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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.
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/*
* fb-contrib - Auxiliary detectors for Java programs
* Copyright (C) 2005-2019 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 java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.annotation.Nullable;
import org.apache.bcel.Const;
import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.Method;
import com.mebigfatguy.fbcontrib.utils.BugType;
import com.mebigfatguy.fbcontrib.utils.RegisterUtils;
import com.mebigfatguy.fbcontrib.utils.SignatureUtils;
import com.mebigfatguy.fbcontrib.utils.TernaryPatcher;
import com.mebigfatguy.fbcontrib.utils.ToString;
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.OpcodeStack;
import edu.umd.cs.findbugs.OpcodeStack.CustomUserValue;
import edu.umd.cs.findbugs.ba.ClassContext;
/**
* looks for methods that use an array of length one to pass a variable to
* achieve call by pointer ala C++. It is better to define a proper return class
* type that holds all the relevant information retrieved from the called
* method.
*/
@CustomUserValue
public class ArrayWrappedCallByReference extends BytecodeScanningDetector {
private final BugReporter bugReporter;
private OpcodeStack stack;
private Map wrappers;
/**
* constructs a AWCBR detector given the reporter to report bugs on
*
* @param bugReporter the sync of bug reports
*/
public ArrayWrappedCallByReference(BugReporter bugReporter) {
this.bugReporter = bugReporter;
}
/**
* implement the visitor to create and clear the stack and wrappers
*
* @param classContext the context object of the currently parsed class
*/
@Override
public void visitClassContext(ClassContext classContext) {
try {
stack = new OpcodeStack();
wrappers = new HashMap<>(10);
super.visitClassContext(classContext);
} finally {
stack = null;
wrappers = null;
}
}
/**
* looks for methods that contain a NEWARRAY or ANEWARRAY opcodes
*
* @param method the context object of the current method
* @return if the class uses synchronization
*/
public boolean prescreen(Method method) {
BitSet bytecodeSet = getClassContext().getBytecodeSet(method);
return (bytecodeSet != null) && (bytecodeSet.get(Const.NEWARRAY) || bytecodeSet.get(Const.ANEWARRAY));
}
/**
* implements the visitor to reset the stack of opcodes
*
* @param obj the context object for the currently parsed code block
*/
@Override
public void visitCode(Code obj) {
if (prescreen(getMethod())) {
stack.resetForMethodEntry(this);
wrappers.clear();
super.visitCode(obj);
}
}
/**
* implements the visitor to wrapped array parameter calls
*
* @param seen the currently visitor opcode
*/
@Override
public void sawOpcode(int seen) {
Integer userValue = null;
try {
stack.precomputation(this);
switch (seen) {
case Const.NEWARRAY:
case Const.ANEWARRAY: {
if (stack.getStackDepth() > 0) {
OpcodeStack.Item itm = stack.getStackItem(0);
Integer size = (Integer) itm.getConstant();
if ((size != null) && (size.intValue() == 1)) {
userValue = Values.NEGATIVE_ONE;
}
}
}
break;
case Const.IASTORE:
case Const.LASTORE:
case Const.FASTORE:
case Const.DASTORE:
case Const.AASTORE:
case Const.BASTORE:
case Const.CASTORE:
case Const.SASTORE: {
userValue = processArrayElementStore();
}
break;
case Const.ASTORE:
case Const.ASTORE_0:
case Const.ASTORE_1:
case Const.ASTORE_2:
case Const.ASTORE_3: {
processLocalStore(seen);
}
break;
case Const.INVOKEVIRTUAL:
case Const.INVOKEINTERFACE:
case Const.INVOKESPECIAL:
case Const.INVOKESTATIC: {
processMethodCall();
}
break;
case Const.IALOAD:
case Const.LALOAD:
case Const.FALOAD:
case Const.DALOAD:
case Const.AALOAD:
case Const.BALOAD:
case Const.CALOAD:
case Const.SALOAD: {
if (stack.getStackDepth() >= 2) {
OpcodeStack.Item arItm = stack.getStackItem(1);
int arReg = arItm.getRegisterNumber();
WrapperInfo wi = wrappers.get(Integer.valueOf(arReg));
if ((wi != null) && wi.wasArg) {
userValue = Integer.valueOf(wi.wrappedReg);
}
}
}
break;
case Const.ALOAD:
case Const.ALOAD_0:
case Const.ALOAD_1:
case Const.ALOAD_2:
case Const.ALOAD_3: {
