Method ParseMetaData

cpp/src/parquet/file_reader.cc:439–477

  // exceptions for error handling (with the async path converting to Future/Status).

  void ParseMetaData() {
    int64_t footer_read_size = GetFooterReadSize();
    PARQUET_ASSIGN_OR_THROW(
        auto footer_buffer,
        source_->ReadAt(source_size_ - footer_read_size, footer_read_size));
    uint32_t metadata_len = ParseFooterLength(footer_buffer, footer_read_size);
    int64_t metadata_start = source_size_ - kFooterSize - metadata_len;

    std::shared_ptr<::arrow::Buffer> metadata_buffer;
    if (footer_read_size >= (metadata_len + kFooterSize)) {
      metadata_buffer = SliceBuffer(
          footer_buffer, footer_read_size - metadata_len - kFooterSize, metadata_len);
    } else {
      PARQUET_ASSIGN_OR_THROW(
          metadata_buffer,
          source_->ReadAt(metadata_start, metadata_len, /*allow_short_read=*/false));
    }

    // Parse the footer depending on encryption type
    const bool is_encrypted_footer =
        memcmp(footer_buffer->data() + footer_read_size - 4, kParquetEMagic, 4) == 0;
    std::shared_ptr<InternalFileDecryptor> file_decryptor;
    if (is_encrypted_footer) {
      // Encrypted file with Encrypted footer.
      const std::pair<int64_t, uint32_t> read_size =
          ParseMetaDataOfEncryptedFileWithEncryptedFooter(metadata_buffer, metadata_len,
                                                          &file_decryptor);
      // Read the actual footer
      metadata_start = read_size.first;
      metadata_len = read_size.second;
      PARQUET_ASSIGN_OR_THROW(
          metadata_buffer,
          source_->ReadAt(metadata_start, metadata_len, /*allow_short_read=*/false));
      // Fall through
    }

    ParseMetaDataFinal(std::move(metadata_buffer), metadata_len, is_encrypted_footer,
                       std::move(file_decryptor));
  }

  // Validate the source size and get the initial read size.
  int64_t GetFooterReadSize() {