diff --git a/change_log.txt b/change_log.txt
index e663dea3f..38bb8ffd6 100644
--- a/change_log.txt
+++ b/change_log.txt
@@ -1,4 +1,8 @@
  ===== 3.1.25-dev===== (xx.xx.2015)
+ 14.06.2015
+  - bugfix a relative sub template path could fail if template_dir path did contain /../ https://github.com/smarty-php/smarty/issues/50
+  - optimization rework of path normalization
+
  13.06.2015
   - bugfix a custom cache resource using smarty_cachereource_keyvaluestore.php did fail if php.ini mbstring.func_overload = 2 (forum topic 25568)
 
diff --git a/libs/Smarty.class.php b/libs/Smarty.class.php
index 11ebe4600..1ade0c07e 100644
--- a/libs/Smarty.class.php
+++ b/libs/Smarty.class.php
@@ -111,7 +111,7 @@ class Smarty extends Smarty_Internal_TemplateBase
     /**
      * smarty version
      */
-    const SMARTY_VERSION = '3.1.25-dev/6';
+    const SMARTY_VERSION = '3.1.25-dev/7';
 
     /**
      * define variable scopes
@@ -206,8 +206,7 @@ class Smarty extends Smarty_Internal_TemplateBase
     /**
      * contains directories outside of SMARTY_DIR that are to be muted by muteExpectedErrors()
      */
-    public static $_muted_directories = array('./templates_c/' => null,
-                                              './cache/'       => null);
+    public static $_muted_directories = array('./templates_c/' => null, './cache/' => null);
 
     /**
      * Flag denoting if Multibyte String functions are available
@@ -617,10 +616,7 @@ class Smarty extends Smarty_Internal_TemplateBase
      *
      * @var array
      */
-    public $plugin_search_order = array('function',
-                                        'block',
-                                        'compiler',
-                                        'class');
+    public $plugin_search_order = array('function', 'block', 'compiler', 'class');
 
     /**
      * registered objects
@@ -973,7 +969,7 @@ public function setTemplateDir($template_dir)
     {
         $this->template_dir = array();
         foreach ((array) $template_dir as $k => $v) {
-            $this->template_dir[$k] = rtrim(strtr($v, '\\', '/'), '/') . '/';
+            $this->template_dir[$k] = rtrim($v, '/\\') . DS;
         }
         $this->joined_template_dir = join(' # ', $this->template_dir);
         return $this;
@@ -1021,7 +1017,7 @@ public function setConfigDir($config_dir)
     {
         $this->config_dir = array();
         foreach ((array) $config_dir as $k => $v) {
-            $this->config_dir[$k] = rtrim(strtr($v, '\\', '/'), '/') . '/';
+            $this->config_dir[$k] = rtrim($v, '/\\') . DS;
         }
         $this->joined_config_dir = join(' # ', $this->config_dir);
         return $this;
@@ -1067,10 +1063,7 @@ public function getConfigDir($index = null)
     public function setPluginsDir($plugins_dir)
     {
         $this->plugins_dir = array();
-        foreach ((array) $plugins_dir as $k => $v) {
-            $this->plugins_dir[$k] = rtrim(strtr($v, '\\', '/'), '/') . '/';
-        }
-        $this->_is_file_cache = array();
+        $this->addPluginsDir($plugins_dir);
         return $this;
     }
 
@@ -1083,7 +1076,11 @@ public function setPluginsDir($plugins_dir)
      */
     public function addPluginsDir($plugins_dir)
     {
-        $this->_addDir('plugins_dir', $plugins_dir);
+        // make sure we're dealing with an array
+        $this->plugins_dir = (array) $this->plugins_dir;
+        foreach ((array) $plugins_dir as $v) {
+            $this->plugins_dir[] = rtrim($v, '/\\') . DS;
+        }
         $this->plugins_dir = array_unique($this->plugins_dir);
         $this->_is_file_cache = array();
         return $this;
@@ -1108,7 +1105,7 @@ public function getPluginsDir()
      */
     public function setCompileDir($compile_dir)
     {
-        $this->compile_dir = rtrim(strtr($compile_dir, '\\', '/'), '/') . '/';
+        $this->compile_dir = rtrim($compile_dir, '/\\') . DS;
         if (!isset(Smarty::$_muted_directories[$this->compile_dir])) {
             Smarty::$_muted_directories[$this->compile_dir] = null;
         }
@@ -1135,11 +1132,10 @@ public function getCompileDir()
      */
     public function setCacheDir($cache_dir)
     {
-        $this->cache_dir = rtrim(strtr($cache_dir, '\\', '/'), '/') . '/';
+        $this->cache_dir = rtrim($cache_dir, '/\\') . DS;
         if (!isset(Smarty::$_muted_directories[$this->cache_dir])) {
             Smarty::$_muted_directories[$this->cache_dir] = null;
         }
-
         return $this;
     }
 
