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An auxiliary findbugs.sourceforge.net plugin for java bug detectors that fall outside the narrow scope of detectors to be packaged with the product itself.

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/*
 * fb-contrib - Auxiliary detectors for Java programs
 * Copyright (C) 2005-2019 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.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Objects;
import java.util.Set;

import org.apache.bcel.Const;
import org.apache.bcel.Repository;
import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.JavaClass;

import com.mebigfatguy.fbcontrib.utils.BugType;
import com.mebigfatguy.fbcontrib.utils.CodeByteUtils;
import com.mebigfatguy.fbcontrib.utils.FQMethod;
import com.mebigfatguy.fbcontrib.utils.OpcodeUtils;
import com.mebigfatguy.fbcontrib.utils.QMethod;
import com.mebigfatguy.fbcontrib.utils.SignatureBuilder;
import com.mebigfatguy.fbcontrib.utils.ToString;
import com.mebigfatguy.fbcontrib.utils.UnmodifiableSet;
import com.mebigfatguy.fbcontrib.utils.Values;

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.OpcodeStack.CustomUserValue;
import edu.umd.cs.findbugs.ba.ClassContext;
import edu.umd.cs.findbugs.ba.XField;
import edu.umd.cs.findbugs.ba.XMethod;

/**
 * looks for odd usage patterns when using Maps
 */
@CustomUserValue
public class MapUsageIssues extends BytecodeScanningDetector {

    private static final FQMethod CONTAINS_METHOD = new FQMethod("java/util/Set", "contains",
            SignatureBuilder.SIG_OBJECT_TO_BOOLEAN);
    private static final FQMethod CONTAINSKEY_METHOD = new FQMethod("java/util/Map", "containsKey",
            SignatureBuilder.SIG_OBJECT_TO_BOOLEAN);
    private static final FQMethod GET_METHOD = new FQMethod("java/util/Map", "get",
            SignatureBuilder.SIG_OBJECT_TO_OBJECT);
    private static final FQMethod REMOVE_METHOD = new FQMethod("java/util/Map", "remove",
            SignatureBuilder.SIG_OBJECT_TO_OBJECT);

    private static final QMethod SIZE_METHOD = new QMethod("size", SignatureBuilder.SIG_VOID_TO_INT);

    private static final Set COLLECTION_ACCESSORS = UnmodifiableSet.create("keySet", "entrySet", "values");

    private static JavaClass mapClass;

    static {
        try {
            mapClass = Repository.lookupClass("java/util/Map");
        } catch (ClassNotFoundException cnfe) {
            mapClass = null;
        }
    }

    private BugReporter bugReporter;
    private OpcodeStack stack;
    private Map mapContainsKeyUsed;
    private Map mapGetUsed;

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

    @Override
    public void visitClassContext(ClassContext classContext) {
        try {
            stack = new OpcodeStack();
            mapContainsKeyUsed = new HashMap<>();
            mapGetUsed = new HashMap<>();
            super.visitClassContext(classContext);
        } finally {
            mapContainsKeyUsed = null;
            mapGetUsed = null;
            stack = null;
        }
    }

    @Override
    public void visitCode(Code obj) {
        stack.resetForMethodEntry(this);
        mapContainsKeyUsed.clear();
        mapGetUsed.clear();
        super.visitCode(obj);
    }

    @Override
    public void sawOpcode(int seen) {
        try {
            if (!mapContainsKeyUsed.isEmpty()) {
                Iterator> it = mapContainsKeyUsed.entrySet().iterator();
                int pc = getPC();
                while (it.hasNext()) {
                    Map.Entry entry = it.next();
                    if (!entry.getKey().isValid() || entry.getValue().outOfScope(pc)) {
                        it.remove();
                    }
                }
            }

            // checking for a branch might be overkill, but for now lets go with it
            if (!mapGetUsed.isEmpty() && OpcodeUtils.isBranch(seen)) {
                Iterator> it = mapGetUsed.entrySet().iterator();
                while (it.hasNext()) {
                    it.next();
                    it.remove();
                }
            }

            if ((seen == Const.IFNULL) || (seen == Const.IFNONNULL)) {
                if (stack.getStackDepth() > 0) {
                    OpcodeStack.Item itm = stack.getStackItem(0);
                    XMethod method = itm.getReturnValueOf();
                    if ((method != null) && (mapClass != null)) {
                        if (COLLECTION_ACCESSORS.contains(method.getName())) {

