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SpotBugs: Because it's easy!
/*
* 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.Arrays;
import java.util.BitSet;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.stream.Collectors;
import javax.annotation.CheckForNull;
import javax.annotation.Nonnull;
import javax.annotation.meta.When;
import edu.umd.cs.findbugs.annotations.NonNull;
import org.apache.bcel.Const;
import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.CodeException;
import org.apache.bcel.classfile.ConstantPool;
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.IFNONNULL;
import org.apache.bcel.generic.IFNULL;
import org.apache.bcel.generic.INVOKEDYNAMIC;
import org.apache.bcel.generic.INVOKEINTERFACE;
import org.apache.bcel.generic.INVOKEVIRTUAL;
import org.apache.bcel.generic.Instruction;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.InstructionList;
import org.apache.bcel.generic.InstructionTargeter;
import org.apache.bcel.generic.InvokeInstruction;
import org.apache.bcel.generic.MethodGen;
import org.apache.bcel.generic.PUTFIELD;
import org.apache.bcel.generic.ReturnInstruction;
import org.objectweb.asm.Type;
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.OpcodeStack;
import edu.umd.cs.findbugs.SourceLineAnnotation;
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.CFG;
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.Edge;
import edu.umd.cs.findbugs.ba.Hierarchy;
import edu.umd.cs.findbugs.ba.INullnessAnnotationDatabase;
import edu.umd.cs.findbugs.ba.JavaClassAndMethod;
import edu.umd.cs.findbugs.ba.Location;
import edu.umd.cs.findbugs.ba.MissingClassException;
import edu.umd.cs.findbugs.ba.NullnessAnnotation;
import edu.umd.cs.findbugs.ba.OpcodeStackScanner;
import edu.umd.cs.findbugs.ba.SignatureConverter;
import edu.umd.cs.findbugs.ba.SignatureParser;
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.XMethodParameter;
import edu.umd.cs.findbugs.ba.interproc.ParameterProperty;
import edu.umd.cs.findbugs.ba.jsr305.TypeQualifierAnnotation;
import edu.umd.cs.findbugs.ba.jsr305.TypeQualifierApplications;
import edu.umd.cs.findbugs.ba.jsr305.TypeQualifierValue;
import edu.umd.cs.findbugs.ba.npe.IsNullValue;
import edu.umd.cs.findbugs.ba.npe.IsNullValueDataflow;
import edu.umd.cs.findbugs.ba.npe.IsNullValueFrame;
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.ParameterNullnessPropertyDatabase;
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.TypeQualifierNullnessAnnotationDatabase;
import edu.umd.cs.findbugs.ba.npe.UsagesRequiringNonNullValues;
import edu.umd.cs.findbugs.ba.type.TypeDataflow;
import edu.umd.cs.findbugs.ba.type.TypeFrame;
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.bcel.generic.NullnessConversationInstruction;
import edu.umd.cs.findbugs.classfile.CheckedAnalysisException;
import edu.umd.cs.findbugs.classfile.ClassDescriptor;
import edu.umd.cs.findbugs.classfile.DescriptorFactory;
import edu.umd.cs.findbugs.classfile.Global;
import edu.umd.cs.findbugs.classfile.analysis.AnnotationValue;
import edu.umd.cs.findbugs.internalAnnotations.StaticConstant;
import edu.umd.cs.findbugs.log.Profiler;
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.util.Values;
import edu.umd.cs.findbugs.visitclass.Util;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* 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 FindNullDeref implements Detector, UseAnnotationDatabase, NullDerefAndRedundantComparisonCollector {
private final Logger log = LoggerFactory.getLogger(getClass());
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_NAME = SystemProperties.getProperty("fnd.method");
private static final String CLASS = SystemProperties.getProperty("fnd.class");
// Fields
private final BugReporter bugReporter;
private final BugAccumulator bugAccumulator;
// Cached database stuff
private ParameterNullnessPropertyDatabase unconditionalDerefParamDatabase;
private boolean checkedDatabases = false;
// Transient state
private ClassContext classContext;
private Method method;
private IsNullValueDataflow invDataflow;
private ValueNumberDataflow vnaDataflow;
private BitSet previouslyDeadBlocks;
private NullnessAnnotation methodAnnotation;
public FindNullDeref(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();
if (CLASS != null && !className.equals(CLASS)) {
return;
}
List methodsInCallOrder = classContext.getMethodsInCallOrder();
for (Method method : methodsInCallOrder) {
try {
if (method.isAbstract() || method.isNative() || method.getCode() == null) {
continue;
}
currentMethod = SignatureConverter.convertMethodSignature(jclass, method);
if (METHOD_NAME != null && !method.getName().equals(METHOD_NAME)) {
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 ");
}
if ((method.getAccessFlags() & Const.ACC_BRIDGE) != 0) {
return;
}
MethodGen methodGen = classContext.getMethodGen(method);
if (methodGen == null) {
return;
}
if (!checkedDatabases) {
checkDatabases();
checkedDatabases = true;
}
XMethod xMethod = XFactory.createXMethod(classContext.getJavaClass(), method);
// For junit 4 only (does not apply to junit 5)
ClassDescriptor junitTestAnnotation = DescriptorFactory.createClassDescriptor("org/junit/Test");
AnnotationValue av = xMethod.getAnnotation(junitTestAnnotation);
if (av != null) {
Object value = av.getValue("expected");
if (value instanceof Type) {
String className = ((Type) value).getClassName();
if ("java.lang.NullPointerException".equals(className)) {
return;
}
}
}
// UsagesRequiringNonNullValues uses =
// classContext.getUsagesRequiringNonNullValues(method);
this.method = method;
this.methodAnnotation = getMethodNullnessAnnotation();
if (DEBUG || DEBUG_NULLARG) {
System.out.println("FND: " + SignatureConverter.convertMethodSignature(methodGen));
}
this.previouslyDeadBlocks = findPreviouslyDeadBlocks();
// Get the IsNullValueDataflow for the method from the ClassContext
invDataflow = classContext.getIsNullValueDataflow(method);
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();
checkCallSitesAndReturnInstructions();
}
/**
* 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 i = vnaDataflow.getCFG().blockIterator(); i.hasNext();) {
BasicBlock block = i.next();
ValueNumberFrame vnaFrame = vnaDataflow.getStartFact(block);
if (vnaFrame.isTop()) {
deadBlocks.set(block.getLabel());
}
}
return deadBlocks;
}
/**
* Check whether or not the various interprocedural databases we can use
* exist and are nonempty.
*/
private void checkDatabases() {
AnalysisContext analysisContext = AnalysisContext.currentAnalysisContext();
unconditionalDerefParamDatabase = analysisContext.getUnconditionalDerefParamDatabase();
}
// private > boolean isDatabaseNonEmpty(DatabaseType database) {
// return database != null && !database.isEmpty();
// }
/**
* See if the currently-visited method declares a
*
* @NonNull annotation, or overrides a method which declares a
* @NonNull annotation.
