001: /*
002: * Copyright 2000-2004 The Apache Software Foundation
003: *
004: * Licensed under the Apache License, Version 2.0 (the "License");
005: * you may not use this file except in compliance with the License.
006: * You may obtain a copy of the License at
007: *
008: * http://www.apache.org/licenses/LICENSE-2.0
009: *
010: * Unless required by applicable law or agreed to in writing, software
011: * distributed under the License is distributed on an "AS IS" BASIS,
012: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013: * See the License for the specific language governing permissions and
014: * limitations under the License.
015: *
016: */
017: package org.apache.bcel.verifier.structurals;
018:
019: import java.io.PrintWriter;
020: import java.io.StringWriter;
021: import java.util.ArrayList;
022: import java.util.List;
023: import java.util.Random;
024: import java.util.Vector;
025:
026: import org.apache.bcel.Constants;
027: import org.apache.bcel.Repository;
028: import org.apache.bcel.classfile.JavaClass;
029: import org.apache.bcel.classfile.Method;
030: import org.apache.bcel.generic.ConstantPoolGen;
031: import org.apache.bcel.generic.GETFIELD;
032: import org.apache.bcel.generic.InstructionHandle;
033: import org.apache.bcel.generic.InvokeInstruction;
034: import org.apache.bcel.generic.JsrInstruction;
035: import org.apache.bcel.generic.LoadInstruction;
036: import org.apache.bcel.generic.MethodGen;
037: import org.apache.bcel.generic.ObjectType;
038: import org.apache.bcel.generic.RET;
039: import org.apache.bcel.generic.ReturnInstruction;
040: import org.apache.bcel.generic.ReturnaddressType;
041: import org.apache.bcel.generic.Type;
042: import org.apache.bcel.verifier.PassVerifier;
043: import org.apache.bcel.verifier.VerificationResult;
044: import org.apache.bcel.verifier.Verifier;
045: import org.apache.bcel.verifier.exc.AssertionViolatedException;
046: import org.apache.bcel.verifier.exc.StructuralCodeConstraintException;
047: import org.apache.bcel.verifier.exc.VerifierConstraintViolatedException;
048:
049: /**
050: * This PassVerifier verifies a method of class file according to pass 3,
051: * so-called structural verification as described in The Java Virtual Machine
052: * Specification, 2nd edition.
053: * More detailed information is to be found at the do_verify() method's
054: * documentation.
055: *
056: * @version $Id: ModifiedPass3bVerifier.java,v 1.3 2007-11-08 17:22:56 ebruneton Exp $
057: * @author Enver Haase
058: * @see #do_verify()
059: */
060:
061: public final class ModifiedPass3bVerifier extends PassVerifier {
062: /* TODO: Throughout pass 3b, upper halves of LONG and DOUBLE
063: are represented by Type.UNKNOWN. This should be changed
064: in favour of LONG_Upper and DOUBLE_Upper as in pass 2. */
065:
066: /**
067: * An InstructionContextQueue is a utility class that holds
068: * (InstructionContext, ArrayList) pairs in a Queue data structure.
069: * This is used to hold information about InstructionContext objects
070: * externally --- i.e. that information is not saved inside the
071: * InstructionContext object itself. This is useful to save the
072: * execution path of the symbolic execution of the
073: * Pass3bVerifier - this is not information
074: * that belongs into the InstructionContext object itself.
075: * Only at "execute()"ing
076: * time, an InstructionContext object will get the current information
077: * we have about its symbolic execution predecessors.
078: */
079: private static final class InstructionContextQueue {
080: private List ics = new Vector(); // Type: InstructionContext
081: private List ecs = new Vector(); // Type: ArrayList (of InstructionContext)
082:
083: public void add(InstructionContext ic, ArrayList executionChain) {
084: ics.add(ic);
085: ecs.add(executionChain);
086: }
087:
088: public boolean isEmpty() {
089: return ics.isEmpty();
090: }
091:
092: public void remove() {
093: this .remove(0);
094: }
095:
096: public void remove(int i) {
097: ics.remove(i);
098: ecs.remove(i);
099: }
100:
101: public InstructionContext getIC(int i) {
102: return (InstructionContext) ics.get(i);
103: }
104:
105: public ArrayList getEC(int i) {
106: return (ArrayList) ecs.get(i);
107: }
108:
109: public int size() {
110: return ics.size();
111: }
112: } // end Inner Class InstructionContextQueue
113:
114: /** In DEBUG mode, the verification algorithm is not randomized. */
115: private static final boolean DEBUG = true;
116:
117: private JavaClass jc;
118:
119: /** The method number to verify. */
120: private int method_no;
121:
122: /**
123: * This class should only be instantiated by a Verifier.
