/*
* 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.HashMap;
import java.util.Iterator;
import java.util.Map;
import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.JavaClass;
import com.mebigfatguy.fbcontrib.utils.BugType;
import com.mebigfatguy.fbcontrib.utils.RegisterUtils;
import com.mebigfatguy.fbcontrib.utils.SignatureBuilder;
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.OpcodeStack;
import edu.umd.cs.findbugs.OpcodeStack.CustomUserValue;
import edu.umd.cs.findbugs.ba.XField;
/**
* looks for loops that transfers the contents of one collection to another. These collection sources might be local variables or member fields, including sets,
* maps key/values, lists, or arrays. It is simpler to just use the addAll method of the collection class. In the case where the source is an array, you can use
* Arrays.asList(array), and use that as the source to addAll.
*/
@CustomUserValue
public class UseAddAll extends AbstractCollectionScanningDetector {
/** register/field to alias register/field */
private Map<Comparable<?>, Comparable<?>> userValues;
/** alias register to loop info */
private Map<Comparable<?>, LoopInfo> loops;
private boolean isInstanceMethod;
/**
* constructs a UAA detector given the reporter to report bugs on
*
* @param bugReporter
* the sync of bug reports
*/
public UseAddAll(BugReporter bugReporter) {
super(bugReporter, Values.SLASHED_JAVA_UTIL_COLLECTION);
}
/**
* implements the visitor to reset the userValues and loops
*
* @param obj
* the context object of the currently parsed code block
*/
@Override
public void visitCode(Code obj) {
try {
userValues = new HashMap<>();
loops = new HashMap<>();
isInstanceMethod = !getMethod().isStatic();
super.visitCode(obj);
} finally {
userValues = null;
loops = null;
}
}
/**
* implements the visitor to look for manually copying of collections to collections
*
* @param seen
* the opcode of the currently parsed instruction
*/
@Override
public void sawOpcode(int seen) {
Comparable<?> regOrField = null;
Comparable<?> uValue;
boolean sawAlias = false;
boolean sawLoad = false;
try {
stack.precomputation(this);
int pc = getPC();
Iterator<LoopInfo> it = loops.values().iterator();
while (it.hasNext()) {
LoopInfo loop = it.next();
if ((loop.getEndPC() - 3) <= pc) {
int loopPC = loop.getAddPC();
if (loopPC > 0) {
bugReporter.reportBug(new BugInstance(this, BugType.UAA_USE_ADD_ALL.name(), NORMAL_PRIORITY).addClass(this).addMethod(this)
.addSourceLine(this, loopPC));
}
it.remove();
} else if ((loop.getEndPC() > pc) && (loop.addPC < (pc - 5)) && (loop.addPC > 0)) {
it.remove();
}
}
if (seen == INVOKEINTERFACE) {
String methodName = getNameConstantOperand();
String signature = getSigConstantOperand();
if ("get".equals(methodName) && SignatureBuilder.SIG_INT_TO_OBJECT.equals(signature)) {
if (stack.getStackDepth() > 1) {
OpcodeStack.Item itm = stack.getStackItem(1);
int reg = isLocalCollection(itm);
if (reg >= 0) {
regOrField = Integer.valueOf(reg);
sawAlias = true;
} else {
String field = isFieldCollection(itm);
if (field != null) {
regOrField = field;
sawAlias = true;
}
}
}
} else if ("keySet".equals(methodName) || "values".equals(methodName) || "iterator".equals(methodName) || "next".equals(methodName)
|| "hasNext".equals(methodName)) {
if (stack.getStackDepth() > 0) {
OpcodeStack.Item itm = stack.getStackItem(0);
int reg = isLocalCollection(itm);
if (reg >= 0) {
regOrField = Integer.valueOf(reg);
sawAlias = true;
} else {
String field = isFieldCollection(itm);
if (field != null) {
regOrField = field;
sawAlias = true;
}
}
}
} else if ("add".equals(methodName) && SignatureBuilder.SIG_OBJECT_TO_BOOLEAN.equals(signature) && (stack.getStackDepth() > 1)) {
OpcodeStack.Item colItem = stack.getStackItem(1);
OpcodeStack.Item valueItem = stack.getStackItem(0);
int reg = isLocalCollection(colItem);
if (reg >= 0) {
regOrField = Integer.valueOf(reg);
uValue = (Comparable<?>) valueItem.getUserValue();
if (uValue != null) {
LoopInfo loop = loops.get(uValue);
if ((loop != null) && loop.isInLoop(pc) && (this.getCodeByte(getNextPC()) == POP)) {
loop.foundAdd(pc);
}
}
} else {
String field = isFieldCollection(colItem);
if (field != null) {
regOrField = field;
