/*
* FindBugs - Find bugs in Java programs
* Copyright (C) 2004-2006 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.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import org.apache.bcel.classfile.Code;
import edu.umd.cs.findbugs.BugAccumulator;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.Priorities;
import edu.umd.cs.findbugs.bcel.OpcodeStackDetector;
import edu.umd.cs.findbugs.charsets.UTF8;
public class Noise extends OpcodeStackDetector {
class HashQueue {
HashQueue(int size) throws NoSuchAlgorithmException {
md = MessageDigest.getInstance("SHA");
this.size = size;
this.data = new byte[size];
}
MessageDigest md;
final int size;
int next = 0; // 0 <= next < size
final byte[] data;
// data is next..size-1, 0..next-1
public void push(byte b) {
data[next++] = b;
if (next == size) {
next = 0;
}
}
public void reset() {
next = 0;
for (int i = 0; i < size; i++) {
data[i] = 0;
}
}
public void push(String s) {
for (byte b : UTF8.getBytes(s)) {
push(b);
}
}
public void pushHash(Object x) {
push(x.hashCode());
}
public void push(int x) {
push((byte) (x));
push((byte) (x >> 8));
push((byte) (x >> 16));
push((byte) (x >> 24));
}
public int getHash() {
md.update(primer);
md.update(data, next, size - next);
md.update(data, 0, next);
byte[] hash = md.digest();
int result = (hash[0] & 0xff) | (hash[1] & 0xff) << 8 | (hash[2] & 0xff) << 16 | (hash[3] & 0x7f) << 24;
return result;
}
public int getPriority() {
int hash = getHash();
if ((hash & 0x1ff0) == 0) {
hash = hash & 0xf;
if (hash < 1) {
return Priorities.HIGH_PRIORITY;
} else if (hash < 1 + 2) {
return Priorities.NORMAL_PRIORITY;
} else if (hash < 1 + 2 + 4) {
return Priorities.LOW_PRIORITY;
} else {
return Priorities.IGNORE_PRIORITY;
}
} else {
return Priorities.IGNORE_PRIORITY + 1;
}
}
}
// final BugReporter bugReporter;
final BugAccumulator accumulator;
final HashQueue hq;
byte[] primer;
public Noise(BugReporter bugReporter) throws NoSuchAlgorithmException {
// this.bugReporter = bugReporter;
this.accumulator = new BugAccumulator(bugReporter);
hq = new HashQueue(24);
}
@Override
public void visit(Code code) {
primer = UTF8.getBytes(getFullyQualifiedMethodName());
super.visit(code); // make callbacks to sawOpcode for all opcodes
accumulator.reportAccumulatedBugs();
}
@Override
public void sawInt(int i) {
hq.push(i);
}
@Override
public void sawLong(long x) {
hq.push((int) (x >> 0));
hq.push((int) (x >> 32));
}
@Override
public void sawString(String s) {
hq.pushHash(s);
}
@Override
public void sawClass() {
hq.push(getClassConstantOperand());
}
@Override
public void sawOpcode(int seen) {
int priority;
switch (seen) {
case INVOKEINTERFACE:
case INVOKEVIRTUAL:
case INVOKESPECIAL:
case INVOKESTATIC:
hq.pushHash(getClassConstantOperand());
if (getNameConstantOperand().indexOf('$') == -1) {
hq.pushHash(getNameConstantOperand());
}
hq.pushHash(getSigConstantOperand());
priority = hq.getPriority();
if (priority <= Priorities.LOW_PRIORITY) {
accumulator.accumulateBug(new BugInstance(this, "NOISE_METHOD_CALL", priority).addClassAndMethod(this)
.addCalledMethod(this), this);
}
break;
case GETFIELD:
case PUTFIELD:
case GETSTATIC:
case PUTSTATIC:
hq.pushHash(getClassConstantOperand());
if (getNameConstantOperand().indexOf('$') == -1) {
hq.pushHash(getNameConstantOperand());
}
hq.pushHash(getSigConstantOperand());
priority = hq.getPriority();
if (priority <= Priorities.LOW_PRIORITY) {
accumulator.accumulateBug(new BugInstance(this, "NOISE_FIELD_REFERENCE", priority).addClassAndMethod(this)
.addReferencedField(this), this);
}
break;
case CHECKCAST:
case INSTANCEOF:
case NEW:
hq.pushHash(getClassConstantOperand());
break;
case IFEQ:
case IFNE:
case IFNONNULL:
case IFNULL:
case IF_ICMPEQ:
case IF_ICMPNE:
case IF_ICMPLE:
case IF_ICMPGE:
case IF_ICMPGT:
case IF_ICMPLT:
case IF_ACMPEQ:
case IF_ACMPNE:
case RETURN:
case ARETURN:
case IRETURN:
case MONITORENTER:
case MONITOREXIT:
case IINC:
case NEWARRAY:
case TABLESWITCH:
case LOOKUPSWITCH:
case LCMP:
case INEG:
case IADD:
case IMUL:
case ISUB:
case IDIV:
case IREM:
case IXOR:
case ISHL:
case ISHR:
case IUSHR:
case IAND:
case IOR:
case LAND:
case LOR:
case LADD:
case LMUL:
case LSUB:
case LDIV:
case LSHL:
case LSHR:
case LUSHR:
case AALOAD:
case AASTORE:
case IALOAD:
case IASTORE:
case BALOAD:
case BASTORE:
hq.push(seen);
priority = hq.getPriority();
if (priority <= Priorities.LOW_PRIORITY) {
accumulator.accumulateBug(
new BugInstance(this, "NOISE_OPERATION", priority).addClassAndMethod(this).addString(OPCODE_NAMES[seen]),
this);
}
break;
default:
break;
}
}
}