diff --git a/phpBB/phpbb/filesystem/helper.php b/phpBB/phpbb/filesystem/helper.php
new file mode 100644
index 0000000000..2549a49929
--- /dev/null
+++ b/phpBB/phpbb/filesystem/helper.php
@@ -0,0 +1,365 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\filesystem;
+
+class helper
+{
+	/**
+	 * Eliminates useless . and .. components from specified path.
+	 *
+	 * @param string $path Path to clean
+	 *
+	 * @return string Cleaned path
+	 */
+	public static function clean_path($path)
+	{
+		$exploded = explode('/', $path);
+		$filtered = array();
+		foreach ($exploded as $part)
+		{
+			if ($part === '.' && !empty($filtered))
+			{
+				continue;
+			}
+
+			if ($part === '..' && !empty($filtered) && $filtered[sizeof($filtered) - 1] !== '.' && $filtered[sizeof($filtered) - 1] !== '..')
+			{
+				array_pop($filtered);
+			}
+			else
+			{
+				$filtered[] = $part;
+			}
+		}
+		$path = implode('/', $filtered);
+		return $path;
+	}
+
+	/**
+	 * Checks if a path is absolute or not
+	 *
+	 * @param string	$path	Path to check
+	 *
+	 * @return	bool	true if the path is absolute, false otherwise
+	 */
+	public static function is_absolute_path($path)
+	{
+		return (isset($path[0]) && $path[0] === '/' || preg_match('#^[a-z]:[/\\\]#i', $path)) ? true : false;
+	}
+
+	/**
+	 * Try to resolve real path when PHP's realpath failes to do so
+	 *
+	 * @param string	$path
+	 * @return bool|string
+	 */
+	protected static function phpbb_own_realpath($path)
+	{
+
+		// Replace all directory separators with '/'
+		$path = str_replace(DIRECTORY_SEPARATOR, '/', $path);
+
+		$is_absolute_path = false;
+		$path_prefix = '';
+
+		if (self::is_absolute_path($path))
+		{
+			$is_absolute_path = true;
+		}
+		else
+		{
+			if (function_exists('getcwd'))
+			{
+				$working_directory = str_replace(DIRECTORY_SEPARATOR, '/', getcwd());
+			}
+
+			//
+			// From this point on we really just guessing
+			// If chdir were called we screwed
+			//
+			else if (function_exists('debug_backtrace'))
+			{
+				$call_stack = debug_backtrace(0);
+				$working_directory = str_replace(DIRECTORY_SEPARATOR, '/', dirname($call_stack[sizeof($call_stack) - 1]['file']));
+			}
+			else
+			{
+				//
+				// Assuming that the working directory is phpBB root
+				// we could use this as a fallback, when phpBB will use controllers
+				// everywhere this will be a safe assumption
+				//
+				//$dir_parts = explode(DIRECTORY_SEPARATOR, __DIR__);
+				//$namespace_parts = explode('\\', trim(__NAMESPACE__, '\\'));
+
+				//$namespace_part_count = sizeof($namespace_parts);
+
+				// Check if we still loading from root
+				//if (array_slice($dir_parts, -$namespace_part_count) === $namespace_parts)
+				//{
+				//	$working_directory = implode('/', array_slice($dir_parts, 0, -$namespace_part_count));
+				//}
+				//else
+				//{
+				//	$working_directory = false;
+				//}
+
+				$working_directory = false;
+			}
+
+			if ($working_directory !== false)
+			{
+				$is_absolute_path = true;
+				$path = $working_directory . '/' . $path;
+			}
+		}
+
+		if ($is_absolute_path)
+		{
+			if (defined('PHP_WINDOWS_VERSION_MAJOR'))
+			{
+				$path_prefix = $path[0] . ':';
+				$path = substr($path, 2);
+			}
+			else
+			{
+				$path_prefix = '';
+			}
+		}
+
+		$resolved_path = self::resolve_path($path, $path_prefix, $is_absolute_path);
+		if ($resolved_path === false)
+		{
+			return false;
+		}
+
+		if (!@file_exists($resolved_path) || (!@is_dir($resolved_path . '/') && !is_file($resolved_path)))
+		{
+			return false;
+		}
+
+		// Return OS specific directory separators
+		$resolved = str_replace('/', DIRECTORY_SEPARATOR, $resolved_path);
+
+		// Check for DIRECTORY_SEPARATOR at the end (and remove it!)
