Status ReadBlock()

in table/format.cc [66:143]
66 lines of code
10 McCabe index (conditional complexity)

Status ReadBlock(RandomAccessFile* file,
                 const ReadOptions& options,
                 const BlockHandle& handle,
                 BlockContents* result) {
  result->data = Slice();
  result->cachable = false;
  result->heap_allocated = false;

  // Read the block contents as well as the type/crc footer.
  // See table_builder.cc for the code that built this structure.
  size_t n = static_cast<size_t>(handle.size());
  char* buf = new char[n + kBlockTrailerSize];
  Slice contents;
  Status s = file->Read(handle.offset(), n + kBlockTrailerSize, &contents, buf);
  if (!s.ok()) {
    delete[] buf;
    return s;
  }
  if (contents.size() != n + kBlockTrailerSize) {
    delete[] buf;
    return Status::Corruption("truncated block read");
  }

  // Check the crc of the type and the block contents
  const char* data = contents.data();    // Pointer to where Read put the data
  if (options.verify_checksums) {
    const uint32_t crc = crc32c::Unmask(DecodeFixed32(data + n + 1));
    const uint32_t actual = crc32c::Value(data, n + 1);
    if (actual != crc) {
      delete[] buf;
      s = Status::Corruption("block checksum mismatch");
      return s;
    }
  }

  switch (data[n]) {
    case kNoCompression:
      if (data != buf) {
        // File implementation gave us pointer to some other data.
        // Use it directly under the assumption that it will be live
        // while the file is open.
        delete[] buf;
        result->data = Slice(data, n);
        result->heap_allocated = false;
        result->cachable = false;  // Do not double-cache
      } else {
        result->data = Slice(buf, n);
        result->heap_allocated = true;
        result->cachable = true;
      }

      // Ok
      break;
    case kSnappyCompression: {
      size_t ulength = 0;
      if (!port::Snappy_GetUncompressedLength(data, n, &ulength)) {
        delete[] buf;
        return Status::Corruption("corrupted compressed block contents");
      }
      char* ubuf = new char[ulength];
      if (!port::Snappy_Uncompress(data, n, ubuf)) {
        delete[] buf;
        delete[] ubuf;
        return Status::Corruption("corrupted compressed block contents");
      }
      delete[] buf;
      result->data = Slice(ubuf, ulength);
      result->heap_allocated = true;
      result->cachable = true;
      break;
    }
    default:
      delete[] buf;
      return Status::Corruption("bad block type");
  }

  return Status::OK();
}