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A Java Optimization Framework
package soot.dava.toolkits.base.misc;
/*-
* #%L
* Soot - a J*va Optimization Framework
* %%
* Copyright (C) 2003 Jerome Miecznikowski
* %%
* 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.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import soot.Body;
import soot.G;
import soot.PatchingChain;
import soot.RefType;
import soot.Scene;
import soot.Singletons;
import soot.SootClass;
import soot.SootMethod;
import soot.Trap;
import soot.Type;
import soot.Unit;
import soot.jimple.Stmt;
import soot.jimple.ThrowStmt;
import soot.jimple.internal.JExitMonitorStmt;
import soot.jimple.toolkits.callgraph.CallGraph;
import soot.jimple.toolkits.callgraph.CallGraphBuilder;
import soot.jimple.toolkits.callgraph.Edge;
import soot.util.Chain;
import soot.util.IterableSet;
/*
* Nomair A. Naeem 7th April 2006
* This class detects and propagates whether the signature of a method should have some throws Exception constructs.
*
* The reason we need to do this is since the JVM does not force all compilers to store throws information
* as attributes (javac does it ) but other compilers are not forced to do it
*
* Hence if we are coming from javac we dont need to perform this analysis since we already have the information
* if we are not coming from javac then we need to perform this analysis to say
* what the checked exceptions are for this method.
*
* Alls good until u try to decompile code like this
* try{
* synchronized(bla){
* bla
* bla
* }
* }catch(InterruptedException e){
* bla
* }
*
* If you create bytecode for this you will notice that because exitmointer has to be invoked if an exception occurs
* this is done by catching a Throwable(all possible exceptions) exiting the monitor and rethrowing the exception.
*
* Now that is alright the problem occurs because InterruptedExceptions will be caught but since we are throwing the
* general Throwable exception this algorithm says that the method should state in its signature that it throws
* java.lang,Throwable.
* CHANGE LOG: current fix is to hack into the algo find the place where we are about to add the java.lang.Throwable
* and if it is near an exit monitor we know dava is going to convert this to a synch and hence not add this exception!!
*
*
*/
public class ThrowFinder {
private static final Logger logger = LoggerFactory.getLogger(ThrowFinder.class);
public ThrowFinder(Singletons.Global g) {
}
public static ThrowFinder v() {
return G.v().soot_dava_toolkits_base_misc_ThrowFinder();
}
private HashSet registeredMethods;
private HashMap> protectionSet;
public static boolean DEBUG = false;
public void find() {
logger.debug("" + "Verifying exception handling.. ");
registeredMethods = new HashSet();
protectionSet = new HashMap>();
CallGraph cg;
if (Scene.v().hasCallGraph()) {
cg = Scene.v().getCallGraph();
} else {
new CallGraphBuilder().build();
cg = Scene.v().getCallGraph();
Scene.v().releaseCallGraph();
}
IterableSet worklist = new IterableSet();
logger.debug("\b. ");
// Get all the methods, and find protection for every statement.
Iterator classIt = Scene.v().getApplicationClasses().iterator();
while (classIt.hasNext()) {
Iterator methodIt = classIt.next().methodIterator();
while (methodIt.hasNext()) {
SootMethod m = (SootMethod) methodIt.next();
register_AreasOfProtection(m);
worklist.add(m);
}
}
// Build the subClass and superClass mappings.
HashMap subClassSet = new HashMap(),
superClassSet = new HashMap();
HashSet applicationClasses = new HashSet();
applicationClasses.addAll(Scene.v().getApplicationClasses());
classIt = Scene.v().getApplicationClasses().iterator();
while (classIt.hasNext()) {
SootClass c = (SootClass) classIt.next();
IterableSet superClasses = superClassSet.get(c);
if (superClasses == null) {
superClasses = new IterableSet();
superClassSet.put(c, superClasses);
}
IterableSet subClasses = subClassSet.get(c);
if (subClasses == null) {
subClasses = new IterableSet();
subClassSet.put(c, subClasses);
}
if (c.hasSuperclass()) {
SootClass superClass = c.getSuperclass();
IterableSet superClassSubClasses = subClassSet.get(superClass);
if (superClassSubClasses == null) {
superClassSubClasses = new IterableSet();
subClassSet.put(superClass, superClassSubClasses);
}
superClassSubClasses.add(c);
superClasses.add(superClass);
}
Iterator interfaceIt = c.getInterfaces().iterator();
while (interfaceIt.hasNext()) {
SootClass interfaceClass = (SootClass) interfaceIt.next();
IterableSet interfaceClassSubClasses = subClassSet.get(interfaceClass);
if (interfaceClassSubClasses == null) {
interfaceClassSubClasses = new IterableSet();
subClassSet.put(interfaceClass, interfaceClassSubClasses);
}
interfaceClassSubClasses.add(c);
superClasses.add(interfaceClass);
}
}
// Build the subMethod and superMethod mappings.
