Class NoiseNullDeref

java.lang.Object

edu.umd.cs.findbugs.detect.NoiseNullDeref

All Implemented Interfaces:

NullDerefAndRedundantComparisonCollector, Detector, Priorities, UseAnnotationDatabase

public class NoiseNullDeref
extends Object
implements Detector, UseAnnotationDatabase, NullDerefAndRedundantComparisonCollector

A Detector to find instructions where a NullPointerException might be raised. We also look for useless reference comparisons involving null and non-null values.

See Also:

• IsNullValueAnalysis

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	NoiseNullDeref.CheckCallSitesAndReturnInstructions

Field Summary

Fields

Modifier and Type	Field	Description
private final BugAccumulator	bugAccumulator
private final BugReporter	bugReporter
private static final String	CLASS
private ClassContext	classContext
static final boolean	DEBUG
private static final boolean	DEBUG_NULLARG
private static final boolean	MARK_DOOMED
private org.apache.bcel.classfile.Method	method
private static final String	METHOD_NAME
private ValueNumberDataflow	vnaDataflow

Fields inherited from interface Priorities

EXP_PRIORITY, HIGH_PRIORITY, IGNORE_PRIORITY, LOW_PRIORITY, NORMAL_PRIORITY

Constructor Summary

Constructors

Constructor	Description
NoiseNullDeref(BugReporter bugReporter)

Method Summary

Modifier and Type	Method	Description
private void	addPropertiesForDereferenceLocations(WarningPropertySet<WarningProperty> propertySet, Collection<Location> derefLocationSet)
private void	addPropertiesForMethodContainingWarning(WarningPropertySet<WarningProperty> propertySet)
private void	analyzeMethod(ClassContext classContext, org.apache.bcel.classfile.Method method)
private BitSet	findPreviouslyDeadBlocks()	Find set of blocks which were known to be dead before doing the null pointer analysis.
void	foundGuaranteedNullDeref(Set<Location> assignedNullLocationSet, Set<Location> derefLocationSet, SortedSet<Location> doomedLocations, ValueNumberDataflow vna, ValueNumber refValue, BugAnnotation variableAnnotation, NullValueUnconditionalDeref deref, boolean npeIfStatementCovered)	Subclasses should override this method to capture values assigned null (or that become null through a comparison and branch) that are guaranteed to reach a dereference (ignoring implicit exception paths).
void	foundNullDeref(Location location, ValueNumber valueNumber, IsNullValue refValue, ValueNumberFrame vnaFrame)	Deprecated. Use foundNullDeref(Location,ValueNumber,IsNullValue,ValueNumberFrame,boolean) instead
void	foundNullDeref(Location location, ValueNumber valueNumber, IsNullValue refValue, ValueNumberFrame vnaFrame, boolean isConsistent)	Subclasses should override this method to capture locations where a null pointer is dereferenced.
void	foundRedundantNullCheck(Location location, RedundantBranch redundantBranch)	Subclasses should override this method to capture locations where a redundant null comparison is performed.
(package private) String	getDescription(Location loc, ValueNumber refValue)
(package private) boolean	inCatchNullBlock(Location loc)
private boolean	isDoomed(Location loc)
static boolean	isThrower(BasicBlock target)
void	report()	This method is called after all classes to be visited.
private void	reportNullDeref(WarningPropertySet<WarningProperty> propertySet, Location location, String type, int priority, BugAnnotation cause, BugAnnotation variable)
boolean	skipIfInsideCatchNull()
private boolean	uniqueLocations(Collection<Location> derefLocationSet)
void	visitClassContext(ClassContext classContext)	Visit the ClassContext for a class which should be analyzed for instances of bug patterns.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

DEBUG

public static final boolean DEBUG

DEBUG_NULLARG

private static final boolean DEBUG_NULLARG

MARK_DOOMED

private static final boolean MARK_DOOMED

METHOD_NAME

private static final String METHOD_NAME

CLASS

private static final String CLASS

bugReporter

private final BugReporter bugReporter

bugAccumulator

private final BugAccumulator bugAccumulator

classContext

private ClassContext classContext

method

private org.apache.bcel.classfile.Method method

vnaDataflow

private ValueNumberDataflow vnaDataflow

Constructor Details

NoiseNullDeref

public NoiseNullDeref(BugReporter bugReporter)

Method Details

visitClassContext

public void visitClassContext(ClassContext classContext)

Description copied from interface: Detector

Visit the ClassContext for a class which should be analyzed for instances of bug patterns.