int reg = RegisterUtils.getALoadReg(this, seen);
WrapperInfo wi = wrappers.get(Integer.valueOf(reg));
if (wi != null) {
userValue = Integer.valueOf(wi.wrappedReg);
}
}
break;
case Const.ISTORE:
case Const.ISTORE_0:
case Const.ISTORE_1:
case Const.ISTORE_2:
case Const.ISTORE_3:
case Const.LSTORE:
case Const.LSTORE_0:
case Const.LSTORE_1:
case Const.LSTORE_2:
case Const.LSTORE_3:
case Const.DSTORE:
case Const.DSTORE_0:
case Const.DSTORE_1:
case Const.DSTORE_2:
case Const.DSTORE_3:
case Const.FSTORE:
case Const.FSTORE_0:
case Const.FSTORE_1:
case Const.FSTORE_2:
case Const.FSTORE_3: {
if (stack.getStackDepth() == 0) {
break;
}
OpcodeStack.Item itm = stack.getStackItem(0);
Integer elReg = (Integer) itm.getUserValue();
if (elReg == null) {
break;
}
int reg = RegisterUtils.getStoreReg(this, seen);
if (elReg.intValue() == reg) {
bugReporter.reportBug(
new BugInstance(this, BugType.AWCBR_ARRAY_WRAPPED_CALL_BY_REFERENCE.name(), NORMAL_PRIORITY)
.addClass(this).addMethod(this).addSourceLine(this));
}
}
break;
default:
break;
}
} finally {
TernaryPatcher.pre(stack, seen);
stack.sawOpcode(this, seen);
TernaryPatcher.post(stack, seen);
if ((userValue != null) && (stack.getStackDepth() > 0)) {
OpcodeStack.Item itm = stack.getStackItem(0);
itm.setUserValue(userValue);
}
}
}
/**
* looks for stores to registers, if that store is an array, builds a wrapper
* info for it and stores it in the wrappers collection. If it is a regular
* store, sees if this value, came from a wrapper array passed into a method,
* and if so reports it.
*
* @param seen the currently parsed opcode
*/
private void processLocalStore(int seen) {
if (stack.getStackDepth() == 0) {
return;
}
OpcodeStack.Item itm = stack.getStackItem(0);
String sig = itm.getSignature();
if (sig.startsWith(Values.SIG_ARRAY_PREFIX)) {
int reg = RegisterUtils.getAStoreReg(this, seen);
Integer elReg = (Integer) itm.getUserValue();
if (elReg != null) {
wrappers.put(Integer.valueOf(reg), new WrapperInfo(elReg.intValue()));
}
} else {
Integer elReg = (Integer) itm.getUserValue();
if ((elReg != null) && (elReg.intValue() == RegisterUtils.getAStoreReg(this, seen))) {
bugReporter.reportBug(
new BugInstance(this, BugType.AWCBR_ARRAY_WRAPPED_CALL_BY_REFERENCE.name(), NORMAL_PRIORITY)
.addClass(this).addMethod(this).addSourceLine(this));
}
}
}
/**
* processes a store to an array element to see if this array is being used as a
* wrapper array, and if so records the register that is stored within it.
*
* @return the user value representing the stored register value
*/
@Nullable
private Integer processArrayElementStore() {
if (stack.getStackDepth() >= 2) {
OpcodeStack.Item itm = stack.getStackItem(2);
int reg = itm.getRegisterNumber();
if (reg != -1) {
WrapperInfo wi = wrappers.get(Integer.valueOf(reg));
if (wi != null) {
OpcodeStack.Item elItm = stack.getStackItem(0);
wi.wrappedReg = elItm.getRegisterNumber();
}
} else {
OpcodeStack.Item elItm = stack.getStackItem(0);
reg = elItm.getRegisterNumber();
if (reg != -1) {
return Integer.valueOf(reg);
}
}
}
return null;
}
/**
* processes a method call looking for parameters that are arrays. If this array
* was seen earlier as a simple wrapping array, then it marks it as being having
* been used as a parameter.
*
*/
private void processMethodCall() {
if ("invoke".equals(getNameConstantOperand()) && "java/lang/reflect/Method".equals(getClassConstantOperand())) {
return;
}
String sig = getSigConstantOperand();
List args = SignatureUtils.getParameterSignatures(sig);
if (stack.getStackDepth() >= args.size()) {
for (int i = 0; i < args.size(); i++) {
String argSig = args.get(i);
if (argSig.startsWith(Values.SIG_ARRAY_PREFIX)) {
OpcodeStack.Item itm = stack.getStackItem(args.size() - i - 1);
int arrayReg = itm.getRegisterNumber();
WrapperInfo wi = wrappers.get(Integer.valueOf(arrayReg));
if (wi != null) {
wi.wasArg = true;
}
}
}
}
}
/**
* represents a local array that is stored, for wrapping a value
*/
static class WrapperInfo {
int wrappedReg;
boolean wasArg;
WrapperInfo(int reg) {
wrappedReg = reg;
wasArg = false;
}
@Override
public String toString() {
return ToString.build(this);
}
}
}