/*
* 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.ArrayDeque;
import java.util.BitSet;
import java.util.Deque;
import java.util.Set;
import org.apache.bcel.Constants;
import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.ConstantInvokeDynamic;
import org.apache.bcel.classfile.ConstantNameAndType;
import org.apache.bcel.classfile.ConstantPool;
import org.apache.bcel.classfile.ConstantUtf8;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Method;
import com.mebigfatguy.fbcontrib.utils.BugType;
import com.mebigfatguy.fbcontrib.utils.FQMethod;
import com.mebigfatguy.fbcontrib.utils.ToString;
import com.mebigfatguy.fbcontrib.utils.UnmodifiableSet;
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 various issues around use of java.util.Optional
*/
@CustomUserValue
public class OptionalIssues extends BytecodeScanningDetector {
private static Set<String> BOXED_OPTIONAL_TYPES = UnmodifiableSet.create("Ljava/lang/Integer;", "Ljava/lang/Long;", "Ljava/lang/Double;");
private static final FQMethod OPTIONAL_OR_ELSE_METHOD = new FQMethod("java/util/Optional", "orElse", "(Ljava/lang/Object;)Ljava/lang/Object;");
private static final FQMethod OPTIONAL_OR_ELSE_GET_METHOD = new FQMethod("java/util/Optional", "orElseGet",
"(Ljava/util/function/Supplier;)Ljava/lang/Object;");
private static final FQMethod OPTIONAL_GET_METHOD = new FQMethod("java/util/Optional", "get", "()Ljava/lang/Object;");
private static final Set<FQMethod> OR_ELSE_METHODS = UnmodifiableSet.create(
// @formatter:off
OPTIONAL_OR_ELSE_METHOD,
new FQMethod("java/util/OptionalDouble", "orElse", "(D)D"),
new FQMethod("java/util/OptionalInt", "orElse", "(I)I"),
new FQMethod("java/util/OptionalLong", "orElse", "(J)J")
// @formatter:on
);
private static final Set<FQMethod> OR_ELSE_GET_METHODS = UnmodifiableSet.create(
// @formatter:off
OPTIONAL_OR_ELSE_GET_METHOD,
new FQMethod("java/util/OptionalDouble", "orElseGet", "(Ljava/util/function/DoubleSupplier;)D"),
new FQMethod("java/util/OptionalInt", "orElseGet", "(Ljava/util/function/IntSupplier;)I"),
new FQMethod("java/util/OptionalLong", "orElseGet", "(Ljava/util/function/LongSupplier;)J")
// @formatter:on
);
private static final BitSet INVOKE_OPS = new BitSet();
private BugReporter bugReporter;
private OpcodeStack stack;
private JavaClass currentClass;
private Deque<ActiveStackOp> activeStackOps;
static {
INVOKE_OPS.set(INVOKEINTERFACE);
INVOKE_OPS.set(INVOKEVIRTUAL);
INVOKE_OPS.set(INVOKESTATIC);
INVOKE_OPS.set(INVOKESPECIAL);
INVOKE_OPS.set(INVOKEDYNAMIC);
}
/**
* constructs a OI detector given the reporter to report bugs on
*
* @param bugReporter
* the sync of bug reports
*/
public OptionalIssues(BugReporter bugReporter) {
this.bugReporter = bugReporter;
}
/**
* implements the visitor to filter out pre-1.8 classes, for 1.8+ classes, it creates the opcode stack and active stack ops
*
* @param classContext
* the context object of the currently parsed class
*/
@Override
public void visitClassContext(ClassContext classContext) {
currentClass = classContext.getJavaClass();
if (currentClass.getMajor() >= Constants.MAJOR_1_8) {
try {
stack = new OpcodeStack();
activeStackOps = new ArrayDeque<>();
super.visitClassContext(classContext);
} finally {
activeStackOps = null;
stack = null;
}
}
currentClass = null;
}
/**
* implements the visitor clear the stacks
*
* @param obj
* the context object of the currently parsed code block
*/
@Override
public void visitCode(Code obj) {
stack.resetForMethodEntry(this);
activeStackOps.clear();
super.visitCode(obj);
}
/**
* implements the visitor to look for reference compares of Optional, Optional use when more specific Optionals should be used, and use of orElse when
* orElseGet would be more appropriate
*
* @param seen
* the opcode of the currently parsed instruction
*/
@Override
public void sawOpcode(int seen) {
FQMethod curCalledMethod = null;
Boolean sawPlainOptional = null;
try {
switch (seen) {
case IFNULL:
case IFNONNULL:
if (stack.getStackDepth() > 0) {
OpcodeStack.Item itm = stack.getStackItem(0);
if ("Ljava/util/Optional;".equals(itm.getSignature())) {
bugReporter.reportBug(new BugInstance(this, BugType.OI_OPTIONAL_ISSUES_CHECKING_REFERENCE.name(), NORMAL_PRIORITY).addClass(this)
.addMethod(this).addSourceLine(this));
}
}
break;
case INVOKEDYNAMIC:
// smells like a hack. Not sure how to do this better
ConstantInvokeDynamic id = (ConstantInvokeDynamic) getConstantRefOperand();
ConstantPool cp = getConstantPool();
ConstantNameAndType nameAndType = (ConstantNameAndType) cp.getConstant(id.getNameAndTypeIndex());
ConstantUtf8 typeConstant = (ConstantUtf8) cp.getConstant(nameAndType.getSignatureIndex());
curCalledMethod = new FQMethod(getClassName(), "lambda$" + id.getBootstrapMethodAttrIndex(), typeConstant.getBytes());