*/
private NullnessAnnotation getMethodNullnessAnnotation() {
if (method.getSignature().indexOf(")L") >= 0 || method.getSignature().indexOf(")[") >= 0) {
if (DEBUG_NULLRETURN) {
System.out.println("Checking return annotation for "
+ SignatureConverter.convertMethodSignature(classContext.getJavaClass(), method));
}
XMethod m = XFactory.createXMethod(classContext.getJavaClass(), method);
return AnalysisContext.currentAnalysisContext().getNullnessAnnotationDatabase().getResolvedAnnotation(m, false);
}
return NullnessAnnotation.UNKNOWN_NULLNESS;
}
static class CheckCallSitesAndReturnInstructions {
}
private void checkCallSitesAndReturnInstructions() {
Profiler profiler = Global.getAnalysisCache().getProfiler();
profiler.start(CheckCallSitesAndReturnInstructions.class);
try {
ConstantPoolGen cpg = classContext.getConstantPoolGen();
TypeDataflow typeDataflow = classContext.getTypeDataflow(method);
for (Iterator i = classContext.getCFG(method).locationIterator(); i.hasNext();) {
Location location = i.next();
Instruction ins = location.getHandle().getInstruction();
try {
ValueNumberFrame vnaFrame = classContext.getValueNumberDataflow(method).getFactAtLocation(location);
if (!vnaFrame.isValid()) {
continue;
}
if (ins instanceof InvokeInstruction) {
examineCallSite(location, cpg, typeDataflow);
} else if (methodAnnotation == NullnessAnnotation.NONNULL && ins.getOpcode() == Const.ARETURN) {
examineReturnInstruction(location);
} else if (ins instanceof PUTFIELD) {
examinePutfieldInstruction(location, (PUTFIELD) ins, cpg);
}
} catch (ClassNotFoundException e) {
bugReporter.reportMissingClass(e);
}
}
} catch (CheckedAnalysisException e) {
AnalysisContext.logError("error:", e);
} finally {
profiler.end(CheckCallSitesAndReturnInstructions.class);
}
}
private void examineCallSite(Location location, ConstantPoolGen cpg, TypeDataflow typeDataflow)
throws DataflowAnalysisException, CFGBuilderException, ClassNotFoundException {
InvokeInstruction invokeInstruction = (InvokeInstruction) location.getHandle().getInstruction();
String methodName = invokeInstruction.getName(cpg);
String signature = invokeInstruction.getSignature(cpg);
// Don't check equals() calls.
// If an equals() call unconditionally dereferences the parameter,
// it is the fault of the method, not the caller.
if ("equals".equals(methodName) && "(Ljava/lang/Object;)Z".equals(signature)) {
return;
}
int returnTypeStart = signature.indexOf(')');
if (returnTypeStart < 0) {
return;
}
String paramList = signature.substring(0, returnTypeStart + 1);
if ("()".equals(paramList) || (paramList.indexOf('L') < 0 && paramList.indexOf('[') < 0)) {
// Method takes no arguments, or takes no reference arguments
return;
}
// See if any null arguments are passed
IsNullValueFrame frame = classContext.getIsNullValueDataflow(method).getFactAtLocation(location);
if (!frame.isValid()) {
return;
}
/*
if (false && methodName.equals("checkNotNull")
&& invokeInstruction.getClassName(cpg).equals("com.google.common.base.Preconditions")) {
SignatureParser sigParser = new SignatureParser(signature);
int numParameters = sigParser.getNumParameters();
IsNullValue value = frame.getArgument(invokeInstruction, cpg, 0, sigParser);
if (value.isDefinitelyNotNull()) {
TypeFrame typeFrame = typeDataflow.getFactAtLocation(location);
int priority = NORMAL_PRIORITY;
String pattern = "RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE";
ValueNumberFrame vnFrame = vnaDataflow.getFactAtLocation(location);
ValueNumber valueNumber = vnFrame.getArgument(invokeInstruction, cpg, 0, sigParser);
org.apache.bcel.generic.Type typeOfFirstArgument = typeFrame.getArgument(invokeInstruction, cpg, 0, sigParser);
String signature2 = typeOfFirstArgument.getSignature();
boolean constantStringForFirstArgument = signature2.equals("Ljava/lang/String;")
&& valueNumber.hasFlag(ValueNumber.CONSTANT_VALUE);
@CheckForNull
BugAnnotation annotation = BugInstance.getSourceForStackValue(classContext, method, location, numParameters - 1);
if (value.wouldHaveBeenAKaboom()) {
pattern = "RCN_REDUNDANT_NULLCHECK_WOULD_HAVE_BEEN_A_NPE";
priority = HIGH_PRIORITY;
} else if (constantStringForFirstArgument) {
annotation = null;
priority = HIGH_PRIORITY;
if (numParameters == 2) {
IsNullValue secondValue = frame.getArgument(invokeInstruction, cpg, 1, sigParser);
if (!secondValue.isDefinitelyNotNull()) {
pattern = "DMI_ARGUMENTS_WRONG_ORDER";
priority = NORMAL_PRIORITY;
}
}
}
BugInstance warning = new BugInstance(this, pattern, priority)
.addClassAndMethod(classContext.getJavaClass(), method).addOptionalAnnotation(annotation)
.addCalledMethod(cpg, invokeInstruction).addSourceLine(classContext, method, location);
bugReporter.reportBug(warning);
}
}
*/
BitSet nullArgSet = frame.getArgumentSet(invokeInstruction, cpg,
// Only choose non-exception values.
// Values null on an exception path might be due to infeasible control flow.
value -> value.mightBeNull() && !value.isException() && !value.isReturnValue());
BitSet definitelyNullArgSet = frame.getArgumentSet(invokeInstruction, cpg, value -> value.isDefinitelyNull());
nullArgSet.and(definitelyNullArgSet);
if (nullArgSet.isEmpty()) {
return;
}
if (DEBUG_NULLARG) {
System.out.println("Null arguments passed: " + nullArgSet);
System.out.println("Frame is: " + frame);
System.out.println("# arguments: " + frame.getNumArguments(invokeInstruction, cpg));
if (!(invokeInstruction instanceof INVOKEDYNAMIC)) {
XMethod xm = XFactory.createXMethod(invokeInstruction, cpg);
System.out.print("Signature: " + xm.getSignature());
}
}
if (unconditionalDerefParamDatabase != null) {
checkUnconditionallyDereferencedParam(location, cpg, typeDataflow, invokeInstruction, nullArgSet,
definitelyNullArgSet);
}
if (DEBUG_NULLARG) {
System.out.println("Checking nonnull params");
}
checkNonNullParam(location, cpg, typeDataflow, invokeInstruction, nullArgSet, definitelyNullArgSet);
}
private void examinePutfieldInstruction(Location location, PUTFIELD ins, ConstantPoolGen cpg)
throws DataflowAnalysisException {
IsNullValueFrame frame = invDataflow.getFactAtLocation(location);
if (!frame.isValid()) {
return;
}
IsNullValue tos = frame.getTopValue();
if (tos.isDefinitelyNull()) {
XField field = XFactory.createXField(ins, cpg);
NullnessAnnotation annotation = AnalysisContext.currentAnalysisContext().getNullnessAnnotationDatabase()
.getResolvedAnnotation(field, false);
if (annotation == NullnessAnnotation.NONNULL) {
BugAnnotation variableAnnotation = null;
try {
ValueNumberFrame vnaFrame = classContext.getValueNumberDataflow(method).getFactAtLocation(location);
ValueNumber valueNumber = vnaFrame.getTopValue();
variableAnnotation = ValueNumberSourceInfo.findAnnotationFromValueNumber(method, location, valueNumber,
vnaFrame, "VALUE_OF");
} catch (DataflowAnalysisException e) {
AnalysisContext.logError("error", e);
} catch (CFGBuilderException e) {
AnalysisContext.logError("error", e);
}
BugInstance warning = new BugInstance(this, "NP_STORE_INTO_NONNULL_FIELD", tos.isDefinitelyNull() ? HIGH_PRIORITY
: NORMAL_PRIORITY).addClassAndMethod(classContext.getJavaClass(), method).addField(field)
