// http://docs.aws.amazon.com/AmazonS3/latest/API/multiobjectdeleteapi.html
	if _, ok := r.Header[xhttp.ContentMD5]; !ok {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrMissingContentMD5), r.URL)
		return
	}

	// Content-Length is required and should be non-zero
	// http://docs.aws.amazon.com/AmazonS3/latest/API/multiobjectdeleteapi.html
	if r.ContentLength <= 0 {

		return strings.HasPrefix(input1, input2)
	}
	return false
}

// checkPostPolicy - apply policy conditions and validate input values.
// (http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-HTTPPOSTConstructPolicy.html)
func checkPostPolicy(formValues http.Header, postPolicyForm PostPolicyForm) error {
	// Check if policy document expiry date is still not reached
	if !postPolicyForm.Expiration.After(UTCNow()) {

	defer c.RUnlock()
	return fmt.Errorf("[%s] %w", c.lastErrTime.Format(time.RFC3339), c.lastErr)
}

// computes the exponential backoff duration according to
// https://www.awsarchitectureblog.com/2015/03/backoff.html
func exponentialBackoffWait(r *rand.Rand, unit, cap time.Duration) func(uint) time.Duration {
	if unit > time.Hour {
		// Protect against integer overflow
		panic("unit cannot exceed one hour")
	}

// Streaming signature clients can have custom content-encoding such as
// `aws-chunked,gzip` here we need to only save `gzip`.
// For more refer http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-streaming.html
func trimAwsChunkedContentEncoding(contentEnc string) (trimmedContentEnc string) {
	if contentEnc == "" {
		return contentEnc
	}
	var newEncs []string
	for _, enc := range strings.Split(contentEnc, ",") {

func (db *DB) Update(column string, value interface{}) (tx *DB) {
	tx = db.getInstance()
	tx.Statement.Dest = map[string]interface{}{column: value}
	return tx.callbacks.Update().Execute(tx)
}

// Updates updates attributes using callbacks. values must be a struct or map. Reference: https://gorm.io/docs/update.html#Update-Changed-Fields

			// handle otherwise we would see a signature mismatch.
			// `aws-cli` sets this as part of signed headers.
			//
			// According to
			// http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.20
			// Expect header is always of form:
			//
			//   Expect       =  "Expect" ":" 1#expectation
			//   expectation  =  "100-continue" | expectation-extension
			//

// PutBucketReplicationConfigHandler - PUT Bucket replication configuration.
// ----------
// Add a replication configuration on the specified bucket as specified in https://docs.aws.amazon.com/AmazonS3/latest/API/API_PutBucketReplication.html
func (api objectAPIHandlers) PutBucketReplicationConfigHandler(w http.ResponseWriter, r *http.Request) {
	ctx := newContext(r, w, "PutBucketReplicationConfig")
	defer logger.AuditLog(ctx, w, r, mustGetClaimsFromToken(r))

//	db.Where(User{Name: "jinzhu"}).Attrs(User{Email: "******@****.***"}).FirstOrInit(&user)
//	// user -> User{Name: "jinzhu", Age: 20}
//
// [FirstOrCreate]: https://gorm.io/docs/advanced_query.html#FirstOrCreate
// [FirstOrInit]: https://gorm.io/docs/advanced_query.html#FirstOrInit
func (db *DB) Attrs(attrs ...interface{}) (tx *DB) {
	tx = db.getInstance()
	tx.Statement.attrs = attrs
	return
}

	//
	// It is recommended that PAX be chosen over GNU unless the target
	// application can only parse GNU formatted archives.
	//
	// Reference:
	//	https://www.gnu.org/software/tar/manual/html_node/Standard.html
	FormatGNU

	// Schily's tar format, which is incompatible with USTAR.
	// This does not cover STAR extensions to the PAX format; these fall under
	// the PAX format.
	formatSTAR

	formatMax
)

		return "", fmt.Errorf(`found backend type %s, expected %s or %s - to migrate to a supported backend visit https://min.io/docs/minio/linux/operations/install-deploy-manage/migrate-fs-gateway.html`, meta.Format, formatBackendErasure, formatBackendErasureSingle)
	}
	// Erasure backend found, proceed to detect version.
	format := &formatErasureVersionDetect{}
	if err := json.Unmarshal(b, format); err != nil {