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// This is a modified version of BCEL's Pass3bVerifier. See below for details.
/*
* 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.plumelib.bcelutil;
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.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.VerificationResult;
import org.apache.bcel.verifier.exc.AssertionViolatedException;
import org.apache.bcel.verifier.exc.StructuralCodeConstraintException;
import org.apache.bcel.verifier.exc.VerifierConstraintViolatedException;
import org.apache.bcel.verifier.structurals.ControlFlowGraph;
import org.apache.bcel.verifier.structurals.ExceptionHandler;
import org.apache.bcel.verifier.structurals.ExecutionVisitor;
import org.apache.bcel.verifier.structurals.Frame;
import org.apache.bcel.verifier.structurals.InstConstraintVisitor;
import org.apache.bcel.verifier.structurals.InstructionContext;
import org.apache.bcel.verifier.structurals.LocalVariables;
import org.apache.bcel.verifier.structurals.OperandStack;
import org.apache.bcel.verifier.structurals.UninitializedObjectType;
import org.checkerframework.checker.index.qual.NonNegative;
import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
import org.checkerframework.checker.nullness.qual.NonNull;
/**
* This is a slightly modified version of Pass3bVerifier from BCEL. It uses NoConstaintsVisitor as
* InstConstraintVisitor appears to be quite out of date and incorrectly fails on many valid class
* files. Hence, StackVer assumes the method is valid and is only interested in the result of the
* symbolic execution in order to capture the state of the local variables and stack at the start of
* each byte code instruction.
*
* To see the diffs, you will need a git clone of [email protected]:apache/commons-bcel.git. The
* particular version StackVer is based on can be retrieved with
* git show e6dcacb9ca1d:src/main/java/org/apache/bcel/verifier/structurals/Pass3bVerifier.java
* then run google-java-format on the downloaded file.
*
*
The original documentation follows.
*
*
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.
*
* @see #do_stack_ver
*/
@SuppressWarnings({"rawtypes", "nullness"}) // third-party code
public final class StackVer {
/* 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 {
// The following two fields together represent the queue.
/** The first elements from pairs in the queue. */
private final List ics = new Vector<>();
/** The second elements from pairs in the queue. */
private final List> ecs = new Vector<>();
/**
* Adds an (InstructionContext, ExecutionChain) pair to this queue.
*
* @param ic the InstructionContext
* @param executionChain the ExecutionChain
*/
public void add(
final InstructionContext ic, final ArrayList executionChain) {
ics.add(ic);
ecs.add(executionChain);
}
/**
* Tests if InstructionContext queue is empty.
*
* @return true if the InstructionContext queue is empty.
*/
public boolean isEmpty() {
return ics.isEmpty();
}
/**
* Removes a specific (InstructionContext, ExecutionChain) pair from their respective queues.
*
* @param i the index of the items to be removed
*/
public void remove(final @NonNegative int i) {
ics.remove(i);
ecs.remove(i);
}
/**
* Gets a specific InstructionContext from the queue.
*
* @param i the index of the item to be fetched
* @return the indicated InstructionContext
*/
public InstructionContext getIC(final @NonNegative int i) {
return ics.get(i);
}
/**
* Gets a specific ExecutionChain from the queue.
*
* @param i the index of the item to be fetched
* @return the indicated ExecutionChain
*/
public ArrayList getEC(final @NonNegative int i) {
return ecs.get(i);
}
/**
* Gets the size of the InstructionContext queue.
*
* @return the size of the InstructionQueue
*/
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;
*/
/** The types on the stack for each instruction by byte code offset. */
// Set by do_stack_ver().
private @MonotonicNonNull StackTypes stack_types;
/**
* This class should only be instantiated by a Verifier.
*
* @see org.apache.bcel.verifier.Verifier
*/
public StackVer() {
/*
myOwner = owner;
this.method_no = method_no;
*/
}
/**
* Return the types on the stack at each byte code offset. Only valid after do_stack_ver() is
* called.
*
* @return the StackTypes object for the method being verified
*/
public StackTypes get_stack_types() {
return stack_types;
}
/**
* 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();
execute(start, 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) {
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
final ArrayList oldchain = (ArrayList) (ec.clone());
@SuppressWarnings("unchecked") // ec is of type ArrayList
final 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.
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 (execute(theSuccessor, u.getOutFrame(oldchain), newchain, icv, ev)) {
@SuppressWarnings(
"unchecked") // newchain is already of type ArrayList
final ArrayList newchainClone =
(ArrayList) 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 (execute(v, u.getOutFrame(oldchain), newchain, icv, ev)) {
@SuppressWarnings(
"unchecked") // newchain is already of type ArrayList
final ArrayList newchainClone =
(ArrayList) 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 (execute(v, 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 (execute(
v,
new Frame(
u.getOutFrame(oldchain).getLocals(),
new OperandStack(
u.getOutFrame(oldchain).getStack().maxStack(),
exc_hd.getExceptionType() == null
? Type.THROWABLE
: exc_hd.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)))) {
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());
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
+ "'.");
}
}
/* This code from Pass3bVerifier incorrectly fails on some valid class files.
// 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.
*
* @param returnedType the type of the returned expression
* @param m the method we are processing
* @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].
*
* @param mg MethodGen for the method to be verified
* @return the VerificationResult
* @see org.apache.bcel.verifier.statics.LocalVariablesInfo
* @see org.apache.bcel.verifier.statics.Pass2Verifier#getLocalVariablesInfo(int)
*/
public VerificationResult do_stack_ver(MethodGen mg) {
/* This code is not needed for StackVer.
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 = mg.getConstantPool();
// Init Visitors
final InstConstraintVisitor icv = new NoConstraintsVisitor();
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 {
stack_types = new StackTypes(mg);
icv.setMethodGen(mg);
////////////// DFA BEGINS HERE ////////////////
if (!(mg.isAbstract() || mg.isNative())) { // IF mg HAS CODE (See pass 2)
// false says don't check if jsr subroutine is covered by exception handler
final ControlFlowGraph cfg = new ControlFlowGraph(mg, false);
// 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(new ObjectType(mg.getClassName())));
f.getLocals().set(0, Frame.getThis());
} else {
@SuppressWarnings("nullness") // unannotated: org.apache.bcel.verifier.structurals.Frame
@NonNull UninitializedObjectType dummy = null;
Frame.setThis(dummy);
f.getLocals().set(0, new ObjectType(mg.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 '" + mg + "':\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 '"
+ mg.getClassName()
+ "', method '"
+ mg
+ "'. Original RuntimeException's stack trace:\n---\n"
+ sw
+ "---\n",
re);
}
return VerificationResult.VR_OK;
}
/** Returns the method number as supplied when instantiating. */
/* Removed from StackVer
public int getMethodNo() {
return method_no;
}
*/
/** Like InstructionContext.execute, but also sets stack_types. */
boolean execute(
InstructionContext ic,
Frame inFrame,
ArrayList executionPredecessors,
InstConstraintVisitor icv,
ExecutionVisitor ev) {
stack_types.set(ic.getInstruction().getPosition(), inFrame);
return ic.execute(inFrame, executionPredecessors, icv, ev);
}
// Code from PassVerifier in BCEL so that we don't have to extend it
/** The (warning) messages. */
private ArrayList messages = new ArrayList<>();
/**
* This method adds a (warning) message to the message pool of this PassVerifier.
*
* @param message the String containing the warning message
*/
public void addMessage(String message) {
messages.add(message);
}
}