.addOptionalAnnotation(variableAnnotation).addSourceLine(classContext, method, location);
bugReporter.reportBug(warning);
}
}
}
private void examineReturnInstruction(Location location) throws DataflowAnalysisException, CFGBuilderException {
if (DEBUG_NULLRETURN) {
System.out.println("Checking null return at " + location);
}
IsNullValueDataflow invDataflow = classContext.getIsNullValueDataflow(method);
IsNullValueFrame frame = invDataflow.getFactAtLocation(location);
ValueNumberFrame vnaFrame = classContext.getValueNumberDataflow(method).getFactAtLocation(location);
if (!vnaFrame.isValid()) {
return;
}
ValueNumber valueNumber = vnaFrame.getTopValue();
if (!frame.isValid()) {
return;
}
IsNullValue tos = frame.getTopValue();
if (tos.isDefinitelyNull()) {
BugAnnotation variable = ValueNumberSourceInfo.findAnnotationFromValueNumber(method, location, valueNumber, vnaFrame,
"VALUE_OF");
String bugPattern = "NP_NONNULL_RETURN_VIOLATION";
int priority = NORMAL_PRIORITY;
if (tos.isDefinitelyNull() && !tos.isException()) {
priority = HIGH_PRIORITY;
}
String methodName = method.getName();
if ("clone".equals(methodName)) {
bugPattern = "NP_CLONE_COULD_RETURN_NULL";
priority = NORMAL_PRIORITY;
} else if ("toString".equals(methodName)) {
bugPattern = "NP_TOSTRING_COULD_RETURN_NULL";
priority = NORMAL_PRIORITY;
}
BugInstance warning = new BugInstance(this, bugPattern, priority).addClassAndMethod(classContext.getJavaClass(),
method).addOptionalAnnotation(variable);
bugAccumulator.accumulateBug(warning, SourceLineAnnotation.fromVisitedInstruction(classContext, method, location));
}
}
private boolean hasManyPreceedingNullTests(int pc) {
int ifNullTests = 0;
BitSet seen = new BitSet();
try {
for (Iterator i = classContext.getCFG(method).locationIterator(); i.hasNext();) {
Location loc = i.next();
int pc2 = loc.getHandle().getPosition();
if (pc2 >= pc || pc2 < pc - 30) {
continue;
}
Instruction ins = loc.getHandle().getInstruction();
if ((ins instanceof IFNONNULL || ins instanceof IFNULL || ins instanceof NullnessConversationInstruction)
&& !seen.get(pc2)) {
ifNullTests++;
seen.set(pc2);
}
}
boolean result = ifNullTests > 2;
// System.out.println("Preceding null tests " + ifNullTests + " " +
// ifNonnullTests + " " + result);
return result;
} catch (CFGBuilderException e) {
return false;
}
}
@StaticConstant
public static final Set catchTypesForNull = Collections.unmodifiableSet(new HashSet<>(Arrays.asList(
"java/lang/NullPointerException", "java/lang/RuntimeException", "java/lang/Exception")));
public static boolean catchesNull(ConstantPool constantPool, Code code, Location location) {
int position = location.getHandle().getPosition();
for (String t : catchTypesForNull) {
int catchSize = Util.getSizeOfSurroundingTryBlock(constantPool, code, t, position);
if (catchSize < Integer.MAX_VALUE) {
return true;
}
}
return false;
}
private boolean safeCallToPrimateParseMethod(XMethod calledMethod, Location location) {
int position = location.getHandle().getPosition();
if (Values.DOTTED_JAVA_LANG_INTEGER.equals(calledMethod.getClassName())) {
ConstantPool constantPool = classContext.getJavaClass().getConstantPool();
Code code = method.getCode();
int catchSize;
catchSize = Util.getSizeOfSurroundingTryBlock(constantPool, code, "java/lang/NumberFormatException", position);
if (catchSize < Integer.MAX_VALUE) {
return true;
}
catchSize = Util.getSizeOfSurroundingTryBlock(constantPool, code, "java/lang/IllegalArgumentException", position);
if (catchSize < Integer.MAX_VALUE) {
return true;
}
catchSize = Util.getSizeOfSurroundingTryBlock(constantPool, code, "java/lang/RuntimeException", position);
if (catchSize < Integer.MAX_VALUE) {
return true;
}
catchSize = Util.getSizeOfSurroundingTryBlock(constantPool, code, "java/lang/Exception", position);
if (catchSize < Integer.MAX_VALUE) {
return true;
}
}
return false;
}
private void checkUnconditionallyDereferencedParam(Location location, ConstantPoolGen cpg, TypeDataflow typeDataflow,
InvokeInstruction invokeInstruction, BitSet nullArgSet, BitSet definitelyNullArgSet)
throws DataflowAnalysisException, ClassNotFoundException {
if (inExplicitCatchNullBlock(location)) {
return;
}
boolean caught = inIndirectCatchNullBlock(location);
if (caught && skipIfInsideCatchNull()) {
return;
}
if (invokeInstruction instanceof INVOKEDYNAMIC) {
return;
}
// See what methods might be called here
XMethod calledMethod = XFactory.createXMethod(invokeInstruction, cpg);
// If a parameter is already marked as nonnull, don't complain about
// it here.
nullArgSet = (BitSet) nullArgSet.clone();
definitelyNullArgSet = (BitSet) definitelyNullArgSet.clone();
ClassDescriptor nonnullClassDesc = DescriptorFactory.createClassDescriptor(Nonnull.class);
TypeQualifierValue nonnullTypeQualifierValue = TypeQualifierValue.getValue(nonnullClassDesc, null);
for (int i = nullArgSet.nextSetBit(0); i >= 0; i = nullArgSet.nextSetBit(i + 1)) {
TypeQualifierAnnotation tqa = TypeQualifierApplications.getEffectiveTypeQualifierAnnotation(calledMethod, i,
nonnullTypeQualifierValue);
if (tqa != null && tqa.when == When.ALWAYS) {
nullArgSet.clear(i);
definitelyNullArgSet.clear(i);
}
}
TypeFrame typeFrame = typeDataflow.getFactAtLocation(location);
Set targetMethodSet = Hierarchy.resolveMethodCallTargets(invokeInstruction, typeFrame, cpg);
if (DEBUG_NULLARG) {
System.out.println("Possibly called methods: " + targetMethodSet);
}
// See if any call targets unconditionally dereference one of the null
// arguments
BitSet unconditionallyDereferencedNullArgSet = new BitSet();
List dangerousCallTargetList = new LinkedList<>();
List veryDangerousCallTargetList = new LinkedList<>();
for (JavaClassAndMethod targetMethod : targetMethodSet) {
if (DEBUG_NULLARG) {
System.out.println("For target method " + targetMethod);
}
ParameterProperty property = unconditionalDerefParamDatabase.getProperty(targetMethod.toMethodDescriptor());
if (property == null) {
continue;
}
if (DEBUG_NULLARG) {
System.out.println("\tUnconditionally dereferenced params: " + property);
}
BitSet targetUnconditionallyDereferencedNullArgSet = property.getMatchingParameters(nullArgSet);
if (targetUnconditionallyDereferencedNullArgSet.isEmpty()) {
continue;
}
dangerousCallTargetList.add(targetMethod);
unconditionallyDereferencedNullArgSet.or(targetUnconditionallyDereferencedNullArgSet);
if (!property.getMatchingParameters(definitelyNullArgSet).isEmpty()) {
veryDangerousCallTargetList.add(targetMethod);
}
}
if (dangerousCallTargetList.isEmpty()) {
return;
}
WarningPropertySet propertySet = new WarningPropertySet<>();
// See if there are any safe targets
Set safeCallTargetSet = new HashSet<>(targetMethodSet);
safeCallTargetSet.removeAll(dangerousCallTargetList);
if (safeCallTargetSet.isEmpty()) {
propertySet.addProperty(NullArgumentWarningProperty.ALL_DANGEROUS_TARGETS);
if (dangerousCallTargetList.size() == 1) {
propertySet.addProperty(NullArgumentWarningProperty.MONOMORPHIC_CALL_SITE);
}
}
// Call to private method? In theory there should be only one possible
// target.
