoreClass(cl, parentClass)) {
return true;
}
worklist.addAll(getSubclassesOf(cl));
}
return false;
}
} else if (child instanceof ArrayType) {
ArrayType achild = (ArrayType) child;
if (parent instanceof RefType) {
// From Java Language Spec 2nd ed., Chapter 10, Arrays
return parent == rtObject || parent == rtSerializable || parent == rtCloneable;
} else if (!(parent instanceof ArrayType)) {
return false;
}
ArrayType aparent = (ArrayType) parent;
// You can store a int[][] in a Object[]. Yuck!
// Also, you can store a Interface[] in a Object[]
if (achild.numDimensions == aparent.numDimensions) {
if (achild.baseType.equals(aparent.baseType)) {
return true;
} else if (!(achild.baseType instanceof RefType)) {
return false;
} else if (!(aparent.baseType instanceof RefType)) {
return false;
} else {
return canStoreType(achild.baseType, aparent.baseType);
}
} else if (achild.numDimensions > aparent.numDimensions) {
if (aparent.baseType == rtObject) {
return true;
} else if (aparent.baseType == rtSerializable || aparent.baseType == rtCloneable) {
return true;
} else {
return false;
}
} else {
return false;
}
} else {
return false;
}
}
/**
* Given an object of declared type child, returns true if the object can be stored in a variable of type parent. If child
* is an interface that is not a subinterface of parent, this method will return false even though some objects
* implementing the child interface may also implement the parent interface.
*/
public boolean canStoreClass(SootClass child, SootClass parent) {
parent.checkLevel(SootClass.HIERARCHY);
child.checkLevel(SootClass.HIERARCHY);
Interval parentInterval = classToInterval.get(parent);
Interval childInterval = classToInterval.get(child);
if (parentInterval != null && childInterval != null) {
return parentInterval.isSubrange(childInterval);
} else if (childInterval == null) { // child is interface
if (parentInterval != null) { // parent is not interface
return parent == rtObject.getSootClass();
} else {
return getAllSubinterfaces(parent).contains(child);
}
} else {
final Set impl = getAllImplementersOfInterface(parent);
if (impl.size() > 1000) {
// If we have more than 1000 entries it is quite time consuming to check each and every implementing class
// if it is the "child" class. Therefore we use an alternative implementation which just checks the client
// class it's super classes and all the interfaces it implements.
return canStoreClassClassic(child, parent);
} else {
// If we only have a few entries, you can't beat the performance of a plain old loop
// in combination with the interval approach.
for (SootClass c : impl) {
Interval interval = classToInterval.get(c);
if (interval != null && interval.isSubrange(childInterval)) {
return true;
}
}
return false;
}
}
}
/**
* "Classic" implementation using the intuitive approach (without using {@link Interval}) to check whether
* child can be stored in a type of parent:
*
*
* If parent is not an interface we simply traverse and check the super-classes of child.
*
*
*
* If parent is an interface we traverse the super-classes of child and check each interface
* implemented by this class. Also each interface is checked recursively for super interfaces it implements.
*
*
*
* This implementation can be much faster (compared to the interval based implementation of
* {@link #canStoreClass(SootClass, SootClass)} in cases where one interface is implemented in thousands of classes.
*
*
* @param child
* @param parent
* @return
*/
protected boolean canStoreClassClassic(final SootClass child, final SootClass parent) {
SootClass sc = child;
final boolean parentIsInterface = parent.isInterface();
while (sc != null) {
if (sc == parent) {
// We finally found the correct class/interface
return true;
}
if (parentIsInterface) {
// Interfaces can only extend other interfaces - therefore we only have to consider the
// interfaces of the child class if parent is an interface.