+		if (substr($resolved, -1) === DIRECTORY_SEPARATOR)
+		{
+			return substr($resolved, 0, -1);
+		}
+
+		return $resolved;
+	}
+
+	/**
+	 * A wrapper for PHP's realpath
+	 *
+	 * Try to resolve realpath when PHP's realpath is not available, or
+	 * known to be buggy.
+	 *
+	 * @param string	$path	Path to resolve
+	 *
+	 * @return string	Resolved path
+	 */
+	public static function realpath($path)
+	{
+		if (!function_exists('realpath'))
+		{
+			return self::phpbb_own_realpath($path);
+		}
+
+		$realpath = realpath($path);
+
+		// Strangely there are provider not disabling realpath but returning strange values. :o
+		// We at least try to cope with them.
+		if ((!self::is_absolute_path($path) && $realpath === $path) || $realpath === false)
+		{
+			return self::phpbb_own_realpath($path);
+		}
+
+		// Check for DIRECTORY_SEPARATOR at the end (and remove it!)
+		if (substr($realpath, -1) === DIRECTORY_SEPARATOR)
+		{
+			$realpath = substr($realpath, 0, -1);
+		}
+
+		return $realpath;
+	}
+
+	/**
+	 * Given an existing path, convert it to a path relative to a given starting path
+	 *
+	 * @param string $end_path		Absolute path of target
+	 * @param string $start_path	Absolute path where traversal begins
+	 *
+	 * @return string Path of target relative to starting path
+	 */
+	public static function make_path_relative($end_path, $start_path)
+	{
+		$symfony_filesystem = new \Symfony\Component\Filesystem\Filesystem();
+		return $symfony_filesystem->makePathRelative($end_path, $start_path);
+	}
+
+	/**
+	 * Try to resolve symlinks in path
+	 *
+	 * @param string	$path			The path to resolve
+	 * @param string	$prefix			The path prefix (on windows the drive letter)
+	 * @param bool 		$absolute		Whether or not the path is absolute
+	 * @param bool		$return_array	Whether or not to return path parts
+	 *
+	 * @return string|array|bool	returns the resolved path or an array of parts of the path if $return_array is true
+	 * 								or false if path cannot be resolved
+	 */
+	protected static function resolve_path($path, $prefix = '', $absolute = false, $return_array = false)
+	{
+		if ($return_array)
+		{
+			$path = str_replace(DIRECTORY_SEPARATOR, '/', $path);
+		}
+
+		trim ($path, '/');
+		$path_parts = explode('/', $path);
+		$resolved = array();
+		$resolved_path = $prefix;
+		$file_found = false;
+
+		foreach ($path_parts as $path_part)
+		{
+			if ($file_found)
+			{
+				return false;
+			}
+
+			if (empty($path_part) || ($path_part === '.' && ($absolute || !empty($resolved))))
+			{
+				continue;
+			}
+			else if ($absolute && $path_part === '..')
+			{
+				if (empty($resolved))
+				{
+					// No directories above root
+					return false;
+				}
+
+				array_pop($resolved);
+				$resolved_path = false;
+			}
+			else if ($path_part === '..' && !empty($resolved) && !in_array($resolved[sizeof($resolved) - 1], array('.', '..')))
+			{
+				array_pop($resolved);
+				$resolved_path = false;
+			}
+			else
+			{
+				if ($resolved_path === false)
+				{
+					if (empty($resolved))
+					{
+						$resolved_path = ($absolute) ? $prefix . '/' . $path_part : $path_part;
+					}
+					else
+					{
+						$tmp_array = $resolved;
+						if ($absolute)
+						{
+							array_unshift($tmp_array, $prefix);
+						}
+
+						$resolved_path = implode('/', $tmp_array);
+					}
+				}
+
+				$current_path = $resolved_path . '/' . $path_part;
+
+				// Resolve symlinks
+				if (is_link($current_path))
+				{
+					if (!function_exists('readlink'))
+					{
+						return false;
+					}
+
+					$link = readlink($current_path);
+
+					// Is link has an absolute path in it?
