/**
* Check to see if the instruction has a null check associated with it, and if so, add a
* dereference.
*
* @param location the Location of the instruction
* @param vnaFrame ValueNumberFrame at the Location of the instruction
* @param fact the dataflow value to modify
* @throws DataflowAnalysisException
*/
private void checkInstance(
Location location, ValueNumberFrame vnaFrame, UnconditionalValueDerefSet fact)
throws DataflowAnalysisException {
// See if this instruction has a null check.
// If it does, the fall through predecessor will be
// identify itself as the null check.
if (!location.isFirstInstructionInBasicBlock()) {
return;
}
if (invDataflow == null) {
return;
}
BasicBlock fallThroughPredecessor =
cfg.getPredecessorWithEdgeType(location.getBasicBlock(), EdgeTypes.FALL_THROUGH_EDGE);
if (fallThroughPredecessor == null || !fallThroughPredecessor.isNullCheck()) {
return;
}
// Get the null-checked value
ValueNumber vn =
vnaFrame.getInstance(location.getHandle().getInstruction(), methodGen.getConstantPool());
// Ignore dereferences of this
if (!methodGen.isStatic()) {
ValueNumber v = vnaFrame.getValue(0);
if (v.equals(vn)) {
return;
}
}
if (vn.hasFlag(ValueNumber.CONSTANT_CLASS_OBJECT)) {
return;
}
IsNullValueFrame startFact = null;
startFact = invDataflow.getStartFact(fallThroughPredecessor);
if (!startFact.isValid()) {
return;
}
int slot =
startFact.getInstanceSlot(
location.getHandle().getInstruction(), methodGen.getConstantPool());
if (!reportDereference(startFact, slot)) {
return;
}
if (DEBUG) {
System.out.println("FOUND GUARANTEED DEREFERENCE");
System.out.println("Load: " + vnaFrame.getLoad(vn));
System.out.println("Pred: " + fallThroughPredecessor);
System.out.println("startFact: " + startFact);
System.out.println("Location: " + location);
System.out.println("Value number frame: " + vnaFrame);
System.out.println("Dereferenced valueNumber: " + vn);
System.out.println("invDataflow: " + startFact);
System.out.println("IGNORE_DEREF_OF_NCP: " + IGNORE_DEREF_OF_NCP);
}
// Mark the value number as being dereferenced at this location
fact.addDeref(vn, location);
}
private void analyzeMethod(ClassContext classContext, Method method)
throws CFGBuilderException, DataflowAnalysisException {
if (BCELUtil.isSynthetic(method)
|| (method.getAccessFlags() & Const.ACC_BRIDGE) == Const.ACC_BRIDGE) {
return;
}
CFG cfg = classContext.getCFG(method);
ConstantPoolGen cpg = classContext.getConstantPoolGen();
TypeDataflow typeDataflow = classContext.getTypeDataflow(method);
for (Iterator<BasicBlock> i = cfg.blockIterator(); i.hasNext(); ) {
BasicBlock basicBlock = i.next();
// Check if it's a method invocation.
if (!basicBlock.isExceptionThrower()) {
continue;
}
InstructionHandle thrower = basicBlock.getExceptionThrower();
Instruction ins = thrower.getInstruction();
if (!(ins instanceof InvokeInstruction)) {
continue;
}
InvokeInstruction inv = (InvokeInstruction) ins;
boolean foundThrower = false;
boolean foundNonThrower = false;
if (inv instanceof INVOKEINTERFACE) {
continue;
}
String className = inv.getClassName(cpg);
Location loc = new Location(thrower, basicBlock);
TypeFrame typeFrame = typeDataflow.getFactAtLocation(loc);
XMethod primaryXMethod = XFactory.createXMethod(inv, cpg);
// if (primaryXMethod.isAbstract()) continue;
Set<XMethod> targetSet = null;
try {
if (className.startsWith("[")) {
continue;
}
String methodSig = inv.getSignature(cpg);
if (!methodSig.endsWith("V")) {
continue;
}
targetSet = Hierarchy2.resolveMethodCallTargets(inv, typeFrame, cpg);
for (XMethod xMethod : targetSet) {
if (DEBUG) {
System.out.println("\tFound " + xMethod);
}
boolean isUnconditionalThrower =
xMethod.isUnconditionalThrower()
&& !xMethod.isUnsupported()
&& !xMethod.isSynthetic();
if (isUnconditionalThrower) {
foundThrower = true;
if (DEBUG) {
System.out.println("Found thrower");
}
} else {
foundNonThrower = true;
if (DEBUG) {
System.out.println("Found non thrower");
}
}
}
} catch (ClassNotFoundException e) {
analysisContext.getLookupFailureCallback().reportMissingClass(e);
}
boolean newResult = foundThrower && !foundNonThrower;
if (newResult) {
bugReporter.reportBug(
new BugInstance(this, "TESTING", Priorities.NORMAL_PRIORITY)
.addClassAndMethod(classContext.getJavaClass(), method)
.addString("Call to method that always throws Exception")
.addMethod(primaryXMethod)
.describe(MethodAnnotation.METHOD_CALLED)
.addSourceLine(classContext, method, loc));
}
}
}