HashMap agreementMethodSet = new HashMap();
// Get exceptions from throw statements and add them to the exceptions that the method throws.
Iterator worklistIt = worklist.iterator();
while (worklistIt.hasNext()) {
SootMethod m = (SootMethod) worklistIt.next();
if (!m.isAbstract() && !m.isNative()) {
List exceptionList = m.getExceptions();
IterableSet exceptionSet = new IterableSet(exceptionList);
boolean changed = false;
Iterator it = m.retrieveActiveBody().getUnits().iterator();
while (it.hasNext()) {
Unit u = (Unit) it.next();
HashSet handled = protectionSet.get(u);
if (u instanceof ThrowStmt) {
Type t = ((ThrowStmt) u).getOp().getType();
if (t instanceof RefType) {
SootClass c = ((RefType) t).getSootClass();
if ((handled_Exception(handled, c) == false) && (exceptionSet.contains(c) == false)) {
/*
* Nomair A Naeem 7th April HACK TRYING TO MATCH PATTERN label0: r3 = r0; entermonitor r0; label1: r1.up();
* r0.wait(); exitmonitor r3; label2: goto label6; label3: $r5 := @caughtexception; label4: r4 = $r5;
* exitmonitor r3; label5: throw r4; HERE IS THE THROW WE JUST DETECTED LOOK and see if the previous unit is
* an exitmonitor label6: goto label8; label7: $r6 := @caughtexception; r7 = $r6; label8: r1.down(); return;
* catch java.lang.Throwable from label1 to label2 with label3; catch java.lang.Throwable from label4 to
* label5 with label3; catch java.lang.InterruptedException from label0 to label6 with label7;
*
*/
PatchingChain list = m.retrieveActiveBody().getUnits();
Unit pred = (Unit) list.getPredOf(u);
if (!(pred instanceof JExitMonitorStmt)) {
exceptionSet.add(c);
changed = true;
if (DEBUG) {
System.out.println("Added exception which is explicitly thrown" + c.getName());
}
} else {
if (DEBUG) {
System.out.println("Found monitor exit" + pred + " hence not adding");
}
}
}
}
}
}
it = cg.edgesOutOf(m);
while (it.hasNext()) {
Edge e = (Edge) it.next();
Stmt callSite = e.srcStmt();
if (callSite == null) {
continue;
}
HashSet handled = protectionSet.get(callSite);
SootMethod target = e.tgt();
Iterator exceptionIt = target.getExceptions().iterator();
while (exceptionIt.hasNext()) {
SootClass exception = exceptionIt.next();
if ((handled_Exception(handled, exception) == false) && (exceptionSet.contains(exception) == false)) {
exceptionSet.add(exception);
changed = true;
}
}
}
if (changed) {
exceptionList.clear();
exceptionList.addAll(exceptionSet);
}
}
// While we're at it, put the superMethods and the subMethods in the agreementMethodSet.
find_OtherMethods(m, agreementMethodSet, subClassSet, applicationClasses);
find_OtherMethods(m, agreementMethodSet, superClassSet, applicationClasses);
}
// Perform worklist algorithm to propegate the throws information.
