/*
* FindBugs - Find bugs in Java programs
* Copyright (C) 2004 Dave Brosius <dbrosius@users.sourceforge.net>
* Copyright (C) 2003,2004 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.Collection;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;
import org.apache.bcel.classfile.Field;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.LocalVariable;
import org.apache.bcel.classfile.LocalVariableTable;
import org.apache.bcel.classfile.Method;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.FieldAnnotation;
import edu.umd.cs.findbugs.SystemProperties;
import edu.umd.cs.findbugs.ba.AnalysisContext;
import edu.umd.cs.findbugs.ba.ClassContext;
import edu.umd.cs.findbugs.ba.XClass;
import edu.umd.cs.findbugs.ba.XFactory;
import edu.umd.cs.findbugs.ba.XField;
import edu.umd.cs.findbugs.classfile.CheckedAnalysisException;
import edu.umd.cs.findbugs.classfile.ClassDescriptor;
import edu.umd.cs.findbugs.classfile.Global;
public class FindMaskedFields extends BytecodeScanningDetector {
private BugReporter bugReporter;
private int numParms;
private Map<String, Field> classFields = new HashMap<String, Field>();
private boolean staticMethod;
private Collection<RememberedBug> rememberedBugs = new LinkedList<RememberedBug>();
static class RememberedBug {
BugInstance bug;
XField maskingField, maskedField;
RememberedBug(BugInstance bug, FieldAnnotation maskingField, FieldAnnotation maskedField) {
this.bug = bug;
this.maskingField = XFactory.createXField(maskingField);
this.maskedField = XFactory.createXField(maskedField);
}
}
public FindMaskedFields(BugReporter bugReporter) {
this.bugReporter = bugReporter;
}
@Override
public void visitClassContext(ClassContext classContext) {
JavaClass obj = classContext.getJavaClass();
if (!obj.isInterface())
classContext.getJavaClass().accept(this);
}
@Override
public void visit(JavaClass obj) {
classFields.clear();
Field[] fields = obj.getFields();
String fieldName;
for (Field field : fields)
if (!field.isStatic() && !field.isPrivate()) {
fieldName = field.getName();
classFields.put(fieldName, field);
}
// Walk up the super class chain, looking for name collisions
XClass c = getXClass();
while (true) {
ClassDescriptor s = c.getSuperclassDescriptor();
if (s == null || s.getClassName().equals("java/lang/Object"))
break;
try {
c = Global.getAnalysisCache().getClassAnalysis(XClass.class, s);
} catch (CheckedAnalysisException e) {
break;
}
XClass superClass = c;
for (XField fld : c.getXFields()) {
if (!fld.isStatic() && (fld.isPublic() || fld.isProtected())) {
fieldName = fld.getName();
if (fieldName.length() == 1)
continue;
if (fieldName.equals("serialVersionUID"))
continue;
String superClassName = s.getClassName();
if (superClassName.startsWith("java/io")
&& (superClassName.endsWith("InputStream") && fieldName.equals("in") || superClassName
.endsWith("OutputStream") && fieldName.equals("out")))
continue;
if (classFields.containsKey(fieldName)) {
Field maskingField = classFields.get(fieldName);
String mClassName = getDottedClassName();
FieldAnnotation fa = new FieldAnnotation(mClassName, maskingField.getName(), maskingField.getSignature(),
maskingField.isStatic());
int priority = NORMAL_PRIORITY;
if (maskingField.isStatic() || maskingField.isFinal())
priority++;
else if (fld.getSignature().charAt(0) == 'L' && !fld.getSignature().startsWith("Ljava/lang/")
|| fld.getSignature().charAt(0) == '[')
priority--;
if (!fld.getSignature().equals(maskingField.getSignature()))
priority += 2;
else if (fld.getAccessFlags() != maskingField.getAccessFlags())
priority++;
if (fld.isSynthetic() || fld.getName().indexOf('$') >= 0)
priority++;
FieldAnnotation maskedFieldAnnotation = FieldAnnotation.fromFieldDescriptor(fld.getFieldDescriptor());
BugInstance bug = new BugInstance(this, "MF_CLASS_MASKS_FIELD", priority).addClass(this).addField(fa)
.describe("FIELD_MASKING").addField(maskedFieldAnnotation).describe("FIELD_MASKED");
rememberedBugs.add(new RememberedBug(bug, fa, maskedFieldAnnotation));
}
}
}
}
super.visit(obj);
}
@Override
public void visit(Method obj) {
super.visit(obj);
numParms = getNumberMethodArguments();
if (!obj.isStatic())
numParms++;
// System.out.println(obj);
// System.out.println(numParms);
staticMethod = obj.isStatic();
}
/**
* This property enables production of warnings for locals which obscure
* fields.
*/
private static final boolean ENABLE_LOCALS = SystemProperties.getBoolean("findbugs.maskedfields.locals");
@Override
public void visit(LocalVariableTable obj) {
if (ENABLE_LOCALS) {
if (staticMethod)
return;
LocalVariable[] vars = obj.getLocalVariableTable();
// System.out.println("Num params = " + numParms);
for (LocalVariable var : vars) {
if (var.getIndex() < numParms)
continue;
String varName = var.getName();
if (varName.equals("serialVersionUID"))
continue;
Field f = classFields.get(varName);
// System.out.println("Checking " + varName);
// System.out.println(" got " + f);
// TODO: we could distinguish between obscuring a field in the
// same class
// vs. obscuring a field in a superclass. Not sure how important
// that is.
if (f != null) {
FieldAnnotation fa = FieldAnnotation.fromBCELField(getDottedClassName(), f);
if (true || var.getStartPC() > 0)
bugReporter.reportBug(new BugInstance(this, "MF_METHOD_MASKS_FIELD", LOW_PRIORITY)
.addClassAndMethod(this).addField(fa).addSourceLine(this, var.getStartPC() - 1));
}
}
}
super.visit(obj);
}
@Override
public void report() {
UnreadFieldsData unreadFields = AnalysisContext.currentAnalysisContext().getUnreadFieldsData();
for (RememberedBug rb : rememberedBugs) {
BugInstance bug = rb.bug;
int score1 = 0;
int score2 = 0;
int priority = bug.getPriority();
if (unreadFields.classesScanned.contains(rb.maskedField.getClassName())) {
if (unreadFields.getReadFields().contains(rb.maskedField))
score1++;
if (unreadFields.getWrittenFields().contains(rb.maskedField))
score1++;
if (unreadFields.isWrittenOutsideOfInitialization(rb.maskedField))
score1++;
} else
score1 += 2;
if (unreadFields.getReadFields().contains(rb.maskingField))
score2++;
if (unreadFields.getWrittenFields().contains(rb.maskingField))
score2++;
if (unreadFields.isWrittenOutsideOfInitialization(rb.maskingField))
score2++;
int score = score1 + score2;
if (score1 == 0 || score2 == 0)
bug.setPriority(priority + 1);
else if (score >= 5)
bug.setPriority(priority - 1);
else if (score < 3)
bug.setPriority(priority + 1);
bugReporter.reportBug(bug);
}
}
}
// vim:ts=4