// Storage class is special, it can be replaced regardless of the
	// metadata directive, if set should be preserved and replaced
	// to the destination metadata.
	sc := r.Header.Get(xhttp.AmzStorageClass)
	if sc == "" {
		sc = r.Form.Get(xhttp.AmzStorageClass)
	}

	// if x-amz-metadata-directive says REPLACE then
	// we extract metadata from the input headers.

		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrInvalidMetadataDirective: {
		Code:           "InvalidArgument",
		Description:    "Unknown metadata directive.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrInvalidStorageClass: {
		Code:           "InvalidStorageClass",
		Description:    "Invalid storage class.",
		HTTPStatusCode: http.StatusBadRequest,
	},

	if err = checkPathLength(filePath); err != nil {
		return err
	}

	flags := os.O_CREATE | os.O_WRONLY | os.O_TRUNC

	var w *os.File
	if sync {
		// Perform DirectIO along with fdatasync for larger xl.meta, mostly when
		// xl.meta has "inlined data" we prefer writing O_DIRECT and then doing
		// fdatasync() at the end instead of opening the file with O_DSYNC.
		//

	StreamHandlerFn func(ctx context.Context, payload []byte, in <-chan []byte, out chan<- []byte) *RemoteErr

	// StreamHandler handles fully bidirectional streams,
	// There is flow control in both directions.
	StreamHandler struct {
		// Handle an incoming request. Initial payload is sent.
		// Additional input packets (if any) are streamed to request.
		// Upstream will block when request channel is full.

   See the License for the specific language governing permissions and
   limitations under the License.
================================================================

github.com/ncw/directio
https://github.com/ncw/directio
----------------------------------------------------------------
Copyright (C) 2012 by Nick Craig-Wood http://www.craig-wood.com/nick/

	if !fi1.ModTime().Equal(fi2.ModTime()) {
		return false
	}
	if fi1.Mode() != fi2.Mode() {
		return false
	}
	return fi1.Size() == fi2.Size()
}

// DirectioAlignSize - DirectIO alignment needs to be 4K. Defined here as
// directio.AlignSize is defined as 0 in MacOS causing divide by 0 error.
const DirectioAlignSize = 4096

// CopyAligned - copies from reader to writer using the aligned input

github.com/nats-io/stan.go v0.10.4 h1:19GS/eD1SeQJaVkeM9EkvEYattnvnWrZ3wkSWSw4uXw=
github.com/nats-io/stan.go v0.10.4/go.mod h1:3XJXH8GagrGqajoO/9+HgPyKV5MWsv7S5ccdda+pc6k=
github.com/ncw/directio v1.0.5 h1:JSUBhdjEvVaJvOoyPAbcW0fnd0tvRXD76wEfZ1KcQz4=
github.com/ncw/directio v1.0.5/go.mod h1:rX/pKEYkOXBGOggmcyJeJGloCkleSvphPx2eV3t6ROk=
github.com/nsqio/go-nsq v1.1.0 h1:PQg+xxiUjA7V+TLdXw7nVrJ5Jbl3sN86EhGCQj4+FYE=

			req.Header.Set(k, v)
		}
		if testCase.metadataReplace {
			req.Header.Set("X-Amz-Metadata-Directive", "REPLACE")
		}
		if testCase.metadataCopy {
			req.Header.Set("X-Amz-Metadata-Directive", "COPY")
		}
		if testCase.metadataGarbage {
			req.Header.Set("X-Amz-Metadata-Directive", "Unknown")
		}
		// Since `apiRouter` satisfies `http.Handler` it has a ServeHTTP to execute the logic of the handler.