{file: "myobject", offset: 1, length: 120, algorithm: SHA256, expError: errFileCorrupt},     // 4
	{file: "myobject", offset: 3, length: 1100, algorithm: SHA256, expError: nil},               // 5
	{file: "myobject", offset: 2, length: 100, algorithm: SHA256, expError: errFileCorrupt},     // 6
	{file: "myobject", offset: 1000, length: 1001, algorithm: SHA256, expError: nil},            // 7

		Description:    "Requests specifying Server Side Encryption with Customer provided keys must provide a valid encryption algorithm.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrInvalidSSECustomerKey: {
		Code:           "InvalidArgument",
		Description:    "The secret key was invalid for the specified algorithm.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrMissingSSECustomerKey: {

   *
   * The Least Recently Used page replacement algorithm was chosen due to its simplicity, high hit
   * rate, and ability to be implemented with O(1) time complexity. The initial LRU implementation
   * operates per-segment rather than globally for increased implementation simplicity. We expect
   * the cache hit rate to be similar to that of a global LRU algorithm.
   */

  // Constants

  /**

   *
   * The Least Recently Used page replacement algorithm was chosen due to its simplicity, high hit
   * rate, and ability to be implemented with O(1) time complexity. The initial LRU implementation
   * operates per-segment rather than globally for increased implementation simplicity. We expect
   * the cache hit rate to be similar to that of a global LRU algorithm.
   */

  // Constants

  /**

	region := globalSite.Region()
	date := UTCNow()
	scope := getScope(date, region)
	credential := fmt.Sprintf("%s/%s", accessKeyID, scope)

	// Set URL query.
	query := req.URL.Query()
	query.Set("X-Amz-Algorithm", signV4Algorithm)
	query.Set("X-Amz-Date", date.Format(iso8601Format))
	query.Set("X-Amz-Expires", strconv.FormatInt(expires, 10))
	query.Set("X-Amz-SignedHeaders", "host")
	query.Set("X-Amz-Credential", credential)

   * once after loading completes). Much internal cache management is performed at the segment
   * granularity. For example, access queues and write queues are kept per segment when they are
   * required by the selected eviction algorithm. As such, when writing unit tests it is not
   * uncommon to specify {@code concurrencyLevel(1)} in order to achieve more deterministic eviction
   * behavior.
   *

)

func (e VersionType) valid() bool {
	return e > invalidVersionType && e < lastVersionType
}

// ErasureAlgo defines common type of different erasure algorithms
type ErasureAlgo uint8

// List of currently supported erasure coding algorithms
const (
	invalidErasureAlgo ErasureAlgo = 0
	ReedSolomon        ErasureAlgo = 1
	lastErasureAlgo    ErasureAlgo = 2
)

func (e ErasureAlgo) valid() bool {

	// undefined.
	if !st.Mode().IsRegular() {
		return 0, errIsNotRegular
	}

	if verifier == nil {
		n, err = file.ReadAt(buffer, offset)
		return int64(n), err
	}

	h := verifier.algorithm.New()
	if _, err = io.Copy(h, io.LimitReader(file, offset)); err != nil {
		return 0, err
	}

	if n, err = io.ReadFull(file, buffer); err != nil {
		return int64(n), err
	}

			partPath := pathJoin(object, metaArr[index].DataDir, fmt.Sprintf("part.%d", partNumber))
			readers[index] = newBitrotReader(disk, metaArr[index].Data, bucket, partPath, tillOffset,
				checksumInfo.Algorithm, checksumInfo.Hash, erasure.ShardSize())

			// Prefer local disks
			prefer[index] = disk.Hostname() == ""
		}

		written, err := erasure.Decode(ctx, writer, readers, partOffset, partLength, partSize, prefer)