@@ -1167,23 +1163,21 @@ private function _addDir($dirName, $dir, $key = null)
 
         if (is_array($dir)) {
             foreach ($dir as $k => $v) {
-                $v = rtrim(strtr($v, '\\', '/'), '/') . '/';
                 if (is_int($k)) {
                     // indexes are not merged but appended
-                    $this->{$dirName}[] = $v;
+                    $this->{$dirName}[] = rtrim($v, '/\\') . DS;
                 } else {
                     // string indexes are overridden
-                    $this->{$dirName}[$k] = $v;
+                    $this->{$dirName}[$k] = rtrim($v, '/\\') . DS;
                 }
             }
         } else {
-            $v = rtrim(strtr($dir, '\\', '/'), '/') . '/';
             if ($key !== null) {
                 // override directory at specified index
-                $this->{$dirName}[$key] = $v;
+                $this->{$dirName}[$key] = rtrim($dir, '/\\') . DS;
             } else {
                 // append new directory
-                $this->{$dirName}[] = $v;
+                $this->{$dirName}[] = rtrim($dir, '/\\') . DS;
             }
         }
     }
@@ -1420,8 +1414,7 @@ public function loadPlugin($plugin_name, $check = true)
 
         // loop through plugin dirs and find the plugin
         foreach ($this->getPluginsDir() as $_plugin_dir) {
-            $names = array($_plugin_dir . $_plugin_filename,
-                           $_plugin_dir . strtolower($_plugin_filename),);
+            $names = array($_plugin_dir . $_plugin_filename, $_plugin_dir . strtolower($_plugin_filename),);
             foreach ($names as $file) {
                 if (isset($this->_is_file_cache[$file]) ? $this->_is_file_cache[$file] : $this->_is_file_cache[$file] = is_file($file)) {
                     require_once($file);
@@ -1678,10 +1671,8 @@ public function __destruct()
      */
     public function __get($name)
     {
-        $allowed = array('template_dir' => 'getTemplateDir',
-                         'config_dir'   => 'getConfigDir',
-                         'plugins_dir'  => 'getPluginsDir',
-                         'compile_dir'  => 'getCompileDir',
+        $allowed = array('template_dir' => 'getTemplateDir', 'config_dir' => 'getConfigDir',
+                         'plugins_dir'  => 'getPluginsDir', 'compile_dir' => 'getCompileDir',
                          'cache_dir'    => 'getCacheDir',);
 
         if (isset($allowed[$name])) {
@@ -1701,10 +1692,8 @@ public function __get($name)
      */
     public function __set($name, $value)
     {
-        $allowed = array('template_dir' => 'setTemplateDir',
-                         'config_dir'   => 'setConfigDir',
-                         'plugins_dir'  => 'setPluginsDir',
-                         'compile_dir'  => 'setCompileDir',
+        $allowed = array('template_dir' => 'setTemplateDir', 'config_dir' => 'setConfigDir',
+                         'plugins_dir'  => 'setPluginsDir', 'compile_dir' => 'setCompileDir',
                          'cache_dir'    => 'setCacheDir',);
 
         if (isset($allowed[$name])) {
@@ -1750,8 +1739,7 @@ public static function mutingErrorHandler($errno, $errstr, $errfile, $errline, $
                     unset(Smarty::$_muted_directories[$key]);
                     continue;
                 }
-                $dir = array('file'   => $file,
-                             'length' => strlen($file),);
+                $dir = array('file' => $file, 'length' => strlen($file),);
             }
             if (!strncmp($errfile, $dir['file'], $dir['length'])) {
                 $_is_muted_directory = true;
@@ -1793,8 +1781,7 @@ public static function muteExpectedErrors()
                 - between file_exists() and filemtime() a possible race condition is opened,
                   which does not exist using the simple @filemtime() approach.
         */
-        $error_handler = array('Smarty',
-                               'mutingErrorHandler');
+        $error_handler = array('Smarty', 'mutingErrorHandler');
         $previous = set_error_handler($error_handler);
 
