[#207] Fix part-number-marker handling

Signed-off-by: Marina Biryukova <m.biryukova@yadro.com>

api/handler/multipart_upload.go

@@ -600,7 +600,7 @@ func (h *handler) ListPartsHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if queryValues.Get("part-number-marker") != "" {
-		if partNumberMarker, err = strconv.Atoi(queryValues.Get("part-number-marker")); err != nil || partNumberMarker <= 0 {
+		if partNumberMarker, err = strconv.Atoi(queryValues.Get("part-number-marker")); err != nil || partNumberMarker < 0 {
 			h.logAndSendError(w, "invalid PartNumberMarker", reqInfo, err, additional...)
 			return
 		}

api/layer/multipart_upload.go

@@ -548,6 +548,11 @@ func (n *layer) ListParts(ctx context.Context, p *ListPartsParams) (*ListPartsIn
 		return parts[i].PartNumber < parts[j].PartNumber
 	})
 
+	if p.PartNumberMarker >= parts[len(parts)-1].PartNumber {
+		res.Parts = make([]*Part, 0)
+		return &res, nil
+	}
+
 	if p.PartNumberMarker != 0 {
 		for i, part := range parts {
 			if part.PartNumber > p.PartNumberMarker {