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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 Kevin Lubick
 * 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.Map;

import org.apache.bcel.Const;
import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.Field;

import com.mebigfatguy.fbcontrib.utils.OpcodeUtils;
import com.mebigfatguy.fbcontrib.utils.RegisterUtils;
import com.mebigfatguy.fbcontrib.utils.SignatureUtils;
import com.mebigfatguy.fbcontrib.utils.TernaryPatcher;
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.ba.ClassContext;
import edu.umd.cs.findbugs.ba.XField;
import edu.umd.cs.findbugs.internalAnnotations.DottedClassName;

/**
 * an abstract base class for WriteOnlyCollections and HttpClientProblems, looks
 * for calls that are expected to be made, but are not.
 */
public abstract class MissingMethodsDetector extends BytecodeScanningDetector {

    private final BugReporter bugReporter;
    private OpcodeStack stack;
    private String clsSignature;
    /** register to first allocation PC */
    private Map localSpecialObjects;
    /** fieldname to field sig */
    private Map fieldSpecialObjects;
    private boolean sawTernary;
    private boolean isInnerClass;

    protected MissingMethodsDetector(BugReporter bugReporter) {
        this.bugReporter = bugReporter;
    }

    /**
     * overrides the visitor to initialize and tear down the opcode stack
     *
     * @param classContext the context object of the currently parsed class
     */
    @Override
    public void visitClassContext(ClassContext classContext) {
        try {
            String clsName = classContext.getJavaClass().getClassName();
            isInnerClass = clsName.indexOf(Values.INNER_CLASS_SEPARATOR) >= 0;

            clsSignature = SignatureUtils.classToSignature(clsName);
            stack = new OpcodeStack();
            localSpecialObjects = new HashMap<>();
            fieldSpecialObjects = new HashMap<>();
            super.visitClassContext(classContext);

            if (!isInnerClass && !fieldSpecialObjects.isEmpty()) {

                for (Map.Entry entry : fieldSpecialObjects.entrySet()) {
                    String fieldName = entry.getKey();
                    String signature = entry.getValue();
                    bugReporter.reportBug(
                            makeFieldBugInstance().addClass(this).addField(clsName, fieldName, signature, false));
                }
            }
        } finally {
            stack = null;
            localSpecialObjects = null;
            fieldSpecialObjects = null;
        }
    }

    @Override
    public void visitField(Field obj) {
        if (!isInnerClass && obj.isPrivate() && !obj.isSynthetic()) {
            String sig = obj.getSignature();
            if (sig.startsWith(Values.SIG_QUALIFIED_CLASS_PREFIX)) {
                String type = SignatureUtils.stripSignature(sig);
                if (doesObjectNeedToBeWatched(type)) {
                    fieldSpecialObjects.put(obj.getName(), obj.getSignature());
                }
            }
        }
    }

    /**
     * overrides the visitor reset the stack
     *
     * @param obj the context object of the currently parsed code block
     */
    @Override
    public void visitCode(Code obj) {

        stack.resetForMethodEntry(this);
        localSpecialObjects.clear();
        sawTernary = false;
        super.visitCode(obj);

        for (Integer pc : localSpecialObjects.values()) {
            bugReporter.reportBug(
                    makeLocalBugInstance().addClass(this).addMethod(this).addSourceLine(this, pc.intValue()));
        }
    }

    /**
     * overrides the visitor to look for uses of collections where the only access
     * to to the collection is to write to it
     *
     * @param seen the opcode of the currently visited instruction
     */
    @edu.umd.cs.findbugs.annotations.SuppressFBWarnings(value = "SF_SWITCH_FALLTHROUGH", justification = "This fall-through is deliberate and documented")
    @Override
    public void sawOpcode(int seen) {
        Object userObject = null;

