size += len(block)
	}
	return size
}

// Writes all the data blocks from encoded blocks until requested
// outSize length. Provides a way to skip bytes until the offset.
func writeDataBlocks(ctx context.Context, dst io.Writer, enBlocks [][]byte, dataBlocks int, offset int64, length int64) (int64, error) {
	// Offset and out size cannot be negative.
	if offset < 0 || length < 0 {
		return 0, errUnexpected
	}

					if decoded[j] == nil {
						t.Errorf("Test %d: failed to reconstruct data shard %d", i, j)
					}
				}
			}

			decodedData := new(bytes.Buffer)
			if _, err = writeDataBlocks(context.Background(), decodedData, decoded, test.dataBlocks, 0, int64(len(data))); err != nil {
				t.Errorf("Test %d: failed to write data blocks: %v", i, err)
			}
			if !bytes.Equal(decodedData.Bytes(), data) {

			// For all errors that cannot be reconstructed fail the read operation.
			return -1, err
		}

		if err = e.DecodeDataBlocks(bufs); err != nil {
			return -1, err
		}

		n, err := writeDataBlocks(ctx, writer, bufs, e.dataBlocks, blockOffset, blockLength)
		if err != nil {
			return -1, err
		}

		bytesWritten += n
	}

	if bytesWritten != length {
		return bytesWritten, errLessData
	}