break;
case INVOKESTATIC:
case INVOKEINTERFACE:
case INVOKESPECIAL:
String clsName = getClassConstantOperand();
String methodName = getNameConstantOperand();
curCalledMethod = new FQMethod(clsName, methodName, getSigConstantOperand());
if ("java/util/Optional".equals(clsName) && "of".equals(methodName)) {
if (stack.getStackDepth() > 0) {
OpcodeStack.Item itm = stack.getStackItem(0);
String itmSig = itm.getSignature();
if (BOXED_OPTIONAL_TYPES.contains(itmSig)) {
bugReporter.reportBug(new BugInstance(this, BugType.OI_OPTIONAL_ISSUES_PRIMITIVE_VARIANT_PREFERRED.name(), LOW_PRIORITY)
.addClass(this).addMethod(this).addSourceLine(this));
}
}
}
break;
case INVOKEVIRTUAL:
curCalledMethod = new FQMethod(getClassConstantOperand(), getNameConstantOperand(), getSigConstantOperand());
if (OR_ELSE_METHODS.contains(curCalledMethod)) {
if (stack.getStackDepth() > 0) {
OpcodeStack.Item itm = stack.getStackItem(0);
if ((itm.getReturnValueOf() != null) && !isTrivialStackOps()) {
bugReporter.reportBug(new BugInstance(this, BugType.OI_OPTIONAL_ISSUES_USES_IMMEDIATE_EXECUTION.name(), NORMAL_PRIORITY)
.addClass(this).addMethod(this).addSourceLine(this));
}
}
if (OPTIONAL_OR_ELSE_METHOD.equals(curCalledMethod)) {
sawPlainOptional = Boolean.TRUE;
}
} else if (OR_ELSE_GET_METHODS.contains(curCalledMethod)) {
if (!activeStackOps.isEmpty()) {
ActiveStackOp op = activeStackOps.getLast();
Method getMethod = getLambdaMethod(op.getMethod().getMethodName());
if (getMethod != null) {
byte[] byteCode = getMethod.getCode().getCode();
if (byteCode.length <= 4) {
// we are looking for ALOAD, GETFIELD, or LDC followed by ARETURN, that should fit in 4 bytes
if (!hasInvoke(byteCode)) {
bugReporter.reportBug(new BugInstance(this, BugType.OI_OPTIONAL_ISSUES_USES_DELAYED_EXECUTION.name(), LOW_PRIORITY)
.addClass(this).addMethod(this).addSourceLine(this));
}
}
}
}
if (OPTIONAL_OR_ELSE_GET_METHOD.equals(curCalledMethod)) {
sawPlainOptional = Boolean.TRUE;
}
} else if (OPTIONAL_GET_METHOD.equals(curCalledMethod)) {
sawPlainOptional = Boolean.TRUE;
}
break;
}
} finally {
stack.sawOpcode(this, seen);
int stackDepth = stack.getStackDepth();
if (stackDepth == 0) {
activeStackOps.clear();
} else {
activeStackOps.addLast(new ActiveStackOp(seen, curCalledMethod));
while (activeStackOps.size() > stackDepth) {
activeStackOps.removeFirst();
}
if (sawPlainOptional != null) {
OpcodeStack.Item itm = stack.getStackItem(0);
itm.setUserValue(sawPlainOptional);
}
}
}
}
/**
* returns whether the set of operations that contributed to the current stack form, are trivial or not, specifically boxing a primitive value, or appending
* to strings or such.
*
* @return the operations that caused the current stack to exist are trivial
*/
private boolean isTrivialStackOps() {
int invokeCount = 0;
for (ActiveStackOp op : activeStackOps) {
if (INVOKE_OPS.get(op.getOpcode())) {
invokeCount++;
}
}
if (invokeCount == 1) {
FQMethod method = activeStackOps.getLast().getMethod();
if (method == null) {
return false;
}
if ("valueOf".equals(method.getMethodName()) && method.getClassName().startsWith("java/lang/")) {
return true;
}
}
// do simple string appending?
return false;
}
/**
* finds the bootstrap method for a lambda (invokedynamic call. As findbugs doesn't support bcel 6, have to cheat a little here.
*
* @param methodName
* the lambda name
* @return the method object if it exists
*/
private Method getLambdaMethod(String methodName) {
for (Method method : currentClass.getMethods()) {
if (methodName.equals(method.getName())) {
return method;
}
}
return null;
}
/**
* returns whether the byte code of a method has an invokeXXX statement in it
*
* @param byteCode
* the byte code of a method to check
* @return if there is an invokeXX method found
*/
private boolean hasInvoke(byte[] byteCode) {
for (byte b : byteCode) {
if (INVOKE_OPS.get(b & 0x00FF)) {
return true;
}
}
return false;
}
/**
* represents an opcode that was issued while there is still active elements on the stack.
*/
static class ActiveStackOp {
private int opcode;
FQMethod method;
public ActiveStackOp(int op) {
opcode = op;
}
public ActiveStackOp(int op, FQMethod calledMethod) {
opcode = op;
method = calledMethod;
}
public int getOpcode() {
return opcode;
}
public FQMethod getMethod() {
return method;
}
@Override
public int hashCode() {
return opcode ^ ((method != null) ? method.hashCode() : -1);
}
@Override
public boolean equals(Object o) {
if (!(o instanceof ActiveStackOp)) {
return false;
}
ActiveStackOp that = (ActiveStackOp) o;
return (opcode == that.opcode) && ((method == that.method) || ((method != null) && method.equals(that.method)));
}
@Override
public String toString() {
return ToString.build(this);
}
}
}