                            JavaClass cls = Repository.lookupClass(method.getClassName());
                            if (cls.implementationOf(mapClass)) {
                                bugReporter.reportBug(
                                        new BugInstance(this, BugType.MUI_NULL_CHECK_ON_MAP_SUBSET_ACCESSOR.name(),
                                                NORMAL_PRIORITY).addClass(this).addMethod(this).addSourceLine(this));
                            }

                        }
                    }
                }
            } else if (seen == Const.INVOKEINTERFACE) {
                FQMethod fqm = new FQMethod(getClassConstantOperand(), getNameConstantOperand(),
                        getSigConstantOperand());
                if (CONTAINS_METHOD.equals(fqm)) {
                    if (stack.getStackDepth() >= 2) {
                        OpcodeStack.Item item = stack.getStackItem(1);
                        if ((item.getRegisterNumber() < 0) && (item.getXField() == null)) {
                            XMethod xm = item.getReturnValueOf();
                            if ((xm != null) && COLLECTION_ACCESSORS.contains(xm.getName())
                                    && Values.DOTTED_JAVA_UTIL_MAP.equals(xm.getClassName())) {
                                bugReporter.reportBug(
                                        new BugInstance(this, BugType.MUI_USE_CONTAINSKEY.name(), NORMAL_PRIORITY)
                                                .addClass(this).addMethod(this).addSourceLine(this));
                            }
                        }
                    }
                } else if (CONTAINSKEY_METHOD.equals(fqm)) {
                    if (getNextOpcode() == Const.IFEQ) {
                        int ifEnd = getNextPC() + CodeByteUtils.getshort(getCode().getCode(), getNextPC() + 1);
                        if (stack.getStackDepth() >= 2) {
                            OpcodeStack.Item itm = stack.getStackItem(1);
                            mapContainsKeyUsed.put(new MapRef(itm), new ContainsKey(stack.getStackItem(0), ifEnd));
                        }
                    }
                } else if (GET_METHOD.equals(fqm)) {
                    if (stack.getStackDepth() >= 2) {
                        OpcodeStack.Item itm = stack.getStackItem(1);
                        ContainsKey ck = mapContainsKeyUsed.remove(new MapRef(itm));
                        if ((ck != null) && new ContainsKey(stack.getStackItem(0), 0).equals(ck)) {
                            bugReporter.reportBug(new BugInstance(this, BugType.MUI_CONTAINSKEY_BEFORE_GET.name(),
                                    ck.getReportLevel()).addClass(this).addMethod(this).addSourceLine(this));
                        }

                        mapGetUsed.put(new MapRef(itm), new Get(stack.getStackItem(0)));
                    }
                } else if (REMOVE_METHOD.equals(fqm)) {
                    if (stack.getStackDepth() >= 2) {
                        OpcodeStack.Item itm = stack.getStackItem(1);
                        Get get = mapGetUsed.remove(new MapRef(itm));
                        if ((get != null) && new Get(stack.getStackItem(0)).equals(get)) {
                            bugReporter.reportBug(
                                    new BugInstance(this, BugType.MUI_GET_BEFORE_REMOVE.name(), get.getReportLevel())
                                            .addClass(this).addMethod(this).addSourceLine(this));
                        }
                    }
                }

                QMethod qm = new QMethod(getNameConstantOperand(), getSigConstantOperand());
                if (SIZE_METHOD.equals(qm)) {
                    if (stack.getStackDepth() > 0) {
                        OpcodeStack.Item itm = stack.getStackItem(0);
                        if ((itm.getRegisterNumber() < 0) && (itm.getXField() == null)) {
                            XMethod xm = itm.getReturnValueOf();
                            if ((xm != null) && Values.DOTTED_JAVA_UTIL_MAP.equals(xm.getClassName())
                                    && COLLECTION_ACCESSORS.contains(xm.getName())) {
                                bugReporter.reportBug(
                                        new BugInstance(this, BugType.MUI_CALLING_SIZE_ON_SUBCONTAINER.name(),
                                                NORMAL_PRIORITY).addClass(this).addMethod(this).addSourceLine(this));
                            }
                        }
                    }
                }
            }
        } catch (ClassNotFoundException e) {
            bugReporter.reportMissingClass(e);
        } finally {
            stack.sawOpcode(this, seen);
        }
    }

