[ticket/11362] Move phpbb_clean_path into a simple filesystem service

PHPBB3-11362

phpBB/includes/filesystem.php

@@ -0,0 +1,52 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2013 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* A class with various functions that are related to paths, files and the filesystem
+* @package phpBB3
+*/
+class phpbb_filesystem
+{
+	/**
+	* Eliminates useless . and .. components from specified path.
+	*
+	* @param string $path Path to clean
+	* @return string Cleaned path
+	*/
+	public function clean_path($path)
+	{
+		$exploded = explode('/', $path);
+		$filtered = array();
+		foreach ($exploded as $part)
+		{
+			if ($part === '.' && !empty($filtered))
+			{
+				continue;
+			}
+
+			if ($part === '..' && !empty($filtered) && $filtered[sizeof($filtered) - 1] !== '..')
+			{
+				array_pop($filtered);
+			}
+			else
+			{
+				$filtered[] = $part;
+			}
+		}
+		$path = implode('/', $filtered);
+		return $path;
+	}
+}