/*
* FindBugs - Find bugs in Java programs
* Copyright (C) 2004-2006 University of Maryland
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package edu.umd.cs.findbugs.detect;
import org.apache.bcel.classfile.Method;
import org.apache.bcel.generic.Type;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.OpcodeStack;
import edu.umd.cs.findbugs.StatelessDetector;
import edu.umd.cs.findbugs.SystemProperties;
import edu.umd.cs.findbugs.ba.XFactory;
import edu.umd.cs.findbugs.ba.XMethod;
import edu.umd.cs.findbugs.bcel.OpcodeStackDetector;
public class InfiniteRecursiveLoop extends OpcodeStackDetector implements
StatelessDetector {
private BugReporter bugReporter;
private boolean seenTransferOfControl;
private boolean seenReturn;
private boolean seenThrow;
private boolean seenStateChange;
private int largestBranchTarget;
private final static boolean DEBUG = SystemProperties.getBoolean("irl.debug");
public InfiniteRecursiveLoop(BugReporter bugReporter) {
this.bugReporter = bugReporter;
}
@Override
public void visit(Method obj) {
seenTransferOfControl = false;
seenStateChange = false;
seenReturn = false;
seenThrow = false;
largestBranchTarget = -1;
if (DEBUG) {
System.out.println();
System.out.println(" --- " + getFullyQualifiedMethodName());
System.out.println();
}
}
@Override
public void sawBranchTo(int seen) {
if (largestBranchTarget < seen)
largestBranchTarget = seen;
seenTransferOfControl = true;
}
/** Signal an infinite loop if either:
* we see a call to the same method with the same parameters, or
* we see a call to the same (dynamically dispatched method), and there
* has been no transfer of control.
*/
@Override
public void sawOpcode(int seen) {
if (seenReturn && seenTransferOfControl && seenStateChange)
return;
if (DEBUG) {
System.out.println(stack);
System.out.println(getPC() + " : " + OPCODE_NAMES[seen]);
}
if ((seen == INVOKEVIRTUAL || seen == INVOKEINTERFACE)
&& getNameConstantOperand().equals("add")
&& getSigConstantOperand().equals("(Ljava/lang/Object;)Z")
&& stack.getStackDepth() >= 2) {
OpcodeStack.Item it0 = stack.getStackItem(0);
int r0 = it0.getRegisterNumber();
OpcodeStack.Item it1 = stack.getStackItem(1);
int r1 = it1.getRegisterNumber();
if (r0 == r1 && r0 > 0)
bugReporter.reportBug(new BugInstance(this, "IL_CONTAINER_ADDED_TO_ITSELF",
NORMAL_PRIORITY).addClassAndMethod(this).addSourceLine(this));
}
if ((seen == INVOKEVIRTUAL || seen == INVOKESPECIAL || seen == INVOKEINTERFACE || seen == INVOKESTATIC)
&& getNameConstantOperand().equals(getMethodName())
&& getSigConstantOperand().equals(getMethodSig())
&& (seen == INVOKESTATIC) == getMethod().isStatic()
&& (seen == INVOKESPECIAL) == (getMethod().isPrivate() || getMethodName().equals("<init>"))
) {
Type arguments[] = getMethod().getArgumentTypes();
// stack.getStackDepth() >= parameters
int parameters = arguments.length;
if (!getMethod().isStatic()) parameters++;
XMethod xMethod = XFactory.createReferencedXMethod(this);
if (DEBUG) {
System.out.println("IL: Checking...");
System.out.println(xMethod);
System.out.println("vs. " + getClassName() + "." + getMethodName() + " : "
+ getMethodSig());
}
if (xMethod.getClassName().replace('.','/').equals(getClassName()) || seen == INVOKEINTERFACE) {
// Invocation of same method
// Now need to see if parameters are the same
int firstParameter = 0;
if (getMethodName().equals("<init>"))
firstParameter = 1;
// match1 should be true if it is any call to the exact same method
// and no state has been change.
// if match1 is true, the method may not always perform
// a recursive infinite loop, but this particular method call is an infinite
// recursive loop
boolean match1 = !seenStateChange;
for (int i = firstParameter; match1 && i < parameters; i++) {
OpcodeStack.Item it = stack.getStackItem(parameters - 1 - i);
if (!it.isInitialParameter() || it.getRegisterNumber() != i)
match1 = false;
}
boolean sameMethod = seen == INVOKESTATIC
|| getNameConstantOperand().equals("<init>");
if (!sameMethod) {
// Have to check if first parmeter is the same
// know there must be a this argument
if (DEBUG)
System.out.println("Stack is " + stack);
OpcodeStack.Item p = stack.getStackItem(parameters - 1);
if (DEBUG)
System.out.println("parameters = " + parameters + ", Item is " + p);
String sig = p.getSignature();
sameMethod = p.isInitialParameter() && p.getRegisterNumber() == 0 && sig.equals("L" + getClassName() +";");
}
// match2 and match3 are two different ways of seeing if the call site
// postdominates the method entry.
// technically, we use (!seenTransferOfControl || !seenReturn && largestBranchTarget < getPC())
// as a check that the call site postdominates the method entry. If those are true,
// and sameMethod is true, we have a guaranteed IL.
boolean match2 = sameMethod && !seenTransferOfControl;
boolean match3 = sameMethod && !seenReturn && largestBranchTarget < getPC();
if (match1 || match2 || match3) {
if (DEBUG)
System.out.println("IL: " + sameMethod + " " + match1 + " " + match2 + " " + match3);
int priority = HIGH_PRIORITY;
if (!match1 && !match2 && seenThrow) priority = NORMAL_PRIORITY;
if (seen == INVOKEINTERFACE) priority = NORMAL_PRIORITY;
bugReporter.reportBug(new BugInstance(this, "IL_INFINITE_RECURSIVE_LOOP",
HIGH_PRIORITY).addClassAndMethod(this).addSourceLine(this));
}
}
}
switch (seen) {
case ARETURN:
case IRETURN:
case LRETURN:
case RETURN:
case DRETURN:
case FRETURN:
seenReturn = true;
seenTransferOfControl = true;
break;
case ATHROW:
seenThrow = true;
seenTransferOfControl = true;
break;
case PUTSTATIC:
case PUTFIELD:
case IASTORE:
case AASTORE:
case DASTORE:
case FASTORE:
case LASTORE:
case SASTORE:
case CASTORE:
case BASTORE:
case INVOKEVIRTUAL:
case INVOKESPECIAL:
case INVOKEINTERFACE:
case INVOKESTATIC:
seenStateChange = true;
break;
}
}
}