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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.program.mutators;
import dexfuzz.Log;
import dexfuzz.MutationStats;
import dexfuzz.program.MInsn;
import dexfuzz.program.MutatableCode;
import dexfuzz.program.Mutation;
import dexfuzz.rawdex.formats.ContainsConst;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
public class ConstantValueChanger extends CodeMutator {
/**
* Every CodeMutator has an AssociatedMutation, representing the
* mutation that this CodeMutator can perform, to allow separate
* generateMutation() and applyMutation() phases, allowing serialization.
*/
public static class AssociatedMutation extends Mutation {
public int constInsnIdx;
public long newConstant;
@Override
public String getString() {
StringBuilder builder = new StringBuilder();
builder.append(constInsnIdx).append(" ");
builder.append(newConstant);
return builder.toString();
}
@Override
public void parseString(String[] elements) {
constInsnIdx = Integer.parseInt(elements[2]);
newConstant = Long.parseLong(elements[3]);
}
}
// The following two methods are here for the benefit of MutationSerializer,
// so it can create a CodeMutator and get the correct associated Mutation, as it
// reads in mutations from a dump of mutations.
@Override
public Mutation getNewMutation() {
return new AssociatedMutation();
}
public ConstantValueChanger() { }
public ConstantValueChanger(Random rng, MutationStats stats, List<Mutation> mutations) {
super(rng, stats, mutations);
likelihood = 70;
}
// A cache that should only exist between generateMutation() and applyMutation(),
// or be created at the start of applyMutation(), if we're reading in mutations from
// a file.
private List<MInsn> constInsns = null;
private void generateCachedConstInsns(MutatableCode mutatableCode) {
if (constInsns != null) {
return;
}
constInsns = new ArrayList<MInsn>();
for (MInsn mInsn : mutatableCode.getInstructions()) {
if (mInsn.insn.info.format instanceof ContainsConst) {
constInsns.add(mInsn);
}
}
}
@Override
protected boolean canMutate(MutatableCode mutatableCode) {
for (MInsn mInsn : mutatableCode.getInstructions()) {
if (mInsn.insn.info.format instanceof ContainsConst) {
return true;
}
}
Log.debug("Method contains no const instructions.");
return false;
}
@Override
protected Mutation generateMutation(MutatableCode mutatableCode) {
generateCachedConstInsns(mutatableCode);
// Pick a random const instruction.
int constInsnIdx = rng.nextInt(constInsns.size());
MInsn constInsn = constInsns.get(constInsnIdx);
// Get the constant.
long oldConstant = ((ContainsConst)constInsn.insn.info.format).getConst(constInsn.insn);
long newConstant = oldConstant;
// Make a new constant.
while (newConstant == oldConstant) {
newConstant = rng.nextLong()
% ((ContainsConst)constInsn.insn.info.format).getConstRange();
}
AssociatedMutation mutation = new AssociatedMutation();
mutation.setup(this.getClass(), mutatableCode);
mutation.constInsnIdx = constInsnIdx;
mutation.newConstant = newConstant;
return mutation;
}
@Override
protected void applyMutation(Mutation uncastMutation) {
// Cast the Mutation to our AssociatedMutation, so we can access its fields.
AssociatedMutation mutation = (AssociatedMutation) uncastMutation;
MutatableCode mutatableCode = mutation.mutatableCode;
generateCachedConstInsns(mutatableCode);
MInsn constInsn = constInsns.get(mutation.constInsnIdx);
long oldConstant = ((ContainsConst)constInsn.insn.info.format).getConst(constInsn.insn);
Log.info("Changed constant value #" + oldConstant + " to #" + mutation.newConstant
+ " in " + constInsn);
stats.incrementStat("Changed constant value");
// Set the new constant.
((ContainsConst)constInsn.insn.info.format).setConst(constInsn.insn, mutation.newConstant);
// Clear cache.
constInsns = null;
}
}
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