// JoinLoaders - joins multiple loaders into a single loader. The returned
// loader will call each of the given loaders in order. If any of the loaders
// return an error, the returned loader will return that error.
func JoinLoaders(loaders ...MetricsLoaderFn) MetricsLoaderFn {
	return func(ctx context.Context, m MetricValues, c *metricsCache) error {
		for _, loader := range loaders {
			if err := loader(ctx, m, c); err != nil {

			return
		}
		if globalBucketVersioningSys.PrefixEnabled(srcBucket, srcObject) && gr != nil {
			// Versioning enabled quite possibly object is deleted might be delete-marker
			// if present set the headers, no idea why AWS S3 sets these headers.
			if gr.ObjInfo.VersionID != "" && gr.ObjInfo.DeleteMarker {
				w.Header()[xhttp.AmzVersionID] = []string{gr.ObjInfo.VersionID}

	doneCh := make(chan error, 1)
	defer xioutil.SafeClose(doneCh)

	// Save rebalance.bin periodically.
	go func() {
		// Update rebalance.bin periodically once every 5-10s, chosen randomly
		// to avoid multiple pool leaders herding to update around the same
		// time.
		r := rand.New(rand.NewSource(time.Now().UnixNano()))
		randSleepFor := func() time.Duration {
			return 5*time.Second + time.Duration(float64(5*time.Second)*r.Float64())
		}

	// handler for validating incoming authorization headers.
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		tc, ok := r.Context().Value(mcontext.ContextTraceKey).(*mcontext.TraceCtxt)

		aType := getRequestAuthType(r)
		switch aType {
		case authTypeSigned, authTypeSignedV2, authTypeStreamingSigned, authTypeStreamingSignedTrailer:
			// Verify if date headers are set, if not reject the request

	got, err := scanDataFolder(context.Background(), nil, base, dataUsageCache{Info: dataUsageCacheInfo{Name: "bucket"}}, getSize, 0, weSleep)
	if err != nil {
		t.Fatal(err)
	}
	if got.root() == nil {
		t.Log("cached folders:")
		for folder := range got.Cache {
			t.Log("folder:", folder)
		}
		t.Fatal("got nil root.")
	}

	// Test dirs
	want := []struct {
		path       string
		isNil      bool
		size, objs int

func (e NotImplemented) Error() string {
	return e.Message
}

// UnsupportedMetadata - unsupported metadata
type UnsupportedMetadata struct{}

func (e UnsupportedMetadata) Error() string {
	return "Unsupported headers in Metadata"
}

// isErrBucketNotFound - Check if error type is BucketNotFound.
func isErrBucketNotFound(err error) bool {
	var bkNotFound BucketNotFound
	return errors.As(err, &bkNotFound)
}

}

// Return canonical headers.
func canonicalizedAmzHeadersV2(headers http.Header) string {
	var keys []string
	keyval := make(map[string]string, len(headers))
	for key := range headers {
		lkey := strings.ToLower(key)
		if !strings.HasPrefix(lkey, "x-amz-") {
			continue
		}
		keys = append(keys, lkey)
		keyval[lkey] = strings.Join(headers[key], ",")
	}
	sort.Strings(keys)

			if crypto.SSEC.IsRequested(headers) || crypto.SSECopy.IsRequested(headers) {
				return encrypted, errEncryptedObject
			}
		}

		if crypto.S3KMS.IsEncrypted(info.UserDefined) && r.Header.Get(xhttp.AmzCopySource) == "" {
			if crypto.SSEC.IsRequested(headers) || crypto.SSECopy.IsRequested(headers) {
				return encrypted, errEncryptedObject
			}
		}

		if _, err = info.DecryptedSize(); err != nil {

	"X-Minio-Replication-Server-Side-Encryption-Iv",
	"X-Minio-Replication-Encrypted-Multipart",
	"X-Minio-Replication-Actual-Object-Size",
	// Add more supported headers here.
}

// mapping of internal headers to allowed replication headers
var validSSEReplicationHeaders = map[string]string{
	"X-Minio-Internal-Server-Side-Encryption-Sealed-Key":     "X-Minio-Replication-Server-Side-Encryption-Sealed-Key",

// enforceRetentionBypassForDelete enforces whether an existing object under governance can be deleted
// with governance bypass headers set in the request.
// Objects under site wide WORM can never be overwritten.
// For objects in "Governance" mode, overwrite is allowed if a) object retention date is past OR
// governance bypass headers are set and user has governance bypass permissions.