content: /*
   * 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.Instruction;
  import dexfuzz.rawdex.Opcode;
  import dexfuzz.rawdex.OpcodeInfo;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Random;
  
  public class ArithOpChanger 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 arithmeticInsnIdx;
      public int newOpcode;
  
      @Override
      public String getString() {
        StringBuilder builder = new StringBuilder();
        builder.append(arithmeticInsnIdx).append(" ");
        builder.append(newOpcode);
        return builder.toString();
      }
  
      @Override
      public void parseString(String[] elements) {
        arithmeticInsnIdx = Integer.parseInt(elements[2]);
        newOpcode = Integer.parseInt(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 ArithOpChanger() { }
  
    public ArithOpChanger(Random rng, MutationStats stats, List<Mutation> mutations) {
      super(rng, stats, mutations);
      likelihood = 75;
    }
  
    // 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> arithmeticInsns = null;
  
    private void generateCachedArithmeticInsns(MutatableCode mutatableCode) {
      if (arithmeticInsns != null) {
        return;
      }
  
      arithmeticInsns = new ArrayList<MInsn>();
  
      for (MInsn mInsn : mutatableCode.getInstructions()) {
        if (isArithmeticOperation(mInsn)) {
          arithmeticInsns.add(mInsn);
        }
      }
    }
  
    @Override
    protected boolean canMutate(MutatableCode mutatableCode) {
      for (MInsn mInsn : mutatableCode.getInstructions()) {
        if (isArithmeticOperation(mInsn)) {
          return true;
        }
      }
  
      Log.debug("No arithmetic operations in method, skipping...");
      return false;
    }
  
    @Override
    protected Mutation generateMutation(MutatableCode mutatableCode) {
      generateCachedArithmeticInsns(mutatableCode);
  
      int arithmeticInsnIdx = rng.nextInt(arithmeticInsns.size());
  
      MInsn randomInsn = arithmeticInsns.get(arithmeticInsnIdx);
  
      OpcodeInfo oldOpcodeInfo = randomInsn.insn.info;
  
      OpcodeInfo newOpcodeInfo = oldOpcodeInfo;
  
      while (newOpcodeInfo.value == oldOpcodeInfo.value) {
        newOpcodeInfo = Instruction.getOpcodeInfo(getLegalDifferentOpcode(randomInsn));
      }
  
      AssociatedMutation mutation = new AssociatedMutation();
      mutation.setup(this.getClass(), mutatableCode);
      mutation.arithmeticInsnIdx = arithmeticInsnIdx;
      mutation.newOpcode = newOpcodeInfo.value;
      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;
  
      generateCachedArithmeticInsns(mutatableCode);
  
      MInsn randomInsn = arithmeticInsns.get(mutation.arithmeticInsnIdx);
  
      String oldInsnString = randomInsn.toString();
  
      OpcodeInfo newOpcodeInfo = Instruction.getOpcodeInfo(mutation.newOpcode);
  
      randomInsn.insn.info = newOpcodeInfo;
  
      Log.info("Changed " + oldInsnString + " to " + randomInsn);
  
      stats.incrementStat("Changed arithmetic opcode");
  
      // Clear the cache.
      arithmeticInsns = null;
    }
  
    private boolean isArithmeticOperation(MInsn mInsn) {
      Opcode opcode = mInsn.insn.info.opcode;
      if (Opcode.isBetween(opcode, Opcode.ADD_INT, Opcode.USHR_INT_LIT8)) {
        return true;
      }
      return false;
    }
  
    private Opcode getLegalDifferentOpcode(MInsn mInsn) {
      Opcode opcode = mInsn.insn.info.opcode;
  
      for (List<Opcode> opcodeList : opcodeLists) {
        Opcode first = opcodeList.get(0);
        Opcode last = opcodeList.get(opcodeList.size() - 1);
        if (Opcode.isBetween(opcode, first, last)) {
          int newOpcodeIdx = rng.nextInt(opcodeList.size());
          return opcodeList.get(newOpcodeIdx);
        }
      }
  
