/*
* FindBugs - Find bugs in Java programs
* Copyright (C) 2003-2007 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.BitSet;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.Set;
import java.util.SortedSet;
import javax.annotation.CheckForNull;
import javax.annotation.Nonnull;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.LineNumberTable;
import org.apache.bcel.classfile.Method;
import org.apache.bcel.generic.ATHROW;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.FieldInstruction;
import org.apache.bcel.generic.Instruction;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.InstructionTargeter;
import org.apache.bcel.generic.InvokeInstruction;
import org.apache.bcel.generic.MethodGen;
import org.apache.bcel.generic.ReturnInstruction;
import edu.umd.cs.findbugs.BugAccumulator;
import edu.umd.cs.findbugs.BugAnnotation;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.Detector;
import edu.umd.cs.findbugs.FieldAnnotation;
import edu.umd.cs.findbugs.FindBugsAnalysisFeatures;
import edu.umd.cs.findbugs.LocalVariableAnnotation;
import edu.umd.cs.findbugs.MethodAnnotation;
import edu.umd.cs.findbugs.Priorities;
import edu.umd.cs.findbugs.StringAnnotation;
import edu.umd.cs.findbugs.SystemProperties;
import edu.umd.cs.findbugs.UseAnnotationDatabase;
import edu.umd.cs.findbugs.ba.AnalysisContext;
import edu.umd.cs.findbugs.ba.BasicBlock;
import edu.umd.cs.findbugs.ba.CFGBuilderException;
import edu.umd.cs.findbugs.ba.ClassContext;
import edu.umd.cs.findbugs.ba.DataflowAnalysisException;
import edu.umd.cs.findbugs.ba.Location;
import edu.umd.cs.findbugs.ba.MissingClassException;
import edu.umd.cs.findbugs.ba.SignatureConverter;
import edu.umd.cs.findbugs.ba.XFactory;
import edu.umd.cs.findbugs.ba.XField;
import edu.umd.cs.findbugs.ba.XMethod;
import edu.umd.cs.findbugs.ba.npe.IsNullValue;
import edu.umd.cs.findbugs.ba.npe.NullDerefAndRedundantComparisonCollector;
import edu.umd.cs.findbugs.ba.npe.NullDerefAndRedundantComparisonFinder;
import edu.umd.cs.findbugs.ba.npe.NullValueUnconditionalDeref;
import edu.umd.cs.findbugs.ba.npe.PointerUsageRequiringNonNullValue;
import edu.umd.cs.findbugs.ba.npe.RedundantBranch;
import edu.umd.cs.findbugs.ba.npe.ReturnPathType;
import edu.umd.cs.findbugs.ba.npe.ReturnPathTypeDataflow;
import edu.umd.cs.findbugs.ba.npe.UsagesRequiringNonNullValues;
import edu.umd.cs.findbugs.ba.vna.ValueNumber;
import edu.umd.cs.findbugs.ba.vna.ValueNumberDataflow;
import edu.umd.cs.findbugs.ba.vna.ValueNumberFrame;
import edu.umd.cs.findbugs.ba.vna.ValueNumberSourceInfo;
import edu.umd.cs.findbugs.classfile.CheckedAnalysisException;
import edu.umd.cs.findbugs.props.GeneralWarningProperty;
import edu.umd.cs.findbugs.props.WarningProperty;
import edu.umd.cs.findbugs.props.WarningPropertySet;
import edu.umd.cs.findbugs.props.WarningPropertyUtil;
import edu.umd.cs.findbugs.visitclass.Util;
/**
* A Detector to find instructions where a NullPointerException might be raised.
* We also look for useless reference comparisons involving null and non-null
* values.
