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/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package dexfuzz.rawdex;
/**
* Tracks the original and updated positions of a RawDexObject when it is
* parsed in from a DEX file, and written out to a mutated DEX file.
*/
public class Offsettable {
/**
* The position of this Offsettable's item when it was read in.
*/
private int originalPosition;
/**
* Set as we write out any Offsettable, so the Offset knows what its
* new value should be.
*/
private int newPosition;
/**
* The actual Item this Offsettable contains.
*/
private RawDexObject item;
/**
* Set either when getOriginalPosition() is called by the OffsetTracker
* to put the location in the offsettable map, so when Offsets are being
* associated, they know which Offsettable to point at.
* Or when an Offsettable is created that is marked as new, so we don't
* need to know its original position, because an Offset will be directly
* associated with it.
*/
private boolean originalPositionKnown;
/**
* Set when we calculate the new position of this Offsettable as the file is
* being output.
*/
private boolean updated;
/**
* Only the OffsetTracker should be able to create a new Offsettable.
*/
public Offsettable(RawDexObject item, boolean isNew) {
this.item = item;
if (isNew) {
// We no longer care about the original position of the Offsettable, because
// we are at the stage where we manually point Offsets at Offsettables, and
// don't need to use the OffsetTracker's offsettable map.
// So just lie and say we know it now.
originalPositionKnown = true;
}
}
public RawDexObject getItem() {
return item;
}
/**
* Gets the offset from the beginning of the file to the RawDexObject this Offsettable
* contains, when the file was originally read.
* Called when we're associating Offsets with Offsettables using the OffsetTracker's
* offsettable map.
*/
public int getOriginalPosition() {
if (!originalPositionKnown) {
throw new Error("Cannot get the original position of an Offsettable when not yet set.");
}
return originalPosition;
}
public void setOriginalPosition(int pos) {
originalPosition = pos;
originalPositionKnown = true;
}
/**
* Get the new position of this Offsettable, once it's been written out to the output file.
*/
public int getNewPosition() {
if (!updated) {
throw new Error("Cannot request new position before it has been set!");
}
return newPosition;
}
/**
* Record the new position of this Offsettable, as it is written out to the output file.
*/
public void setNewPosition(int pos) {
if (!updated) {
newPosition = pos;
updated = true;
} else {
throw new Error("Cannot update an Offsettable twice!");
}
}
public boolean readyForFinalOffsetToBeWritten() {
return (originalPositionKnown && updated);
}
}
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