private void continueTraversal(int pValue, SMGSingleLinkedListCandidate pCandidate) {
SMGEdgePointsTo pt = smg.getPointer(pValue);
SMGObject object = pt.getObject();
if (!candidates.containsKey(object)) {
startTraversal(object);
}
if (inboundPointers.get(pValue) > 1) {
return;
}
Map<Integer, SMGSingleLinkedListCandidate> objectCandidates = candidates.get(object);
Integer offset = pCandidate.getOffset();
if (!objectCandidates.containsKey(offset)) {
// try to infer a pointer presence: either NULL, or uninitialized
if (smg.isCoveredByNullifiedBlocks(object, offset, AnonymousTypes.dummyPointer)) {
objectCandidates.put(offset, new SMGSingleLinkedListCandidate(object, offset, 1));
}
}
if (objectCandidates.containsKey(offset)) {
SMGSingleLinkedListCandidate myCandidate = objectCandidates.get(offset);
if (pCandidate.isCompatibleWith(myCandidate)) {
objectCandidates.remove(offset);
pCandidate.addLength(myCandidate.getLength());
}
}
}
private void startTraversal(SMGObject pObject) {
if (candidates.containsKey(pObject)) {
// Processed already in continueTraversal
return;
}
candidates.put(pObject, new HashMap<Integer, SMGSingleLinkedListCandidate>());
for (SMGEdgeHasValue hv : smg.getHVEdges(SMGEdgeHasValueFilter.objectFilter(pObject))) {
if (smg.isPointer(hv.getValue())) {
SMGSingleLinkedListCandidate candidate =
new SMGSingleLinkedListCandidate(pObject, hv.getOffset(), 1);
candidates.get(pObject).put(hv.getOffset(), candidate);
continueTraversal(hv.getValue(), candidate);
}
}
}
@Test
public void simpleListTest() {
CLangSMG smg = new CLangSMG(MachineModel.LINUX64);
SMGEdgeHasValue root = TestHelpers.createGlobalList(smg, 5, 16, 8, "pointer");
SMGSingleLinkedListFinder finder = new SMGSingleLinkedListFinder(1);
Set<SMGAbstractionCandidate> candidates = finder.traverse(smg);
Assert.assertEquals(1, candidates.size());
SMGAbstractionCandidate candidate = Iterables.getOnlyElement(candidates);
Assert.assertTrue(candidate instanceof SMGSingleLinkedListCandidate);
SMGSingleLinkedListCandidate sllCandidate = (SMGSingleLinkedListCandidate) candidate;
Assert.assertEquals(5, sllCandidate.getLength());
Assert.assertEquals(8, sllCandidate.getOffset());
SMGRegion expectedStart = (SMGRegion) smg.getPointer(root.getValue()).getObject();
Assert.assertSame(expectedStart, sllCandidate.getStart());
}
@Override
public Set<SMGAbstractionCandidate> traverse(CLangSMG pSmg) {
smg = pSmg;
buildInboundPointers();
for (SMGObject object : smg.getHeapObjects()) {
startTraversal(object);
}
Set<SMGAbstractionCandidate> returnSet = new HashSet<>();
for (Map<Integer, SMGSingleLinkedListCandidate> objCandidates : candidates.values()) {
for (SMGSingleLinkedListCandidate candidate : objCandidates.values()) {
if (candidate.getLength() > seqLengthThreshold) {
returnSet.add(candidate);
}
}
}
return Collections.unmodifiableSet(returnSet);
}
@Test
public void listWithInboundPointersTest() {
CLangSMG smg = new CLangSMG(MachineModel.LINUX64);
Integer tail = TestHelpers.createList(smg, 4, 16, 8, "tail");
SMGEdgeHasValue head = TestHelpers.createGlobalList(smg, 3, 16, 8, "head");
SMGObject inside = new SMGRegion(16, "pointed_at");
SMGEdgeHasValue tailConnection =
new SMGEdgeHasValue(AnonymousTypes.dummyPointer, 8, inside, tail);
Integer addressOfInside = SMGValueFactory.getNewValue();
SMGEdgePointsTo insidePT = new SMGEdgePointsTo(addressOfInside, inside, 0);
SMGRegion inboundPointer = new SMGRegion(8, "inbound_pointer");
SMGEdgeHasValue inboundPointerConnection =
new SMGEdgeHasValue(AnonymousTypes.dummyPointer, 0, inboundPointer, addressOfInside);
SMGObject lastFromHead = smg.getPointer(head.getValue()).getObject();
SMGEdgeHasValue connection = null;
do {
SMGEdgeHasValueFilter filter =
SMGEdgeHasValueFilter.objectFilter(lastFromHead).filterAtOffset(8);
Set<SMGEdgeHasValue> connections = smg.getHVEdges(filter);
connection = null;
if (connections.size() > 0) {
connection = Iterables.getOnlyElement(connections);
lastFromHead = smg.getPointer(connection.getValue()).getObject();
}
} while (connection != null);
for (SMGEdgeHasValue hv : smg.getHVEdges(SMGEdgeHasValueFilter.objectFilter(lastFromHead))) {
smg.removeHasValueEdge(hv);
}
SMGEdgeHasValue headConnection =
new SMGEdgeHasValue(AnonymousTypes.dummyPointer, 8, lastFromHead, addressOfInside);
SMGRegion tailPointer = new SMGRegion(8, "tail_pointer");
SMGEdgeHasValue tailPointerConnection =
new SMGEdgeHasValue(AnonymousTypes.dummyPointer, 0, tailPointer, tail);
smg.addGlobalObject(tailPointer);
smg.addHasValueEdge(tailPointerConnection);
smg.addHeapObject(inside);
smg.addValue(addressOfInside);
smg.addPointsToEdge(insidePT);
smg.addGlobalObject(inboundPointer);
smg.addHasValueEdge(inboundPointerConnection);
smg.addHasValueEdge(tailConnection);
smg.addHasValueEdge(headConnection);
SMGSingleLinkedListFinder finder = new SMGSingleLinkedListFinder(1);
Set<SMGAbstractionCandidate> candidates = finder.traverse(smg);
Assert.assertEquals(2, candidates.size());
boolean sawHead = false;
boolean sawTail = false;
for (SMGAbstractionCandidate candidate : candidates) {
SMGSingleLinkedListCandidate sllCandidate = (SMGSingleLinkedListCandidate) candidate;
if (sllCandidate.getLength() == 3) {
Assert.assertSame(smg.getPointer(head.getValue()).getObject(), sllCandidate.getStart());
Assert.assertFalse(sawHead);
sawHead = true;
} else if (sllCandidate.getLength() == 4) {
Assert.assertSame(smg.getPointer(tail).getObject(), sllCandidate.getStart());
Assert.assertFalse(sawTail);
} else {
Assert.fail("We should not see any candidates with length other than 3 or 4");
}
}
}
private void buildInboundPointers() {
for (Integer pointer : smg.getPTEdges().keySet()) {
inboundPointers.put(
pointer, smg.getHVEdges(new SMGEdgeHasValueFilter().filterHavingValue(pointer)).size());
}
}