add dot and dot dot directories to sftp/ftp file listing

util/util.go

@@ -608,3 +608,12 @@ func GetRedactedURL(rawurl string) string {
 	}
 	return u.Redacted()
 }
+
+// PrependFileInfo prepends a file info to a slice in an efficient way.
+// We, optimistically, assume that the slice has enough capacity
+func PrependFileInfo(files []os.FileInfo, info os.FileInfo) []os.FileInfo {
+	files = append(files, nil)
+	copy(files[1:], files)
+	files[0] = info
+	return files
+}