/*
* Copyright 2000-2004 The Apache Software Foundation
*
* 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 org.apache.bcel.verifier.structurals;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.Vector;
import org.apache.bcel.Constants;
import org.apache.bcel.Repository;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Method;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.JsrInstruction;
import org.apache.bcel.generic.MethodGen;
import org.apache.bcel.generic.ObjectType;
import org.apache.bcel.generic.RET;
import org.apache.bcel.generic.ReturnInstruction;
import org.apache.bcel.generic.ReturnaddressType;
import org.apache.bcel.generic.Type;
import org.apache.bcel.verifier.PassVerifier;
import org.apache.bcel.verifier.VerificationResult;
import org.apache.bcel.verifier.Verifier;
import org.apache.bcel.verifier.exc.AssertionViolatedException;
import org.apache.bcel.verifier.exc.VerifierConstraintViolatedException;
/**
* This PassVerifier verifies a method of class file according to pass 3,
* so-called structural verification as described in The Java Virtual Machine
* Specification, 2nd edition.
* More detailed information is to be found at the do_verify() method's
* documentation.
*
* @version $Id: Pass3bVerifier.java 384759 2006-03-10 10:38:59Z tcurdt $
* @author Enver Haase
* @see #do_verify()
*/
public final class Pass3bVerifier extends PassVerifier{
/* TODO: Throughout pass 3b, upper halves of LONG and DOUBLE
are represented by Type.UNKNOWN. This should be changed
in favour of LONG_Upper and DOUBLE_Upper as in pass 2. */
/**
* An InstructionContextQueue is a utility class that holds
* (InstructionContext, ArrayList) pairs in a Queue data structure.
* This is used to hold information about InstructionContext objects
* externally --- i.e. that information is not saved inside the
* InstructionContext object itself. This is useful to save the
* execution path of the symbolic execution of the
* Pass3bVerifier - this is not information
* that belongs into the InstructionContext object itself.
* Only at "execute()"ing
* time, an InstructionContext object will get the current information
* we have about its symbolic execution predecessors.
*/
private static final class InstructionContextQueue{
private List ics = new Vector(); // Type: InstructionContext
private List ecs = new Vector(); // Type: ArrayList (of InstructionContext)
public void add(InstructionContext ic, ArrayList executionChain){
ics.add(ic);
ecs.add(executionChain);
}
public boolean isEmpty(){
return ics.isEmpty();
}
public void remove(){
this.remove(0);
}
public void remove(int i){
ics.remove(i);
ecs.remove(i);
}
public InstructionContext getIC(int i){
return (InstructionContext) ics.get(i);
}
public ArrayList getEC(int i){
return (ArrayList) ecs.get(i);
}
public int size(){
return ics.size();
}
} // end Inner Class InstructionContextQueue
/** In DEBUG mode, the verification algorithm is not randomized. */
private static final boolean DEBUG = true;
/** The Verifier that created this. */
private Verifier myOwner;
/** The method number to verify. */
private int method_no;
/**
* This class should only be instantiated by a Verifier.
*
* @see org.apache.bcel.verifier.Verifier
*/
public Pass3bVerifier(Verifier owner, int method_no){
myOwner = owner;
this.method_no = method_no;
}
/**
* Whenever the outgoing frame
* situation of an InstructionContext changes, all its successors are
* put [back] into the queue [as if they were unvisited].
* The proof of termination is about the existence of a
* fix point of frame merging.
*/
private void circulationPump(ControlFlowGraph cfg, InstructionContext start, Frame vanillaFrame, InstConstraintVisitor icv, ExecutionVisitor ev){
final Random random = new Random();
InstructionContextQueue icq = new InstructionContextQueue();
start.execute(vanillaFrame, new ArrayList(), icv, ev); // new ArrayList() <=> no Instruction was executed before
// => Top-Level routine (no jsr call before)
icq.add(start, new ArrayList());
// LOOP!
while (!icq.isEmpty()){
InstructionContext u;
ArrayList ec;
if (!DEBUG){
int r = random.nextInt(icq.size());
u = icq.getIC(r);
ec = icq.getEC(r);
icq.remove(r);
}
else{
u = icq.getIC(0);
ec = icq.getEC(0);
icq.remove(0);
}
ArrayList oldchain = (ArrayList) (ec.clone());
ArrayList newchain = (ArrayList) (ec.clone());
newchain.add(u);
if ((u.getInstruction().getInstruction()) instanceof RET){
//System.err.println(u);
// We can only follow _one_ successor, the one after the
// JSR that was recently executed.
