diff --git a/core/includes/file.inc b/core/includes/file.inc
index c2152cb..0758459 100644
--- a/core/includes/file.inc
+++ b/core/includes/file.inc
@@ -332,7 +332,8 @@ function file_prepare_directory(&$directory, $options = FILE_MODIFY_PERMISSIONS)
 function file_directory_is_writable($uri) {
   // By converting the URI to a normal path using drupal_realpath(), we can
   // correctly handle both stream wrappers and normal paths.
-  return is_writable(drupal_realpath($uri)) && drupal_is_executable($uri);
+  $realpath =  \Drupal::service('file_system')->realpath($uri);
+  return is_writable($realpath ? $realpath : $uri) && drupal_is_executable($uri);
 }
 
 /**
@@ -353,7 +354,10 @@ function file_directory_is_writable($uri) {
 function drupal_is_executable($uri) {
   // By converting the URI to a normal path using drupal_realpath(), we can
   // correctly handle both stream wrappers and normal paths.
-  return is_executable(drupal_realpath($uri));
+  $realpath = \Drupal::service('file_system')->realpath($uri);
+  $filename = $realpath ? $realpath : $uri;
+  // Determine whether the URI is an executable file or a directory.
+  return is_executable($filename) || is_dir($filename);
 }
 
 /**