      return opcode;
    }
  
    private static List<Opcode> intOpcodes = new ArrayList<Opcode>();
    private static List<Opcode> int2addrOpcodes = new ArrayList<Opcode>();
    private static List<Opcode> longOpcodes = new ArrayList<Opcode>();
    private static List<Opcode> long2addrOpcodes = new ArrayList<Opcode>();
    private static List<Opcode> floatOpcodes = new ArrayList<Opcode>();
    private static List<Opcode> float2addrOpcodes = new ArrayList<Opcode>();
    private static List<Opcode> doubleOpcodes = new ArrayList<Opcode>();
    private static List<Opcode> double2addrOpcodes = new ArrayList<Opcode>();
    private static List<Opcode> intLit8Opcodes = new ArrayList<Opcode>();
    private static List<Opcode> intLit16Opcodes = new ArrayList<Opcode>();
    private static List<List<Opcode>> opcodeLists = new ArrayList<List<Opcode>>();
  
    static {
      intOpcodes.add(Opcode.ADD_INT);
      intOpcodes.add(Opcode.SUB_INT);
      intOpcodes.add(Opcode.MUL_INT);
      intOpcodes.add(Opcode.DIV_INT);
      intOpcodes.add(Opcode.REM_INT);
      intOpcodes.add(Opcode.AND_INT);
      intOpcodes.add(Opcode.OR_INT);
      intOpcodes.add(Opcode.XOR_INT);
      intOpcodes.add(Opcode.SHL_INT);
      intOpcodes.add(Opcode.SHR_INT);
      intOpcodes.add(Opcode.USHR_INT);
  
      int2addrOpcodes.add(Opcode.ADD_INT_2ADDR);
      int2addrOpcodes.add(Opcode.SUB_INT_2ADDR);
      int2addrOpcodes.add(Opcode.MUL_INT_2ADDR);
      int2addrOpcodes.add(Opcode.DIV_INT_2ADDR);
      int2addrOpcodes.add(Opcode.REM_INT_2ADDR);
      int2addrOpcodes.add(Opcode.AND_INT_2ADDR);
      int2addrOpcodes.add(Opcode.OR_INT_2ADDR);
      int2addrOpcodes.add(Opcode.XOR_INT_2ADDR);
      int2addrOpcodes.add(Opcode.SHL_INT_2ADDR);
      int2addrOpcodes.add(Opcode.SHR_INT_2ADDR);
      int2addrOpcodes.add(Opcode.USHR_INT_2ADDR);
  
      longOpcodes.add(Opcode.ADD_LONG);
      longOpcodes.add(Opcode.SUB_LONG);
      longOpcodes.add(Opcode.MUL_LONG);
      longOpcodes.add(Opcode.DIV_LONG);
      longOpcodes.add(Opcode.REM_LONG);
      longOpcodes.add(Opcode.AND_LONG);
      longOpcodes.add(Opcode.OR_LONG);
      longOpcodes.add(Opcode.XOR_LONG);
      longOpcodes.add(Opcode.SHL_LONG);
      longOpcodes.add(Opcode.SHR_LONG);
      longOpcodes.add(Opcode.USHR_LONG);
  
      long2addrOpcodes.add(Opcode.ADD_LONG_2ADDR);
      long2addrOpcodes.add(Opcode.SUB_LONG_2ADDR);
      long2addrOpcodes.add(Opcode.MUL_LONG_2ADDR);
      long2addrOpcodes.add(Opcode.DIV_LONG_2ADDR);
      long2addrOpcodes.add(Opcode.REM_LONG_2ADDR);
      long2addrOpcodes.add(Opcode.AND_LONG_2ADDR);
      long2addrOpcodes.add(Opcode.OR_LONG_2ADDR);
      long2addrOpcodes.add(Opcode.XOR_LONG_2ADDR);
      long2addrOpcodes.add(Opcode.SHL_LONG_2ADDR);
      long2addrOpcodes.add(Opcode.SHR_LONG_2ADDR);
      long2addrOpcodes.add(Opcode.USHR_LONG_2ADDR);
  
