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An auxiliary findbugs.sourceforge.net plugin for java bug detectors that fall outside the narrow scope of detectors to be packaged with the product itself.
/*
* fb-contrib - Auxiliary detectors for Java programs
* Copyright (C) 2005-2018 Dave Brosius
*
* 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 com.mebigfatguy.fbcontrib.detect;
import java.util.BitSet;
import org.apache.bcel.Constants;
import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.LocalVariable;
import org.apache.bcel.classfile.LocalVariableTable;
import org.apache.bcel.classfile.Method;
import com.mebigfatguy.fbcontrib.utils.BugType;
import com.mebigfatguy.fbcontrib.utils.OpcodeUtils;
import com.mebigfatguy.fbcontrib.utils.RegisterUtils;
import com.mebigfatguy.fbcontrib.utils.SignatureUtils;
import com.mebigfatguy.fbcontrib.utils.Values;
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.internalAnnotations.SlashedClassName;
/**
* looks for manual casts of objects that are more specific then needed as the value is assigned to a class or interface higher up in the inheritance chain. You
* only need to cast to that class or interface.
*/
public class OverzealousCasting extends BytecodeScanningDetector {
enum State {
SAW_NOTHING, SAW_NEXT, SAW_CHECKCAST
}
private BugReporter bugReporter;
private State state;
private LocalVariableTable lvt;
private @SlashedClassName String castClass;
/**
* constructs a OC detector given the reporter to report bugs on
*
* @param bugReporter
* the sync of bug reports
*/
public OverzealousCasting(BugReporter bugReporter) {
this.bugReporter = bugReporter;
}
/**
* implements the visitor to set the state on entry of the code block to SAW_NOTHING, and to see if there is a local variable table
*
* @param obj
* the context object of the currently parsed code block
*/
@Override
public void visitCode(Code obj) {
state = State.SAW_NOTHING;
lvt = obj.getLocalVariableTable();
if ((lvt != null) && prescreen(getMethod())) {
super.visitCode(obj);
}
}
/**
* looks for methods that contain a checkcast instruction
*
* @param method
* the context object of the current method
* @return if the class does checkcast instructions
*/
private boolean prescreen(Method method) {
BitSet bytecodeSet = getClassContext().getBytecodeSet(method);
return (bytecodeSet != null) && (bytecodeSet.get(Constants.CHECKCAST));
}
/**
* implements the visitor to look for a checkcast followed by a astore, where the types of the objects are different.
*
* @param seen
* the opcode of the currently parsed instruction
*/
@Override
public void sawOpcode(int seen) {
switch (state) {
case SAW_NOTHING:
if (seen == CHECKCAST) {
castClass = getClassConstantOperand();
state = State.SAW_CHECKCAST;
} else if (seen == INVOKEINTERFACE) {
// enhanced for loops add an incorrect checkcast instruction, so
// ignore checkcasts after iterator.next()
String clsName = getClassConstantOperand();
String methodName = getNameConstantOperand();
if ("java/util/Iterator".equals(clsName) && "next".equals(methodName)) {
state = State.SAW_NEXT;
}
}
break;
case SAW_CHECKCAST:
if (OpcodeUtils.isAStore(seen)) {
int reg = RegisterUtils.getAStoreReg(this, seen);
LocalVariable lv = lvt.getLocalVariable(reg, getNextPC());
if (lv != null) {
String sig = lv.getSignature();
if (sig.startsWith(Values.SIG_QUALIFIED_CLASS_PREFIX)) {
sig = SignatureUtils.trimSignature(sig);
}
if (!sig.equals(castClass)) {
bugReporter.reportBug(new BugInstance(this, BugType.OC_OVERZEALOUS_CASTING.name(), NORMAL_PRIORITY).addClass(this).addMethod(this)
.addSourceLine(this));
}
}
} else if (seen == PUTFIELD) {
FieldAnnotation f = FieldAnnotation.fromReferencedField(this);
String sig = f.getFieldSignature();
if (sig.startsWith(Values.SIG_QUALIFIED_CLASS_PREFIX)) {
sig = SignatureUtils.trimSignature(sig);
}
// if the signature is Object, the field might be genericized, so ignore
if (!Values.SLASHED_JAVA_LANG_OBJECT.equals(sig) && !sig.equals(castClass)) {
bugReporter.reportBug(new BugInstance(this, BugType.OC_OVERZEALOUS_CASTING.name(), NORMAL_PRIORITY).addClass(this).addMethod(this)
.addSourceLine(this));
}
}
state = State.SAW_NOTHING;
break;
case SAW_NEXT:
default:
state = State.SAW_NOTHING;
break;
}
}
}