/*
* FindBugs - Find bugs in Java programs
* Copyright (C) 2003,2004 University of Maryland
*
* 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 edu.umd.cs.findbugs.detect;
import org.apache.bcel.Constants;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.Instruction;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.InvokeInstruction;
import edu.umd.cs.findbugs.ba.BasicBlock;
import edu.umd.cs.findbugs.ba.DataflowAnalysisException;
import edu.umd.cs.findbugs.ba.Location;
import edu.umd.cs.findbugs.ba.ResourceValue;
import edu.umd.cs.findbugs.ba.ResourceValueFrame;
import edu.umd.cs.findbugs.ba.ResourceValueFrameModelingVisitor;
/**
* A visitor to model the effect of instructions on the status of the resource
* (in this case, Streams).
*/
public class StreamFrameModelingVisitor extends ResourceValueFrameModelingVisitor {
private final StreamResourceTracker resourceTracker;
private final Stream stream;
private Location location;
public StreamFrameModelingVisitor(ConstantPoolGen cpg, StreamResourceTracker resourceTracker, Stream stream) {
super(cpg);
this.resourceTracker = resourceTracker;
this.stream = stream;
}
@Override
public void transferInstruction(InstructionHandle handle, BasicBlock basicBlock) throws DataflowAnalysisException {
// Record what Location we are analyzing
this.location = new Location(handle, basicBlock);
final Instruction ins = handle.getInstruction();
final ResourceValueFrame frame = getFrame();
int status = -1;
boolean created = false;
// Is a resource created, opened, or closed by this instruction?
Location creationPoint = stream.getLocation();
if (handle == creationPoint.getHandle() && basicBlock == creationPoint.getBasicBlock()) {
// Resource creation
if (stream.isOpenOnCreation()) {
status = ResourceValueFrame.OPEN;
stream.setOpenLocation(location);
resourceTracker.addStreamOpenLocation(location, stream);
} else {
status = ResourceValueFrame.CREATED;
}
created = true;
} else if (resourceTracker.isResourceOpen(basicBlock, handle, cpg, stream, frame)) {
// Resource opened
status = ResourceValueFrame.OPEN;
stream.setOpenLocation(location);
resourceTracker.addStreamOpenLocation(location, stream);
} else if (resourceTracker.isResourceClose(basicBlock, handle, cpg, stream, frame)) {
// Resource closed
status = ResourceValueFrame.CLOSED;
}
// Model use of instance values in frame slots
analyzeInstruction(ins);
// If needed, update frame status
if (status != -1) {
frame.setStatus(status);
if (created) {
frame.setValue(frame.getNumSlots() - 1, ResourceValue.instance());
}
}
}
@Override
protected boolean instanceEscapes(InvokeInstruction inv, int instanceArgNum) {
ConstantPoolGen cpg = getCPG();
String className = inv.getClassName(cpg);
// System.out.print("[Passed as arg="+instanceArgNum+" at " + inv +
// "]");
boolean escapes = (inv.getOpcode() == Constants.INVOKESTATIC || instanceArgNum != 0);
String methodName = inv.getMethodName(cpg);
String methodSig = inv.getSignature(cpg);
if (inv.getOpcode() == Constants.INVOKEVIRTUAL
&& (methodName.equals("load") || methodName.equals("loadFromXml") || methodName.equals("store") || methodName
.equals("save")) && className.equals("java.util.Properties")) {
escapes = false;
}
if (inv.getOpcode() == Constants.INVOKEVIRTUAL && (methodName.equals("load") || methodName.equals("store"))
&& className.equals("java.security.KeyStore")) {
escapes = false;
}
if (inv.getOpcode() == Constants.INVOKEVIRTUAL && "getChannel".equals(methodName)
&& "()Ljava/nio/channels/FileChannel;".equals(methodSig)) {
escapes = true;
}
if (FindOpenStream.DEBUG && escapes) {
System.out.println("ESCAPE at " + location + " at call to " + className + "." + methodName + ":" + methodSig);
}
// Record the fact that this might be a stream escape
if (stream.getOpenLocation() != null) {
resourceTracker.addStreamEscape(stream, location);
}
return escapes;
}
}