/*
* 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.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import org.apache.bcel.classfile.Code;
import com.mebigfatguy.fbcontrib.utils.BugType;
import com.mebigfatguy.fbcontrib.utils.FQMethod;
import com.mebigfatguy.fbcontrib.utils.RegisterUtils;
import com.mebigfatguy.fbcontrib.utils.SignatureBuilder;
import com.mebigfatguy.fbcontrib.utils.TernaryPatcher;
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 creation of java.awt.Graphics object that do not have the
* .dispose() method called on them when finished. These objects will be cleaned
* up by the Garbage collector, bug given the likelyhood that large numbers of
* these objects can be created in a short period of time, it is better to
* dispose them as soon as possible
*/
@CustomUserValue
public class LingeringGraphicsObjects extends BytecodeScanningDetector {
private static final Set<FQMethod> GRAPHICS_PRODUCERS;
private static final Set<FQMethod> GRAPHICS_DISPOSERS;
static {
Set<FQMethod> gp = new HashSet<FQMethod>();
gp.add(new FQMethod("java/awt/image/BufferedImage", "getGraphics", new SignatureBuilder().withReturnType("java/awt/Graphics").toString()));
gp.add(new FQMethod("java/awt/Graphics", "create", new SignatureBuilder().withReturnType("java/awt/Graphics").toString()));
GRAPHICS_PRODUCERS = Collections.<FQMethod>unmodifiableSet(gp);
Set<FQMethod> gd = new HashSet<FQMethod>();
gd.add(new FQMethod("java/awt/Graphics", "dispose", SignatureBuilder.SIG_VOID_TO_VOID));
gd.add(new FQMethod("java/awt/Graphics2D", "dispose", SignatureBuilder.SIG_VOID_TO_VOID));
GRAPHICS_DISPOSERS = Collections.<FQMethod>unmodifiableSet(gd);
}
private final BugReporter bugReporter;
private OpcodeStack stack;
private Map<Integer, Integer> graphicsRegs; // reg->pc
public LingeringGraphicsObjects(BugReporter bugReporter) {
this.bugReporter = bugReporter;
}
/**
* overrides the visitor to set up the opcode stack
*
* @param classContext the context object of the currently parsed class
*/
@Override
public void visitClassContext(ClassContext classContext) {
try {
stack = new OpcodeStack();
graphicsRegs = new HashMap<Integer, Integer>(5);
super.visitClassContext(classContext);
} finally {
stack = null;
graphicsRegs = null;
}
}
/**
* overrides the visitor to check for registers that have been assigned Graphics objects that haven't been disposed
*
* @param obj the code block of the currently parsed method
*/
@Override
public void visitCode(Code obj) {
stack.resetForMethodEntry(this);
graphicsRegs.clear();
super.visitCode(obj);
for (Integer pc : graphicsRegs.values()) {
bugReporter.reportBug(new BugInstance(this, BugType.LGO_LINGERING_GRAPHICS_OBJECT.name(), NORMAL_PRIORITY).addClass(this).addMethod(this)
.addSourceLine(this, pc.intValue()));
}
}
@Override
public void sawOpcode(int seen) {
Integer sawNewGraphicsAt = null;
try {
stack.precomputation(this);
switch (seen) {
case ALOAD:
case ALOAD_0:
case ALOAD_1:
case ALOAD_2:
case ALOAD_3: {
int reg = RegisterUtils.getALoadReg(this, seen);
sawNewGraphicsAt = graphicsRegs.get(Integer.valueOf(reg));
}
break;
case ASTORE:
case ASTORE_0:
case ASTORE_1:
case ASTORE_2:
case ASTORE_3: {
if (stack.getStackDepth() > 0) {
OpcodeStack.Item item = stack.getStackItem(0);
sawNewGraphicsAt = (Integer) item.getUserValue();
Integer reg = Integer.valueOf(RegisterUtils.getAStoreReg(this, seen));
if (sawNewGraphicsAt != null) {
graphicsRegs.put(reg, sawNewGraphicsAt);
} else {
graphicsRegs.remove(reg);
}
sawNewGraphicsAt = null;
}
}
break;
case ARETURN:
if (stack.getStackDepth() > 0) {
OpcodeStack.Item item = stack.getStackItem(0);
graphicsRegs.remove(Integer.valueOf(item.getRegisterNumber()));
}
break;
case INVOKEVIRTUAL:
String clsName = getClassConstantOperand();
String methodName = getNameConstantOperand();
String methodSig = getSigConstantOperand();
FQMethod methodInfo = new FQMethod(clsName, methodName, methodSig);
if (GRAPHICS_PRODUCERS.contains(methodInfo)) {
sawNewGraphicsAt = Integer.valueOf(getPC());
} else if (GRAPHICS_DISPOSERS.contains(methodInfo) && (stack.getStackDepth() > 0)) {
OpcodeStack.Item item = stack.getStackItem(0);
graphicsRegs.remove(Integer.valueOf(item.getRegisterNumber()));
}
break;
default:
break;
}
} finally {
TernaryPatcher.pre(stack, seen);
stack.sawOpcode(this, seen);
TernaryPatcher.post(stack, seen);
if ((sawNewGraphicsAt != null) && (stack.getStackDepth() > 0)) {
OpcodeStack.Item item = stack.getStackItem(0);
item.setUserValue(sawNewGraphicsAt);
}
}
}
}