        // saving and restoring the userobject of the top item, works around a
        // bug in Findbugs proper
        if (stack.getStackDepth() > 0) {
            userObject = stack.getStackItem(0).getUserValue();
        }
        stack.precomputation(this);
        if (stack.getStackDepth() > 0) {
            stack.getStackItem(0).setUserValue(userObject);
            userObject = null;
        }

        try {
            switch (seen) {
            case Const.INVOKESPECIAL:
                userObject = sawInvokeSpecial(userObject);
                break;
            case Const.INVOKEINTERFACE:
            case Const.INVOKEVIRTUAL:
                sawInvokeInterfaceVirtual();
                break;
            case Const.INVOKESTATIC:
                userObject = sawInvokeStatic(userObject);
                //$FALL-THROUGH$
            case Const.INVOKEDYNAMIC:
                processMethodParms();
                break;
            case Const.ARETURN:
                if (stack.getStackDepth() > 0) {
                    OpcodeStack.Item item = stack.getStackItem(0);
                    clearUserValue(item);
                } else {
                    // bad findbugs bug, which clears the stack after an ALOAD, in some cases
                    int prevOp = getPrevOpcode(1);
                    if (OpcodeUtils.isALoad(prevOp)) {
                        localSpecialObjects.clear();
                    }
                }
                break;

            case Const.ASTORE_0:
            case Const.ASTORE_1:
            case Const.ASTORE_2:
            case Const.ASTORE_3:
            case Const.ASTORE:
                sawAStore(seen);
                break;

            case Const.ALOAD_0:
            case Const.ALOAD_1:
            case Const.ALOAD_2:
            case Const.ALOAD_3:
            case Const.ALOAD:
                userObject = sawLoad(seen, userObject);
                break;

            case Const.AASTORE:
                if (stack.getStackDepth() >= 3) {
                    OpcodeStack.Item item = stack.getStackItem(0);
                    clearUserValue(item);
                }
                break;

            case Const.PUTFIELD:
                sawPutField();
                break;

            case Const.GETFIELD:
                userObject = sawGetField(userObject);
                break;

            case Const.PUTSTATIC:
                sawPutStatic();
                break;

            case Const.GETSTATIC:
                userObject = sawGetStatic(userObject);
                break;

            case Const.GOTO:
            case Const.IFNULL:
            case Const.IFNONNULL:
                if (stack.getStackDepth() > 0) {
                    OpcodeStack.Item item = stack.getStackItem(0);
                    Object uo = item.getUserValue();
                    if ((uo != null) && !(uo instanceof Boolean)) {
                        clearUserValue(item);
                    }
                    sawTernary = true;
                }
                break;
            default:
                break;
            }
        } finally {
            TernaryPatcher.pre(stack, seen);
            stack.sawOpcode(this, seen);
            TernaryPatcher.post(stack, seen);
            if ((userObject != null) && (stack.getStackDepth() > 0)) {
                OpcodeStack.Item item = stack.getStackItem(0);
                item.setUserValue(userObject);
            }
            if (sawTernary) {
                handleTernary(seen);
            }
        }
    }

    private void handleTernary(int seen) {
        if (((seen == Const.GETFIELD) || OpcodeUtils.isALoad(seen)) && (stack.getStackDepth() > 0)) {
            OpcodeStack.Item item = stack.getStackItem(0);
            clearUserValue(item);
        }
        /*
         * check ALOAD_0, as if it's a field the statement after a GOTO will be loading
         * 'this'
         */
        if ((seen != Const.GOTO) && (seen != Const.IFNULL) && (seen != Const.IFNONNULL) && (seen != Const.ALOAD_0)) {
            sawTernary = false;
        }
    }

    private void sawPutStatic() {
        if (stack.getStackDepth() > 0) {
            OpcodeStack.Item item = stack.getStackItem(0);
            Object uo = item.getUserValue();
            if ((uo != null) && !(uo instanceof Boolean)) {
                clearUserValue(item);
            }
        }
    }

    // TODO: returning two types of objects, this awful, need to fix at some point
    private Object sawGetStatic(Object userObject) {
        XField field = getXFieldOperand();
        if (field != null) {
            String fieldName = field.getName();
            if (fieldSpecialObjects.containsKey(fieldName)) {
                return fieldName;
            }
        }
        return userObject;
    }

    private void sawPutField() {
        if (stack.getStackDepth() > 1) {
            OpcodeStack.Item item = stack.getStackItem(0);
            Object uo = item.getUserValue();
            if ((uo != null) && !(uo instanceof Boolean)) {
                clearUserValue(item);
            }
        }
    }

    private Object sawGetField(Object userObject) {
        if (stack.getStackDepth() > 0) {
            OpcodeStack.Item item = stack.getStackItem(0);
            String sig = item.getSignature();
            if ((item.getRegisterNumber() == 0) || ((sig != null) && sig.equals(clsSignature))) {
                return sawGetStatic(userObject);
            }
        }
        return userObject;
    }