124: *
125: * @see org.apache.bcel.verifier.Verifier
126: */
127: public ModifiedPass3bVerifier(JavaClass jc, int method_no) {
128: this .jc = jc;
129: this .method_no = method_no;
130: }
131:
132: /**
133: * Whenever the outgoing frame
134: * situation of an InstructionContext changes, all its successors are
135: * put [back] into the queue [as if they were unvisited].
136: * The proof of termination is about the existence of a
137: * fix point of frame merging.
138: */
139: private void circulationPump(MethodGen m, ControlFlowGraph cfg,
140: InstructionContext start, Frame vanillaFrame,
141: InstConstraintVisitor icv, ExecutionVisitor ev) {
142: final Random random = new Random();
143: InstructionContextQueue icq = new InstructionContextQueue();
144:
145: start.execute(vanillaFrame, new ArrayList(), icv, ev); // new ArrayList() <=> no Instruction was executed before
146: // => Top-Level routine (no jsr call before)
147: icq.add(start, new ArrayList());
148:
149: // LOOP!
150: while (!icq.isEmpty()) {
151: InstructionContext u;
152: ArrayList ec;
153: if (!DEBUG) {
154: int r = random.nextInt(icq.size());
155: u = icq.getIC(r);
156: ec = icq.getEC(r);
157: icq.remove(r);
158: } else {
159: u = icq.getIC(0);
160: ec = icq.getEC(0);
161: icq.remove(0);
162: }
163:
164: ArrayList oldchain = (ArrayList) (ec.clone());
165: ArrayList newchain = (ArrayList) (ec.clone());
166: newchain.add(u);
167:
168: if ((u.getInstruction().getInstruction()) instanceof RET) {
169: //System.err.println(u);
170: // We can only follow _one_ successor, the one after the
171: // JSR that was recently executed.
172: RET ret = (RET) (u.getInstruction().getInstruction());
173: ReturnaddressType t = (ReturnaddressType) u
174: .getOutFrame(oldchain).getLocals().get(
175: ret.getIndex());
176: InstructionContext theSuccessor = cfg.contextOf(t
177: .getTarget());
178:
179: // Sanity check
180: InstructionContext lastJSR = null;
181: int skip_jsr = 0;
182: for (int ss = oldchain.size() - 1; ss >= 0; ss--) {
183: if (skip_jsr < 0) {
184: throw new AssertionViolatedException(
185: "More RET than JSR in execution chain?!");
186: }
187: //System.err.println("+"+oldchain.get(ss));
188: if (((InstructionContext) oldchain.get(ss))
189: .getInstruction().getInstruction() instanceof JsrInstruction) {
190: if (skip_jsr == 0) {
191: lastJSR = (InstructionContext) oldchain
192: .get(ss);
193: break;
194: } else {
195: skip_jsr--;
196: }
197: }
198: if (((InstructionContext) oldchain.get(ss))
199: .getInstruction().getInstruction() instanceof RET) {
200: skip_jsr++;
201: }
202: }
203: if (lastJSR == null) {
204: throw new AssertionViolatedException(
205: "RET without a JSR before in ExecutionChain?! EC: '"
206: + oldchain + "'.");
207: }
208: JsrInstruction jsr = (JsrInstruction) (lastJSR
209: .getInstruction().getInstruction());
210: if (theSuccessor != (cfg.contextOf(jsr
211: .physicalSuccessor()))) {
212: throw new AssertionViolatedException("RET '"
213: + u.getInstruction()
214: + "' info inconsistent: jump back to '"
215: + theSuccessor + "' or '"
216: + cfg.contextOf(jsr.physicalSuccessor())
217: + "'?");
218: }
219:
220: if (theSuccessor.execute(u.getOutFrame(oldchain),
221: newchain, icv, ev)) {
222: icq.add(theSuccessor, (ArrayList) newchain.clone());
223: }
224: } else {// "not a ret"
225:
226: // Normal successors. Add them to the queue of successors.
