file.php

<?php
// If the URI has a scheme, don't override the umask - schemes can handle this
  // issue in their own implementation.
  if (file_uri_scheme($uri)) {
    return _drupal_mkdir_call($uri, $mode, $recursive, $context);
  }

  // If recursive, create each missing component of the parent directory
  // individually and set the mode explicitly to override the umask.
  if ($recursive) {
    $components = explode(DIRECTORY_SEPARATOR, $uri);
    array_pop($components);
    $recursive_path = '';
    foreach ($components as $component) {
      $recursive_path .= $component;

      if (!file_exists($recursive_path)) {
        if (!_drupal_mkdir_call($recursive_path, $mode, FALSE, $context)) {
          return FALSE;
        }
        // Not necessary to use drupal_chmod() as there is no scheme.
        if (!chmod($recursive_path, $mode)) {
          return FALSE;
        }
      }

      $recursive_path .= DIRECTORY_SEPARATOR;
    }
  }