if _, ok := r.Header[xhttp.AmzCopySource]; ok {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrInvalidCopySource), r.URL)
		return
	}

	clientETag, err := etag.FromContentMD5(r.Header)
	if err != nil {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrInvalidDigest), r.URL)
		return
	}

	// if Content-Length is unknown/missing, throw away
	size := r.ContentLength