227: InstructionContext[] succs = u.getSuccessors();
228: for (int s = 0; s < succs.length; s++) {
229: InstructionContext v = succs[s];
230: if (v.execute(u.getOutFrame(oldchain), newchain,
231: icv, ev)) {
232: icq.add(v, (ArrayList) newchain.clone());
233: }
234: }
235: }// end "not a ret"
236:
237: // Exception Handlers. Add them to the queue of successors.
238: // [subroutines are never protected; mandated by JustIce]
239: ExceptionHandler[] exc_hds = u.getExceptionHandlers();
240: for (int s = 0; s < exc_hds.length; s++) {
241: InstructionContext v = cfg.contextOf(exc_hds[s]
242: .getHandlerStart());
243: // TODO: the "oldchain" and "newchain" is used to determine the subroutine
244: // we're in (by searching for the last JSR) by the InstructionContext
245: // implementation. Therefore, we should not use this chain mechanism
246: // when dealing with exception handlers.
247: // Example: a JSR with an exception handler as its successor does not
248: // mean we're in a subroutine if we go to the exception handler.
249: // We should address this problem later; by now we simply "cut" the chain
250: // by using an empty chain for the exception handlers.
251: //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){
252: //icq.add(v, (ArrayList) newchain.clone());
253: if (v.execute(new Frame(u.getOutFrame(oldchain)
254: .getLocals(), new OperandStack(u.getOutFrame(
255: oldchain).getStack().maxStack(), (exc_hds[s]
256: .getExceptionType() == null ? Type.THROWABLE
257: : exc_hds[s].getExceptionType()))),
258: new ArrayList(), icv, ev)) {
259: icq.add(v, new ArrayList());
260: }
261: }
262:
263: }// while (!icq.isEmpty()) END
264:
265: InstructionHandle ih = start.getInstruction();
266: do {
267: if ((ih.getInstruction() instanceof ReturnInstruction)
268: && (!(cfg.isDead(ih)))) {
269: InstructionContext ic = cfg.contextOf(ih);
270: 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?
271: LocalVariables lvs = f.getLocals();
272: for (int i = 0; i < lvs.maxLocals(); i++) {
273: if (lvs.get(i) instanceof UninitializedObjectType) {
274: this
275: .addMessage("Warning: ReturnInstruction '"
276: + ic
277: + "' may leave method with an uninitialized object in the local variables array '"
278: + lvs + "'.");
279: }
280: }
281: OperandStack os = f.getStack();
282: for (int i = 0; i < os.size(); i++) {
283: if (os.peek(i) instanceof UninitializedObjectType) {
284: this
285: .addMessage("Warning: ReturnInstruction '"
286: + ic
287: + "' may leave method with an uninitialized object on the operand stack '"
288: + os + "'.");
289: }
290: }
291: //see JVM $4.8.2
292: //TODO implement all based on stack
293: Type returnedType = null;
294: if (ih.getPrev().getInstruction() instanceof InvokeInstruction) {
295: returnedType = ((InvokeInstruction) ih.getPrev()
296: .getInstruction()).getType(m
297: .getConstantPool());
298: }
299: if (ih.getPrev().getInstruction() instanceof LoadInstruction) {
300: int index = ((LoadInstruction) ih.getPrev()
301: .getInstruction()).getIndex();
302: returnedType = lvs.get(index);
303: }
304: if (ih.getPrev().getInstruction() instanceof GETFIELD) {
305: returnedType = ((GETFIELD) ih.getPrev()
306: .getInstruction()).getType(m
307: .getConstantPool());
308: }
309: if (returnedType != null) {
310: if (returnedType instanceof ObjectType) {
311: try {
312: if (!((ObjectType) returnedType)
313: .isAssignmentCompatibleWith(m
314: .getReturnType())) {
315: throw new StructuralCodeConstraintException(
316: "Returned type "
317: + returnedType
318: + " does not match Method's return type "
319: + m.getReturnType());
320: }
321: } catch (ClassNotFoundException e) {
322: //dont know what do do now, so raise RuntimeException
323: throw new RuntimeException(e);
324: }
325: } else if (!returnedType.equals(m.getReturnType())) {
326: throw new StructuralCodeConstraintException(
327: "Returned type "
328: + returnedType
329: + " does not match Method's return type "
330: + m.getReturnType());
331: }
332: }
333: }
334: } while ((ih = ih.getNext()) != null);
335:
336: }
337:
338: /**
339: * Pass 3b implements the data flow analysis as described in the Java Virtual
340: * Machine Specification, Second Edition.
