subroutines.java

Java Bytecode Editor 是一个 JAVA 的字节码反汇编和修改器。它可以很方便的修改已经编译成 Class 文件的 JAVA 文件。

package org.apache.bcel.verifier.structurals;

/* ====================================================================
 * The Apache Software License, Version 1.1
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 * modification, are permitted provided that the following conditions
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 *
 * 1. Redistributions of source code must retain the above copyright
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 *
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 *
 * 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.
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import org.apache.bcel.generic.*;
import org.apache.bcel.verifier.exc.*;
import java.awt.Color;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;

	/**
	 * Instances of this class contain information about the subroutines
	 * found in a code array of a method.
	 * This implementation considers the top-level (the instructions
	 * reachable without a JSR or JSR_W starting off from the first
	 * instruction in a code array of a method) being a special subroutine;
	 * see getTopLevel() for that.
	 * Please note that the definition of subroutines in the Java Virtual
	 * Machine Specification, Second Edition is somewhat incomplete.
	 * Therefore, JustIce uses an own, more rigid notion.
	 * Basically, a subroutine is a piece of code that starts at the target
	 * of a JSR of JSR_W instruction and ends at a corresponding RET
	 * instruction. Note also that the control flow of a subroutine
	 * may be complex and non-linear; and that subroutines may be nested.
	 * JustIce also mandates subroutines not to be protected by exception
	 * handling code (for the sake of control flow predictability).
	 * To understand JustIce's notion of subroutines, please read
   *
	 * TODO: refer to the paper.
	 *
	 * @version $Id: Subroutines.java,v 1.3 2006/09/18 14:51:46 andos Exp $
	 * @author <A HREF="http://www.inf.fu-berlin.de/~ehaase"/>Enver Haase</A>
	 * @see #getTopLevel()
	 */
public class Subroutines{
	/**
	 * This inner class implements the Subroutine interface.
	 */
	private class SubroutineImpl implements Subroutine{
		/**
		 * UNSET, a symbol for an uninitialized localVariable
		 * field. This is used for the "top-level" Subroutine;
		 * i.e. no subroutine.
		 */
		private final int UNSET = -1;

		/**
		 * The Local Variable slot where the first
		 * instruction of this subroutine (an ASTORE) stores
		 * the JsrInstruction's ReturnAddress in and
		 * the RET of this subroutine operates on.
		 */
		private int localVariable = UNSET;

		/** The instructions that belong to this subroutine. */
		private HashSet<InstructionHandle> instructions = new HashSet<InstructionHandle>(); // Elements: InstructionHandle
		
		/*
		 * Refer to the Subroutine interface for documentation.
		 */
		public boolean contains(InstructionHandle inst){
			return instructions.contains(inst);
		}
		
		/**
		 * The JSR or JSR_W instructions that define this
		 * subroutine by targeting it.
		 */
		private HashSet<InstructionHandle> theJSRs = new HashSet<InstructionHandle>();
		
		/**
		 * The RET instruction that leaves this subroutine.
		 */
		private InstructionHandle theRET;
		
		/**
		 * Returns a String representation of this object, merely
		 * for debugging purposes.
		 * (Internal) Warning: Verbosity on a problematic subroutine may cause
		 * stack overflow errors due to recursive subSubs() calls.
		 * Don't use this, then.
		 */
		public String toString(){
			String ret = "Subroutine: Local variable is '"+localVariable+"', JSRs are '"+theJSRs+"', RET is '"+theRET+"', Instructions: '"+instructions.toString()+"'.";
			
			ret += " Accessed local variable slots: '";
			int[] alv = getAccessedLocalsIndices();
			for (int i=0; i<alv.length; i++){
				ret += alv[i]+" ";
			}
			ret+="'.";

			ret += " Recursively (via subsub...routines) accessed local variable slots: '";
			alv = getRecursivelyAccessedLocalsIndices();
			for (int i=0; i<alv.length; i++){
				ret += alv[i]+" ";
			}
			ret+="'.";

			return ret;
		}
		
		/**
		 * Sets the leaving RET instruction. Must be invoked after all instructions are added.
		 * Must not be invoked for top-level 'subroutine'.
		 */
		void setLeavingRET(){
			if (localVariable == UNSET){
				throw new AssertionViolatedException("setLeavingRET() called for top-level 'subroutine' or forgot to set local variable first.");
			}
			Iterator iter = instructions.iterator();
			InstructionHandle ret = null;
			while(iter.hasNext()){
				InstructionHandle actual = (InstructionHandle) iter.next();
				if (actual.getInstruction() instanceof RET){
					if (ret != null){
						throw new StructuralCodeConstraintException("Subroutine with more then one RET detected: '"+ret+"' and '"+actual+"'.");
					}
					else{
						ret = actual;
					}
				}
			}
			if (ret == null){
				throw new StructuralCodeConstraintException("Subroutine without a RET detected.");
			}
			if (((RET) ret.getInstruction()).getIndex() != localVariable){
				throw new StructuralCodeConstraintException("Subroutine uses '"+ret+"' which does not match the correct local variable '"+localVariable+"'.");
			}
			theRET = ret;
		}
				
		/*
		 * Refer to the Subroutine interface for documentation.
		 */
		public InstructionHandle[] getEnteringJsrInstructions(){
			if (this == TOPLEVEL) {
				throw new AssertionViolatedException("getLeavingRET() called on top level pseudo-subroutine.");
			}
			InstructionHandle[] jsrs = new InstructionHandle[theJSRs.size()];
			return (InstructionHandle[]) (theJSRs.toArray(jsrs));
		}
	