boolean privateCall = safeCallTargetSet.isEmpty() && dangerousCallTargetList.size() == 1
&& dangerousCallTargetList.get(0).getMethod().isPrivate();
String bugType;
int priority;
if (privateCall || invokeInstruction.getOpcode() == Const.INVOKESTATIC
|| invokeInstruction.getOpcode() == Const.INVOKESPECIAL) {
bugType = "NP_NULL_PARAM_DEREF_NONVIRTUAL";
priority = HIGH_PRIORITY;
} else if (safeCallTargetSet.isEmpty()) {
bugType = "NP_NULL_PARAM_DEREF_ALL_TARGETS_DANGEROUS";
priority = NORMAL_PRIORITY;
} else {
return;
}
if (caught) {
priority++;
}
if (dangerousCallTargetList.size() > veryDangerousCallTargetList.size()) {
priority++;
} else {
propertySet.addProperty(NullArgumentWarningProperty.ACTUAL_PARAMETER_GUARANTEED_NULL);
}
XMethod calledFrom = XFactory.createXMethod(classContext.getJavaClass(), method);
if (safeCallToPrimateParseMethod(calledMethod, location)) {
return;
}
BugInstance warning = new BugInstance(this, bugType, priority).addClassAndMethod(classContext.getJavaClass(), method)
.addMethod(calledMethod).describe(MethodAnnotation.METHOD_CALLED).addSourceLine(classContext, method, location);
// boolean uncallable = false;
if (!AnalysisContext.currentXFactory().isCalledDirectlyOrIndirectly(calledFrom) && calledFrom.isPrivate()) {
propertySet.addProperty(GeneralWarningProperty.IN_UNCALLABLE_METHOD);
// uncallable = true;
}
// Check which params might be null
addParamAnnotations(location, definitelyNullArgSet, unconditionallyDereferencedNullArgSet, propertySet, warning);
if ("NP_NULL_PARAM_DEREF_ALL_TARGETS_DANGEROUS".equals(bugType)) {
// Add annotations for dangerous method call targets
for (JavaClassAndMethod dangerousCallTarget : veryDangerousCallTargetList) {
warning.addMethod(dangerousCallTarget).describe(MethodAnnotation.METHOD_DANGEROUS_TARGET_ACTUAL_GUARANTEED_NULL);
}
dangerousCallTargetList.removeAll(veryDangerousCallTargetList);
if (DEBUG_NULLARG) {
// Add annotations for dangerous method call targets
for (JavaClassAndMethod dangerousCallTarget : dangerousCallTargetList) {
warning.addMethod(dangerousCallTarget).describe(MethodAnnotation.METHOD_DANGEROUS_TARGET);
}
// Add safe method call targets.
// This is useful to see which other call targets the analysis
// considered.
for (JavaClassAndMethod safeMethod : safeCallTargetSet) {
warning.addMethod(safeMethod).describe(MethodAnnotation.METHOD_SAFE_TARGET);
}
}
}
decorateWarning(location, propertySet, warning);
bugReporter.reportBug(warning);
}
private void decorateWarning(Location location, WarningPropertySet propertySet, BugInstance warning) {
if (FindBugsAnalysisFeatures.isRelaxedMode()) {
WarningPropertyUtil.addPropertiesForDataMining(propertySet, classContext, method, location);
}
propertySet.decorateBugInstance(warning);
}
private void addParamAnnotations(Location location, BitSet definitelyNullArgSet, BitSet violatedParamSet,
WarningPropertySet propertySet, BugInstance warning) {
ValueNumberFrame vnaFrame = null;
try {
vnaFrame = classContext.getValueNumberDataflow(method).getFactAtLocation(location);
} catch (DataflowAnalysisException e) {
AnalysisContext.logError("error", e);
} catch (CFGBuilderException e) {
AnalysisContext.logError("error", e);
}
InvokeInstruction instruction = (InvokeInstruction) location.getHandle().getInstruction();
SignatureParser sigParser = new SignatureParser(instruction.getSignature(classContext.getConstantPoolGen()));
for (int i = violatedParamSet.nextSetBit(0); i >= 0; i = violatedParamSet.nextSetBit(i + 1)) {
boolean definitelyNull = definitelyNullArgSet.get(i);
if (definitelyNull) {
propertySet.addProperty(NullArgumentWarningProperty.ARG_DEFINITELY_NULL);
}
ValueNumber valueNumber = null;
if (vnaFrame != null) {
try {
valueNumber = vnaFrame.getArgument(instruction, classContext.getConstantPoolGen(), i, sigParser);
BugAnnotation variableAnnotation = ValueNumberSourceInfo.findAnnotationFromValueNumber(method, location,
valueNumber, vnaFrame, "VALUE_OF");
warning.addOptionalAnnotation(variableAnnotation);
} catch (DataflowAnalysisException e) {
AnalysisContext.logError("error", e);
}
}
// Note: we report params as being indexed starting from 1, not
// 0
warning.addParameterAnnotation(i, definitelyNull ? "INT_NULL_ARG" : "INT_MAYBE_NULL_ARG");
}
}
/**
* We have a method invocation in which a possibly or definitely null
* parameter is passed. Check it against the library of nonnull annotations.
*
* @param location
* @param cpg
* @param typeDataflow
* @param invokeInstruction
* @param nullArgSet
* @param definitelyNullArgSet
*/
private void checkNonNullParam(Location location, ConstantPoolGen cpg, TypeDataflow typeDataflow,
InvokeInstruction invokeInstruction, BitSet nullArgSet, BitSet definitelyNullArgSet) {
if (inExplicitCatchNullBlock(location)) {
return;
}
boolean caught = inIndirectCatchNullBlock(location);
if (caught && skipIfInsideCatchNull()) {
return;
}
if (invokeInstruction instanceof INVOKEDYNAMIC) {
return;
}
XMethod m = XFactory.createXMethod(invokeInstruction, cpg);
INullnessAnnotationDatabase db = AnalysisContext.currentAnalysisContext().getNullnessAnnotationDatabase();
SignatureParser sigParser = new SignatureParser(invokeInstruction.getSignature(cpg));
for (int i = nullArgSet.nextSetBit(0); i >= 0; i = nullArgSet.nextSetBit(i + 1)) {
if (db.parameterMustBeNonNull(m, i)) {
boolean definitelyNull = definitelyNullArgSet.get(i);
if (DEBUG_NULLARG) {
System.out.println("Checking " + m);
System.out.println("QQQ2: " + i + " -- " + i + " is null");
System.out.println("QQQ nullArgSet: " + nullArgSet);
System.out.println("QQQ dnullArgSet: " + definitelyNullArgSet);
}
BugAnnotation variableAnnotation = null;
try {
ValueNumberFrame vnaFrame = classContext.getValueNumberDataflow(method).getFactAtLocation(location);
ValueNumber valueNumber = vnaFrame.getArgument(invokeInstruction, cpg, i, sigParser);
variableAnnotation = ValueNumberSourceInfo.findAnnotationFromValueNumber(method, location, valueNumber,
vnaFrame, "VALUE_OF");
} catch (DataflowAnalysisException e) {
AnalysisContext.logError("error", e);
} catch (CFGBuilderException e) {
AnalysisContext.logError("error", e);
}
int priority = definitelyNull ? HIGH_PRIORITY : NORMAL_PRIORITY;
if (caught) {
priority++;
}
if (m.isPrivate() && priority == HIGH_PRIORITY) {
priority = NORMAL_PRIORITY;
}
String description = definitelyNull ? "INT_NULL_ARG" : "INT_MAYBE_NULL_ARG";
WarningPropertySet propertySet = new WarningPropertySet<>();
Set derefLocationSet = Collections.singleton(location);
addPropertiesForDereferenceLocations(propertySet, derefLocationSet, false);
boolean duplicated = isDuplicated(propertySet, location.getHandle().getPosition(), false);
if (duplicated) {
return;
}
BugInstance warning = new BugInstance(this, "NP_NONNULL_PARAM_VIOLATION", priority)
.addClassAndMethod(classContext.getJavaClass(), method).addMethod(m)
.describe(MethodAnnotation.METHOD_CALLED).addParameterAnnotation(i, description)
.addOptionalAnnotation(variableAnnotation).addSourceLine(classContext, method, location);
propertySet.decorateBugInstance(warning);
bugReporter.reportBug(warning);
}
}
}
@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
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) {
WarningPropertySet propertySet = new WarningPropertySet<>();
if (valueNumber.hasFlag(ValueNumber.CONSTANT_CLASS_OBJECT)) {
return;
}
boolean onExceptionPath = refValue.isException();
if (onExceptionPath) {
propertySet.addProperty(GeneralWarningProperty.ON_EXCEPTION_PATH);
}
int pc = location.getHandle().getPosition();
