/*
* FindBugs - Find bugs in Java programs
* 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.HashSet;
import java.util.Set;
import org.apache.bcel.Repository;
import org.apache.bcel.classfile.Field;
import org.apache.bcel.classfile.JavaClass;
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;
public class FindDoubleCheck extends BytecodeScanningDetector {
static final boolean DEBUG = false;
int stage = 0;
int startPC, endPC;
int count;
boolean sawMonitorEnter;
Set<FieldAnnotation> fields = new HashSet<FieldAnnotation>();
Set<FieldAnnotation> twice = new HashSet<FieldAnnotation>();
FieldAnnotation pendingFieldLoad;
int countSinceGetReference;
int countSinceGetBoolean;
private final BugReporter bugReporter;
public FindDoubleCheck(BugReporter bugReporter) {
this.bugReporter = bugReporter;
}
@Override
public void visit(Method obj) {
if (DEBUG) {
System.out.println(getFullyQualifiedMethodName());
}
super.visit(obj);
fields.clear();
twice.clear();
stage = 0;
count = 0;
countSinceGetReference = 1000;
countSinceGetBoolean = 1000;
sawMonitorEnter = false;
pendingFieldLoad = null;
}
@Override
public void sawOpcode(int seen) {
if (DEBUG) {
System.out.println(getPC() + "\t" + OPCODE_NAMES[seen] + "\t" + stage + "\t" + count + "\t" + countSinceGetReference);
}
if (seen == MONITORENTER) {
sawMonitorEnter = true;
}
if (seen == GETFIELD || seen == GETSTATIC) {
pendingFieldLoad = FieldAnnotation.fromReferencedField(this);
if (DEBUG) {
System.out.println("\t" + pendingFieldLoad);
}
String sig = getSigConstantOperand();
if (sig.equals("Z")) {
countSinceGetBoolean = 0;
countSinceGetReference++;
} else if (sig.startsWith("L") || sig.startsWith("[")) {
countSinceGetBoolean++;
countSinceGetReference = 0;
}
} else {
countSinceGetReference++;
}
switch (stage) {
case 0:
if (((seen == IFNULL || seen == IFNONNULL) && countSinceGetReference < 5)
|| ((seen == IFEQ || seen == IFNE) && countSinceGetBoolean < 5)) {
int b = getBranchOffset();
if (DEBUG) {
System.out.println("branch offset is : " + b);
}
if (b > 0 && !(seen == IFNULL && b > 9) && !(seen == IFEQ && (b > 9 && b < 34))
&& !(seen == IFNE && (b > 9 && b < 34)) && (!sawMonitorEnter)) {
fields.add(pendingFieldLoad);
startPC = getPC();
stage = 1;
}
}
count = 0;
break;
case 1:
if (seen == MONITORENTER) {
stage = 2;
count = 0;
} else if (((seen == IFNULL || seen == IFNONNULL) && countSinceGetReference < 5)
|| ((seen == IFEQ || seen == IFNE) && countSinceGetBoolean < 5)) {
int b = getBranchOffset();
if (b > 0 && (seen == IFNONNULL || b < 10)) {
fields.add(pendingFieldLoad);
startPC = getPC();
count = 0;
}
} else {
count++;
if (count > 10) {
stage = 0;
}
}
break;
case 2:
if (((seen == IFNULL || seen == IFNONNULL) && countSinceGetReference < 5)
|| ((seen == IFEQ || seen == IFNE) && countSinceGetBoolean < 5)) {
if (getBranchOffset() >= 0 && fields.contains(pendingFieldLoad)) {
endPC = getPC();
stage++;
twice.add(pendingFieldLoad);
break;
}
}
count++;
if (count > 10) {
stage = 0;
}
break;
case 3:
if (seen == PUTFIELD || seen == PUTSTATIC) {
FieldAnnotation f = FieldAnnotation.fromReferencedField(this);
if (DEBUG) {
System.out.println("\t" + f);
}
if (twice.contains(f) && !getNameConstantOperand().startsWith("class$")
&& !getSigConstantOperand().equals("Ljava/lang/String;")) {
Field declaration = findField(getClassConstantOperand(), getNameConstantOperand());
/*
* System.out.println(f); System.out.println(declaration);
* System.out.println(getSigConstantOperand());
*/
if (declaration == null || !declaration.isVolatile()) {
bugReporter.reportBug(new BugInstance(this, "DC_DOUBLECHECK", NORMAL_PRIORITY).addClassAndMethod(this)
.addField(f).describe("FIELD_ON").addSourceLineRange(this, startPC, endPC));
}
stage++;
}
}
break;
default:
break;
}
}
Field findField(String className, String fieldName) {
try {
// System.out.println("Looking for " + className);
JavaClass fieldDefinedIn = getThisClass();
if (!className.equals(getClassName())) {
// System.out.println("Using repository to look for " +
// className);
fieldDefinedIn = Repository.lookupClass(className);
}
Field[] f = fieldDefinedIn.getFields();
for (Field aF : f) {
if (aF.getName().equals(fieldName)) {
// System.out.println("Found " + f[i]);
return aF;
}
}
return null;
} catch (ClassNotFoundException e) {
return null;
}
}
}