MutableLock.java

/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 2003-2005 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 java.util.HashSet;
import java.util.Set;

import org.apache.bcel.classfile.Field;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Method;

import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.StatelessDetector;

public class MutableLock extends BytecodeScanningDetector implements StatelessDetector {
    Set<String> setFields = new HashSet<String>();

    Set<String> finalFields = new HashSet<String>();

    boolean thisOnTOS = false;

    private BugReporter bugReporter;

    public MutableLock(BugReporter bugReporter) {
        this.bugReporter = bugReporter;
    }

    @Override
    public void visit(JavaClass obj) {
        finalFields.clear();
        super.visit(obj);
    }

    @Override
    public void visit(Field obj) {
        super.visit(obj);
        if (obj.isFinal())
            finalFields.add(obj.getName());
    }

    @Override
    public void visit(Method obj) {
        super.visit(obj);
        setFields.clear();
        thisOnTOS = false;
    }

    @Override
    public void sawOpcode(int seen) {

        switch (seen) {
        case ALOAD_0:
            thisOnTOS = true;
            return;
        case MONITOREXIT:
            setFields.clear();
            break;
        case PUTFIELD:
            if (getClassConstantOperand().equals(getClassName()))
                setFields.add(getNameConstantOperand());
            break;
        case GETFIELD:
            if (thisOnTOS && getClassConstantOperand().equals(getClassName()) && setFields.contains(getNameConstantOperand())
                    && asUnsignedByte(codeBytes[getPC() + 3]) == DUP && asUnsignedByte(codeBytes[getPC() + 5]) == MONITORENTER

                    && !finalFields.contains(getNameConstantOperand()))
                bugReporter.reportBug(new BugInstance(this, "ML_SYNC_ON_UPDATED_FIELD", NORMAL_PRIORITY).addClassAndMethod(this)
                        .addReferencedField(this).addSourceLine(this, getPC() + 5));
            break;
        default:
        }
        thisOnTOS = false;
    }
}