BugAnnotation variable = ValueNumberSourceInfo.findAnnotationFromValueNumber(method, location, valueNumber, vnaFrame,
"VALUE_OF");
addPropertiesForDereferenceLocations(propertySet, Collections.singleton(location), isConsistent);
Instruction ins = location.getHandle().getInstruction();
if (ins instanceof InvokeInstruction && refValue.isDefinitelyNull()) {
InvokeInstruction iins = (InvokeInstruction) ins;
if ("close".equals(iins.getMethodName(classContext.getConstantPoolGen()))
&& "()V".equals(iins.getSignature(classContext.getConstantPoolGen()))) {
propertySet.addProperty(NullDerefProperty.CLOSING_NULL);
}
}
boolean duplicated = isDuplicated(propertySet, pc, isConsistent);
if (inExplicitCatchNullBlock(location)) {
return;
}
boolean caught = inIndirectCatchNullBlock(location);
if (caught && skipIfInsideCatchNull()) {
return;
}
if (refValue.isDefinitelyNull()) {
String type = "NP_ALWAYS_NULL";
if (propertySet.containsProperty(NullDerefProperty.CLOSING_NULL)
&& !propertySet.containsProperty(NullDerefProperty.DEREFS_ARE_CLONED)) {
type = "NP_CLOSING_NULL";
} else if (onExceptionPath) {
type = "NP_ALWAYS_NULL_EXCEPTION";
} else if (duplicated) {
type = "NP_NULL_ON_SOME_PATH";
}
int priority = onExceptionPath ? NORMAL_PRIORITY : HIGH_PRIORITY;
if (caught) {
priority++;
}
reportNullDeref(propertySet, location, type, priority, variable);
} else if (refValue.mightBeNull() && refValue.isParamValue()) {
String type;
int priority = NORMAL_PRIORITY;
if (caught) {
priority++;
}
if ("equals".equals(method.getName()) && "(Ljava/lang/Object;)Z".equals(method.getSignature())) {
if (caught) {
return;
}
type = "NP_EQUALS_SHOULD_HANDLE_NULL_ARGUMENT";
} else {
type = "NP_ARGUMENT_MIGHT_BE_NULL";
}
if (DEBUG) {
System.out.println("Reporting null on some path: value=" + refValue);
}
reportNullDeref(propertySet, location, type, priority, variable);
}
}
public boolean isDuplicated(WarningPropertySet propertySet, int pc, boolean isConsistent) {
boolean duplicated = false;
if (!isConsistent) {
if (propertySet.containsProperty(NullDerefProperty.DEREFS_ARE_CLONED)) {
duplicated = true;
} else {
try {
CFG cfg = classContext.getCFG(method);
if (cfg.getLocationsContainingInstructionWithOffset(pc).size() > 1) {
propertySet.addProperty(NullDerefProperty.DEREFS_ARE_INLINED_FINALLY_BLOCKS);
duplicated = true;
}
} catch (CFGBuilderException e) {
AnalysisContext.logError("Error while analyzing " + classContext.getFullyQualifiedMethodName(method), e);
}
}
}
return duplicated;
}
private void reportNullDeref(WarningPropertySet propertySet, Location location, String type, int priority,
@CheckForNull BugAnnotation variable) {
BugInstance bugInstance = new BugInstance(this, type, priority).addClassAndMethod(classContext.getJavaClass(), method);
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), false);
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) {
boolean isChecked = redundantBranch.firstValue.isChecked();
boolean wouldHaveBeenAKaboom = redundantBranch.firstValue.wouldHaveBeenAKaboom();
boolean isParameter = redundantBranch.firstValue.isParamValue();
Location locationOfKaBoom = redundantBranch.firstValue.getLocationOfKaBoom();
if (isParameter && !wouldHaveBeenAKaboom) {
return;
}
boolean createdDeadCode = false;
boolean infeasibleEdgeSimplyThrowsException = false;
Edge infeasibleEdge = redundantBranch.infeasibleEdge;
if (infeasibleEdge != null) {
if (DEBUG) {
System.out.println("Check if " + redundantBranch + " creates dead code");
}
BasicBlock target = infeasibleEdge.getTarget();
if (DEBUG) {
System.out.println("Target block is "
+ (target.isExceptionThrower() ? " exception thrower" : " not exception thrower"));
}
// If the block is empty, it probably doesn't matter that it was
// killed.
// FIXME: really, we should crawl the immediately reachable blocks
// starting at the target block to see if any of them are dead and
// nonempty.
boolean empty = !target.isExceptionThrower()
&& (target.isEmpty() || isGoto(target.getFirstInstruction().getInstruction()));
if (!empty) {
try {
if (classContext.getCFG(method).getNumIncomingEdges(target) > 1) {
if (DEBUG) {
System.out.println("Target of infeasible edge has multiple incoming edges");
}
empty = true;
}
} catch (CFGBuilderException e) {
assert true; // ignore it
}
}
if (DEBUG) {
System.out.println("Target block is " + (empty ? "empty" : "not empty"));
}
if (!empty) {
if (isThrower(target)) {
infeasibleEdgeSimplyThrowsException = true;
}
}
if (!empty && !previouslyDeadBlocks.get(target.getLabel())) {
if (DEBUG) {
System.out.println("target was alive previously");
}
// Block was not dead before the null pointer analysis.
// See if it is dead now by inspecting the null value frame.
// If it's TOP, then the block became dead.
IsNullValueFrame invFrame = invDataflow.getStartFact(target);
createdDeadCode = invFrame.isTop();
if (DEBUG) {
System.out.println("target is now " + (createdDeadCode ? "dead" : "alive"));
}
}
}
int priority;
boolean valueIsNull = true;
String warning;
int pc = location.getHandle().getPosition();
OpcodeStack stack = null;
OpcodeStack.Item item1 = null;
OpcodeStack.Item item2 = null;
try {
stack = OpcodeStackScanner.getStackAt(classContext.getJavaClass(), method, pc);
item1 = stack.getStackItem(0);
} catch (RuntimeException e) {
if (SystemProperties.ASSERTIONS_ENABLED) {
AnalysisContext.logError("Error getting stack at specific PC", e);
}
assert true;
}
if (redundantBranch.secondValue == null) {
if (isGeneratedCodeInCatchBlock(method, pc)) {
log.debug("skip RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE found in the generated code at {}", location);
return;
} else if (redundantBranch.firstValue.isDefinitelyNull()) {
warning = "RCN_REDUNDANT_NULLCHECK_OF_NULL_VALUE";
priority = NORMAL_PRIORITY;
} else {
warning = "RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE";
valueIsNull = false;
priority = isChecked ? HIGH_PRIORITY : NORMAL_PRIORITY;
}
if (infeasibleEdgeSimplyThrowsException) {
priority++;
}
} else {
if (stack != null) {
item2 = stack.getStackItem(1);
}
boolean bothNull = redundantBranch.firstValue.isDefinitelyNull() && redundantBranch.secondValue.isDefinitelyNull();
if (redundantBranch.secondValue.isChecked()) {
isChecked = true;
}
if (redundantBranch.secondValue.wouldHaveBeenAKaboom()) {
wouldHaveBeenAKaboom = true;
locationOfKaBoom = redundantBranch.secondValue.getLocationOfKaBoom();
}
if (bothNull) {
warning = "RCN_REDUNDANT_COMPARISON_TWO_NULL_VALUES";
priority = NORMAL_PRIORITY;
} else {
warning = "RCN_REDUNDANT_COMPARISON_OF_NULL_AND_NONNULL_VALUE";
priority = isChecked ? NORMAL_PRIORITY : LOW_PRIORITY;
}
}
if (wouldHaveBeenAKaboom) {
priority = HIGH_PRIORITY;
warning = "RCN_REDUNDANT_NULLCHECK_WOULD_HAVE_BEEN_A_NPE";
if (locationOfKaBoom == null) {
throw new NullPointerException("location of KaBoom is null");
}
}
if (DEBUG) {
System.out.println(createdDeadCode + " " + infeasibleEdgeSimplyThrowsException + " " + valueIsNull + " " + priority);
}
if (createdDeadCode && !infeasibleEdgeSimplyThrowsException) {
priority += 0;
} else if (createdDeadCode && infeasibleEdgeSimplyThrowsException) {
// throw clause
if (valueIsNull) {
priority += 0;
} else {
priority += 1;
}
} else {
// didn't create any dead code
priority += 1;
}
if (DEBUG) {
System.out.println("RCN " + priority + " " + redundantBranch.firstValue + " =? " + redundantBranch.secondValue + " : "
+ warning);
if (isChecked) {
System.out.println("isChecked");
}
if (wouldHaveBeenAKaboom) {