RET ret = (RET) (u.getInstruction().getInstruction());
ReturnaddressType t = (ReturnaddressType) u.getOutFrame(oldchain).getLocals().get(ret.getIndex());
InstructionContext theSuccessor = cfg.contextOf(t.getTarget());
// Sanity check
InstructionContext lastJSR = null;
int skip_jsr = 0;
for (int ss=oldchain.size()-1; ss >= 0; ss--){
if (skip_jsr < 0){
throw new AssertionViolatedException("More RET than JSR in execution chain?!");
}
//System.err.println("+"+oldchain.get(ss));
if (((InstructionContext) oldchain.get(ss)).getInstruction().getInstruction() instanceof JsrInstruction){
if (skip_jsr == 0){
lastJSR = (InstructionContext) oldchain.get(ss);
break;
}
else{
skip_jsr--;
}
}
if (((InstructionContext) oldchain.get(ss)).getInstruction().getInstruction() instanceof RET){
skip_jsr++;
}
}
if (lastJSR == null){
throw new AssertionViolatedException("RET without a JSR before in ExecutionChain?! EC: '"+oldchain+"'.");
}
JsrInstruction jsr = (JsrInstruction) (lastJSR.getInstruction().getInstruction());
if ( theSuccessor != (cfg.contextOf(jsr.physicalSuccessor())) ){
throw new AssertionViolatedException("RET '"+u.getInstruction()+"' info inconsistent: jump back to '"+theSuccessor+"' or '"+cfg.contextOf(jsr.physicalSuccessor())+"'?");
}
if (theSuccessor.execute(u.getOutFrame(oldchain), newchain, icv, ev)){
icq.add(theSuccessor, (ArrayList) newchain.clone());
}
}
else{// "not a ret"
// Normal successors. Add them to the queue of successors.
InstructionContext[] succs = u.getSuccessors();
for (int s=0; s<succs.length; s++){
InstructionContext v = succs[s];
if (v.execute(u.getOutFrame(oldchain), newchain, icv, ev)){
icq.add(v, (ArrayList) newchain.clone());
}
}
}// end "not a ret"
// Exception Handlers. Add them to the queue of successors.
// [subroutines are never protected; mandated by JustIce]
ExceptionHandler[] exc_hds = u.getExceptionHandlers();
for (int s=0; s<exc_hds.length; s++){
InstructionContext v = cfg.contextOf(exc_hds[s].getHandlerStart());
// TODO: the "oldchain" and "newchain" is used to determine the subroutine
// we're in (by searching for the last JSR) by the InstructionContext
// implementation. Therefore, we should not use this chain mechanism
// when dealing with exception handlers.
// Example: a JSR with an exception handler as its successor does not
// mean we're in a subroutine if we go to the exception handler.
// We should address this problem later; by now we simply "cut" the chain
// by using an empty chain for the exception handlers.
//if (v.execute(new Frame(u.getOutFrame(oldchain).getLocals(), new OperandStack (u.getOutFrame().getStack().maxStack(), (exc_hds[s].getExceptionType()==null? Type.THROWABLE : exc_hds[s].getExceptionType())) ), newchain), icv, ev){
//icq.add(v, (ArrayList) newchain.clone());
if (v.execute(new Frame(u.getOutFrame(oldchain).getLocals(), new OperandStack (u.getOutFrame(oldchain).getStack().maxStack(), (exc_hds[s].getExceptionType()==null? Type.THROWABLE : exc_hds[s].getExceptionType())) ), new ArrayList(), icv, ev)){
icq.add(v, new ArrayList());
}
}
}// while (!icq.isEmpty()) END
InstructionHandle ih = start.getInstruction();
do{
if ((ih.getInstruction() instanceof ReturnInstruction) && (!(cfg.isDead(ih)))) {
InstructionContext ic = cfg.contextOf(ih);
Frame f = ic.getOutFrame(new ArrayList()); // TODO: This is buggy, we check only the top-level return instructions this way. Maybe some maniac returns from a method when in a subroutine?