+					if (self::is_absolute_path($link))
+					{
+						if (defined('PHP_WINDOWS_VERSION_MAJOR'))
+						{
+							$prefix = $link[0] . ':';
+							$link = substr($link, 2);
+						}
+						else
+						{
+							$prefix = '';
+						}
+
+						$resolved = self::resolve_path($link, $prefix, true, true);
+						$absolute = true;
+					}
+					else
+					{
+						$resolved = self::resolve_path($resolved_path . '/' . $link, $prefix, $absolute, true);
+					}
+
+					if (!$resolved)
+					{
+						return false;
+					}
+
+					$resolved_path = false;
+				}
+				else if (is_dir($current_path . '/'))
+				{
+					$resolved[] = $path_part;
+					$resolved_path = $current_path;
+				}
+				else if (is_file($current_path))
+				{
+					$resolved[] = $path_part;
+					$resolved_path = $current_path;
+					$file_found = true;
+				}
+				else
+				{
+					return false;
+				}
+			}
+		}
+
+		// If at the end of the path there were a .. or .
+		// we need to build the path again.
+		// Only doing this when a string is expected in return
+		if ($resolved_path === false && $return_array === false)
+		{
+			if (empty($resolved))
+			{
+				$resolved_path = ($absolute) ? $prefix . '/' : './';
+			}
+			else
+			{
+				$tmp_array = $resolved;
+				if ($absolute)
+				{
+					array_unshift($tmp_array, $prefix);
+				}
+
+				$resolved_path = implode('/', $tmp_array);
+			}
+		}
+
+		return ($return_array) ? $resolved : $resolved_path;
+	}
+}
diff --git a/tests/filesystem/helper_clean_path_test.php b/tests/filesystem/helper_clean_path_test.php
new file mode 100644
index 0000000000..21a4dfe238
--- /dev/null
+++ b/tests/filesystem/helper_clean_path_test.php
@@ -0,0 +1,52 @@
+<?php
+/**
+*
+* This file is part of the phpBB Forum Software package.
+*
+* @copyright (c) phpBB Limited <https://www.phpbb.com>
+* @license GNU General Public License, version 2 (GPL-2.0)
+*
+* For full copyright and license information, please see
+* the docs/CREDITS.txt file.
+*
+*/
+
+class phpbb_filesystem_helper_clean_path_test extends phpbb_test_case
+{
+
+	public function setUp()
+	{
+		parent::setUp();
+	}
+
+	public function clean_path_data()
+	{
+		return array(
+			array('foo', 'foo'),
+			array('foo/bar', 'foo/bar'),
+			array('foo/bar/', 'foo/bar/'),
+			array('foo/./bar', 'foo/bar'),
+			array('foo/./././bar', 'foo/bar'),
+			array('foo/bar/.', 'foo/bar'),
+			array('./foo/bar', './foo/bar'),
+			array('../foo/bar', '../foo/bar'),
+			array('./../foo/bar', './../foo/bar'),
+			array('././../foo/bar', './../foo/bar'),
+			array('one/two/three', 'one/two/three'),
+			array('one/two/../three', 'one/three'),
+			array('one/../two/three', 'two/three'),
+			array('one/two/..', 'one'),
+			array('one/two/../', 'one/'),
+			array('one/two/../three/../four', 'one/four'),
+			array('one/two/three/../../four', 'one/four'),
+		);
+	}
+
+	/**
+	* @dataProvider clean_path_data
+	*/
+	public function test_clean_path($input, $expected)
+	{
+		$this->assertEquals($expected, \phpbb\filesystem\helper::clean_path($input));
+	}
+}
diff --git a/tests/filesystem/helper_is_absolute_test.php b/tests/filesystem/helper_is_absolute_test.php
new file mode 100644
index 0000000000..52b5d9e1b9
--- /dev/null
+++ b/tests/filesystem/helper_is_absolute_test.php
@@ -0,0 +1,64 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+class phpbb_filesystem_helper_is_absolute_test extends phpbb_test_case
+{
+
+	public function setUp()