System.out.println("wouldHaveBeenAKaboom");
}
if (createdDeadCode) {
System.out.println("createdDeadCode");
}
}
if (priority > LOW_PRIORITY) {
return;
}
BugAnnotation variableAnnotation = null;
try {
// Get the value number
ValueNumberFrame vnaFrame = classContext.getValueNumberDataflow(method).getFactAtLocation(location);
if (vnaFrame.isValid()) {
Instruction ins = location.getHandle().getInstruction();
ValueNumber valueNumber = vnaFrame.getInstance(ins, classContext.getConstantPoolGen());
if (valueNumber.hasFlag(ValueNumber.CONSTANT_CLASS_OBJECT)) {
return;
}
variableAnnotation = ValueNumberSourceInfo.findAnnotationFromValueNumber(method, location, valueNumber, vnaFrame,
"VALUE_OF");
if (variableAnnotation instanceof LocalVariableAnnotation) {
LocalVariableAnnotation local = (LocalVariableAnnotation) variableAnnotation;
if (!local.isNamed()) {
if ("RCN_REDUNDANT_NULLCHECK_OF_NULL_VALUE".equals(warning)) {
return;
}
priority++;
}
}
}
} catch (DataflowAnalysisException e) {
// ignore
} catch (CFGBuilderException e) {
// ignore
}
BugInstance bugInstance = new BugInstance(this, warning, priority).addClassAndMethod(classContext.getJavaClass(), method);
LocalVariableAnnotation fallback = new LocalVariableAnnotation("?", -1, -1);
boolean foundSource = bugInstance.tryAddingOptionalUniqueAnnotations(variableAnnotation,
BugInstance.getFieldOrMethodValueSource(item1), BugInstance.getFieldOrMethodValueSource(item2));
if (!foundSource) {
if ("RCN_REDUNDANT_NULLCHECK_OF_NULL_VALUE".equals(warning)) {
return;
}
bugInstance.setPriority(priority + 1);
bugInstance.add(fallback);
}
if (wouldHaveBeenAKaboom) {
bugInstance.addSourceLine(classContext, method, locationOfKaBoom);
}
if (FindBugsAnalysisFeatures.isRelaxedMode()) {
WarningPropertySet propertySet = new WarningPropertySet<>();
WarningPropertyUtil.addPropertiesForDataMining(propertySet, classContext, method, location);
if (isChecked) {
propertySet.addProperty(NullDerefProperty.CHECKED_VALUE);
}
if (wouldHaveBeenAKaboom) {
propertySet.addProperty(NullDerefProperty.WOULD_HAVE_BEEN_A_KABOOM);
}
if (createdDeadCode) {
propertySet.addProperty(NullDerefProperty.CREATED_DEAD_CODE);
}
propertySet.decorateBugInstance(bugInstance);
}
SourceLineAnnotation sourceLine = SourceLineAnnotation.fromVisitedInstruction(classContext, method, location);
sourceLine.setDescription("SOURCE_REDUNDANT_NULL_CHECK");
bugAccumulator.accumulateBug(bugInstance, sourceLine);
}
BugAnnotation getVariableAnnotation(Location location) {
BugAnnotation variableAnnotation = null;
try {
// Get the value number
ValueNumberFrame vnaFrame = classContext.getValueNumberDataflow(method).getFactAtLocation(location);
if (vnaFrame.isValid()) {
Instruction ins = location.getHandle().getInstruction();
ValueNumber valueNumber = vnaFrame.getInstance(ins, classContext.getConstantPoolGen());
if (valueNumber.hasFlag(ValueNumber.CONSTANT_CLASS_OBJECT)) {
return null;
}
variableAnnotation = ValueNumberSourceInfo.findAnnotationFromValueNumber(method, location, valueNumber, vnaFrame,
"VALUE_OF");
}
} catch (DataflowAnalysisException e) {
// ignore
} catch (CFGBuilderException e) {
// ignore
}
return variableAnnotation;
}
/**
* Determine whether or not given instruction is a goto.
*
* @param instruction
* the instruction
* @return true if the instruction is a goto, false otherwise
*/
private boolean isGoto(Instruction instruction) {
return instruction.getOpcode() == Const.GOTO || instruction.getOpcode() == Const.GOTO_W;
}
int minPC(Collection locs) {
int result = 1000000;
for (Location l : locs) {
if (result > l.getHandle().getPosition()) {
result = l.getHandle().getPosition();
}
}
return result;
}
int maxPC(Collection locs) {
int result = -1000000;
for (Location l : locs) {
if (result < l.getHandle().getPosition()) {
result = l.getHandle().getPosition();
}
}
return result;
}
boolean callToAssertionMethod(Location loc) {
InstructionHandle h = loc.getHandle();
int firstPos = h.getPosition();
LineNumberTable ln = method.getLineNumberTable();
int firstLine = ln == null ? -1 : ln.getSourceLine(firstPos);
while (h != null) {
int pos = h.getPosition();
if (ln == null) {
if (pos > firstPos + 15) {
break;
}
} else {
int line = ln.getSourceLine(pos);
// For a call such as checkNotNull(get()) the 'pos' would be 'firstPos' + 3
// Break the loop if we moved to a different source line AND moved the PC by at least 3
// checkNotNull (or similar) might be formatted on a different line than its argument
if (line != firstLine && pos > firstPos + 3) {
break;
}
}
Instruction i = h.getInstruction();
if (i instanceof InvokeInstruction) {
InvokeInstruction ii = (InvokeInstruction) i;
String name = ii.getMethodName(classContext.getConstantPoolGen());
String className = ii.getClassName(classContext.getConstantPoolGen());
if (("requireNonNull".equals(name) && "java.util.Objects".equals(className))
|| name.startsWith("check") || name.startsWith("assert")) {
return true;
}
}
h = h.getNext();
}
return false;
}
/*
* (non-Javadoc)
*
* @seeedu.umd.cs.findbugs.ba.npe.NullDerefAndRedundantComparisonCollector#
* foundGuaranteedNullDeref(java.util.Set, java.util.Set,
* edu.umd.cs.findbugs.ba.vna.ValueNumber, boolean)
*/
@Override
public void foundGuaranteedNullDeref(@Nonnull Set assignedNullLocationSet, @Nonnull Set derefLocationSet,
SortedSet doomedLocations, ValueNumberDataflow vna, ValueNumber refValue,
@CheckForNull BugAnnotation variableAnnotation, NullValueUnconditionalDeref deref, boolean npeIfStatementCovered) {
if (refValue.hasFlag(ValueNumber.CONSTANT_CLASS_OBJECT)) {
return;
}
if (DEBUG) {
System.out.println("Found guaranteed null deref in " + method.getName());
for (Location loc : doomedLocations) {
System.out.println("Doomed at " + loc);
}
}
String bugType;
int priority = npeIfStatementCovered ? HIGH_PRIORITY : NORMAL_PRIORITY;
if (deref.isMethodReturnValue()) {
if (deref.isReadlineValue()) {
bugType = "NP_DEREFERENCE_OF_READLINE_VALUE";
} else {
bugType = "NP_NULL_ON_SOME_PATH_FROM_RETURN_VALUE";
}
} else if (derefLocationSet.size() > 1) {
if (!deref.isAlwaysOnExceptionPath()) {
bugType = "NP_GUARANTEED_DEREF";
} else {
bugType = "NP_GUARANTEED_DEREF_ON_EXCEPTION_PATH";
}
} else if (!deref.isAlwaysOnExceptionPath()) {
bugType = "NP_NULL_ON_SOME_PATH";
} else {
bugType = "NP_NULL_ON_SOME_PATH_EXCEPTION";
}
boolean allCallToAssertionMethod = !doomedLocations.isEmpty();
for (Location loc : doomedLocations) {
if (!callToAssertionMethod(loc)) {
allCallToAssertionMethod = false;
}
}
if (allCallToAssertionMethod) {
return;
}
// Add Locations in the set of locations at least one of which
// is guaranteed to be dereferenced
SortedSet sourceLocations;
if (doomedLocations.isEmpty() || doomedLocations.size() > 3 && doomedLocations.size() > assignedNullLocationSet.size()) {
sourceLocations = new TreeSet<>(assignedNullLocationSet);
} else {
sourceLocations = doomedLocations;
}
if (doomedLocations.isEmpty() || derefLocationSet.isEmpty()) {
return;
}
WarningPropertySet propertySet = new WarningPropertySet<>();
addPropertiesForDereferenceLocations(propertySet, derefLocationSet, false);
int minDereferencePC = minPC(derefLocationSet);
int distance1 = minDereferencePC - maxPC(assignedNullLocationSet);
int distance2 = minDereferencePC - maxPC(doomedLocations);
int distance = Math.max(distance1, distance2);
/*
if (false) {
System.out.printf("%9d %9d %9d RANGE %s.%s%s\n", distance, distance1, distance2, classContext.getClassDescriptor()
.toDottedClassName(), method.getName(), method.getSignature());
}
*/
