update_engine/payload_generator/ab_generator.cc

//
// Copyright (C) 2015 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.
//

#include "update_engine/payload_generator/ab_generator.h"

#include <algorithm>
#include <utility>

#include <base/strings/stringprintf.h>

#include "update_engine/common/hash_calculator.h"
#include "update_engine/common/utils.h"
#include "update_engine/payload_consumer/payload_constants.h"
#include "update_engine/payload_generator/annotated_operation.h"
#include "update_engine/payload_generator/bzip.h"
#include "update_engine/payload_generator/delta_diff_generator.h"
#include "update_engine/payload_generator/delta_diff_utils.h"

using chromeos_update_engine::diff_utils::IsAReplaceOperation;
using std::string;
using std::vector;

namespace chromeos_update_engine {

bool ABGenerator::GenerateOperations(const PayloadGenerationConfig& config,
                                     const PartitionConfig& old_part,
                                     const PartitionConfig& new_part,
                                     BlobFileWriter* blob_file,
                                     vector<AnnotatedOperation>* aops) {
  TEST_AND_RETURN_FALSE(old_part.name == new_part.name);

  ssize_t hard_chunk_blocks =
      (config.hard_chunk_size == -1
           ? -1
           : config.hard_chunk_size / config.block_size);
  size_t soft_chunk_blocks = config.soft_chunk_size / config.block_size;

  aops->clear();
  TEST_AND_RETURN_FALSE(diff_utils::DeltaReadPartition(aops,
                                                       old_part,
                                                       new_part,
                                                       hard_chunk_blocks,
                                                       soft_chunk_blocks,
                                                       config.version,
                                                       blob_file));
  LOG(INFO) << "done reading " << new_part.name;

  SortOperationsByDestination(aops);

  // Use the soft_chunk_size when merging operations to prevent merging all
  // the operations into a huge one if there's no hard limit.
  size_t merge_chunk_blocks = soft_chunk_blocks;
  if (hard_chunk_blocks != -1 &&
      static_cast<size_t>(hard_chunk_blocks) < soft_chunk_blocks) {
    merge_chunk_blocks = hard_chunk_blocks;
  }

  LOG(INFO) << "Merging " << aops->size() << " operations.";
  TEST_AND_RETURN_FALSE(MergeOperations(
      aops, config.version, merge_chunk_blocks, new_part.path, blob_file));
  LOG(INFO) << aops->size() << " operations after merge.";

  if (config.version.minor >= kOpSrcHashMinorPayloadVersion)
    TEST_AND_RETURN_FALSE(AddSourceHash(aops, old_part.path));

  return true;
}

void ABGenerator::SortOperationsByDestination(
    vector<AnnotatedOperation>* aops) {
  sort(aops->begin(), aops->end(), diff_utils::CompareAopsByDestination);
}

bool ABGenerator::FragmentOperations(const PayloadVersion& version,
                                     vector<AnnotatedOperation>* aops,
                                     const string& target_part_path,
                                     BlobFileWriter* blob_file) {
  vector<AnnotatedOperation> fragmented_aops;
  for (const AnnotatedOperation& aop : *aops) {
    // Only do split if the operation has more than one dst extents.
    if (aop.op.dst_extents_size() > 1) {
      if (aop.op.type() == InstallOperation::SOURCE_COPY) {
        TEST_AND_RETURN_FALSE(SplitSourceCopy(aop, &fragmented_aops));
        continue;
      }
      if (IsAReplaceOperation(aop.op.type())) {
        TEST_AND_RETURN_FALSE(SplitAReplaceOp(
            version, aop, target_part_path, &fragmented_aops, blob_file));
        continue;
      }
    }
    fragmented_aops.push_back(aop);
  }
  *aops = std::move(fragmented_aops);
  return true;
}

