func optimalPartSize(objectSize int64) (partSize int64, err error) {
	// object size is '-1' set it to 5TiB.
	if objectSize == -1 {
		objectSize = maxMultipartPutObjectSize
	}

	// object size is larger than supported maximum.
	if objectSize > maxMultipartPutObjectSize {
		err = errors.New("entity too large")
		return
	}

	configuredPartSize := minPartSize
	// Use floats for part size for all calculations to avoid

	//
	// While this format is compatible with most tar readers,
	// the format has several limitations making it unsuitable for some usages.
	// Most notably, it cannot support sparse files, files larger than 8GiB,
	// filenames larger than 256 characters, and non-ASCII filenames.
	//
	// Reference:
	//	http://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13_06
	FormatUSTAR

	if err != nil {
		return nil, err
	}

	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	if accessToken != "" {
		req.Header.Set("Authorization", "Bearer "+accessToken)
	}

	client := &http.Client{
		Transport: transport,
	}

	resp, err := client.Do(req)
	if err != nil {
		return nil, err
	}

	defer xhttp.DrainBody(resp.Body)

var errSignatureMismatch = errors.New("Signature does not match")

// When upload object size is greater than 5G in a single PUT/POST operation.
var errDataTooLarge = errors.New("Object size larger than allowed limit")

// When upload object size is less than what was expected.
var errDataTooSmall = errors.New("Object size smaller than expected")

// errServerNotInitialized - server not initialized.

//     kmskey: "key-id" # match objects with KMS key-id (applicable only for sse-kms)
//   notify:
//     endpoint: "https://notify.endpoint" # notification endpoint to receive job status events
//     token: "Bearer xxxxx" # optional authentication token for the notification endpoint

//   retry:
//     attempts: 10 # number of retries for the job before giving up
//     delay: "500ms" # least amount of delay between each retry

		s.err = err
	}
}

// Buffer sets the initial buffer to use when scanning
// and the maximum size of buffer that may be allocated during scanning.
// The maximum token size must be less than the larger of max and cap(buf).
// If max <= cap(buf), [Scanner.Scan] will use this buffer only and do no allocation.
//
// By default, [Scanner.Scan] uses an internal buffer and sets the
// maximum token size to [MaxScanTokenSize].

//           # retainVersions: 5 # keep the latest 5 versions of the object including delete markers.
//
//   notify:
//     endpoint: https://notify.endpoint # notification endpoint to receive job completion status
//     token: Bearer xxxxx # optional authentication token for the notification endpoint
//
//   retry:
//     attempts: 10 # number of retries for the job before giving up
//     delay: 500ms # least amount of delay between each retry

		dialer.Timeout = defaultDialTimeout
		if c.dialer != nil {
			dialer.NetDial = c.dialer.DialContext
		}
		if c.header == nil {
			c.header = make(http.Header, 2)
		}
		c.header.Set("Authorization", "Bearer "+c.auth(""))
		c.header.Set("X-Minio-Time", time.Now().UTC().Format(time.RFC3339))

		if len(c.header) > 0 {
			dialer.Header = ws.HandshakeHeaderHTTP(c.header)
		}
		dialer.TLSConfig = c.tlsConfig

		actual := LastIndexByte([]byte(test.a), test.b[0])
		if actual != test.i {
			t.Errorf("LastIndexByte(%q,%c) = %v; want %v", test.a, test.b[0], actual, test.i)
		}
	}
}

// test a larger buffer with different sizes and alignments
func TestIndexByteBig(t *testing.T) {
	var n = 1024
	if testing.Short() {
		n = 128
	}
	b := make([]byte, n)
	for i := 0; i < n; i++ {

	// strongly recommend that you make no assumptions about the maximum size. As
	// of this writing, the typical size is less than 4096 bytes, but that can vary.
	// Also, future updates to AWS might require larger sizes.
	Credentials auth.Credentials `xml:",omitempty"`

	// A percentage value that indicates the size of the policy in packed form.
	// The service rejects any policy with a packed size greater than 100 percent,