/*
* 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.Map;
import org.apache.bcel.classfile.Code;
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.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;
/**
* looks for code that builds an array of values from a collection, by manually looping over the elements of the collection, and adding them to the array. It is
* simpler and cleaner to use mycollection.toArray(new type[mycollection.size()].
*/
@CustomUserValue
public class UseToArray extends AbstractCollectionScanningDetector {
private Map<Integer, Object> userValues;
/**
* constructs a UTA detector given the reporter to report bugs on
*
* @param bugReporter
* the sync of bug reports
*/
public UseToArray(BugReporter bugReporter) {
super(bugReporter, Values.SLASHED_JAVA_UTIL_COLLECTION);
}
/**
* implements the visitor to reset the uservalues
*
* @param obj
* the context object of the currently parsed code block
*/
@Override
public void visitCode(Code obj) {
try {
userValues = new HashMap<>();
super.visitCode(obj);
} finally {
userValues = null;
}
}
/**
* implements the visitor to look for manual copying of collections to arrays
*
* @param seen
* the opcode of the currently parsed instruction
*/
@Override
public void sawOpcode(int seen) {
int reg = -1;
Object uValue = null;
boolean sawAlias = false;
boolean sawLoad = false;
boolean sawNewArray = false;
try {
stack.precomputation(this);
if (seen == INVOKEINTERFACE) {
String methodName = getNameConstantOperand();
String signature = getSigConstantOperand();
if ("size".equals(methodName) && SignatureBuilder.SIG_VOID_TO_INT.equals(signature)) {
if (stack.getStackDepth() > 0) {
OpcodeStack.Item itm = stack.getStackItem(0);
reg = isLocalCollection(itm);
if (reg >= 0) {
sawAlias = true;
}
}
} else if ("get".equals(methodName) && SignatureBuilder.SIG_INT_TO_OBJECT.equals(signature)) {
if (stack.getStackDepth() > 1) {
OpcodeStack.Item itm = stack.getStackItem(1);
reg = isLocalCollection(itm);
if (reg >= 0) {
sawAlias = true;
}
}
} else if (("keySet".equals(methodName) || "values".equals(methodName) || "iterator".equals(methodName) || "next".equals(methodName))
&& (stack.getStackDepth() > 0)) {
OpcodeStack.Item itm = stack.getStackItem(0);
reg = isLocalCollection(itm);
if (reg >= 0) {
sawAlias = true;
}
}
} else if (((seen == ISTORE) || ((seen >= ISTORE_0) && (seen <= ISTORE_3))) || ((seen == ASTORE) || ((seen >= ASTORE_0) && (seen <= ASTORE_3)))) {
if (stack.getStackDepth() > 0) {
uValue = 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 == ANEWARRAY) {
if (stack.getStackDepth() > 0) {
OpcodeStack.Item itm = stack.getStackItem(0);
uValue = itm.getUserValue();
sawNewArray = true;
}
} else if (seen == IF_ICMPGE) {
if (stack.getStackDepth() > 1) {
OpcodeStack.Item itm1 = stack.getStackItem(1);
OpcodeStack.Item itm2 = stack.getStackItem(0);
reg = itm1.getRegisterNumber();
if ((reg >= 0) && (itm1.couldBeZero())) {
uValue = itm2.getUserValue();
if (uValue != null) {
userValues.put(Integer.valueOf(reg), uValue);
}
}
}
} else if ((seen >= IASTORE) && (seen <= SASTORE)) {
if (stack.getStackDepth() > 2) {
OpcodeStack.Item arItem = stack.getStackItem(2);
OpcodeStack.Item idxItem = stack.getStackItem(1);
OpcodeStack.Item valueItem = stack.getStackItem(0);
reg = isLocalCollection(arItem);
if ((reg >= 0) && (idxItem.getUserValue() != null) && (valueItem.getUserValue() != null)) {
bugReporter.reportBug(
new BugInstance(this, BugType.UTA_USE_TO_ARRAY.name(), NORMAL_PRIORITY).addClass(this).addMethod(this).addSourceLine(this));
}
}
} else if ((seen == CHECKCAST) && (stack.getStackDepth() > 0)) {
OpcodeStack.Item itm = stack.getStackItem(0);
uValue = itm.getUserValue();
if (uValue instanceof Integer) {
reg = ((Integer) uValue).intValue();
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(Integer.valueOf(reg));
}
} else if (sawLoad) {
if (stack.getStackDepth() > 0) {
OpcodeStack.Item itm = stack.getStackItem(0);
reg = itm.getRegisterNumber();
if (reg >= 0) {
uValue = userValues.get(Integer.valueOf(reg));
itm.setUserValue(uValue);
}
}
} else if (sawNewArray && (stack.getStackDepth() > 0)) {
OpcodeStack.Item itm = stack.getStackItem(0);
itm.setUserValue(uValue);
}
}
}
}