bool ABGenerator::SplitSourceCopy(const AnnotatedOperation& original_aop,
                                  vector<AnnotatedOperation>* result_aops) {
  InstallOperation original_op = original_aop.op;
  TEST_AND_RETURN_FALSE(original_op.type() == InstallOperation::SOURCE_COPY);
  // Keeps track of the index of curr_src_ext.
  int curr_src_ext_index = 0;
  Extent curr_src_ext = original_op.src_extents(curr_src_ext_index);
  for (int i = 0; i < original_op.dst_extents_size(); i++) {
    const Extent& dst_ext = original_op.dst_extents(i);
    // The new operation which will have only one dst extent.
    InstallOperation new_op;
    uint64_t blocks_left = dst_ext.num_blocks();
    while (blocks_left > 0) {
      if (curr_src_ext.num_blocks() <= blocks_left) {
        // If the curr_src_ext is smaller than dst_ext, add it.
        blocks_left -= curr_src_ext.num_blocks();
        *(new_op.add_src_extents()) = curr_src_ext;
        if (curr_src_ext_index + 1 < original_op.src_extents().size()) {
          curr_src_ext = original_op.src_extents(++curr_src_ext_index);
        } else {
          break;
        }
      } else {
        // Split src_exts that are bigger than the dst_ext we're dealing with.
        Extent first_ext;
        first_ext.set_num_blocks(blocks_left);
        first_ext.set_start_block(curr_src_ext.start_block());
        *(new_op.add_src_extents()) = first_ext;
        // Keep the second half of the split op.
        curr_src_ext.set_num_blocks(curr_src_ext.num_blocks() - blocks_left);
        curr_src_ext.set_start_block(curr_src_ext.start_block() + blocks_left);
        blocks_left -= first_ext.num_blocks();
      }
    }
    // Fix up our new operation and add it to the results.
    new_op.set_type(InstallOperation::SOURCE_COPY);
    *(new_op.add_dst_extents()) = dst_ext;

    AnnotatedOperation new_aop;
    new_aop.op = new_op;
    new_aop.name = base::StringPrintf("%s:%d", original_aop.name.c_str(), i);
    result_aops->push_back(new_aop);
  }
  if (curr_src_ext_index != original_op.src_extents().size() - 1) {
    LOG(FATAL) << "Incorrectly split SOURCE_COPY operation. Did not use all "
               << "source extents.";
  }
  return true;
}

bool ABGenerator::SplitAReplaceOp(const PayloadVersion& version,
                                  const AnnotatedOperation& original_aop,
                                  const string& target_part_path,
                                  vector<AnnotatedOperation>* result_aops,
                                  BlobFileWriter* blob_file) {
  InstallOperation original_op = original_aop.op;
  TEST_AND_RETURN_FALSE(IsAReplaceOperation(original_op.type()));
  const bool is_replace = original_op.type() == InstallOperation::REPLACE;

  uint64_t data_offset = original_op.data_offset();
  for (int i = 0; i < original_op.dst_extents_size(); i++) {
    const Extent& dst_ext = original_op.dst_extents(i);
    // Make a new operation with only one dst extent.
    InstallOperation new_op;
    *(new_op.add_dst_extents()) = dst_ext;
    uint64_t data_size = dst_ext.num_blocks() * kBlockSize;
    // If this is a REPLACE, attempt to reuse portions of the existing blob.
    if (is_replace) {
      new_op.set_type(InstallOperation::REPLACE);
      new_op.set_data_length(data_size);
      new_op.set_data_offset(data_offset);
      data_offset += data_size;
    }

    AnnotatedOperation new_aop;
    new_aop.op = new_op;
    new_aop.name = base::StringPrintf("%s:%d", original_aop.name.c_str(), i);
    TEST_AND_RETURN_FALSE(
        AddDataAndSetType(&new_aop, version, target_part_path, blob_file));

    result_aops->push_back(new_aop);
  }
  return true;
}

bool ABGenerator::MergeOperations(vector<AnnotatedOperation>* aops,
                                  const PayloadVersion& version,
                                  size_t chunk_blocks,
                                  const string& target_part_path,
                                  BlobFileWriter* blob_file) {
  vector<AnnotatedOperation> new_aops;
  for (const AnnotatedOperation& curr_aop : *aops) {
    if (new_aops.empty()) {
      new_aops.push_back(curr_aop);
      continue;
    }
    AnnotatedOperation& last_aop = new_aops.back();
    bool last_is_a_replace = IsAReplaceOperation(last_aop.op.type());