      floatOpcodes.add(Opcode.ADD_FLOAT);
      floatOpcodes.add(Opcode.SUB_FLOAT);
      floatOpcodes.add(Opcode.MUL_FLOAT);
      floatOpcodes.add(Opcode.DIV_FLOAT);
      floatOpcodes.add(Opcode.REM_FLOAT);
  
      float2addrOpcodes.add(Opcode.ADD_FLOAT_2ADDR);
      float2addrOpcodes.add(Opcode.SUB_FLOAT_2ADDR);
      float2addrOpcodes.add(Opcode.MUL_FLOAT_2ADDR);
      float2addrOpcodes.add(Opcode.DIV_FLOAT_2ADDR);
      float2addrOpcodes.add(Opcode.REM_FLOAT_2ADDR);
  
      doubleOpcodes.add(Opcode.ADD_DOUBLE);
      doubleOpcodes.add(Opcode.SUB_DOUBLE);
      doubleOpcodes.add(Opcode.MUL_DOUBLE);
      doubleOpcodes.add(Opcode.DIV_DOUBLE);
      doubleOpcodes.add(Opcode.REM_DOUBLE);
  
      double2addrOpcodes.add(Opcode.ADD_DOUBLE_2ADDR);
      double2addrOpcodes.add(Opcode.SUB_DOUBLE_2ADDR);
      double2addrOpcodes.add(Opcode.MUL_DOUBLE_2ADDR);
      double2addrOpcodes.add(Opcode.DIV_DOUBLE_2ADDR);
      double2addrOpcodes.add(Opcode.REM_DOUBLE_2ADDR);
  
      intLit8Opcodes.add(Opcode.ADD_INT_LIT8);
      intLit8Opcodes.add(Opcode.RSUB_INT_LIT8);
      intLit8Opcodes.add(Opcode.MUL_INT_LIT8);
      intLit8Opcodes.add(Opcode.DIV_INT_LIT8);
      intLit8Opcodes.add(Opcode.REM_INT_LIT8);
      intLit8Opcodes.add(Opcode.AND_INT_LIT8);
      intLit8Opcodes.add(Opcode.OR_INT_LIT8);
      intLit8Opcodes.add(Opcode.XOR_INT_LIT8);
      intLit8Opcodes.add(Opcode.SHL_INT_LIT8);
      intLit8Opcodes.add(Opcode.SHR_INT_LIT8);
      intLit8Opcodes.add(Opcode.USHR_INT_LIT8);
  
      intLit16Opcodes.add(Opcode.ADD_INT_LIT16);
      intLit16Opcodes.add(Opcode.RSUB_INT);
      intLit16Opcodes.add(Opcode.MUL_INT_LIT16);
      intLit16Opcodes.add(Opcode.DIV_INT_LIT16);
      intLit16Opcodes.add(Opcode.REM_INT_LIT16);
      intLit16Opcodes.add(Opcode.AND_INT_LIT16);
      intLit16Opcodes.add(Opcode.OR_INT_LIT16);
      intLit16Opcodes.add(Opcode.XOR_INT_LIT16);
  
      opcodeLists.add(intOpcodes);
      opcodeLists.add(longOpcodes);
      opcodeLists.add(floatOpcodes);
      opcodeLists.add(doubleOpcodes);
      opcodeLists.add(int2addrOpcodes);
      opcodeLists.add(long2addrOpcodes);
      opcodeLists.add(float2addrOpcodes);
      opcodeLists.add(double2addrOpcodes);
      opcodeLists.add(intLit8Opcodes);
      opcodeLists.add(intLit16Opcodes);
    }
  }
  