CodeIgniter-Router的BUG（3.0.0版本）

好久没有更新Blog了，前一段时间在研究nginx源码。相比redis，nginx的代码量要多几倍，结构也比较复杂，稍后将补充nginx的源码分析。

在研究nginx的同时，笔者也开始着手阅读CodeIgniter源码。CodeIgniter是一款非常流行且轻量级的框架。CodeIgniter，设计灵活，扩展性强，低耦合。

在阅读源码CodeIgniter3.0.0的时候，笔者发现Router.php的一个BUG,此BUG在后期的版本已修复。

protected function _set_routing(){    if ($this->enable_query_strings)    {        $_d = $this->config->item('directory_trigger');        $_d = isset($_GET[$_d]) ? trim($_GET[$_d], " \t\n\r\0\x0B/") : '';        if ($_d !== '')        {            $this->uri->filter_uri($_d);            $this->set_directory($_d);        }        //获取control参数        $_c = trim($this->config->item('controller_trigger'));        if ( ! empty($_GET[$_c]))        {            $this->uri->filter_uri($_GET[$_c]);            $this->set_class($_GET[$_c]);            //获取方法            $_f = trim($this->config->item('function_trigger'));            if ( ! empty($_GET[$_f]))            {                $this->uri->filter_uri($_GET[$_f]);                $this->set_method($_GET[$_f]);            }            $this->uri->rsegments = array(                1 => $this->class,                2 => $this->method            );        }        else        {            $this->_set_default_controller();        }        // Routing rules don't apply to query strings and we don't need to detect        // directories, so we're done here        return;    }    //加载routes配置文件    if (file_exists(APPPATH.'config/routes.php'))    {        include(APPPATH.'config/routes.php');    }    if (file_exists(APPPATH.'config/'.ENVIRONMENT.'/routes.php'))    {        include(APPPATH.'config/'.ENVIRONMENT.'/routes.php');    }    // Validate & get reserved routes    if (isset($route) && is_array($route))    {        isset($route['default_controller']) && $this->default_controller = $route['default_controller'];        isset($route['translate_uri_dashes']) && $this->translate_uri_dashes = $route['translate_uri_dashes'];        unset($route['default_controller'], $route['translate_uri_dashes']);        $this->routes = $route;    }    // Is there anything to parse?    if ($this->uri->uri_string !== '')    {        $this->_parse_routes();    }    else    {        $this->_set_default_controller();    }}

从上面的代码可以看出，当$this->enable_query_strings 条件为true 时，系统首先会判断url是否带有controller_trigger 配置参数。若存在，则继续获取function_trigger 配置参数值；若不存在，则调用$this->_set_default_controller() 方法。而此时，$this->_set_default_controller 并未定义。so，此时访问会出现报错的情况。简而言之，就是在$this->enable_query_strings 为True时，/index.php访问会出现报错。

解决方法：只要把line42~60行的代码放置该流程之前运行。

protected function _set_routing(){    // Load the routes.php file.    //修复CI框架BUG，default_controller放在函数顶部进行初始化    //加载routes配置文件    if (file_exists(APPPATH.'config/routes.php'))    {        include(APPPATH.'config/routes.php');    }    if (file_exists(APPPATH.'config/'.ENVIRONMENT.'/routes.php'))    {        include(APPPATH.'config/'.ENVIRONMENT.'/routes.php');    }    // Validate & get reserved routes    if (isset($route) && is_array($route))    {        isset($route['default_controller']) && $this->default_controller = $route['default_controller'];        isset($route['translate_uri_dashes']) && $this->translate_uri_dashes = $route['translate_uri_dashes'];        unset($route['default_controller'], $route['translate_uri_dashes']);        $this->routes = $route;    }    if ($this->enable_query_strings)    {        $_d = $this->config->item('directory_trigger');        $_d = isset($_GET[$_d]) ? trim($_GET[$_d], " \t\n\r\0\x0B/") : '';        if ($_d !== '')        {            $this->uri->filter_uri($_d);            $this->set_directory($_d);        }        //获取control参数        $_c = trim($this->config->item('controller_trigger'));        if ( ! empty($_GET[$_c]))        {            $this->uri->filter_uri($_GET[$_c]);            $this->set_class($_GET[$_c]);            //获取方法            $_f = trim($this->config->item('function_trigger'));            if ( ! empty($_GET[$_f]))            {                $this->uri->filter_uri($_GET[$_f]);                $this->set_method($_GET[$_f]);            }            $this->uri->rsegments = array(                1 => $this->class,                2 => $this->method            );        }        else        {            $this->_set_default_controller();        }        // Routing rules don't apply to query strings and we don't need to detect        // directories, so we're done here        return;    }    // Is there anything to parse?    if ($this->uri->uri_string !== '')    {        $this->_parse_routes();    }    else    {        $this->_set_default_controller();    }}

总结
很多开源软件之所以优秀，并不在于它的代码有多么美观，而是在于它的设计思想。很多时候我们只掌握了它的用法，并未理解它真正的含义。如果能耐心地测试，加以推敲，我们就能快速地理解它的意图，了解其设计的精髓。