/*
* FindBugs - Find Bugs in Java programs
* Copyright (C) 2005, 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.Iterator;
import org.apache.bcel.classfile.Method;
import org.apache.bcel.generic.ARETURN;
import org.apache.bcel.generic.Instruction;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.ReferenceType;
import edu.umd.cs.findbugs.FindBugsAnalysisFeatures;
import edu.umd.cs.findbugs.SystemProperties;
import edu.umd.cs.findbugs.ba.AnalysisContext;
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.Location;
import edu.umd.cs.findbugs.ba.XFactory;
import edu.umd.cs.findbugs.ba.XMethod;
import edu.umd.cs.findbugs.ba.npe.IsNullValue;
import edu.umd.cs.findbugs.ba.npe.IsNullValueDataflow;
import edu.umd.cs.findbugs.ba.npe.IsNullValueFrame;
/**
* Build database of methods that return values guaranteed to be nonnull
*
*/
public class BuildNonnullReturnDatabase {
public static final boolean VERBOSE_DEBUG = SystemProperties.getBoolean("fnd.debug.nullarg.verbose");
private static final boolean DEBUG = SystemProperties.getBoolean("fnd.debug.nullarg") || VERBOSE_DEBUG;
public void visitClassContext(ClassContext classContext) {
boolean fullAnalysis = AnalysisContext.currentAnalysisContext().getBoolProperty(
FindBugsAnalysisFeatures.INTERPROCEDURAL_ANALYSIS_OF_REFERENCED_CLASSES);
if (!fullAnalysis && !AnalysisContext.currentAnalysisContext()./*
* getSubtypes
* ().
*/isApplicationClass(classContext.getJavaClass())) {
return;
}
if (VERBOSE_DEBUG) {
System.out.println("Visiting class " + classContext.getJavaClass().getClassName());
}
for (Method m : classContext.getMethodsInCallOrder()) {
considerMethod(classContext, m);
}
}
private void considerMethod(ClassContext classContext, Method method) {
if ((method.getReturnType() instanceof ReferenceType) && classContext.getMethodGen(method) != null) {
if (VERBOSE_DEBUG) {
System.out.println("Check " + method);
}
analyzeMethod(classContext, method);
}
}
protected int returnsReference;
protected int returnsNonNull;
private void analyzeMethod(ClassContext classContext, Method method) {
returnsReference++;
try {
CFG cfg = classContext.getCFG(method);
IsNullValueDataflow inv = classContext.getIsNullValueDataflow(method);
boolean guaranteedNonNull = true;
for (Iterator<Location> i = cfg.locationIterator(); i.hasNext();) {
Location location = i.next();
InstructionHandle handle = location.getHandle();
Instruction ins = handle.getInstruction();
if (!(ins instanceof ARETURN)) {
continue;
}
IsNullValueFrame frame = inv.getFactAtLocation(location);
if (!frame.isValid()) {
continue;
}
IsNullValue value = frame.getTopValue();
if (!value.isDefinitelyNotNull()) {
guaranteedNonNull = false;
break;
}
}
XMethod xmethod = XFactory.createXMethod(classContext.getJavaClass(), method);
if (guaranteedNonNull) {
returnsNonNull++;
AnalysisContext.currentAnalysisContext().getReturnValueNullnessPropertyDatabase()
.setProperty(xmethod.getMethodDescriptor(), guaranteedNonNull);
if (DEBUG) {
System.out.println("Unconditional deref: " + xmethod + "=" + guaranteedNonNull);
}
}
} catch (CFGBuilderException e) {
XMethod xmethod = XFactory.createXMethod(classContext.getJavaClass(), method);
AnalysisContext.currentAnalysisContext().getLookupFailureCallback()
.logError("Error analyzing " + xmethod + " for unconditional deref training", e);
} catch (DataflowAnalysisException e) {
XMethod xmethod = XFactory.createXMethod(classContext.getJavaClass(), method);
AnalysisContext.currentAnalysisContext().getLookupFailureCallback()
.logError("Error analyzing " + xmethod + " for unconditional deref training", e);
}
}
}