for (SootClass interf : sc.getInterfaces()) {
if (canStoreClassClassic(interf, parent)) {
return true;
}
}
}
sc = sc.getSuperclassUnsafe();
}
return false;
}
public Collection resolveConcreteDispatchWithoutFailing(Collection concreteTypes, SootMethod m,
RefType declaredTypeOfBase) {
Set ret = new HashSet();
SootClass declaringClass = declaredTypeOfBase.getSootClass();
declaringClass.checkLevel(SootClass.HIERARCHY);
for (final Type t : concreteTypes) {
if (t instanceof AnySubType) {
HashSet s = new HashSet();
s.add(declaringClass);
while (!s.isEmpty()) {
SootClass c = s.iterator().next();
s.remove(c);
if (!c.isInterface() && !c.isAbstract() && canStoreClass(c, declaringClass)) {
SootMethod concreteM = resolveConcreteDispatch(c, m);
if (concreteM != null) {
ret.add(concreteM);
}
}
{
Set subclasses = classToSubclasses.get(c);
if (subclasses != null) {
s.addAll(subclasses);
}
}
{
Set subinterfaces = interfaceToSubinterfaces.get(c);
if (subinterfaces != null) {
s.addAll(subinterfaces);
}
}
{
Set implementers = interfaceToImplementers.get(c);
if (implementers != null) {
s.addAll(implementers);
}
}
}
return ret;
} else if (t instanceof RefType) {
RefType concreteType = (RefType) t;
SootClass concreteClass = concreteType.getSootClass();
if (!canStoreClass(concreteClass, declaringClass)) {
continue;
}
SootMethod concreteM = null;
try {
concreteM = resolveConcreteDispatch(concreteClass, m);
} catch (Exception e) {
concreteM = null;
}
if (concreteM != null) {
ret.add(concreteM);
}
} else if (t instanceof ArrayType) {
SootMethod concreteM = null;
try {
concreteM = resolveConcreteDispatch(RefType.v("java.lang.Object").getSootClass(), m);
} catch (Exception e) {
concreteM = null;
}
if (concreteM != null) {
ret.add(concreteM);
}
} else {
throw new RuntimeException("Unrecognized reaching type " + t);
}
}
return ret;
}
public Collection resolveConcreteDispatch(Collection concreteTypes, SootMethod m,
RefType declaredTypeOfBase) {
Set ret = new HashSet();
SootClass declaringClass = declaredTypeOfBase.getSootClass();
declaringClass.checkLevel(SootClass.HIERARCHY);
for (final Type t : concreteTypes) {
if (t instanceof AnySubType) {
HashSet s = new HashSet();
s.add(declaringClass);
while (!s.isEmpty()) {
SootClass c = s.iterator().next();
s.remove(c);
if (!c.isInterface() && !c.isAbstract() && canStoreClass(c, declaringClass)) {
SootMethod concreteM = resolveConcreteDispatch(c, m);
if (concreteM != null) {
ret.add(concreteM);
}
}
{
Set subclasses = classToSubclasses.get(c);
if (subclasses != null) {
s.addAll(subclasses);
}
}
{
Set subinterfaces = interfaceToSubinterfaces.get(c);
if (subinterfaces != null) {
s.addAll(subinterfaces);
}
}
{
Set implementers = interfaceToImplementers.get(c);
if (implementers != null) {
s.addAll(implementers);
}
}
}
return ret;
} else if (t instanceof RefType) {
RefType concreteType = (RefType) t;
SootClass concreteClass = concreteType.getSootClass();
if (!canStoreClass(concreteClass, declaringClass)) {
continue;
}
SootMethod concreteM = resolveConcreteDispatch(concreteClass, m);
if (concreteM != null) {
ret.add(concreteM);
}
} else if (t instanceof ArrayType) {
SootMethod concreteM = resolveConcreteDispatch(rtObject.getSootClass(), m);
if (concreteM != null) {
ret.add(concreteM);
}
} else {
throw new RuntimeException("Unrecognized reaching type " + t);
}
}
return ret;
}
// Questions about method invocation.
