URLProblems.java

/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 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.regex.Pattern;

import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Signature;

import edu.umd.cs.findbugs.BugAccumulator;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.OpcodeStack;
import edu.umd.cs.findbugs.bcel.OpcodeStackDetector;

/**
 * equals and hashCode are blocking methods on URL's. Warn about invoking equals
 * or hashCode on them, or defining Set or Maps with them as keys.
 */
public class URLProblems extends OpcodeStackDetector {

    final static String[] BAD_SIGNATURES = { "Hashtable<Ljava/net/URL", "Map<Ljava/net/URL", "Set<Ljava/net/URL" };

    final private BugReporter bugReporter;

    final private BugAccumulator accumulator;

    public URLProblems(BugReporter bugReporter) {
        this.bugReporter = bugReporter;
        this.accumulator = new BugAccumulator(bugReporter);
    }

    @Override
    public void visitAfter(JavaClass obj) {
        accumulator.reportAccumulatedBugs();
    }

    @Override
    public void visit(Signature obj) {
        String sig = obj.getSignature();
        for (String s : BAD_SIGNATURES)
            if (sig.indexOf(s) >= 0) {
                if (visitingField())
                    bugReporter.reportBug(new BugInstance(this, "DMI_COLLECTION_OF_URLS", HIGH_PRIORITY).addClass(this)
                            .addVisitedField(this));
                else if (visitingMethod())
                    bugReporter.reportBug(new BugInstance(this, "DMI_COLLECTION_OF_URLS", HIGH_PRIORITY).addClassAndMethod(this));
                else
                    bugReporter.reportBug(new BugInstance(this, "DMI_COLLECTION_OF_URLS", HIGH_PRIORITY).addClass(this).addClass(
                            this));
            }
    }

    void check(String className, Pattern name, int target, int url) {
        if (!name.matcher(getNameConstantOperand()).matches())
            return;
        if (stack.getStackDepth() <= target)
            return;
        OpcodeStack.Item targetItem = stack.getStackItem(target);
        OpcodeStack.Item urlItem = stack.getStackItem(url);
        if (!urlItem.getSignature().equals("Ljava/net/URL;"))
            return;
        if (!targetItem.getSignature().equals(className))
            return;
        accumulator.accumulateBug(new BugInstance(this, "DMI_COLLECTION_OF_URLS", HIGH_PRIORITY).addClassAndMethod(this)
                .addCalledMethod(this), this);
    }

    @Override
    public void sawOpcode(int seen) {

        // System.out.println(getPC() + " " + OPCODE_NAMES[seen] + " " + stack);
        if (seen == INVOKEVIRTUAL || seen == INVOKEINTERFACE) {
            check("Ljava/util/HashSet;", Pattern.compile("add|remove|contains"), 1, 0);
            check("Ljava/util/HashMap;", Pattern.compile("remove|containsKey|get"), 1, 0);
            check("Ljava/util/HashMap;", Pattern.compile("put"), 2, 1);

        }

        if (seen == INVOKEVIRTUAL && getClassConstantOperand().equals("java/net/URL")) {
            if (getNameConstantOperand().equals("equals") && getSigConstantOperand().equals("(Ljava/lang/Object;)Z")
                    || getNameConstantOperand().equals("hashCode") && getSigConstantOperand().equals("()I")) {
                accumulator.accumulateBug(
                        new BugInstance(this, "DMI_BLOCKING_METHODS_ON_URL", HIGH_PRIORITY).addClassAndMethod(this)
                                .addCalledMethod(this), this);
            }
        }
    }
}