Add PATCH method response

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

api/handler/patch.go

@@ -5,6 +5,7 @@ import (
 	"net/http"
 	"strconv"
 	"strings"
+	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api"
 	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/data"
@@ -108,8 +109,15 @@ func (h *handler) PatchHandler(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set(api.AmzVersionID, extendedObjInfo.ObjectInfo.VersionID())
 	w.Header().Set(api.ETag, data.Quote(extendedObjInfo.ObjectInfo.ETag(h.cfg.MD5Enabled())))
 
-	if err = middleware.WriteSuccessResponseHeadersOnly(w); err != nil {
-		h.logAndSendError(w, "write response", reqInfo, err)
+	resp := PatchObjectResult{
+		Object: PatchObject{
+			LastModified: extendedObjInfo.ObjectInfo.Created.UTC().Format(time.RFC3339),
+			ETag:         data.Quote(extendedObjInfo.ObjectInfo.ETag(h.cfg.MD5Enabled())),
+		},
+	}
+
+	if err = middleware.EncodeToResponse(w, resp); err != nil {
+		h.logAndSendError(w, "could not encode PatchObjectResult to response", reqInfo, err)
 		return
 	}
 }

api/handler/response.go

@@ -192,6 +192,15 @@ type PostResponse struct {
 	ETag   string `xml:"Etag"`
 }
 
+type PatchObjectResult struct {
+	Object PatchObject `xml:"Object"`
+}
+
+type PatchObject struct {
+	LastModified string `xml:"LastModified"`
+	ETag         string `xml:"ETag"`
+}
+
 // MarshalXML -- StringMap marshals into XML.
 func (s StringMap) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
 	tokens := []xml.Token{start}