*
* @author David Hovemeyer
* @author William Pugh
* @see edu.umd.cs.findbugs.ba.npe.IsNullValueAnalysis
*/
public class NoiseNullDeref implements Detector, UseAnnotationDatabase, NullDerefAndRedundantComparisonCollector {
public static final boolean DEBUG = SystemProperties.getBoolean("fnd.debug");
private static final boolean DEBUG_NULLARG = SystemProperties.getBoolean("fnd.debug.nullarg");
// private static final boolean DEBUG_NULLRETURN = SystemProperties.getBoolean("fnd.debug.nullreturn");
private static final boolean MARK_DOOMED = SystemProperties.getBoolean("fnd.markdoomed", true);
private static final String METHOD = SystemProperties.getProperty("fnd.method");
private static final String CLASS = SystemProperties.getProperty("fnd.class");
// Fields
private final BugReporter bugReporter;
private final BugAccumulator bugAccumulator;
// Transient state
private ClassContext classContext;
private Method method;
private ValueNumberDataflow vnaDataflow;
public NoiseNullDeref(BugReporter bugReporter) {
this.bugReporter = bugReporter;
this.bugAccumulator = new BugAccumulator(bugReporter);
}
@Override
public void visitClassContext(ClassContext classContext) {
this.classContext = classContext;
String currentMethod = null;
JavaClass jclass = classContext.getJavaClass();
String className = jclass.getClassName();
String superClassName = jclass.getSuperclassName();
if (superClassName.endsWith("ProtocolMessage")) {
return;
}
if (CLASS != null && !className.equals(CLASS)) {
return;
}
Method[] methodList = jclass.getMethods();
for (Method method : methodList) {
try {
if (method.isAbstract() || method.isNative() || method.getCode() == null) {
continue;
}
currentMethod = SignatureConverter.convertMethodSignature(jclass, method);
if (METHOD != null && !method.getName().equals(METHOD)) {
continue;
}
if (DEBUG || DEBUG_NULLARG) {
System.out.println("Checking for NP in " + currentMethod);
}
analyzeMethod(classContext, method);
} catch (MissingClassException e) {
bugReporter.reportMissingClass(e.getClassNotFoundException());
} catch (DataflowAnalysisException e) {
bugReporter.logError("While analyzing " + currentMethod + ": FindNullDeref caught dae exception", e);
} catch (CFGBuilderException e) {
bugReporter.logError("While analyzing " + currentMethod + ": FindNullDeref caught cfgb exception", e);
}
bugAccumulator.reportAccumulatedBugs();
}
}
private void analyzeMethod(ClassContext classContext, Method method) throws DataflowAnalysisException, CFGBuilderException {
if (DEBUG || DEBUG_NULLARG) {
System.out.println("Pre FND ");
}
MethodGen methodGen = classContext.getMethodGen(method);
if (methodGen == null) {
return;
}
// UsagesRequiringNonNullValues uses =
// classContext.getUsagesRequiringNonNullValues(method);
this.method = method;
if (DEBUG || DEBUG_NULLARG) {
System.out.println("FND: " + SignatureConverter.convertMethodSignature(methodGen));
}
findPreviouslyDeadBlocks();
vnaDataflow = classContext.getValueNumberDataflow(method);
// Create a NullDerefAndRedundantComparisonFinder object to do the
// actual
// work. It will call back to report null derefs and redundant null
// comparisons
// through the NullDerefAndRedundantComparisonCollector interface we
// implement.
NullDerefAndRedundantComparisonFinder worker = new NullDerefAndRedundantComparisonFinder(classContext, method, this);
worker.execute();
}
/**
* Find set of blocks which were known to be dead before doing the null
* pointer analysis.
*
* @return set of previously dead blocks, indexed by block id
* @throws CFGBuilderException
* @throws DataflowAnalysisException
*/
private BitSet findPreviouslyDeadBlocks() throws DataflowAnalysisException, CFGBuilderException {
BitSet deadBlocks = new BitSet();
ValueNumberDataflow vnaDataflow = classContext.getValueNumberDataflow(method);
for (Iterator<BasicBlock> i = vnaDataflow.getCFG().blockIterator(); i.hasNext();) {
BasicBlock block = i.next();
ValueNumberFrame vnaFrame = vnaDataflow.getStartFact(block);
if (vnaFrame.isTop()) {