         // avoid dead loops
diff --git a/libs/sysplugins/smarty_internal_resource_file.php b/libs/sysplugins/smarty_internal_resource_file.php
index 95d229652..1c7051905 100644
--- a/libs/sysplugins/smarty_internal_resource_file.php
+++ b/libs/sysplugins/smarty_internal_resource_file.php
@@ -18,6 +18,8 @@
 class Smarty_Internal_Resource_File extends Smarty_Resource
 {
 
+    private $dsMap = array('/' => array(array('\\', '/./'), '/.'), '\\' => array(array('/', '\\.\\'), '\\.'));
+
     /**
      * build template filepath by traversing the template_dir array
      *
@@ -29,44 +31,30 @@ class Smarty_Internal_Resource_File extends Smarty_Resource
      */
     protected function buildFilepath(Smarty_Template_Source $source, Smarty_Internal_Template $_template = null)
     {
-        $file = str_replace(array('\\', '/./'), '/', $source->name);
-        if ($source->isConfig) {
-            $_directories = $source->smarty->getConfigDir();
-        } else {
-            $_directories = $source->smarty->getTemplateDir();
-        }
-        preg_match('#^((?P<absolute>[\/]|[a-zA-Z]:[\/])|(\[(?P<index>[^\]]+)\])|((?P<rel1>\.[\/])?(?P<rel2>(\.\.[\/])*))|(?P<skip>[\/]))?(?P<file>.+)$#', $file, $fileMatch);
+        $file = $source->name;
+        preg_match('#^(?P<absolute>[\\\/]|[a-zA-Z]:[\\\/])|(\[(?P<index>[^\]]+)\])|(?P<rel>\.[\\\/])#', $file, $fileMatch);
         // save basename
         if (!empty($fileMatch['absolute'])) {
+            $file = $this->normalizePath($file);
             return is_file($file) ? $file : false;
         }
         // go relative to a given template?
-        if ($_template && $_template->parent instanceof Smarty_Internal_Template && (!empty($fileMatch['rel1']) || !empty($fileMatch['rel2']))) {
+        if (!empty($fileMatch['rel']) && $_template && $_template->parent instanceof Smarty_Internal_Template) {
             if ($_template->parent->source->type != 'file' && $_template->parent->source->type != 'extends' && !$_template->parent->allow_relative_path) {
                 throw new SmartyException("Template '{$file}' cannot be relative to template of resource type '{$_template->parent->source->type}'");
             }
-            $path = dirname($_template->parent->source->filepath);
-            if (!preg_match('/^([\/\\\\]|[a-zA-Z]:[\/\\\\])/', $path)) {
-                // the path gained from the parent template is relative to the current working directory
-                // as expansions (like include_path) have already been done
-                $path = str_replace('\\', '/', getcwd()) . '/' . $path;
-            }
+            $path = dirname($_template->parent->source->filepath) . DS . $file;
             // normalize path
-            $path = str_replace(array('\\', './'), array('/', ''), $path);
-            // simple relative
-            if (!empty($fileMatch['rel1'])) {
-                $file = $path . '/' . $fileMatch['file'];
-            } else {
-                for ($i = 1; $i <= substr_count($fileMatch['rel2'], '../'); $i ++) {
-                    $path = substr($path, 0, strrpos($path, '/'));
-                }
-                $file = $path . '/' . $fileMatch['file'];
-            }
+            $path = $this->normalizePath($path);
             // files relative to a template only get one shot
-            return is_file($file) ? $file : false;
+            return is_file($path) ? $path : false;
         }
 
