return x-amz-tag-count header when GET object.

weed/s3api/filer_util_tags.go

@@ -7,7 +7,7 @@ import (
 )
 
 const (
-	S3TAG_PREFIX = "s3-"
+	S3TAG_PREFIX = "s3-tag-"
 )
 
 func (s3a *S3ApiServer) getTags(parentDirectoryPath string, entryName string) (tags map[string]string, err error) {

weed/server/filer_server_handlers_read.go

@@ -93,6 +93,19 @@ func (fs *FilerServer) GetOrHeadHandler(w http.ResponseWriter, r *http.Request,
 		}
 	}
 
+	//set tag count
+	if r.Method == "GET" {
+		tagCount := 0
+		for k, _ := range entry.Extended {
+			if strings.HasPrefix(k, "s3-tag-") {
+				tagCount++
+			}
+		}
+		if tagCount > 0 {
+			w.Header().Set("x-amz-tag-count", strconv.Itoa(tagCount))
+		}
+	}
+
 	// set etag
 	etag := filer.ETagEntry(entry)
 	if inm := r.Header.Get("If-None-Match"); inm == "\""+etag+"\"" {