while (worklist.isEmpty() == false) {
SootMethod m = (SootMethod) worklist.getFirst();
worklist.removeFirst();
IterableSet agreementMethods = agreementMethodSet.get(m);
if (agreementMethods != null) {
Iterator amit = agreementMethods.iterator();
while (amit.hasNext()) {
SootMethod otherMethod = (SootMethod) amit.next();
List otherExceptionsList = otherMethod.getExceptions();
IterableSet otherExceptionSet = new IterableSet(otherExceptionsList);
boolean changed = false;
Iterator exceptionIt = m.getExceptions().iterator();
while (exceptionIt.hasNext()) {
SootClass exception = exceptionIt.next();
if (otherExceptionSet.contains(exception) == false) {
otherExceptionSet.add(exception);
changed = true;
}
}
if (changed) {
otherExceptionsList.clear();
otherExceptionsList.addAll(otherExceptionSet);
if (worklist.contains(otherMethod) == false) {
worklist.addLast(otherMethod);
}
}
}
}
Iterator it = cg.edgesOutOf(m);
while (it.hasNext()) {
Edge e = (Edge) it.next();
Stmt callingSite = e.srcStmt();
if (callingSite == null) {
continue;
}
SootMethod callingMethod = e.src();
List exceptionList = callingMethod.getExceptions();
IterableSet exceptionSet = new IterableSet(exceptionList);
HashSet handled = protectionSet.get(callingSite);
boolean changed = false;
Iterator exceptionIt = m.getExceptions().iterator();
while (exceptionIt.hasNext()) {
SootClass exception = exceptionIt.next();
if ((handled_Exception(handled, exception) == false) && (exceptionSet.contains(exception) == false)) {
exceptionSet.add(exception);
changed = true;
}
}
if (changed) {
exceptionList.clear();
exceptionList.addAll(exceptionSet);
if (worklist.contains(callingMethod) == false) {
worklist.addLast(callingMethod);
}
}
}
}
}
private void find_OtherMethods(SootMethod startingMethod, HashMap methodMapping,
HashMap classMapping, HashSet applicationClasses) {
IterableSet worklist = (IterableSet) classMapping.get(startingMethod.getDeclaringClass()).clone();
HashSet touchSet = new HashSet();
touchSet.addAll(worklist);
String signature = startingMethod.getSubSignature();
while (worklist.isEmpty() == false) {
SootClass currentClass = (SootClass) worklist.getFirst();
worklist.removeFirst();
if (applicationClasses.contains(currentClass) == false) {
continue;
}
if (currentClass.declaresMethod(signature)) {
IterableSet otherMethods = methodMapping.get(startingMethod);
if (otherMethods == null) {
otherMethods = new IterableSet();
methodMapping.put(startingMethod, otherMethods);
}
otherMethods.add(currentClass.getMethod(signature));
}
else {
IterableSet otherClasses = classMapping.get(currentClass);
if (otherClasses != null) {
Iterator ocit = otherClasses.iterator();
while (ocit.hasNext()) {
SootClass otherClass = (SootClass) ocit.next();
if (touchSet.contains(otherClass) == false) {
worklist.addLast(otherClass);
touchSet.add(otherClass);
}
}
}
}
}
}
private void register_AreasOfProtection(SootMethod m) {
if (registeredMethods.contains(m)) {
return;
}
registeredMethods.add(m);
if (m.hasActiveBody() == false) {
return;
}
Body b = m.getActiveBody();
Chain stmts = b.getUnits();
Iterator trapIt = b.getTraps().iterator();
while (trapIt.hasNext()) {
Trap t = (Trap) trapIt.next();
SootClass exception = t.getException();
Iterator sit = stmts.iterator(t.getBeginUnit(), stmts.getPredOf(t.getEndUnit()));
while (sit.hasNext()) {
Stmt s = (Stmt) sit.next();
HashSet handled = null;
if ((handled = protectionSet.get(s)) == null) {
handled = new HashSet();
protectionSet.put(s, handled);
}
if (handled.contains(exception) == false) {
handled.add(exception);
}
}
}
}
private boolean handled_Exception(HashSet handledExceptions, SootClass c) {
SootClass thrownException = c;
if (is_HandledByRuntime(thrownException)) {
return true;
}
if (handledExceptions == null) {
return false;
}
while (true) {
if (handledExceptions.contains(thrownException)) {
return true;
}
if (thrownException.hasSuperclass() == false) {
return false;
}
thrownException = thrownException.getSuperclass();
}
}
private boolean is_HandledByRuntime(SootClass c) {
SootClass thrownException = c, runtimeException = Scene.v().getSootClass("java.lang.RuntimeException"),
error = Scene.v().getSootClass("java.lang.Error");
while (true) {
if ((thrownException == runtimeException) || (thrownException == error)) {
return true;
}
if (thrownException.hasSuperclass() == false) {
return false;
}
thrownException = thrownException.getSuperclass();
}
}
}
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