text: /*
   * Copyright (C) 2019 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.
   */
  
  #define LOG_TAG "TokenHasher"
  
  #include "TokenHasher.h"
  
  #include <android-base/logging.h>
  #include <openssl/sha.h>
  
  #include "NeuralNetworks.h"
  
  namespace android {
  namespace nn {
  
  TokenHasher::TokenHasher(const uint8_t* token) : mIsError(token == nullptr) {
      if (mIsError) {
          return;
      }
      if (SHA256_Init(&mHasher) == 0 ||
          SHA256_Update(&mHasher, token, ANEURALNETWORKS_BYTE_SIZE_OF_CACHE_TOKEN) == 0) {
          mIsError = true;
      }
  }
  
  bool TokenHasher::update(const void* bytes, size_t length) {
      CHECK(!mIsError) << "Calling update on an token in error state";
      if (SHA256_Update(&mHasher, bytes, length) == 0) {
          mIsError = true;
          return false;
      }
      return true;
  }
  
  bool TokenHasher::finish() {
      CHECK(!mIsError) << "Calling finish on an token in error state";
      static_assert(SHA256_DIGEST_LENGTH == ANEURALNETWORKS_BYTE_SIZE_OF_CACHE_TOKEN,
                    "SHA256_DIGEST_LENGTH != ANEURALNETWORKS_BYTE_SIZE_OF_CACHE_TOKEN");
      mToken.resize(ANEURALNETWORKS_BYTE_SIZE_OF_CACHE_TOKEN);
      if (SHA256_Final(mToken.data(), &mHasher) == 0) {
          mToken.clear();
          mIsError = true;
          return false;
      }
      return true;
  }
  
  const uint8_t* TokenHasher::getCacheToken() const {
      if (mIsError) {
          return nullptr;
      } else {
          CHECK(!mToken.empty());
          return mToken.data();
      }
  }
  
  }  // namespace nn
  }  // namespace android
  