    // TODO: returning two types of objects, this awful, need to fix at some point
    private Object sawLoad(int seen, Object userObject) {
        int reg = RegisterUtils.getALoadReg(this, seen);
        if (localSpecialObjects.containsKey(Integer.valueOf(reg))) {
            return Integer.valueOf(reg);
        }
        return userObject;
    }

    private void sawInvokeInterfaceVirtual() {
        String sig = getSigConstantOperand();
        int numParms = SignatureUtils.getNumParameters(sig);
        if (stack.getStackDepth() > numParms) {
            OpcodeStack.Item item = stack.getStackItem(numParms);
            Object uo = item.getUserValue();
            if (uo != null) {
                String name = getNameConstantOperand();
                if (isMethodThatShouldBeCalled(name)) {
                    clearUserValue(item);
                } else if (!"clone".equals(name)) {
                    if ((!Values.SIG_VOID.equals(SignatureUtils.getReturnSignature(sig))) && !nextOpIsPop()) {
                        clearUserValue(item);
                    }
                }
            }
        }
        processMethodParms();
    }

    private Object sawInvokeSpecial(Object userObject) {
        Object returnValue = userObject;
        String methodName = getNameConstantOperand();
        if (Values.CONSTRUCTOR.equals(methodName)) {
            String clsName = getDottedClassConstantOperand();
            if (doesObjectNeedToBeWatched(clsName)) {
                returnValue = Boolean.TRUE;
            }
        }
        processMethodParms();
        return returnValue;
    }

    // TODO: returning two types of objects,this awful, need to fix at some point
    private Object sawInvokeStatic(Object userObject) {
        if (doesStaticFactoryReturnNeedToBeWatched(getClassConstantOperand(), getNameConstantOperand(),
                getSigConstantOperand())) {
            return Boolean.TRUE;
        }
        return userObject;
    }

    private void sawAStore(int seen) {
        int depth = stack.getStackDepth();
        if (depth > 0) {
            OpcodeStack.Item item = stack.getStackItem(0);
            Object uo = item.getUserValue();
            if (uo != null) {
                if (uo instanceof Boolean) {
                    int reg = RegisterUtils.getAStoreReg(this, seen);
                    localSpecialObjects.put(Integer.valueOf(reg), Integer.valueOf(getPC()));
                    if (getPrevOpcode(1) == Const.DUP) {
                        item = stack.getStackItem(1);
                        item.setUserValue(Integer.valueOf(reg));
                    }
                } else {
                    clearUserValue(item);
                }
            }
        }
    }

    private boolean nextOpIsPop() {
        int nextPC = getNextPC();
        return getCode().getCode()[nextPC] == Const.POP;
    }

    private void clearUserValue(OpcodeStack.Item item) {
        Object uo = item.getUserValue();
        if (uo instanceof Integer) {
            localSpecialObjects.remove(uo);
        } else if (uo instanceof String) {
            fieldSpecialObjects.remove(uo);
        } else if (uo instanceof Boolean) {
            localSpecialObjects.remove(Integer.valueOf(item.getRegisterNumber()));
        }
        item.setUserValue(null);
    }

    protected OpcodeStack getStack() {
        return stack;
    }

    /**
     * Checks to see if any of the locals or fields that we are tracking are passed
     * into another method. If they are, we clear out our tracking of them, because
     * we can't easily track their progress into the method.
     *
     * This can be overridden to check for exceptions to this rule, for example,
     * being logged to the console not counting.
     */
    protected void processMethodParms() {
        String sig = getSigConstantOperand();
        int numParms = SignatureUtils.getNumParameters(sig);
        if ((numParms > 0) && (stack.getStackDepth() >= numParms)) {
            for (int i = 0; i < numParms; i++) {
                clearUserValue(stack.getStackItem(i));
            }
        }

    }

    /**
     * informs the missing method detector that a field should no longer be
     * considered special
     *
     * @param name the name of the field
     */
    protected void clearSpecialField(String name) {
        fieldSpecialObjects.remove(name);
    }

    protected abstract BugInstance makeFieldBugInstance();

    protected abstract BugInstance makeLocalBugInstance();

    protected abstract boolean doesObjectNeedToBeWatched(@DottedClassName String type);

    protected abstract boolean doesStaticFactoryReturnNeedToBeWatched(String clsName, String methodName,
            String signature);

    protected abstract boolean isMethodThatShouldBeCalled(String methodName);

}




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