SuspiciousWaitOnConcurrentObject.java

/*
 * fb-contrib - Auxiliary detectors for Java programs
 * Copyright (C) 2005-2017 Dave Brosius
 *
 * 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 com.mebigfatguy.fbcontrib.detect;

import java.util.Set;

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

import com.mebigfatguy.fbcontrib.utils.BugType;
import com.mebigfatguy.fbcontrib.utils.UnmodifiableSet;

import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.OpcodeStack;
import edu.umd.cs.findbugs.ba.ClassContext;

/**
 * looks for calls to the wait method on mutexes defined in the
 * java.util.concurrent package where it is likely that await was intended.
 */
public class SuspiciousWaitOnConcurrentObject extends BytecodeScanningDetector {
    private static final Set<String> concurrentAwaitClasses = UnmodifiableSet.create(
        "java.util.concurrent.CountDownLatch",
        "java.util.concurrent.CyclicBarrier"
    );

    private BugReporter bugReporter;
    private OpcodeStack stack;

    /**
     * constructs a SWCO detector given the reporter to report bugs on
     *
     * @param bugReporter
     *            the sync of bug reports
     */
    public SuspiciousWaitOnConcurrentObject(BugReporter bugReporter) {
        this.bugReporter = bugReporter;
    }

    /**
     * implements the visitor to check for class file version 1.5 or better
     *
     * @param classContext
     *            the context object of the currently parsed class
     */
    @Override
    public void visitClassContext(ClassContext classContext) {
        try {
            JavaClass cls = classContext.getJavaClass();
            int major = cls.getMajor();
            if (major >= Constants.MAJOR_1_5) {
                stack = new OpcodeStack();
                super.visitClassContext(classContext);
            }
        } finally {
            stack = null;
        }
    }

    /**
     * implements the visitor to reset the opcode stack
     *
     * @param obj
     *            the context object for the currently parsed method
     */
    @Override
    public void visitMethod(Method obj) {
        stack.resetForMethodEntry(this);
    }

    /**
     * implements the visitor to look for calls to wait, on java.util.concurrent
     * classes that define await.
     *
     * @param seen
     *            the opcode of the currently visited instruction
     */
    @Override
    public void sawOpcode(int seen) {
        try {
            stack.precomputation(this);

            if ((seen != INVOKEVIRTUAL)
                    || !"wait".equals(getNameConstantOperand())
                    || stack.getStackDepth() == 0) {
                return;
            }
            JavaClass cls = stack.getStackItem(0).getJavaClass();
            if (cls != null) {
                String clsName = cls.getClassName();
                if (concurrentAwaitClasses.contains(clsName)) {
                    bugReporter.reportBug(new BugInstance(this, BugType.SWCO_SUSPICIOUS_WAIT_ON_CONCURRENT_OBJECT.name(), NORMAL_PRIORITY)
                            .addClass(this).addMethod(this).addSourceLine(this));
                }
            }
        } catch (ClassNotFoundException cnfe) {
            bugReporter.reportMissingClass(cnfe);
        } finally {
            stack.sawOpcode(this, seen);
        }
    }
}