		/**
		 * Adds a new JSR or JSR_W that has this subroutine as its target.
		 */
		public void addEnteringJsrInstruction(InstructionHandle jsrInst){
			if ( (jsrInst == null) || (! (jsrInst.getInstruction() instanceof JsrInstruction))){
				throw new AssertionViolatedException("Expecting JsrInstruction InstructionHandle.");
			}
			if (localVariable == UNSET){
				throw new AssertionViolatedException("Set the localVariable first!");
			}
			else{
				// Something is wrong when an ASTORE is targeted that does not operate on the same local variable than the rest of the
				// JsrInstruction-targets and the RET.
				// (We don't know out leader here so we cannot check if we're really targeted!)
				if (localVariable != ((ASTORE) (((JsrInstruction) jsrInst.getInstruction()).getTarget().getInstruction())).getIndex()){
					throw new AssertionViolatedException("Setting a wrong JsrInstruction.");
				}
			}
			theJSRs.add(jsrInst);
		}

		/*
		 * Refer to the Subroutine interface for documentation.
		 */
		public InstructionHandle getLeavingRET(){
			if (this == TOPLEVEL) {
				throw new AssertionViolatedException("getLeavingRET() called on top level pseudo-subroutine.");
			}
			return theRET;
		}
		
		/*
		 * Refer to the Subroutine interface for documentation.
		 */
		public InstructionHandle[] getInstructions(){
			InstructionHandle[] ret = new InstructionHandle[instructions.size()];
			return (InstructionHandle[]) instructions.toArray(ret);
		}
		
		/*
		 * Adds an instruction to this subroutine.
		 * All instructions must have been added before invoking setLeavingRET().
		 * @see #setLeavingRET
		 */
		void addInstruction(InstructionHandle ih){
			if (theRET != null){
				throw new AssertionViolatedException("All instructions must have been added before invoking setLeavingRET().");
			}
			instructions.add(ih);
		}

		/* Satisfies Subroutine.getRecursivelyAccessedLocalsIndices(). */
		public int[] getRecursivelyAccessedLocalsIndices(){
			HashSet<Integer> s = new HashSet<Integer>();
			int[] lvs = getAccessedLocalsIndices();
			for (int j=0; j<lvs.length; j++){
				s.add(new Integer(lvs[j]));
			}
			_getRecursivelyAccessedLocalsIndicesHelper(s, this.subSubs());
			int[] ret = new int[s.size()];
			Iterator i = s.iterator();
			int j=-1;
			while (i.hasNext()){
				j++;
				ret[j] = ((Integer) i.next()).intValue();
			}
			return ret;
		}

		/**
		 * A recursive helper method for getRecursivelyAccessedLocalsIndices().
		 * @see #getRecursivelyAccessedLocalsIndices()
		 */
		private void _getRecursivelyAccessedLocalsIndicesHelper(HashSet<Integer> s, Subroutine[] subs){
			for (int i=0; i<subs.length; i++){
				int[] lvs = subs[i].getAccessedLocalsIndices();
				for (int j=0; j<lvs.length; j++){
					s.add(new Integer(lvs[j]));
				}
				if(subs[i].subSubs().length != 0){
					_getRecursivelyAccessedLocalsIndicesHelper(s, subs[i].subSubs());
				}
			}
		}

		/*
		 * Satisfies Subroutine.getAccessedLocalIndices().
		 */
		public int[] getAccessedLocalsIndices(){
			//TODO: Implement caching.
			HashSet<Integer> acc = new HashSet<Integer>();
			if (theRET == null && this != TOPLEVEL){
				throw new AssertionViolatedException("This subroutine object must be built up completely before calculating accessed locals.");
			}
			Iterator i = instructions.iterator();
			while (i.hasNext()){
				InstructionHandle ih = (InstructionHandle) i.next();
				// RET is not a LocalVariableInstruction in the current version of BCEL.
				if (ih.getInstruction() instanceof LocalVariableInstruction || ih.getInstruction() instanceof RET){
					int idx = ((IndexedInstruction) (ih.getInstruction())).getIndex();
					acc.add(new Integer(idx));
					// LONG? DOUBLE?.
					try{
						// LocalVariableInstruction instances are typed without the need to look into
						// the constant pool.
						if (ih.getInstruction() instanceof LocalVariableInstruction){
							int s = ((LocalVariableInstruction) ih.getInstruction()).getType(null).getSize();
							if (s==2) acc.add(new Integer(idx+1));
						}
					}
					catch(RuntimeException re){
						throw new AssertionViolatedException("Oops. BCEL did not like NULL as a ConstantPoolGen object.");
					}
				}
			}
			
			int[] ret = new int[acc.size()];
			i = acc.iterator();
			int j=-1;
			while (i.hasNext()){
				j++;
				ret[j] = ((Integer) i.next()).intValue();
			}
			return ret;
		}

		/*
		 * Satisfies Subroutine.subSubs().
		 */
		public Subroutine[] subSubs(){
			HashSet<Subroutine> h = new HashSet<Subroutine>();

			Iterator i = instructions.iterator();
			while (i.hasNext()){
				Instruction inst = ((InstructionHandle) i.next()).getInstruction();
				if (inst instanceof JsrInstruction){