(cp ab81e77) fixes #1290 avoid calling external command to calculate directory size

+ add a 5 minutes cache to avoid calculating cache size too often
* tested with anold PHP 5.5 (could work with earlier versions, but I prefer to not take the risk)

admin/include/functions.php

@@ -625,6 +625,28 @@ function get_fs_directories($path, $recursive = true)
   return $dirs;
 }
 
+/**
+ * returns the size (in bytes) of a filesystem directory
+ *
+ * @since 11
+ * @param string path
+ * @return int
+ */
+function get_fs_directory_size($path)
+{
+  $bytestotal = 0;
+  $path = realpath($path);
+
+  if ($path !== false && $path != '' && file_exists($path))
+  {
+    foreach (new RecursiveIteratorIterator(new RecursiveDirectoryIterator($path, FilesystemIterator::SKIP_DOTS)) as $object)
+    {
+      $bytestotal += $object->getSize();
+    }
+  }
+  return $bytestotal;
+}
+
 /**
  * save the rank depending on given categories order
  *