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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * 
 * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
 * 
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 * 
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
 * Sun designates this particular file as subject to the "Classpath" exception
 * as provided by Sun in the GPL Version 2 section of the License file that
 * accompanied this code.  If applicable, add the following below the License
 * Header, with the fields enclosed by brackets [] replaced by your own
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 * elects to include this software in this distribution under the [CDDL or GPL
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 * its licensees as provided above.  However, if you add GPL Version 2 code
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 * only if the new code is made subject to such option by the copyright
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package com.sun.org.apache.bcel.internal.verifier.structurals;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact [email protected].
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache BCEL", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * .
 */

import java.io.*;
import java.util.ArrayList;
import java.util.Random;
import java.util.Vector;
import com.sun.org.apache.bcel.internal.Constants;
import com.sun.org.apache.bcel.internal.Repository;
import com.sun.org.apache.bcel.internal.classfile.*;
import com.sun.org.apache.bcel.internal.generic.*;
import com.sun.org.apache.bcel.internal.verifier.*;
import com.sun.org.apache.bcel.internal.verifier.statics.*;
import com.sun.org.apache.bcel.internal.verifier.exc.*;

/**
 * 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,v 1.3 2007-07-19 04:35:00 ofung Exp $
 * @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 Vector ics = new Vector(); // Type: InstructionContext
		private Vector 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 com.sun.org.apache.bcel.internal.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