deadBlocks.set(block.getLabel());
}
}
return deadBlocks;
}
static class CheckCallSitesAndReturnInstructions {
}
@Override
public void report() {
}
public boolean skipIfInsideCatchNull() {
return classContext.getJavaClass().getClassName().indexOf("Test") >= 0 || method.getName().indexOf("test") >= 0
|| method.getName().indexOf("Test") >= 0;
}
/**
* @deprecated Use
* {@link #foundNullDeref(Location,ValueNumber,IsNullValue,ValueNumberFrame,boolean)}
* instead
*/
@Override
@Deprecated
public void foundNullDeref(Location location, ValueNumber valueNumber, IsNullValue refValue, ValueNumberFrame vnaFrame) {
foundNullDeref(location, valueNumber, refValue, vnaFrame, true);
}
@Override
public void foundNullDeref(Location location, ValueNumber valueNumber, IsNullValue refValue, ValueNumberFrame vnaFrame,
boolean isConsistent) {
if (!refValue.isNullOnComplicatedPath23()) {
return;
}
WarningPropertySet<WarningProperty> propertySet = new WarningPropertySet<WarningProperty>();
if (valueNumber.hasFlag(ValueNumber.CONSTANT_CLASS_OBJECT)) {
return;
}
boolean onExceptionPath = refValue.isException();
if (onExceptionPath) {
propertySet.addProperty(GeneralWarningProperty.ON_EXCEPTION_PATH);
}
BugAnnotation variable = ValueNumberSourceInfo.findAnnotationFromValueNumber(method, location, valueNumber, vnaFrame,
"VALUE_OF");
addPropertiesForDereferenceLocations(propertySet, Collections.singleton(location));
Instruction ins = location.getHandle().getInstruction();
BugAnnotation cause;
final ConstantPoolGen cpg = classContext.getConstantPoolGen();
if (ins instanceof InvokeInstruction) {
InvokeInstruction iins = (InvokeInstruction) ins;
XMethod invokedMethod = XFactory.createXMethod((InvokeInstruction) ins, cpg);
cause = MethodAnnotation.fromXMethod(invokedMethod);
cause.setDescription(MethodAnnotation.METHOD_CALLED);
if (iins.getMethodName(cpg).equals("close") && iins.getSignature(cpg).equals("()V")) {
propertySet.addProperty(NullDerefProperty.CLOSING_NULL);
}
} else if (ins instanceof FieldInstruction) {
FieldInstruction fins = (FieldInstruction) ins;
XField referencedField = XFactory.createXField(fins, cpg);
cause = FieldAnnotation.fromXField(referencedField);
} else {
cause = new StringAnnotation(ins.getName());
}
boolean caught = inCatchNullBlock(location);
if (caught && skipIfInsideCatchNull()) {
return;
}
int basePriority = Priorities.NORMAL_PRIORITY;
if (!refValue.isNullOnComplicatedPath2()) {
basePriority--;
}
reportNullDeref(propertySet, location, "NOISE_NULL_DEREFERENCE", basePriority, cause, variable);
}
private void reportNullDeref(WarningPropertySet<WarningProperty> propertySet, Location location, String type, int priority,
BugAnnotation cause, @CheckForNull BugAnnotation variable) {
BugInstance bugInstance = new BugInstance(this, type, priority).addClassAndMethod(classContext.getJavaClass(), method);
bugInstance.add(cause);
if (variable != null) {
bugInstance.add(variable);
} else {
bugInstance.add(new LocalVariableAnnotation("?", -1, -1));
}
bugInstance.addSourceLine(classContext, method, location).describe("SOURCE_LINE_DEREF");
if (FindBugsAnalysisFeatures.isRelaxedMode()) {
WarningPropertyUtil.addPropertiesForDataMining(propertySet, classContext, method, location);
}
addPropertiesForDereferenceLocations(propertySet, Collections.singleton(location));
propertySet.decorateBugInstance(bugInstance);
bugReporter.reportBug(bugInstance);
}
public static boolean isThrower(BasicBlock target) {
InstructionHandle ins = target.getFirstInstruction();
int maxCount = 7;
while (ins != null) {
if (maxCount-- <= 0) {
break;
}
Instruction i = ins.getInstruction();
if (i instanceof ATHROW) {
return true;
}
if (i instanceof InstructionTargeter || i instanceof ReturnInstruction) {
return false;
}
ins = ins.getNext();
}
return false;
}
@Override
public void foundRedundantNullCheck(Location location, RedundantBranch redundantBranch) {
}
@Override
public void foundGuaranteedNullDeref(@Nonnull Set<Location> assignedNullLocationSet, @Nonnull Set<Location> derefLocationSet,