LocalVariables lvs = f.getLocals();
for (int i=0; i<lvs.maxLocals(); i++){
if (lvs.get(i) instanceof UninitializedObjectType){
this.addMessage("Warning: ReturnInstruction '"+ic+"' may leave method with an uninitialized object in the local variables array '"+lvs+"'.");
}
}
OperandStack os = f.getStack();
for (int i=0; i<os.size(); i++){
if (os.peek(i) instanceof UninitializedObjectType){
this.addMessage("Warning: ReturnInstruction '"+ic+"' may leave method with an uninitialized object on the operand stack '"+os+"'.");
}
}
}
}while ((ih = ih.getNext()) != null);
}
/**
* Pass 3b implements the data flow analysis as described in the Java Virtual
* Machine Specification, Second Edition.
* Later versions will use LocalVariablesInfo objects to verify if the
* verifier-inferred types and the class file's debug information (LocalVariables
* attributes) match [TODO].
*
* @see org.apache.bcel.verifier.statics.LocalVariablesInfo
* @see org.apache.bcel.verifier.statics.Pass2Verifier#getLocalVariablesInfo(int)
*/
public VerificationResult do_verify(){
if (! myOwner.doPass3a(method_no).equals(VerificationResult.VR_OK)){
return VerificationResult.VR_NOTYET;
}
// Pass 3a ran before, so it's safe to assume the JavaClass object is
// in the BCEL repository.
JavaClass jc;
try {
jc = Repository.lookupClass(myOwner.getClassName());
} catch (ClassNotFoundException e) {
// FIXME: maybe not the best way to handle this
throw new AssertionViolatedException("Missing class: " + e.toString());
}
ConstantPoolGen constantPoolGen = new ConstantPoolGen(jc.getConstantPool());
// Init Visitors
InstConstraintVisitor icv = new InstConstraintVisitor();
icv.setConstantPoolGen(constantPoolGen);
ExecutionVisitor ev = new ExecutionVisitor();
ev.setConstantPoolGen(constantPoolGen);
Method[] methods = jc.getMethods(); // Method no "method_no" exists, we ran Pass3a before on it!
try{
MethodGen mg = new MethodGen(methods[method_no], myOwner.getClassName(), constantPoolGen);
icv.setMethodGen(mg);
////////////// DFA BEGINS HERE ////////////////
if (! (mg.isAbstract() || mg.isNative()) ){ // IF mg HAS CODE (See pass 2)
ControlFlowGraph cfg = new ControlFlowGraph(mg);
// Build the initial frame situation for this method.
Frame f = new Frame(mg.getMaxLocals(),mg.getMaxStack());
if ( !mg.isStatic() ){
if (mg.getName().equals(Constants.CONSTRUCTOR_NAME)){
Frame._this = new UninitializedObjectType(new ObjectType(jc.getClassName()));
f.getLocals().set(0, Frame._this);
}
else{
Frame._this = null;
f.getLocals().set(0, new ObjectType(jc.getClassName()));
}
}
Type[] argtypes = mg.getArgumentTypes();
int twoslotoffset = 0;
for (int j=0; j<argtypes.length; j++){
if (argtypes[j] == Type.SHORT || argtypes[j] == Type.BYTE || argtypes[j] == Type.CHAR || argtypes[j] == Type.BOOLEAN){
argtypes[j] = Type.INT;
}
f.getLocals().set(twoslotoffset + j + (mg.isStatic()?0:1), argtypes[j]);
if (argtypes[j].getSize() == 2){
twoslotoffset++;
f.getLocals().set(twoslotoffset + j + (mg.isStatic()?0:1), Type.UNKNOWN);
}
}
circulationPump(cfg, cfg.contextOf(mg.getInstructionList().getStart()), f, icv, ev);
}
}
catch (VerifierConstraintViolatedException ce){
ce.extendMessage("Constraint violated in method '"+methods[method_no]+"':\n","");
return new VerificationResult(VerificationResult.VERIFIED_REJECTED, ce.getMessage());
}
catch (RuntimeException re){
// These are internal errors
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
re.printStackTrace(pw);
throw new AssertionViolatedException("Some RuntimeException occured while verify()ing class '"+jc.getClassName()+"', method '"+methods[method_no]+"'. Original RuntimeException's stack trace:\n---\n"+sw+"---\n");
}
return VerificationResult.VR_OK;
}
/** Returns the method number as supplied when instantiating. */
public int getMethodNo(){
return method_no;
}
}