Method decrypt_aligned_extent

src/librbd/crypto/CryptoInterface.h:64–119

  }

  inline int decrypt_aligned_extent(io::ReadExtent& extent,
                                    uint64_t image_offset) {
    if (extent.length == 0 || extent.bl.length() == 0) {
      return 0;
    }

    if (extent.extent_map.empty()) {
      extent.extent_map.emplace_back(extent.offset, extent.bl.length());
    }

    ceph::bufferlist result_bl;
    io::Extents result_extent_map;

    ceph::bufferlist curr_block_bl;
    auto curr_offset = extent.offset;
    auto curr_block_start_offset = curr_offset;
    auto curr_block_end_offset = curr_offset;

    // this will add a final loop iteration for decrypting the last extent
    extent.extent_map.emplace_back(
            extent.offset + extent.length + get_block_size(), 0);

    for (auto [off, len]: extent.extent_map) {
      auto [aligned_off, aligned_len] = align(off, len);
      if (aligned_off > curr_block_end_offset) {
        curr_block_bl.append_zero(curr_block_end_offset - curr_offset);
        auto curr_block_length = curr_block_bl.length();
        if (curr_block_length > 0) {
          auto r = decrypt(
                  &curr_block_bl,
                  image_offset + curr_block_start_offset - extent.offset);
          if (r != 0) {
            return r;
          }

          curr_block_bl.splice(0, curr_block_length, &result_bl);
          result_extent_map.emplace_back(
                  curr_block_start_offset, curr_block_length);
        }

        curr_block_start_offset = aligned_off;
        curr_block_end_offset = aligned_off + aligned_len;
        curr_offset = aligned_off;
      }

      curr_block_bl.append_zero(off - curr_offset);
      extent.bl.splice(0, len, &curr_block_bl);
      curr_offset = off + len;
      curr_block_end_offset = aligned_off + aligned_len;
    }

    extent.bl = std::move(result_bl);
    extent.extent_map = std::move(result_extent_map);

    return 0;
  }
};