// Create BugInstance
BitSet knownNull = new BitSet();
SortedSet knownNullLocations = new TreeSet<>();
for (Location loc : sourceLocations) {
SourceLineAnnotation sourceLineAnnotation = SourceLineAnnotation.fromVisitedInstruction(classContext, method, loc);
if (sourceLineAnnotation == null) {
continue;
}
int startLine = sourceLineAnnotation.getStartLine();
if (startLine == -1) {
knownNullLocations.add(sourceLineAnnotation);
} else if (!knownNull.get(startLine)) {
knownNull.set(startLine);
knownNullLocations.add(sourceLineAnnotation);
}
}
FieldAnnotation storedField = null;
MethodAnnotation invokedMethod = null;
XMethod invokedXMethod = null;
int parameterNumber = -1;
if (derefLocationSet.size() == 1) {
Location loc = derefLocationSet.iterator().next();
PointerUsageRequiringNonNullValue pu = null;
try {
UsagesRequiringNonNullValues usages = classContext.getUsagesRequiringNonNullValues(method);
pu = usages.get(loc, refValue, vnaDataflow);
} catch (DataflowAnalysisException e) {
AnalysisContext.logError("Error getting UsagesRequiringNonNullValues for " + method, e);
} catch (CFGBuilderException e) {
AnalysisContext.logError("Error getting UsagesRequiringNonNullValues for " + method, e);
}
if (pu == null) {
assert true; // nothing to do
} else if (deref.isReadlineValue()) {
bugType = "NP_DEREFERENCE_OF_READLINE_VALUE";
priority = NORMAL_PRIORITY;
} else if (deref.isMethodReturnValue() && !deref.isReadlineValue()) {
bugType = "NP_NULL_ON_SOME_PATH_FROM_RETURN_VALUE";
priority = NORMAL_PRIORITY;
} else if (pu.isReturnFromNonNullMethod()) {
bugType = "NP_NONNULL_RETURN_VIOLATION";
String methodName = method.getName();
String methodSig = method.getSignature();
if ("clone".equals(methodName) && "()Ljava/lang/Object;".equals(methodSig)) {
bugType = "NP_CLONE_COULD_RETURN_NULL";
priority = NORMAL_PRIORITY;
} else if ("toString".equals(methodName) && "()Ljava/lang/String;".equals(methodSig)) {
bugType = "NP_TOSTRING_COULD_RETURN_NULL";
priority = NORMAL_PRIORITY;
}
} else {
XField f = pu.getNonNullField();
if (f != null) {
storedField = FieldAnnotation.fromXField(f);
bugType = "NP_STORE_INTO_NONNULL_FIELD";
} else {
XMethodParameter mp = pu.getNonNullParameter();
if (mp != null) {
invokedXMethod = mp.getMethod();
for (Location derefLoc : derefLocationSet) {
if (safeCallToPrimateParseMethod(invokedXMethod, derefLoc)) {
return;
}
}
invokedMethod = MethodAnnotation.fromXMethod(mp.getMethod());
if (mp.getParameterNumber() == 0
&& TypeQualifierNullnessAnnotationDatabase.assertsFirstParameterIsNonnull(invokedXMethod)) {
return;
}
parameterNumber = mp.getParameterNumber();
bugType = "NP_NULL_PARAM_DEREF";
}
}
}
}
boolean hasManyNullTests = true;
for (SourceLineAnnotation sourceLineAnnotation : knownNullLocations) {
if (!hasManyPreceedingNullTests(sourceLineAnnotation.getStartBytecode())) {
hasManyNullTests = false;
}
}
if (hasManyNullTests) {
if ("NP_NULL_ON_SOME_PATH".equals(bugType) || "NP_GUARANTEED_DEREF".equals(bugType)) {
bugType = "NP_NULL_ON_SOME_PATH_MIGHT_BE_INFEASIBLE";
} else {
priority++;
}
}
BugInstance bugInstance = new BugInstance(this, bugType, priority).addClassAndMethod(classContext.getJavaClass(), method);
if (invokedMethod != null) {
assert invokedXMethod != null;
XMethod i = invokedXMethod.resolveAccessMethodForMethod();
if (i != invokedXMethod) {
bugInstance.addMethod(i).describe(MethodAnnotation.METHOD_CALLED);
} else {
bugInstance.addMethod(invokedMethod).describe(MethodAnnotation.METHOD_CALLED)
.addParameterAnnotation(parameterNumber, "INT_MAYBE_NULL_ARG");
}
}
if (storedField != null) {
bugInstance.addField(storedField).describe("FIELD_STORED");
}
bugInstance.addOptionalAnnotation(variableAnnotation);
if (variableAnnotation instanceof FieldAnnotation) {
bugInstance.describe("FIELD_CONTAINS_VALUE");
}
addPropertiesForDereferenceLocations(propertySet, derefLocationSet, false);
if (deref.isAlwaysOnExceptionPath()) {
propertySet.addProperty(NullDerefProperty.ALWAYS_ON_EXCEPTION_PATH);
}
if (!assignedNullLocationSet.isEmpty() && distance > 100) {
propertySet.addProperty(NullDerefProperty.LONG_RANGE_NULL_SOURCE);
}
propertySet.decorateBugInstance(bugInstance);
if ("NP_DEREFERENCE_OF_READLINE_VALUE".equals(bugType)) {
int source = -9999;
if (knownNullLocations.size() == 1) {
source = knownNullLocations.iterator().next().getEndBytecode();
}
for (Location loc : derefLocationSet) {
int pos = loc.getHandle().getPosition();
if (pos != source + 3) {
// another detector
bugAccumulator.accumulateBug(bugInstance,
SourceLineAnnotation.fromVisitedInstruction(classContext, method, loc));
}
}
} else {
for (Location loc : derefLocationSet) {
bugInstance.addSourceLine(classContext, method, loc).describe(getDescription(loc, refValue));
}
if (sourceLocations == doomedLocations && assignedNullLocationSet.size() == 1) {
Location assignedNull = assignedNullLocationSet.iterator().next();
SourceLineAnnotation sourceLineAnnotation = SourceLineAnnotation.fromVisitedInstruction(classContext, method,
assignedNull);
if (sourceLineAnnotation != null) {
int startLine = sourceLineAnnotation.getStartLine();
if (startLine > 0 && !knownNull.get(startLine)) {
bugInstance.add(sourceLineAnnotation).describe("SOURCE_LINE_NULL_VALUE");
}
}
}
for (SourceLineAnnotation sourceLineAnnotation : knownNullLocations) {
bugInstance.add(sourceLineAnnotation).describe("SOURCE_LINE_KNOWN_NULL");
}
// Report it
bugReporter.reportBug(bugInstance);
}
}
private void addPropertiesForDereferenceLocations(WarningPropertySet propertySet,
Collection derefLocationSet, boolean isConsistent) {
boolean derefOutsideCatchBlock = false;
boolean derefOutsideCatchNullBlock = false;
boolean allDerefsAtDoomedLocations = true;
for (Location loc : derefLocationSet) {
if (!inExplicitCatchNullBlock(loc)) {
derefOutsideCatchNullBlock = true;
if (!inIndirectCatchNullBlock(loc)) {
derefOutsideCatchBlock = true;
}
}
if (!isDoomed(loc)) {
allDerefsAtDoomedLocations = false;
}
}
if (!derefOutsideCatchNullBlock) {
propertySet.addProperty(GeneralWarningProperty.FALSE_POSITIVE);
return;
}
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 (!isConsistent && !uniqueDereferenceLocations) {
// Add a WarningProperty
propertySet.addProperty(NullDerefProperty.DEREFS_ARE_CLONED);
}
addPropertiesForMethodContainingWarning(propertySet);
}
private boolean uniqueLocations(Collection derefLocationSet) {
boolean uniqueDereferenceLocations = false;
CodeException[] exceptionTable = method.getCode().getExceptionTable();
if (exceptionTable == null) {
return true;
}
checkForCatchAll: {
for (CodeException e : exceptionTable) {
if (e.getCatchType() == 0) {
break checkForCatchAll;
}
}
return true;
}
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 (lineNumber > 0 && !linesMentionedMultipleTimes.get(lineNumber)) {
uniqueDereferenceLocations = true;
}
}
}
return uniqueDereferenceLocations;
}
private void addPropertiesForMethodContainingWarning(WarningPropertySet 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 inExplicitCatchNullBlock(Location loc) {
int pc = loc.getHandle().getPosition();
int catchSize = Util.getSizeOfSurroundingTryBlock(classContext.getJavaClass().getConstantPool(), method.getCode(),
"java/lang/NullPointerException", pc);
return catchSize < Integer.MAX_VALUE;
}
boolean inIndirectCatchNullBlock(Location loc) {
int pc = loc.getHandle().getPosition();
int 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);
return catchSize < 5;
}
/**
* Java 11+ compiler generates redundant null checks for try-with-resources.