+	{
+		parent::setUp();
+	}
+
+	static public function is_absolute_data()
+	{
+		return array(
+			// Empty
+			array('', false),
+
+			// Absolute unix style
+			array('/etc/phpbb', true),
+			// Unix does not support \ so that is not an absolute path
+			array('\etc\phpbb', false),
+
+			// Absolute windows style
+			array('c:\windows', true),
+			array('C:\Windows', true),
+			array('c:/windows', true),
+			array('C:/Windows', true),
+
+			// Executable
+			array('etc/phpbb', false),
+			array('explorer.exe', false),
+
+			// Relative subdir
+			array('Windows\System32', false),
+			array('Windows\System32\explorer.exe', false),
+			array('Windows/System32', false),
+			array('Windows/System32/explorer.exe', false),
+
+			// Relative updir
+			array('..\Windows\System32', false),
+			array('..\Windows\System32\explorer.exe', false),
+			array('../Windows/System32', false),
+			array('../Windows/System32/explorer.exe', false),
+		);
+	}
+
+	/**
+	 * @dataProvider is_absolute_data
+	 */
+	public function test_is_absolute($path, $expected)
+	{
+		$this->assertEquals($expected, \phpbb\filesystem\helper::is_absolute_path($path));
+	}
+}
diff --git a/tests/filesystem/helper_realpath_test.php b/tests/filesystem/helper_realpath_test.php
new file mode 100644
index 0000000000..754d7631a4
--- /dev/null
+++ b/tests/filesystem/helper_realpath_test.php
@@ -0,0 +1,83 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+class phpbb_filesystem_helper_realpath_test extends phpbb_test_case
+{
+	protected static $filesystem_helper_phpbb_own_realpath;
+
+	static public function setUpBeforeClass()
+	{
+		parent::setUpBeforeClass();
+
+		self::$filesystem_helper_phpbb_own_realpath = new ReflectionMethod('\phpbb\filesystem\helper', 'phpbb_own_realpath');
+		self::$filesystem_helper_phpbb_own_realpath->setAccessible(true);
+	}
+
+	public function setUp()
+	{
+		parent::setUp();
+	}
+
+	public function realpath_resolve_absolute_without_symlinks_data()
+	{
+		return array(
+			// Constant data
+			array(__DIR__, __DIR__),
+			array(__DIR__ . '/../filesystem/../filesystem', __DIR__),
+			array(__DIR__ . '/././', __DIR__),
+			array(__DIR__ . '/non_existent', false),
+
+			array(__FILE__, __FILE__),
+			array(__FILE__ . '../', false),
+		);
+	}
+
+	public function realpath_resolve_relative_without_symlinks_data()
+	{
+		if (!function_exists('getcwd'))
+		{
+			return array();
+		}
+
+		$relative_path = \phpbb\filesystem\helper::make_path_relative(__DIR__, getcwd());
+
+		return array(
+			array($relative_path, __DIR__),
+			array($relative_path . '../filesystem/../filesystem', __DIR__),
+			array($relative_path . '././', __DIR__),
+
+			array($relative_path . 'helper_realpath_test.php', __FILE__),
+		);
+	}
+
+	/**
+	 * @dataProvider realpath_resolve_absolute_without_symlinks_data
+	 */
+	public function test_realpath_absolute_without_links($path, $expected)
+	{
+		$this->assertEquals($expected, self::$filesystem_helper_phpbb_own_realpath->invoke(null, $path));
+	}
+
+	/**
+	 * @dataProvider realpath_resolve_relative_without_symlinks_data
+	 */
+	public function test_realpath_relative_without_links($path, $expected)
+	{
+		if (!function_exists('getcwd'))
+		{
+			$this->markTestSkipped('phpbb_own_realpath() cannot be tested with relative paths: getcwd is not available.');
+		}
+
+		$this->assertEquals($expected, self::$filesystem_helper_phpbb_own_realpath->invoke(null, $path));
+	}
+}