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/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 2003,2004 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.Const;
import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.Method;

import edu.umd.cs.findbugs.BugAccumulator;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.Lookup;
import edu.umd.cs.findbugs.StatelessDetector;
import edu.umd.cs.findbugs.SystemProperties;
import edu.umd.cs.findbugs.util.Values;

public class FindFinalizeInvocations extends BytecodeScanningDetector implements StatelessDetector {
    private static final boolean DEBUG = SystemProperties.getBoolean("ffi.debug");

    private final BugReporter bugReporter;

    private final BugAccumulator bugAccumulator;

    public FindFinalizeInvocations(BugReporter bugReporter) {
        this.bugReporter = bugReporter;
        this.bugAccumulator = new BugAccumulator(bugReporter);
    }

    boolean sawSuperFinalize;

    @Override
    public void visit(Method obj) {
        if (DEBUG) {
            System.out.println("FFI: visiting " + getFullyQualifiedMethodName());
        }
        if ("finalize".equals(getMethodName()) && "()V".equals(getMethodSig()) && (obj.getAccessFlags() & (Const.ACC_PUBLIC)) != 0) {
            bugReporter
                    .reportBug(new BugInstance(this, "FI_PUBLIC_SHOULD_BE_PROTECTED", NORMAL_PRIORITY).addClassAndMethod(this));
        }
    }

    @Override
    public void visit(Code obj) {
        sawSuperFinalize = false;
        super.visit(obj);
        bugAccumulator.reportAccumulatedBugs();
        if (!"finalize".equals(getMethodName()) || !"()V".equals(getMethodSig())) {
            return;
        }
        String overridesFinalizeIn = Lookup.findSuperImplementor(getDottedClassName(), "finalize", "()V", bugReporter);
        boolean superHasNoFinalizer = Values.DOTTED_JAVA_LANG_OBJECT.equals(overridesFinalizeIn);
        // System.out.println("superclass: " + superclassName);
        if (obj.getCode().length == 1) {
            if (superHasNoFinalizer) {
                if (!getMethod().isFinal()) {
                    bugReporter.reportBug(new BugInstance(this, "FI_EMPTY", NORMAL_PRIORITY).addClassAndMethod(this));
                }
            } else {
                bugReporter.reportBug(new BugInstance(this, "FI_NULLIFY_SUPER", NORMAL_PRIORITY).addClassAndMethod(this)
                        .addClass(overridesFinalizeIn));
            }
        } else if (obj.getCode().length == 5 && sawSuperFinalize) {
            bugReporter.reportBug(new BugInstance(this, "FI_USELESS", NORMAL_PRIORITY).addClassAndMethod(this));
        } else if (!sawSuperFinalize && !superHasNoFinalizer) {
            bugReporter.reportBug(new BugInstance(this, "FI_MISSING_SUPER_CALL", NORMAL_PRIORITY).addClassAndMethod(this)
                    .addClass(overridesFinalizeIn));
        }
    }

    @Override
    public void sawOpcode(int seen) {
        if (seen == Const.INVOKEVIRTUAL && "finalize".equals(getNameConstantOperand()) && "()V".equals(getSigConstantOperand())) {
            bugAccumulator.accumulateBug(
                    new BugInstance(this, "FI_EXPLICIT_INVOCATION", "finalize".equals(getMethodName())
                            && "()V".equals(getMethodSig()) ? HIGH_PRIORITY : NORMAL_PRIORITY).addClassAndMethod(this)
                            .addCalledMethod(this), this);

        }
        if (seen == Const.INVOKESPECIAL && "finalize".equals(getNameConstantOperand())) {
            sawSuperFinalize = true;
        }
    }
}