* This methods detects the {@code ifnull} bytecode generated by javac,
* to help detector to avoid to report needless {@code RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE} bug.
*
* @param method the method
* @param pc the program counter
* @return true if the pc specifies redundant null check generated by javac
* @see
* false positive RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE on try-with-resources
* @see
* false positive RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE on try-with-resources
*/
public static boolean isGeneratedCodeInCatchBlock(@NonNull Method method, int pc) {
ConstantPool cp = method.getConstantPool();
Code code = method.getCode();
if (code == null) {
return false;
}
CodeException[] table = code.getExceptionTable();
// TODO: This instantiation could be high cost computation
InstructionList list = new InstructionList(code.getCode());
List throwableList = Arrays.stream(table)
.filter(codeException -> {
int catchType = codeException.getCatchType();
if (catchType == 0) {
// '0' means it catches any exceptions
return true;
}
String exceptionName = cp.getConstantString(catchType, Const.CONSTANT_Class);
return "java/lang/Throwable".equals(exceptionName);
})
.collect(Collectors.toList());
LineNumberTable lineNumberTable = code.getLineNumberTable();
if (lineNumberTable != null) {
// this line also marks the end of the try catch block
int line = lineNumberTable.getSourceLine(pc);
if (line > 0) {
return isGeneratedCodeInCatchBlockViaLineNumber(cp, pc, lineNumberTable, line, list, throwableList);
}
}
// assume that programmers rarely catch java.lang.Throwable instance explicitly
return throwableList
.stream()
.anyMatch(codeException -> {
InstructionHandle handle = list.findHandle(codeException.getEndPC());
int insnLength = handle.getInstruction().getLength();
return codeException.getEndPC() + insnLength == pc;
});
}
/**
* Java 11+ compiler generates redundant null checks for try-with-resources.
* This method tries to distinguish such code from manually written code by analysing null numbers.
* @param cp the constant pool
* @param pc the program counter
* @param lineNumberTable the table with the line numbers
* @param line the line which belongs to the program counter
* @param instructions the list of instructions
* @param throwables the list of Throwables in this method
* @return true if the pc specifies redundant null check generated by javac
*/
private static boolean isGeneratedCodeInCatchBlockViaLineNumber(@NonNull ConstantPool cp, int pc, @NonNull LineNumberTable lineNumberTable,
int line,
@NonNull InstructionList instructions, @NonNull List throwables) {
// The compiler generated code can also be written by the regular program. The only
// difference is that the line numbers for a lot of instructions are the same.
// This is what the code below relies on. Line numbers are optional, so it might
// not work in call cases.
//
// The following operations must have the same line numbers as the start or end of the original try catch block.
// - the reported code position (which is the null check)
// - at least one assignment
// - at least one call of addSuppressed
// - at least one throws statement
//
// The two calls to the close method need to have the same line number as the end of a throwables catch block.
// There must be also another catch of Throwable, but the line number does not need to match.
//
// To understand the code, please have a look at the test Issue600Test.
// TryWithResources* are the try-with-resources examples, ExplicitNullCheck* is TryWithResources* compiled and then decompiled.
ConstantPoolGen cpg = new ConstantPoolGen(cp);
// The two generated catch blocks might show different starting line numbers. Both are needed.
Set relevantLineNumbers = throwables.stream()
.map(x -> lineNumberTable.getSourceLine(x.getStartPC()))
.collect(Collectors.toSet());
relevantLineNumbers.add(line);
boolean assignmentPresent = false;
boolean addSuppressedPresent = false;
boolean throwsPresent = false;
int closeCounter = 0;
for (InstructionHandle handle : instructions.getInstructionHandles()) {
int currentLine = lineNumberTable.getSourceLine(handle.getPosition());
switch (handle.getInstruction().getOpcode()) {
case Const.ASTORE:
case Const.ASTORE_0:
case Const.ASTORE_1:
case Const.ASTORE_2:
case Const.ASTORE_3:
if (relevantLineNumbers.contains(currentLine)) {
assignmentPresent = true;
}
break;
case Const.INVOKEVIRTUAL:
if (handle.getInstruction() instanceof INVOKEVIRTUAL) {
String methodName = ((INVOKEVIRTUAL) handle.getInstruction()).getMethodName(cpg);
if ("close".equals(methodName)) {
// the close methods get the line number of the end of the try block assigned
if (throwables.stream().anyMatch(x -> lineNumberTable.getSourceLine(x.getEndPC()) == currentLine)) {
closeCounter++;
}
} else if ("addSuppressed".equals(methodName)) {
if (relevantLineNumbers.contains(currentLine)) {
addSuppressedPresent = true;
}
}
}
break;
case Const.INVOKEINTERFACE:
if (handle.getInstruction() instanceof INVOKEINTERFACE) {
String methodName = ((INVOKEINTERFACE) handle.getInstruction()).getMethodName(cpg);
if ("close".equals(methodName)) {
// the close methods get the line number of the end of the try block assigned
if (throwables.stream().anyMatch(x -> lineNumberTable.getSourceLine(x.getEndPC()) == currentLine)) {
closeCounter++;
}
} else if ("addSuppressed".equals(methodName)) {
if (relevantLineNumbers.contains(currentLine)) {
addSuppressedPresent = true;
}
}
}
break;
case Const.ATHROW:
if (relevantLineNumbers.contains(currentLine) && handle.getInstruction() instanceof ATHROW) {
Class[] exceptions = ((ATHROW) handle.getInstruction()).getExceptions();
if (exceptions.length == 1 && Throwable.class.equals(exceptions[0])) {
// even if try-with-resources catches exceptions, the compiler generates a nested try-catch with Throwable.
throwsPresent = true;
}
}
break;
default:
break;
}
}
boolean matchingCatches = false;
if (throwables.size() >= 2) {
// make sure that the reported line matches the start or end line of the generated try catch blocks
matchingCatches = throwables.stream().anyMatch(
x -> lineNumberTable.getSourceLine(x.getStartPC()) == line) || throwables.stream().anyMatch(
x -> lineNumberTable.getSourceLine(x.getEndPC()) == line);
}
return matchingCatches && assignmentPresent && addSuppressedPresent && throwsPresent && closeCounter >= 2;
}
}