uValue = (Comparable<?>) valueItem.getUserValue();
if (uValue != null) {
LoopInfo loop = loops.get(uValue);
if ((loop != null) && loop.isInLoop(pc) && (this.getCodeByte(getNextPC()) == POP)) {
loop.foundAdd(pc);
}
}
}
}
}
} else if (((seen == ISTORE) || ((seen >= ISTORE_0) && (seen <= ISTORE_3))) || ((seen == ASTORE) || ((seen >= ASTORE_0) && (seen <= ASTORE_3)))) {
if (stack.getStackDepth() > 0) {
uValue = (Comparable<?>) stack.getStackItem(0).getUserValue();
userValues.put(Integer.valueOf(RegisterUtils.getStoreReg(this, seen)), uValue);
}
} else if (((seen == ILOAD) || ((seen >= ILOAD_0) && (seen <= ILOAD_3))) || ((seen == ALOAD) || ((seen >= ALOAD_0) && (seen <= ALOAD_3)))) {
sawLoad = true;
} else if (seen == IFEQ) {
boolean loopFound = false;
if ((stack.getStackDepth() > 0) && (getBranchOffset() > 0)) {
int gotoPos = getBranchTarget() - 3;
byte[] code = getCode().getCode();
if ((0x00FF & code[gotoPos]) == GOTO) {
short brOffset = (short) (0x0FF & code[gotoPos + 1]);
brOffset <<= 8;
brOffset |= (0x0FF & code[gotoPos + 2]);
gotoPos += brOffset;
if (gotoPos < pc) {
OpcodeStack.Item itm = stack.getStackItem(0);
uValue = (Comparable<?>) itm.getUserValue();
if (uValue != null) {
loops.put(uValue, new LoopInfo(pc, getBranchTarget()));
}
loopFound = true;
}
}
if (!loopFound) {
removeLoop(pc);
}
}
} else if (isInstanceMethod && (seen == PUTFIELD)) {
if (stack.getStackDepth() > 1) {
OpcodeStack.Item item = stack.getStackItem(1);
if (item.getRegisterNumber() == 0) {
uValue = (Comparable<?>) stack.getStackItem(0).getUserValue();
userValues.put(getNameConstantOperand(), uValue);
}
}
} else if (isInstanceMethod && (seen == GETFIELD)) {
if (stack.getStackDepth() > 0) {
OpcodeStack.Item item = stack.getStackItem(0);
if (item.getRegisterNumber() == 0) {
sawLoad = true;
}
}
} else if (((seen > IFEQ) && (seen <= GOTO)) || (seen == IFNULL) || (seen == IFNONNULL)) {
removeLoop(pc);
} else if ((seen == CHECKCAST) && (stack.getStackDepth() > 0)) {
OpcodeStack.Item itm = stack.getStackItem(0);
uValue = (Comparable<?>) itm.getUserValue();
if (uValue != null) {
regOrField = uValue;
sawAlias = true;
}
}
} catch (ClassNotFoundException cnfe) {
bugReporter.reportMissingClass(cnfe);
} finally {
TernaryPatcher.pre(stack, seen);
stack.sawOpcode(this, seen);
TernaryPatcher.post(stack, seen);
if (sawAlias) {
if (stack.getStackDepth() > 0) {
OpcodeStack.Item itm = stack.getStackItem(0);
itm.setUserValue(regOrField);
}
} else if (sawLoad && (stack.getStackDepth() > 0)) {
OpcodeStack.Item itm = stack.getStackItem(0);
int reg = itm.getRegisterNumber();
if (reg >= 0) {
uValue = userValues.get(Integer.valueOf(reg));
itm.setUserValue(uValue);
} else {
XField xField = itm.getXField();
if (xField != null) {
uValue = userValues.get(xField.getName());
itm.setUserValue(uValue);
}
}
}
}
}
/**
* determines if the stack item refers to a collection that is stored in a field
*
* @param item
* the stack item to check
*
* @return the field name of the collection, or null
* @throws ClassNotFoundException
* if the items class cannot be found
*/
private String isFieldCollection(OpcodeStack.Item item) throws ClassNotFoundException {
Comparable<?> aliasReg = (Comparable<?>) item.getUserValue();
if (aliasReg instanceof String) {
return (String) aliasReg;
}
XField field = item.getXField();
if (field == null) {
return null;
}
JavaClass cls = item.getJavaClass();
if ((cls != null) && cls.implementationOf(collectionClass)) {
return field.getName();
}
return null;
}
private void removeLoop(int pc) {
Iterator<LoopInfo> it = loops.values().iterator();
while (it.hasNext()) {
if (it.next().isInLoop(pc)) {
it.remove();
}
}
}
/**
* represents a loop, and where an add was found in it
*/
static class LoopInfo {
private final int start;
private final int end;
private int addPC;
LoopInfo(int loopStart, int loopEnd) {
start = loopStart;
end = loopEnd;
addPC = 0;
}
boolean isInLoop(int pc) {
return ((pc >= start) && (pc <= end));
}
void foundAdd(int pc) {
if (addPC == 0) {
addPC = pc;
} else {
addPC = -1;
}
}
int getStartPC() {
return start;
}
int getEndPC() {
return end;
}
int getAddPC() {
return addPC;
}
@Override
public String toString() {
return ToString.build(this);
}
}
}