func newUnsignedV4ChunkedReader(req *http.Request, trailer bool) (io.ReadCloser, APIErrorCode) {
	if trailer {
		// Discard anything unsigned.
		req.Trailer = make(http.Header)
		trailers := req.Header.Values(awsTrailerHeader)
		for _, key := range trailers {
			req.Trailer.Add(key, "")
		}
	} else {
		req.Trailer = nil
	}
	return &s3UnsignedChunkedReader{
		trailers: req.Trailer,
		reader:   bufio.NewReader(req.Body),

func newSignV4ChunkedReader(req *http.Request, trailer bool) (io.ReadCloser, APIErrorCode) {
	cred, seedSignature, region, seedDate, errCode := calculateSeedSignature(req, trailer)
	if errCode != ErrNone {
		return nil, errCode
	}

	if trailer {
		// Discard anything unsigned.
		req.Trailer = make(http.Header)
		trailers := req.Header.Values(awsTrailerHeader)
		for _, key := range trailers {
			req.Trailer.Add(key, "")
		}

   *
   * Note that this method may be called a second time for a single HTTP response if the response
   * includes a trailer. For this obscure HTTP feature, [cookies] contains only the trailer's
   * cookies.
   */
  fun saveFromResponse(
    url: HttpUrl,
    cookies: List<Cookie>,
  )

  /**

	cs, err := GetContentChecksum(req.Header)
	if err != nil {
		return ErrInvalidChecksum
	}
	if cs == nil {
		return nil
	}
	r.contentHash = *cs
	if cs.Type.Trailing() {
		r.trailer = req.Trailer
	}
	return r.AddNonTrailingChecksum(cs, ignoreValue)
}

// AddChecksumNoTrailer will add checksum checks as specified in
// https://docs.aws.amazon.com/AmazonS3/latest/userguide/checking-object-integrity.html

		return FormatUnknown
	}

	// Guess the magic values.
	magic := string(b.toUSTAR().magic())
	version := string(b.toUSTAR().version())
	trailer := string(b.toSTAR().trailer())
	switch {
	case magic == magicUSTAR && trailer == trailerSTAR:
		return formatSTAR
	case magic == magicUSTAR:
		return FormatUSTAR | FormatPAX
	case magic == magicGNU && version == versionGNU:
		return FormatGNU

const unsignedPayload = "UNSIGNED-PAYLOAD"

// http Header "x-amz-content-sha256" == "STREAMING-UNSIGNED-PAYLOAD-TRAILER" indicates that the
// client did not calculate sha256 of the payload and there is a trailer.
const unsignedPayloadTrailer = "STREAMING-UNSIGNED-PAYLOAD-TRAILER"

// skipContentSha256Cksum returns true if caller needs to skip
// payload checksum, false if not.

// If checksum was trailing, they must have been added to r.Trailer.
func TransferChecksumHeader(w http.ResponseWriter, r *http.Request) {
	c, err := GetContentChecksum(r.Header)
	if err != nil || c == nil {
		return
	}
	t, s := c.Type, c.Encoded
	if !c.Type.IsSet() {
		return
	}
	if c.Type.Is(ChecksumTrailing) {
		val := r.Trailer.Get(t.Key())
		if val != "" {
			w.Header().Set(t.Key(), val)
		}

	AmzCredential           = "X-Amz-Credential"
	AmzSecurityToken        = "X-Amz-Security-Token"
	AmzDecodedContentLength = "X-Amz-Decoded-Content-Length"
	AmzTrailer              = "X-Amz-Trailer"
	AmzMaxParts             = "X-Amz-Max-Parts"
	AmzPartNumberMarker     = "X-Amz-Part-Number-Marker"

	// Constants used for GetObjectAttributes and GetObjectVersionAttributes

   * Timing-Allow-Origin}</a> header field name.
   *
   * @since 15.0
   */
  public static final String TIMING_ALLOW_ORIGIN = "Timing-Allow-Origin";
  /** The HTTP {@code Trailer} header field name. */
  public static final String TRAILER = "Trailer";
  /** The HTTP {@code Transfer-Encoding} header field name. */
  public static final String TRANSFER_ENCODING = "Transfer-Encoding";
  /** The HTTP {@code Vary} header field name. */

	return r.Header.Get(xhttp.AmzContentSha256) == streamingContentSHA256Trailer &&
		r.Method == http.MethodPut
}

// Verify if the request has AWS Streaming Signature Version '4', with unsigned content and trailer.
func isRequestUnsignedTrailerV4(r *http.Request) bool {
	return r.Header.Get(xhttp.AmzContentSha256) == unsignedPayloadTrailer &&