Specified by:

visitClassContext in interface Detector

Parameters:

classContext - the ClassContext

analyzeMethod

private void analyzeMethod(ClassContext classContext,
 org.apache.bcel.classfile.Method method)
                    throws DataflowAnalysisException,
CFGBuilderException

Throws:

DataflowAnalysisException

CFGBuilderException

findPreviouslyDeadBlocks

private BitSet findPreviouslyDeadBlocks()
                                 throws DataflowAnalysisException,
CFGBuilderException

Find set of blocks which were known to be dead before doing the null pointer analysis.

Returns:

set of previously dead blocks, indexed by block id

Throws:

CFGBuilderException

DataflowAnalysisException

report

public void report()

Description copied from interface: Detector

This method is called after all classes to be visited. It should be used by any detectors which accumulate information over all visited classes to generate results.

Specified by:

report in interface Detector

skipIfInsideCatchNull

public boolean skipIfInsideCatchNull()

foundNullDeref

@Deprecated
public void foundNullDeref(Location location,
 ValueNumber valueNumber,
 IsNullValue refValue,
 ValueNumberFrame vnaFrame)

Deprecated.

Use foundNullDeref(Location,ValueNumber,IsNullValue,ValueNumberFrame,boolean) instead

Description copied from interface: NullDerefAndRedundantComparisonCollector

Subclasses should override this method to capture locations where a null pointer is dereferenced.

Specified by:

foundNullDeref in interface NullDerefAndRedundantComparisonCollector

Parameters:

location - the Location of the null dereference

valueNumber - the ValueNumber of the possibly-null value

refValue - the kind of possibly-null value dereferenced

vnaFrame - The ValueNumber Frame at the point where the dereference occurred

foundNullDeref

public void foundNullDeref(Location location,
 ValueNumber valueNumber,
 IsNullValue refValue,
 ValueNumberFrame vnaFrame,
 boolean isConsistent)

Description copied from interface: NullDerefAndRedundantComparisonCollector

Subclasses should override this method to capture locations where a null pointer is dereferenced.

Specified by:

foundNullDeref in interface NullDerefAndRedundantComparisonCollector

Parameters:

location - the Location of the null dereference

valueNumber - the ValueNumber of the possibly-null value

refValue - the kind of possibly-null value dereferenced

vnaFrame - The ValueNumber Frame at the point where the dereference occurred

isConsistent - true if the refValue is identical at all clones of the same instruction

reportNullDeref

private void reportNullDeref(WarningPropertySet<WarningProperty> propertySet,
 Location location,
 String type,
 int priority,
 BugAnnotation cause,
 @CheckForNull
 BugAnnotation variable)

isThrower

public static boolean isThrower(BasicBlock target)

foundRedundantNullCheck

public void foundRedundantNullCheck(Location location,
 RedundantBranch redundantBranch)

Description copied from interface: NullDerefAndRedundantComparisonCollector

Subclasses should override this method to capture locations where a redundant null comparison is performed.

Specified by:

foundRedundantNullCheck in interface NullDerefAndRedundantComparisonCollector

Parameters:

location - the Location of the redundant null check

redundantBranch - the RedundantBranch

foundGuaranteedNullDeref

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)

Description copied from interface: NullDerefAndRedundantComparisonCollector

Subclasses should override this method to capture values assigned null (or that become null through a comparison and branch) that are guaranteed to reach a dereference (ignoring implicit exception paths).

Specified by:

foundGuaranteedNullDeref in interface NullDerefAndRedundantComparisonCollector

Parameters:

assignedNullLocationSet - set of locations where the value becomes null

derefLocationSet - set of locations where dereferences occur

doomedLocations - locations at which the value is doomed

vna - ValueNumberDataflow

refValue - the null value

variableAnnotation - TODO

deref - TODO

npeIfStatementCovered - true if doom location is a statement

addPropertiesForDereferenceLocations

private void addPropertiesForDereferenceLocations(WarningPropertySet<WarningProperty> propertySet,
 Collection<Location> derefLocationSet)

uniqueLocations

private boolean uniqueLocations(Collection<Location> derefLocationSet)

addPropertiesForMethodContainingWarning

private void addPropertiesForMethodContainingWarning(WarningPropertySet<WarningProperty> propertySet)

isDoomed

private boolean isDoomed(Location loc)

getDescription

String getDescription(Location loc,
 ValueNumber refValue)

inCatchNullBlock

boolean inCatchNullBlock(Location loc)