SortedSet<Location> doomedLocations, ValueNumberDataflow vna, ValueNumber refValue,
@CheckForNull BugAnnotation variableAnnotation, NullValueUnconditionalDeref deref, boolean npeIfStatementCovered) {
}
private void addPropertiesForDereferenceLocations(WarningPropertySet<WarningProperty> propertySet,
Collection<Location> derefLocationSet) {
boolean derefOutsideCatchBlock = false;
boolean allDerefsAtDoomedLocations = true;
for (Location loc : derefLocationSet) {
if (!inCatchNullBlock(loc)) {
derefOutsideCatchBlock = true;
}
if (!isDoomed(loc)) {
allDerefsAtDoomedLocations = false;
}
}
if (allDerefsAtDoomedLocations) {
// Add a WarningProperty
propertySet.addProperty(DoomedCodeWarningProperty.DOOMED_CODE);
}
boolean uniqueDereferenceLocations = uniqueLocations(derefLocationSet);
if (!derefOutsideCatchBlock) {
if (!uniqueDereferenceLocations || skipIfInsideCatchNull()) {
propertySet.addProperty(GeneralWarningProperty.FALSE_POSITIVE);
} else {
propertySet.addProperty(NullDerefProperty.DEREFS_IN_CATCH_BLOCKS);
}
}
if (!uniqueDereferenceLocations) {
// Add a WarningProperty
propertySet.addProperty(NullDerefProperty.DEREFS_ARE_CLONED);
}
addPropertiesForMethodContainingWarning(propertySet);
}
private boolean uniqueLocations(Collection<Location> derefLocationSet) {
boolean uniqueDereferenceLocations = false;
LineNumberTable table = method.getLineNumberTable();
if (table == null) {
uniqueDereferenceLocations = true;
} else {
BitSet linesMentionedMultipleTimes = classContext.linesMentionedMultipleTimes(method);
for (Location loc : derefLocationSet) {
int lineNumber = table.getSourceLine(loc.getHandle().getPosition());
if (!linesMentionedMultipleTimes.get(lineNumber)) {
uniqueDereferenceLocations = true;
}
}
}
return uniqueDereferenceLocations;
}
private void addPropertiesForMethodContainingWarning(WarningPropertySet<WarningProperty> propertySet) {
XMethod xMethod = XFactory.createXMethod(classContext.getJavaClass(), method);
boolean uncallable = !AnalysisContext.currentXFactory().isCalledDirectlyOrIndirectly(xMethod) && xMethod.isPrivate();
if (uncallable) {
propertySet.addProperty(GeneralWarningProperty.IN_UNCALLABLE_METHOD);
}
}
private boolean isDoomed(Location loc) {
if (!MARK_DOOMED) {
return false;
}
ReturnPathTypeDataflow rptDataflow;
try {
rptDataflow = classContext.getReturnPathTypeDataflow(method);
ReturnPathType rpt = rptDataflow.getFactAtLocation(loc);
return !rpt.canReturnNormally();
} catch (CheckedAnalysisException e) {
AnalysisContext.logError("Error getting return path type", e);
return false;
}
}
String getDescription(Location loc, ValueNumber refValue) {
PointerUsageRequiringNonNullValue pu;
try {
UsagesRequiringNonNullValues usages = classContext.getUsagesRequiringNonNullValues(method);
pu = usages.get(loc, refValue, vnaDataflow);
if (pu == null) {
return "SOURCE_LINE_DEREF";
}
return pu.getDescription();
} catch (DataflowAnalysisException e) {
AnalysisContext.logError("Error getting UsagesRequiringNonNullValues for " + method, e);
return "SOURCE_LINE_DEREF";
} catch (CFGBuilderException e) {
AnalysisContext.logError("Error getting UsagesRequiringNonNullValues for " + method, e);
return "SOURCE_LINE_DEREF";
}
}
boolean inCatchNullBlock(Location loc) {
int pc = loc.getHandle().getPosition();
int catchSize = Util.getSizeOfSurroundingTryBlock(classContext.getJavaClass().getConstantPool(), method.getCode(),
"java/lang/NullPointerException", pc);
if (catchSize < Integer.MAX_VALUE) {
return true;
}
catchSize = Util.getSizeOfSurroundingTryBlock(classContext.getJavaClass().getConstantPool(), method.getCode(),
"java/lang/Exception", pc);
if (catchSize < 5) {
return true;
}
catchSize = Util.getSizeOfSurroundingTryBlock(classContext.getJavaClass().getConstantPool(), method.getCode(),
"java/lang/RuntimeException", pc);
if (catchSize < 5) {
return true;
}
catchSize = Util.getSizeOfSurroundingTryBlock(classContext.getJavaClass().getConstantPool(), method.getCode(),
"java/lang/Throwable", pc);
if (catchSize < 5) {
return true;
}
return false;
}
}