    @SuppressWarnings("CPD-START")
    static class ContainsKey {
        private Object keyValue;
        private int scopeEnd;
        private int reportLevel;

        public ContainsKey(OpcodeStack.Item itm, int ifEnd) {
            scopeEnd = ifEnd;
            int reg = itm.getRegisterNumber();
            if (reg >= 0) {
                keyValue = Integer.valueOf(reg);
                reportLevel = NORMAL_PRIORITY;
            } else {
                XField xf = itm.getXField();
                if (xf != null) {
                    keyValue = xf;
                    reportLevel = NORMAL_PRIORITY;
                } else {
                    Object cons = itm.getConstant();
                    if (cons != null) {
                        keyValue = cons;
                        reportLevel = NORMAL_PRIORITY;
                    } else {
                        XMethod xm = itm.getReturnValueOf();
                        if (xm != null) {
                            keyValue = xm;
                            reportLevel = LOW_PRIORITY;
                        }
                    }
                }
            }
        }

        public boolean outOfScope(int pc) {
            return pc >= scopeEnd;
        }

        public int getReportLevel() {
            return reportLevel;
        }

        @Override
        public boolean equals(Object o) {
            if (!(o instanceof ContainsKey)) {
                return false;
            }

            ContainsKey that = (ContainsKey) o;

            if ((keyValue == null) || (that.keyValue == null)) {
                return false;
            }

            return keyValue.equals(that.keyValue);
        }

        @Override
        public int hashCode() {
            return keyValue == null ? 0 : keyValue.hashCode();
        }

        @Override
        public String toString() {
            return ToString.build(this);
        }
    }

    static class Get {
        private Object keyValue;
        private int reportLevel;

        public Get(OpcodeStack.Item itm) {
            int reg = itm.getRegisterNumber();
            if (reg >= 0) {
                keyValue = Integer.valueOf(reg);
                reportLevel = NORMAL_PRIORITY;
            } else {
                XField xf = itm.getXField();
                if (xf != null) {
                    keyValue = xf;
                    reportLevel = NORMAL_PRIORITY;
                } else {
                    Object cons = itm.getConstant();
                    if (cons != null) {
                        keyValue = cons;
                        reportLevel = NORMAL_PRIORITY;
                    } else {
                        XMethod xm = itm.getReturnValueOf();
                        if (xm != null) {
                            keyValue = xm;
                            reportLevel = LOW_PRIORITY;
                        }
                        keyValue = null;
                    }
                }
            }
        }

        @Override
        public boolean equals(Object o) {
            if (!(o instanceof Get)) {
                return false;
            }

            Get that = (Get) o;

            if ((keyValue == null) || (that.keyValue == null)) {
                return false;
            }

            return keyValue.equals(that.keyValue);
        }

        @Override
        public int hashCode() {
            return keyValue == null ? 0 : keyValue.hashCode();
        }

        public int getReportLevel() {
            return reportLevel;
        }

        @Override
        public String toString() {
            return ToString.build(this);
        }
    }

    static class MapRef {
        private int register;
        private XField field;

        public MapRef(OpcodeStack.Item itm) {
            int reg = itm.getRegisterNumber();
            if (reg >= 0) {
                register = reg;
            } else {
                XField xf = itm.getXField();
                if (xf != null) {
                    field = xf;
                }
                register = -1;
            }
        }

        @Override
        public int hashCode() {
            if (register >= 0) {
                return register;
            }

            if (field != null) {
                return field.hashCode();
            }

            return Integer.MAX_VALUE;
        }

        public boolean isValid() {
            return (register >= 0) || (field != null);
        }

        @Override
        public boolean equals(Object o) {
            if (!(o instanceof MapRef)) {
                return false;
            }

            MapRef that = (MapRef) o;

            return (register == that.register) && Objects.equals(field, that.field);
        }

        @Override
        public String toString() {
            return ToString.build(this);
        }
    }
}




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