-        $_filepath = null;
+        if ($source->isConfig) {
+            $_directories = $source->smarty->getConfigDir();
+        } else {
+            $_directories = $source->smarty->getTemplateDir();
+        }
         // template_dir index?
         if (!empty($fileMatch['index'])) {
             $index = $fileMatch['index'];
@@ -86,29 +74,24 @@ protected function buildFilepath(Smarty_Template_Source $source, Smarty_Internal
                 }
             }
             if ($_directory) {
-                $_filepath = $_directory . $fileMatch['file'];
-                if (is_file($_filepath)) {
-                    return $_filepath;
+                preg_match('#\](.+)$#', $file, $fileMatch);
+                $path = $_directory . $fileMatch[1];
+                $path = $this->normalizePath($path);
+                if (is_file($path)) {
+                    return $path;
                 }
+            } else {
+                // index not found
+                return false;
             }
         }
 
         // relative file name?
         foreach ($_directories as $_directory) {
-            if (empty($fileMatch['rel2'])) {
-                $_filepath = $_directory . $fileMatch['file'];
-            } else {
-                if (false === strpos($_directory, '..')) {
-                    for ($i = 1; $i <= substr_count($fileMatch['rel2'], '../') + 1; $i ++) {
-                        $_directory = substr($_directory, 0, strrpos($_directory, '/'));
-                    }
-                    $_filepath = $_directory . '/' . $fileMatch['file'];
-                } else {
-                    $_filepath = $_directory . $file;
-                }
-            }
-            if (is_file($_filepath)) {
-                return $_filepath;
+            $_filepath = $_directory . $file;
+            $path = $this->normalizePath($_filepath);
+            if (is_file($path)) {
+                return $path;
             }
             if ($source->smarty->use_include_path && !preg_match('/^([\/\\\\]|[a-zA-Z]:[\/\\\\])/', $_directory)) {
                 // try PHP include_path
@@ -117,25 +100,38 @@ protected function buildFilepath(Smarty_Template_Source $source, Smarty_Internal
                 } else {
                     $_filepath = Smarty_Internal_Get_Include_Path::getIncludePath($_filepath);
                 }
-
                 if ($_filepath !== false) {
-                    if (is_file($_filepath)) {
-                        return $_filepath;
+                    $path = $this->normalizePath($_filepath);
+                    if (is_file($path)) {
+                        return $path;
                     }
                 }
             }
         }
         // Could be relative to cwd
-        $path = str_replace('\\', '/', getcwd());
-        if (empty($fileMatch['rel2'])) {
-            $file = $path . '/' . $fileMatch['file'];
-        } else {
-            for ($i = 1; $i <= substr_count($fileMatch['rel2'], '../'); $i ++) {
-                $path = substr($path, 0, strrpos($path, '/'));
-            }
-            $file = $path . '/' . $fileMatch['file'];
+        $path = $this->normalizePath(getcwd() . DS . $file);
+        return is_file($path) ? $path : false;
+    }
+
+    /**
+     * Normalize path
+     *  - remove /./ and /../
+     *  - make it absolute
+     *
+     * @param string $path file path
+     *
+     * @return string
+     */
+    public function normalizePath($path)
+    {
+        if ($path[0] == '.') {
+            $path = getcwd() . DS . $path;
+        }
+        $path = str_replace($this->dsMap[DS][0], DS, $path);
+        while (strrpos($path, $this->dsMap[DS][1]) !== false) {
+            $path = preg_replace('#([\\\/][.][\\\/])|([\\\/][^\\\/]+[\\\/][.][.][\\\/])#', DS, $path);
         }
-        return is_file($file) ? $file : false;
+        return $path;
     }
 
     /**
@@ -166,13 +162,10 @@ public function populate(Smarty_Template_Source $source, Smarty_Internal_Templat
             if (is_object($source->smarty->security_policy)) {
                 $source->smarty->security_policy->isTrustedResourceDir($source->filepath);
             }
-
-            $source->uid = sha1(getcwd() . $source->filepath);
+            $source->exists = true;
+            $source->uid = sha1($source->filepath);
             if ($source->smarty->compile_check && !isset($source->timestamp)) {
-                $source->timestamp = $source->exists = is_file($source->filepath);
-                if ($source->exists) {
-                    $source->timestamp = @filemtime($source->filepath);
-                }
+                $source->timestamp = @filemtime($source->filepath);
             }
         } else {
             $source->timestamp = false;