341: * Later versions will use LocalVariablesInfo objects to verify if the
342: * verifier-inferred types and the class file's debug information (LocalVariables
343: * attributes) match [TODO].
344: *
345: * @see org.apache.bcel.verifier.statics.LocalVariablesInfo
346: * @see org.apache.bcel.verifier.statics.Pass2Verifier#getLocalVariablesInfo(int)
347: */
348: public VerificationResult do_verify() {
349: /*if (! myOwner.doPass3a(method_no).equals(VerificationResult.VR_OK)){
350: return VerificationResult.VR_NOTYET;
351: }
352:
353: // Pass 3a ran before, so it's safe to assume the JavaClass object is
354: // in the BCEL repository.
355: JavaClass jc;
356: try {
357: jc = Repository.lookupClass(myOwner.getClassName());
358: } catch (ClassNotFoundException e) {
359: // FIXME: maybe not the best way to handle this
360: throw new AssertionViolatedException("Missing class: " + e.toString());
361: }*/
362:
363: ConstantPoolGen constantPoolGen = new ConstantPoolGen(jc
364: .getConstantPool());
365: // Init Visitors
366: InstConstraintVisitor icv = new InstConstraintVisitor();
367: icv.setConstantPoolGen(constantPoolGen);
368:
369: ExecutionVisitor ev = new ExecutionVisitor();
370: ev.setConstantPoolGen(constantPoolGen);
371:
372: Method[] methods = jc.getMethods(); // Method no "method_no" exists, we ran Pass3a before on it!
373:
374: try {
375:
376: MethodGen mg = new MethodGen(methods[method_no], jc
377: .getClassName(), constantPoolGen);
378:
379: icv.setMethodGen(mg);
380:
381: ////////////// DFA BEGINS HERE ////////////////
382: if (!(mg.isAbstract() || mg.isNative())) { // IF mg HAS CODE (See pass 2)
383:
384: ControlFlowGraph cfg = new ControlFlowGraph(mg);
385:
386: // Build the initial frame situation for this method.
387: Frame f = new Frame(mg.getMaxLocals(), mg.getMaxStack());
388: if (!mg.isStatic()) {
389: if (mg.getName().equals(Constants.CONSTRUCTOR_NAME)) {
390: Frame._this = new UninitializedObjectType(
391: new ObjectType(jc.getClassName()));
392: f.getLocals().set(0, Frame._this );
393: } else {
394: Frame._this = null;
395: f.getLocals().set(0,
396: new ObjectType(jc.getClassName()));
397: }
398: }
399: Type[] argtypes = mg.getArgumentTypes();
400: int twoslotoffset = 0;
401: for (int j = 0; j < argtypes.length; j++) {
402: if (argtypes[j] == Type.SHORT
403: || argtypes[j] == Type.BYTE
404: || argtypes[j] == Type.CHAR
405: || argtypes[j] == Type.BOOLEAN) {
406: argtypes[j] = Type.INT;
407: }
408: f.getLocals()
409: .set(
410: twoslotoffset + j
411: + (mg.isStatic() ? 0 : 1),
412: argtypes[j]);
413: if (argtypes[j].getSize() == 2) {
414: twoslotoffset++;
415: f.getLocals().set(
416: twoslotoffset + j
417: + (mg.isStatic() ? 0 : 1),
418: Type.UNKNOWN);
419: }
420: }
421: circulationPump(mg, cfg, cfg.contextOf(mg
422: .getInstructionList().getStart()), f, icv, ev);
423: }
424: } catch (VerifierConstraintViolatedException ce) {
425: ce.extendMessage("Constraint violated in method '"
426: + methods[method_no] + "':\n", "");
427: return new VerificationResult(
428: VerificationResult.VERIFIED_REJECTED, ce
429: .getMessage());
430: } catch (RuntimeException re) {
431: // These are internal errors
432:
433: StringWriter sw = new StringWriter();
434: PrintWriter pw = new PrintWriter(sw);
435: re.printStackTrace(pw);
436:
437: throw new AssertionViolatedException(
438: "Some RuntimeException occured while verify()ing class '"
439: + jc.getClassName()
440: + "', method '"
441: + methods[method_no]
442: + "'. Original RuntimeException's stack trace:\n---\n"
443: + sw + "---\n");
444: }
445: return VerificationResult.VR_OK;
446: }
447:
448: /** Returns the method number as supplied when instantiating. */
449: public int getMethodNo() {
450: return method_no;
451: }
452: }
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