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.Opcode;
  
  import java.util.List;
  import java.util.Random;
  
  public class InstructionDuplicator 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 insnToDuplicateIdx;
  
      @Override
      public String getString() {
        return Integer.toString(insnToDuplicateIdx);
      }
  
      @Override
      public void parseString(String[] elements) {
        insnToDuplicateIdx = 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 InstructionDuplicator() { }
  
    public InstructionDuplicator(Random rng, MutationStats stats, List<Mutation> mutations) {
      super(rng, stats, mutations);
      likelihood = 80;
    }
  
    @Override
    protected Mutation generateMutation(MutatableCode mutatableCode) {
      boolean foundInsn = false;
      int insnIdx = 0;
  
      while (!foundInsn) {
        // Pick an instruction at random...
        insnIdx = rng.nextInt(mutatableCode.getInstructionCount());
        MInsn oldInsn = mutatableCode.getInstructionAt(insnIdx);
        foundInsn = true;
        Opcode opcode = oldInsn.insn.info.opcode;
        // ...check it's a legal instruction to duplicate.
        if (opcode == Opcode.SPARSE_SWITCH || opcode == Opcode.PACKED_SWITCH
            || opcode == Opcode.FILL_ARRAY_DATA || oldInsn.insn.justRaw) {
          foundInsn = false;
        }
      }
  
      AssociatedMutation mutation = new AssociatedMutation();
      mutation.setup(this.getClass(), mutatableCode);
      mutation.insnToDuplicateIdx = insnIdx;
      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;
  
      MInsn oldInsn = mutatableCode.getInstructionAt(mutation.insnToDuplicateIdx);
  
      MInsn newInsn = oldInsn.clone();
  
      Log.info("Duplicating " + oldInsn);
  
      stats.incrementStat("Duplicated instruction");
  
      mutatableCode.insertInstructionAt(newInsn, mutation.insnToDuplicateIdx);
    }
  }
  