    if (last_aop.op.dst_extents_size() <= 0 ||
        curr_aop.op.dst_extents_size() <= 0) {
      new_aops.push_back(curr_aop);
      continue;
    }
    uint32_t last_dst_idx = last_aop.op.dst_extents_size() - 1;
    uint32_t last_end_block =
        last_aop.op.dst_extents(last_dst_idx).start_block() +
        last_aop.op.dst_extents(last_dst_idx).num_blocks();
    uint32_t curr_start_block = curr_aop.op.dst_extents(0).start_block();
    uint32_t combined_block_count =
        last_aop.op.dst_extents(last_dst_idx).num_blocks() +
        curr_aop.op.dst_extents(0).num_blocks();
    bool is_a_replace = IsAReplaceOperation(curr_aop.op.type());

    bool is_delta_op = curr_aop.op.type() == InstallOperation::SOURCE_COPY;
    if (((is_delta_op && (last_aop.op.type() == curr_aop.op.type())) ||
         (is_a_replace && last_is_a_replace)) &&
        last_end_block == curr_start_block &&
        combined_block_count <= chunk_blocks) {
      // If the operations have the same type (which is a type that we can
      // merge), are contiguous, are fragmented to have one destination extent,
      // and their combined block count would be less than chunk size, merge
      // them.
      last_aop.name = base::StringPrintf(
          "%s,%s", last_aop.name.c_str(), curr_aop.name.c_str());

      if (is_delta_op) {
        ExtendExtents(last_aop.op.mutable_src_extents(),
                      curr_aop.op.src_extents());
      }
      ExtendExtents(last_aop.op.mutable_dst_extents(),
                    curr_aop.op.dst_extents());
      // Set the data length to zero so we know to add the blob later.
      if (is_a_replace)
        last_aop.op.set_data_length(0);
    } else {
      // Otherwise just include the extent as is.
      new_aops.push_back(curr_aop);
    }
  }

  // Set the blobs for REPLACE/REPLACE_BZ/REPLACE_XZ operations that have been
  // merged.
  for (AnnotatedOperation& curr_aop : new_aops) {
    if (curr_aop.op.data_length() == 0 &&
        IsAReplaceOperation(curr_aop.op.type())) {
      TEST_AND_RETURN_FALSE(
          AddDataAndSetType(&curr_aop, version, target_part_path, blob_file));
    }
  }

  *aops = new_aops;
  return true;
}

bool ABGenerator::AddDataAndSetType(AnnotatedOperation* aop,
                                    const PayloadVersion& version,
                                    const string& target_part_path,
                                    BlobFileWriter* blob_file) {
  TEST_AND_RETURN_FALSE(IsAReplaceOperation(aop->op.type()));

  vector<Extent> dst_extents;
  ExtentsToVector(aop->op.dst_extents(), &dst_extents);
  brillo::Blob data(utils::BlocksInExtents(dst_extents) * kBlockSize);
  TEST_AND_RETURN_FALSE(utils::ReadExtents(
      target_part_path, dst_extents, &data, data.size(), kBlockSize));

  brillo::Blob blob;
  InstallOperation::Type op_type;
  TEST_AND_RETURN_FALSE(
      diff_utils::GenerateBestFullOperation(data, version, &blob, &op_type));

  // If the operation doesn't point to a data blob or points to a data blob of
  // a different type then we add it.
  if (aop->op.type() != op_type || aop->op.data_length() != blob.size()) {
    aop->op.set_type(op_type);
    aop->SetOperationBlob(blob, blob_file);
  }

  return true;
}

bool ABGenerator::AddSourceHash(vector<AnnotatedOperation>* aops,
                                const string& source_part_path) {
  for (AnnotatedOperation& aop : *aops) {
    if (aop.op.src_extents_size() == 0)
      continue;

    vector<Extent> src_extents;
    ExtentsToVector(aop.op.src_extents(), &src_extents);
    brillo::Blob src_data, src_hash;
    uint64_t src_length =
        aop.op.has_src_length()
            ? aop.op.src_length()
            : utils::BlocksInExtents(aop.op.src_extents()) * kBlockSize;
    TEST_AND_RETURN_FALSE(utils::ReadExtents(
        source_part_path, src_extents, &src_data, src_length, kBlockSize));
    TEST_AND_RETURN_FALSE(HashCalculator::RawHashOfData(src_data, &src_hash));
    aop.op.set_src_sha256_hash(src_hash.data(), src_hash.size());
  }
  return true;
}

}  // namespace chromeos_update_engine