Pass3bVerifier.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.Const;
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.ReferenceType;
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.StructuralCodeConstraintException;
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 1749603 2016-06-21 20:50:19Z ggregory $
* @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 final List<InstructionContext> ics = new Vector<>();
private final List<ArrayList<InstructionContext>> ecs = new Vector<>();
public void add(final InstructionContext ic, final ArrayList<InstructionContext> executionChain) {
ics.add(ic);
ecs.add(executionChain);
}
public boolean isEmpty() {
return ics.isEmpty();
}
public void remove(final int i) {
ics.remove(i);
ecs.remove(i);
}
public InstructionContext getIC(final int i) {
return ics.get(i);
}
public ArrayList<InstructionContext> getEC(final int i) {
return 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 final Verifier myOwner;
/** The method number to verify. */
private final int method_no;
/**
* This class should only be instantiated by a Verifier.
*
* @see org.apache.bcel.verifier.Verifier
*/
public Pass3bVerifier(final Verifier owner, final 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(final MethodGen m,final ControlFlowGraph cfg, final InstructionContext start,
final Frame vanillaFrame, final InstConstraintVisitor icv, final ExecutionVisitor ev) {
final Random random = new Random();
final InstructionContextQueue icq = new InstructionContextQueue();
start.execute(vanillaFrame, new ArrayList<InstructionContext>(), icv, ev);
// new ArrayList() <=> no Instruction was executed before
// => Top-Level routine (no jsr call before)
icq.add(start, new ArrayList<InstructionContext>());
// LOOP!
while (!icq.isEmpty()) {
InstructionContext u;
ArrayList<InstructionContext> ec;
if (!DEBUG) {
final 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);
}
@SuppressWarnings("unchecked") // ec is of type ArrayList<InstructionContext>
final
ArrayList<InstructionContext> oldchain = (ArrayList<InstructionContext>) (ec.clone());
@SuppressWarnings("unchecked") // ec is of type ArrayList<InstructionContext>
final
ArrayList<InstructionContext> newchain = (ArrayList<InstructionContext>) (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.
final RET ret = (RET) (u.getInstruction().getInstruction());
final ReturnaddressType t = (ReturnaddressType) u.getOutFrame(oldchain).getLocals().get(ret.getIndex());
final 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 ((oldchain.get(ss)).getInstruction().getInstruction() instanceof JsrInstruction) {
if (skip_jsr == 0) {
lastJSR = oldchain.get(ss);
break;
}
skip_jsr--;
}
if ((oldchain.get(ss)).getInstruction().getInstruction() instanceof RET) {
skip_jsr++;
}
}
if (lastJSR == null) {
throw new AssertionViolatedException("RET without a JSR before in ExecutionChain?! EC: '"+oldchain+"'.");
}
final 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)) {
@SuppressWarnings("unchecked") // newchain is already of type ArrayList<InstructionContext>
final
ArrayList<InstructionContext> newchainClone = (ArrayList<InstructionContext>) newchain.clone();
icq.add(theSuccessor, newchainClone);
}
}
else{// "not a ret"
// Normal successors. Add them to the queue of successors.
final InstructionContext[] succs = u.getSuccessors();
for (final InstructionContext v : succs) {
if (v.execute(u.getOutFrame(oldchain), newchain, icv, ev)) {
@SuppressWarnings("unchecked") // newchain is already of type ArrayList<InstructionContext>
final
ArrayList<InstructionContext> newchainClone = (ArrayList<InstructionContext>) newchain.clone();
icq.add(v, newchainClone);
}
}
}// end "not a ret"
// Exception Handlers. Add them to the queue of successors.
// [subroutines are never protected; mandated by JustIce]
final ExceptionHandler[] exc_hds = u.getExceptionHandlers();
for (final ExceptionHandler exc_hd : exc_hds) {
final InstructionContext v = cfg.contextOf(exc_hd.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_hd.getExceptionType()==null? Type.THROWABLE : exc_hd.getExceptionType())),
new ArrayList<InstructionContext>(), icv, ev)) {
icq.add(v, new ArrayList<InstructionContext>());
}
}
}// while (!icq.isEmpty()) END
InstructionHandle ih = start.getInstruction();
do{
if ((ih.getInstruction() instanceof ReturnInstruction) && (!(cfg.isDead(ih)))) {
final InstructionContext ic = cfg.contextOf(ih);
// 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?
final Frame f = ic.getOutFrame(new ArrayList<InstructionContext>());
final 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+"'.");
}
}
final 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+"'.");
}
}
//see JVM $4.8.2
Type returnedType = null;
final OperandStack inStack = ic.getInFrame().getStack();
if (inStack.size() >= 1) {
returnedType = inStack.peek();
} else {
returnedType = Type.VOID;
}
if (returnedType != null) {
if (returnedType instanceof ReferenceType) {
try {
if (!((ReferenceType) returnedType).isCastableTo(m.getReturnType())) {
invalidReturnTypeError(returnedType, m);
}
} catch (final ClassNotFoundException e) {
// Don't know what do do now, so raise RuntimeException
throw new RuntimeException(e);
}
} else if (!returnedType.equals(m.getReturnType().normalizeForStackOrLocal())) {
invalidReturnTypeError(returnedType, m);
}
}
}
} while ((ih = ih.getNext()) != null);
}
/**
* Throws an exception indicating the returned type is not compatible with the return type of the given method
* @throws StructuralCodeConstraintException always
* @since 6.0
*/
public void invalidReturnTypeError(final Type returnedType, final MethodGen m) {
throw new StructuralCodeConstraintException(
"Returned type "+returnedType+" does not match Method's return type "+m.getReturnType());
}
/**
* 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)
*/
@Override
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 (final ClassNotFoundException e) {
// FIXME: maybe not the best way to handle this
throw new AssertionViolatedException("Missing class: " + e, e);
}
final ConstantPoolGen constantPoolGen = new ConstantPoolGen(jc.getConstantPool());
// Init Visitors
final InstConstraintVisitor icv = new InstConstraintVisitor();
icv.setConstantPoolGen(constantPoolGen);
final ExecutionVisitor ev = new ExecutionVisitor();
ev.setConstantPoolGen(constantPoolGen);
final Method[] methods = jc.getMethods(); // Method no "method_no" exists, we ran Pass3a before on it!
try{
final 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)
final ControlFlowGraph cfg = new ControlFlowGraph(mg);
// Build the initial frame situation for this method.
final Frame f = new Frame(mg.getMaxLocals(),mg.getMaxStack());
if ( !mg.isStatic() ) {
if (mg.getName().equals(Const.CONSTRUCTOR_NAME)) {
Frame.setThis(new UninitializedObjectType(ObjectType.getInstance(jc.getClassName())));
f.getLocals().set(0, Frame.getThis());
}
else{
Frame.setThis(null);
f.getLocals().set(0, ObjectType.getInstance(jc.getClassName()));
}
}
final 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(mg,cfg, cfg.contextOf(mg.getInstructionList().getStart()), f, icv, ev);
}
}
catch (final VerifierConstraintViolatedException ce) {
ce.extendMessage("Constraint violated in method '"+methods[method_no]+"':\n","");
return new VerificationResult(VerificationResult.VERIFIED_REJECTED, ce.getMessage());
}
catch (final RuntimeException re) {
// These are internal errors
final StringWriter sw = new StringWriter();
final 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", re);
}
return VerificationResult.VR_OK;
}
/** Returns the method number as supplied when instantiating. */
public int getMethodNo() {
return method_no;
}
}