payload_generator/extent_utils.h

// Copyright 2015 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UPDATE_ENGINE_PAYLOAD_GENERATOR_EXTENT_UTILS_H_
#define UPDATE_ENGINE_PAYLOAD_GENERATOR_EXTENT_UTILS_H_

#include <vector>

#include "update_engine/update_metadata.pb.h"

// Utility functions for manipulating Extents and lists of blocks.

namespace chromeos_update_engine {

// |block| must either be the next block in the last extent or a block
// in the next extent. This function will not handle inserting block
// into an arbitrary place in the extents.
void AppendBlockToExtents(std::vector<Extent>* extents, uint64_t block);

// Get/SetElement are intentionally overloaded so that templated functions
// can accept either type of collection of Extents.
Extent GetElement(const std::vector<Extent>& collection, size_t index);
Extent GetElement(
    const google::protobuf::RepeatedPtrField<Extent>& collection,
    size_t index);

template<typename T>
uint64_t BlocksInExtents(const T& collection) {
  uint64_t ret = 0;
  for (size_t i = 0; i < static_cast<size_t>(collection.size()); ++i) {
    ret += GetElement(collection, i).num_blocks();
  }
  return ret;
}

// Takes a vector of extents and normalizes those extents. Expects the extents
// to be sorted by start block. E.g. if |extents| is [(1, 2), (3, 5), (10, 2)]
// then |extents| will be changed to [(1, 7), (10, 2)].
void NormalizeExtents(std::vector<Extent>* extents);

// Return a subsequence of the list of blocks passed. Both the passed list of
// blocks |extents| and the return value are expressed as a list of Extent, not
// blocks. The returned list skips the first |block_offset| blocks from the
// |extents| and cotains |block_count| blocks (or less if |extents| is shorter).
std::vector<Extent> ExtentsSublist(const std::vector<Extent>& extents,
                                   uint64_t block_offset, uint64_t block_count);

bool operator==(const Extent& a, const Extent& b);

}  // namespace chromeos_update_engine

#endif  // UPDATE_ENGINE_PAYLOAD_GENERATOR_EXTENT_UTILS_H_