[#451] Don't skip [Next]PartNumberMarker in response

In ListParts response we should always keep PartNumberMarker (even if it's zero)
and NextPartNumberMarker (even if response isn't truncated)

Signed-off-by: Denis Kirillov <d.kirillov@yadro.com>

api/handler/multipart_upload.go

@@ -54,11 +54,11 @@ type (
 		Initiator            Initiator     `xml:"Initiator"`
 		IsTruncated          bool          `xml:"IsTruncated"`
 		Key                  string        `xml:"Key"`
-		MaxParts             int           `xml:"MaxParts,omitempty"`
-		NextPartNumberMarker int           `xml:"NextPartNumberMarker,omitempty"`
+		MaxParts             int           `xml:"MaxParts"`
+		NextPartNumberMarker int           `xml:"NextPartNumberMarker"`
 		Owner                Owner         `xml:"Owner"`
 		Parts                []*layer.Part `xml:"Part"`
-		PartNumberMarker     int           `xml:"PartNumberMarker,omitempty"`
+		PartNumberMarker     int           `xml:"PartNumberMarker"`
 		StorageClass         string        `xml:"StorageClass"`
 		UploadID             string        `xml:"UploadId"`
 	}

api/handler/multipart_upload_test.go

@@ -292,13 +292,19 @@ func TestListParts(t *testing.T) {
 	require.Len(t, list.Parts, 2)
 	require.Equal(t, etag1, list.Parts[0].ETag)
 	require.Equal(t, etag2, list.Parts[1].ETag)
+	require.Zero(t, list.PartNumberMarker)
+	require.Equal(t, 2, list.NextPartNumberMarker)
 
 	list = listParts(hc, bktName, objName, uploadInfo.UploadID, "1", http.StatusOK)
 	require.Len(t, list.Parts, 1)
 	require.Equal(t, etag2, list.Parts[0].ETag)
+	require.Equal(t, 1, list.PartNumberMarker)
+	require.Equal(t, 2, list.NextPartNumberMarker)
 
 	list = listParts(hc, bktName, objName, uploadInfo.UploadID, "2", http.StatusOK)
 	require.Len(t, list.Parts, 0)
+	require.Equal(t, 2, list.PartNumberMarker)
+	require.Equal(t, 0, list.NextPartNumberMarker)
 
 	list = listParts(hc, bktName, objName, uploadInfo.UploadID, "7", http.StatusOK)
 	require.Len(t, list.Parts, 0)

api/layer/multipart_upload.go

@@ -603,10 +603,10 @@ func (n *Layer) ListParts(ctx context.Context, p *ListPartsParams) (*ListPartsIn
 
 	if len(parts) > p.MaxParts {
 		res.IsTruncated = true
-		res.NextPartNumberMarker = parts[p.MaxParts-1].PartNumber
 		parts = parts[:p.MaxParts]
 	}
 
+	res.NextPartNumberMarker = parts[len(parts)-1].PartNumber
 	res.Parts = parts
 
 	return &res, nil