/** Returns true if the method m is visible from code in the class from. */
private boolean isVisible(SootClass from, SootMethod m) {
from.checkLevel(SootClass.HIERARCHY);
if (m.isPublic()) {
return true;
}
if (m.isPrivate()) {
return from.equals(m.getDeclaringClass());
}
if (m.isProtected()) {
return canStoreClass(from, m.getDeclaringClass());
}
// m is package
return from.getJavaPackageName().equals(m.getDeclaringClass().getJavaPackageName());
// || canStoreClass( from, m.getDeclaringClass() );
}
/**
* Given an object of declared type C, returns the methods which could be called on an o.f() invocation.
*/
public Set resolveAbstractDispatch(SootClass abstractType, SootMethod m) {
String methodSig = m.getSubSignature();
HashSet resolved = new HashSet();
HashSet ret = new HashSet();
ArrayDeque worklist = new ArrayDeque();
worklist.add(abstractType);
while (true) {
SootClass concreteType = worklist.poll();
if (concreteType == null) {
break;
}
SootClass savedConcreteType = concreteType;
if (concreteType.isInterface()) {
worklist.addAll(getAllImplementersOfInterface(concreteType));
continue;
}
Collection c = classToSubclasses.get(concreteType);
if (c != null) {
worklist.addAll(c);
}
if (!concreteType.isAbstract()) {
while (true) {
if (resolved.contains(concreteType)) {
break;
}
resolved.add(concreteType);
SootMethod method = concreteType.getMethodUnsafe(methodSig);
if (method != null) {
if (isVisible(concreteType, m)) {
if (method.isAbstract()) {
throw new RuntimeException("abstract dispatch resolved to abstract method!\nAbstract Type: " + abstractType
+ "\nConcrete Type: " + savedConcreteType + "\nMethod: " + m);
} else {
ret.add(method);
break;
}
}
}
SootClass superClass = concreteType.getSuperclassUnsafe();
if (superClass == null) {
if (concreteType.isPhantom()) {
break;
} else {
throw new RuntimeException("could not resolve abstract dispatch!\nAbstract Type: " + abstractType
+ "\nConcrete Type: " + savedConcreteType + "\nMethod: " + m);
}
}
concreteType = superClass;
}
}
}
return ret;
}
/**
* Given an object of actual type C (o = new C()), returns the method which will be called on an o.f() invocation.
*/
public SootMethod resolveConcreteDispatch(SootClass concreteType, SootMethod m) {
concreteType.checkLevel(SootClass.HIERARCHY);
if (concreteType.isInterface()) {
throw new RuntimeException("A concrete type cannot be an interface: " + concreteType);
}
String methodSig = m.getSubSignature();
while (true) {
SootMethod method = concreteType.getMethodUnsafe(methodSig);
if (method != null) {
if (isVisible(concreteType, m)) {
if (method.isAbstract()) {
throw new RuntimeException("Error: Method call resolves to abstract method!");
}
return method;
}
}
concreteType = concreteType.getSuperclassUnsafe();
if (concreteType == null) {
break;
}
}
// When there is no proper dispatch found, we simply return null to let
// the caller decide what to do
return null;
// throw new RuntimeException("could not resolve concrete
// dispatch!\nType: "+concreteType+"\nMethod: "+m);
}
/** Returns the target for the given SpecialInvokeExpr. */
public SootMethod resolveSpecialDispatch(SpecialInvokeExpr ie, SootMethod container) {
SootMethod target = ie.getMethod();
/*
* This is a bizarre condition! Hopefully the implementation is correct. See VM Spec, 2nd Edition, Chapter 6, in the
* definition of invokespecial.
*/
if (target.getName().equals("") || target.isPrivate()) {
return target;
} else if (isSubclass(target.getDeclaringClass(), container.getDeclaringClass())) {
return resolveConcreteDispatch(container.getDeclaringClass(), target);
} else {
return target;
}
}
/**
* Gets the direct subclasses of a given class. The class needs to be resolved at least at the HIERARCHY level.
*
* @param c
* the class
* @return a collection (possibly empty) of the direct subclasses
*/
public Collection getSubclassesOf(SootClass c) {
c.checkLevel(SootClass.HIERARCHY);
Collection ret = classToSubclasses.get(c);
if (ret == null) {
return Collections.emptyList();
}
return ret;
}
}
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