PartNumber: part.PartNumber,
				GotETag:    part.ETag,
			}
			return oi, invp
		}
		expPart := currentFI.Parts[partIdx]

		// ensure that part ETag is canonicalized to strip off extraneous quotes
		part.ETag = canonicalizeETag(part.ETag)
		expETag := tryDecryptETag(objectEncryptionKey, expPart.ETag, kind == crypto.S3)
		if expETag != part.ETag {
			invp := InvalidPart{
				PartNumber: part.PartNumber,

			if len(etag) >= 32 && strings.Count(etag, "-") != 1 {
				etag = etag[len(etag)-32:]
			}
		}
	}

	// We must not use the http.Header().Set method here because some (broken)
	// clients expect the ETag header key to be literally "ETag" - not "Etag" (case-sensitive).
	// Therefore, we have to set the ETag directly as map entry.
	w.Header()[xhttp.ETag] = []string{"\"" + etag + "\""}

		// as well as common modtime, if modtime is not possible
		// verify if it has common "etag" at least.
		if onlineMeta[i].IsValid() && onlineMeta[i].Erasure.Equal(fi.Erasure) {
			ok := onlineMeta[i].ModTime.Equal(modTime)
			if modTime.IsZero() || modTime.Equal(timeSentinel) {
				ok = etag != "" && etag == fi.Metadata["etag"]
			}
			if ok {
				continue
			}

			if kmsCtx, ok := objInfo.UserDefined[crypto.MetaContext]; ok {
				w.Header().Set(xhttp.AmzServerSideEncryptionKmsContext, kmsCtx)
			}
			if len(objInfo.ETag) >= 32 && strings.Count(objInfo.ETag, "-") != 1 {
				objInfo.ETag = objInfo.ETag[len(objInfo.ETag)-32:]
			}
		case crypto.SSEC:
			w.Header().Set(xhttp.AmzServerSideEncryptionCustomerAlgorithm, r.Header.Get(xhttp.AmzServerSideEncryptionCustomerAlgorithm))

func GetObject(ctx context.Context, api ObjectLayer, bucket, object string, startOffset int64, length int64, writer io.Writer, etag string, opts ObjectOptions) (err error) {
	var header http.Header
	if etag != "" {
		header.Set("ETag", etag)
	}
	Range := &HTTPRangeSpec{Start: startOffset, End: startOffset + length}

	reader, err := api.GetObjectNInfo(ctx, bucket, object, Range, header, opts)