diff --git a/phpBB/phpbb/storage/adapter/adapter_interface.php b/phpBB/phpbb/storage/adapter/adapter_interface.php
index b2f6043741..f9fb2438b6 100644
--- a/phpBB/phpbb/storage/adapter/adapter_interface.php
+++ b/phpBB/phpbb/storage/adapter/adapter_interface.php
@@ -85,4 +85,15 @@ interface adapter_interface
 	 * 													When the file cannot be copied
 	 */
 	public function copy($path_orig, $path_dest);
+
+	/**
+	 * Get file info.
+	 *
+	 * @param string	$path	The file
+	 *
+	 * @throws \phpbb\storage\exception\not_implemented	When the adapter doesnt implement the method
+	 *
+	 * @return \phpbb\storage\file_info	Returns file_info object
+	 */
+	public function file_properties($path);
 }
diff --git a/phpBB/phpbb/storage/adapter/local.php b/phpBB/phpbb/storage/adapter/local.php
index 9e7dc7db79..34c2894569 100644
--- a/phpBB/phpbb/storage/adapter/local.php
+++ b/phpBB/phpbb/storage/adapter/local.php
@@ -236,16 +236,43 @@ class local implements adapter_interface, stream_interface
 		}
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function file_properties($path)
 	{
 		return [];
 	}
 
+	/**
+	 * Get file size.
+	 *
+	 * @param string	$path	The file
+	 *
+	 * @throws \phpbb\storage\exception\exception		When cannot get size
+	 *
+	 * @return int File size in bytes
+	 */
 	public function file_size($path)
 	{
-		return filesize($this->root_path . $path);
+		$size = filesize($this->root_path . $path);
+
+		if ($size === null)
+		{
+			throw new exception('STORAGE_CANNOT_GET_FILESIZE');
+		}
+
+		return $size;
 	}
 
+
+	/**
+	 * Get file mimetype.
+	 *
+	 * @param string	$path	The file
+	 *
+	 * @return string	Mime type
+	 */
 	public function file_mimetype($path)
 	{
 		return mime_content_type($this->root_path . $path);
diff --git a/phpBB/phpbb/storage/file_info.php b/phpBB/phpbb/storage/file_info.php
index 04a6eb7e99..ec80eb3ccf 100644
--- a/phpBB/phpbb/storage/file_info.php
+++ b/phpBB/phpbb/storage/file_info.php
@@ -17,10 +17,19 @@ use phpbb\storage\exception\not_implemented;
 
 class file_info
 {
+	/**
+	 * @var \phpbb\storage\adapter\adapter_interface
+	 */
 	protected $adapter;
 
+	/**
+	 * @var string
+	 */
 	protected $path;
 
+	/**
+	 * @var array
+	 */
 	protected $properties;
 
 	public function __construct($adapter, $path)
@@ -29,6 +38,11 @@ class file_info
 		$this->path = $path;
 	}
 
+	/**
+	 * Load propertys lazily.
+	 *
+	 * @param string	path		The file path.
+	 */
 	protected function fill_properties($path)
 	{
 		if ($this->properties === null)
@@ -42,6 +56,13 @@ class file_info
 		}
 	}
 
+	/**
+	 * Load propertys lazily.
+	 *
+	 * @param string	name		The property name.
+	 *
+	 * @return string	Returns the property value
+	 */
 	public function get($name)
 	{
 		$this->fill_properties($this->path);
@@ -59,6 +80,9 @@ class file_info
 		return $this->properties[$name];
 	}
 
+	/**
+	 * Alias of \phpbb\storage\file_info->get()
+	 */
 	public function __get($name)
 	{
 		return $this->get($name);