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 java.util.ArrayList;
  import java.util.List;
  import java.util.Random;
  
  public class ConversionRepeater 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 conversionInsnIdx;
  
      @Override
      public String getString() {
        return Integer.toString(conversionInsnIdx);
      }
  
      @Override
      public void parseString(String[] elements) {
        conversionInsnIdx = Integer.parseInt(elements[2]);
      }
    }
  
    // 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 ConversionRepeater() { }
  
    public ConversionRepeater(Random rng, MutationStats stats, List<Mutation> mutations) {
      super(rng, stats, mutations);
      likelihood = 50;
    }
  
    // 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> conversionInsns = null;
  
    private void generateCachedConversionInsns(MutatableCode mutatableCode) {
      if (conversionInsns != null) {
        return;
      }
  
      conversionInsns = new ArrayList<MInsn>();
  
      for (MInsn mInsn : mutatableCode.getInstructions()) {
        if (isConversionInstruction(mInsn)) {
          conversionInsns.add(mInsn);
        }
      }
    }
  
    @Override
    protected boolean canMutate(MutatableCode mutatableCode) {
      for (MInsn mInsn : mutatableCode.getInstructions()) {
        if (isConversionInstruction(mInsn)) {
          return true;
        }
      }
  
      Log.debug("No conversion operations in method, skipping...");
      return false;
    }
  
    @Override
    protected Mutation generateMutation(MutatableCode mutatableCode) {
      generateCachedConversionInsns(mutatableCode);
      int conversionInsnIdx = rng.nextInt(conversionInsns.size());
      AssociatedMutation mutation = new AssociatedMutation();
      mutation.setup(this.getClass(), mutatableCode);
      mutation.conversionInsnIdx = conversionInsnIdx;
      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;
  
      generateCachedConversionInsns(mutatableCode);
  
      MInsn originalInsn = conversionInsns.get(mutation.conversionInsnIdx);
  
      // We want to create two new instructions:
      // [original conversion] eg float-to-int
      // NEW: [there] eg int-to-float (with vregs of first inst swapped)
      // NEW: [back] eg float-to-int
  
      // Create the "there" instruction.
      MInsn newInsnThere = originalInsn.clone();
  
      // Flip the opcode.
      Opcode oppositeOpcode = null;
      switch (newInsnThere.insn.info.opcode) {
        case INT_TO_LONG:
          oppositeOpcode = Opcode.LONG_TO_INT;
          break;
        case INT_TO_FLOAT:
          oppositeOpcode = Opcode.FLOAT_TO_INT;
          break;
        case INT_TO_DOUBLE:
          oppositeOpcode = Opcode.DOUBLE_TO_INT;
          break;
        case LONG_TO_INT:
          oppositeOpcode = Opcode.INT_TO_LONG;
          break;
        case LONG_TO_FLOAT:
          oppositeOpcode = Opcode.FLOAT_TO_LONG;
          break;
        case LONG_TO_DOUBLE:
          oppositeOpcode = Opcode.DOUBLE_TO_LONG;
          break;
        case FLOAT_TO_INT:
          oppositeOpcode = Opcode.INT_TO_FLOAT;
          break;
        case FLOAT_TO_LONG:
          oppositeOpcode = Opcode.LONG_TO_FLOAT;
          break;
        case FLOAT_TO_DOUBLE:
          oppositeOpcode = Opcode.DOUBLE_TO_FLOAT;
          break;
        case DOUBLE_TO_INT:
          oppositeOpcode = Opcode.INT_TO_DOUBLE;
          break;
        case DOUBLE_TO_LONG:
          oppositeOpcode = Opcode.LONG_TO_DOUBLE;
          break;
        case DOUBLE_TO_FLOAT:
          oppositeOpcode = Opcode.FLOAT_TO_DOUBLE;
          break;
        default:
          Log.errorAndQuit(
              "Trying to repeat the conversion in an insn that is not a conversion insn.");
      }
      newInsnThere.insn.info = Instruction.getOpcodeInfo(oppositeOpcode);
  
      // Swap the vregs.
      long tempReg = newInsnThere.insn.vregA;
      newInsnThere.insn.vregA = newInsnThere.insn.vregB;
      newInsnThere.insn.vregB = tempReg;
  
      // Create the "back" instruction.
      MInsn newInsnBack = originalInsn.clone();
  
      // Get the index into the MutatableCode's mInsns list for this insn.
      int originalInsnIdx = mutatableCode.getInstructionIndex(originalInsn);
  
      // Insert the new instructions.
      mutatableCode.insertInstructionAfter(newInsnThere, originalInsnIdx);
      mutatableCode.insertInstructionAfter(newInsnBack, originalInsnIdx + 1);
  
      Log.info("Performing conversion repetition for " + originalInsn);
  
      stats.incrementStat("Repeating conversion");
  
      // Clear the cache.
      conversionInsns = null;
    }
  
    private boolean isConversionInstruction(MInsn mInsn) {
      Opcode opcode = mInsn.insn.info.opcode;
      if (Opcode.isBetween(opcode, Opcode.INT_TO_LONG, Opcode.DOUBLE_TO_FLOAT)) {
        return true;
      }
      return false;
    }
  }
  