/*
* fb-contrib - Auxiliary detectors for Java programs
* Copyright (C) 2005-2017 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.HashSet;
import java.util.Set;
import org.apache.bcel.Repository;
import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.ConstantString;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Method;
import com.mebigfatguy.fbcontrib.utils.BugType;
import com.mebigfatguy.fbcontrib.utils.QMethod;
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.ba.ClassContext;
/**
* finds methods of abstract classes that do nothing, or just throw exceptions. Since this is an abstract class, it may be more correct to just leave the method
* abstract.
*/
public class AbstractClassEmptyMethods extends BytecodeScanningDetector {
enum State {
SAW_NOTHING, SAW_NEW, SAW_DUP, SAW_LDC, SAW_INVOKESPECIAL, SAW_DONE
}
private final BugReporter bugReporter;
private JavaClass exceptionClass;
private Set<QMethod> interfaceMethods;
private String methodName;
private State state;
/**
* constructs a ACEM detector given the reporter to report bugs on
*
* @param bugReporter
* the sync of bug reports
*/
public AbstractClassEmptyMethods(BugReporter bugReporter) {
this.bugReporter = bugReporter;
try {
exceptionClass = Repository.lookupClass(Values.SLASHED_JAVA_LANG_EXCEPTION);
} catch (ClassNotFoundException e) {
bugReporter.reportMissingClass(e);
}
}
/**
* overrides the visitor to check for abstract classes.
*
* @param classContext
* the context object that holds the JavaClass being parsed
*/
@Override
public void visitClassContext(ClassContext classContext) {
try {
JavaClass cls = classContext.getJavaClass();
if (cls.isAbstract()) {
interfaceMethods = collectInterfaceMethods(cls);
super.visitClassContext(classContext);
}
} catch (ClassNotFoundException cnfe) {
bugReporter.reportMissingClass(cnfe);
} finally {
interfaceMethods = null;
}
}
/**
* overrides the visitor to grab the method name and reset the state.
*
* @param obj
* the method being parsed
*/
@Override
public void visitMethod(Method obj) {
methodName = obj.getName();
state = State.SAW_NOTHING;
}
/**
* overrides the visitor to filter out constructors.
*
* @param obj
* the code to parse
*/
@Override
public void visitCode(Code obj) {
if (Values.CONSTRUCTOR.equals(methodName) || Values.STATIC_INITIALIZER.equals(methodName)) {
return;
}
if (!interfaceMethods.contains(new QMethod(methodName, getMethod().getSignature()))) {
super.visitCode(obj);
}
}
/**
* overrides the visitor to look for empty methods or simple exception throwers.
*
* @param seen
* the opcode currently being parsed
*/
@Override
public void sawOpcode(int seen) {
try {
switch (state) {
case SAW_NOTHING:
if (seen == RETURN) {
bugReporter.reportBug(new BugInstance(this, BugType.ACEM_ABSTRACT_CLASS_EMPTY_METHODS.name(), NORMAL_PRIORITY).addClass(this)
.addMethod(this).addSourceLine(this));
state = State.SAW_DONE;
} else if (seen == NEW) {
String newClass = getClassConstantOperand();
JavaClass exCls = Repository.lookupClass(newClass);
if ((exceptionClass != null) && exCls.instanceOf(exceptionClass)) {
state = State.SAW_NEW;
} else {
state = State.SAW_DONE;
}
} else {
state = State.SAW_DONE;
}
break;
case SAW_NEW:
if (seen == DUP) {
state = State.SAW_DUP;
} else {
state = State.SAW_DONE;
}
break;
case SAW_DUP:
if (((seen == LDC) || (seen == LDC_W)) && (getConstantRefOperand() instanceof ConstantString)) {
state = State.SAW_LDC;
} else {
state = State.SAW_DONE;
}
break;
case SAW_LDC:
if ((seen == INVOKESPECIAL) && Values.CONSTRUCTOR.equals(getNameConstantOperand())) {
state = State.SAW_INVOKESPECIAL;
} else {
state = State.SAW_DONE;
}
break;
case SAW_INVOKESPECIAL:
if (seen == ATHROW) {
bugReporter.reportBug(new BugInstance(this, BugType.ACEM_ABSTRACT_CLASS_EMPTY_METHODS.name(), NORMAL_PRIORITY).addClass(this)
.addMethod(this).addSourceLine(this));
}
state = State.SAW_DONE;
break;
case SAW_DONE:
break;
}
} catch (ClassNotFoundException cnfe) {
bugReporter.reportMissingClass(cnfe);
state = State.SAW_DONE;
}
}
private Set<QMethod> collectInterfaceMethods(JavaClass cls) throws ClassNotFoundException {
Set<QMethod> methods = new HashSet<>();
for (JavaClass inf : cls.getAllInterfaces()) {
for (Method m : inf.getMethods()) {
methods.add(new QMethod(m.getName(), m.getSignature()));
}
}
return methods;
}
}