feat: support tags for PostPolicy upload (#19816)

cmd/api-headers.go

@@ -136,7 +136,7 @@ func setObjectHeaders(ctx context.Context, w http.ResponseWriter, objInfo Object
 	// Set tag count if object has tags
 	if len(objInfo.UserTags) > 0 {
 		tags, _ := tags.ParseObjectTags(objInfo.UserTags)
-		if tags.Count() > 0 {
+		if tags != nil && tags.Count() > 0 {
 			w.Header()[xhttp.AmzTagCount] = []string{strconv.Itoa(tags.Count())}
 			if opts.Tagging {
 				// This is MinIO only extension to return back tags along with the count.

cmd/bucket-handlers.go

@@ -72,6 +72,8 @@ const (
 
 	xMinIOErrCodeHeader = "x-minio-error-code"
 	xMinIOErrDescHeader = "x-minio-error-desc"
+
+	postPolicyBucketTagging = "tagging"
 )
 
 // Check if there are buckets on server without corresponding entry in etcd backend and
@@ -1415,6 +1417,19 @@ func (api objectAPIHandlers) PostPolicyBucketHandler(w http.ResponseWriter, r *h
 		return
 	}
 
+	if formValues.Get(postPolicyBucketTagging) != "" {
+		tags, err := tags.ParseObjectXML(strings.NewReader(formValues.Get(postPolicyBucketTagging)))
+		if err != nil {
+			writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
+			return
+		}
+		tagsStr := tags.String()
+		opts.UserDefined[xhttp.AmzObjectTagging] = tagsStr
+	} else {
+		// avoid user set an invalid tag using `X-Amz-Tagging`
+		delete(opts.UserDefined, xhttp.AmzObjectTagging)
+	}
+
 	objInfo, err := objectAPI.PutObject(ctx, bucket, object, pReader, opts)
 	if err != nil {
 		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)