CodeIgniter框架源码分析第一篇comnon.php

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index.php 定义一些基本的路径及环境信息(默认development)


一. 引导程序——core/CodeIgniter.php


1.constants.php——定义框架常量


例如:

defined('SHOW_DEBUG_BACKTRACE') OR define('SHOW_DEBUG_BACKTRACE', TRUE);——设置打印php运行时的错误信息


2.core/comnon.php——加载全局函数


1) is_php 

    判断php的版本是否等于或者大于给定的值。


2)is_really_writeable

    判断文件是否有可写权限。true——可写,false——不可写


3) load_class——类注册函数 

   定义了一个static $_classes = array();

   如果用&load_class方式调用,实际上指向了$_classes的内存地址。

   该函数首先在application/libraries 文件夹中寻找类名文件,再在system/libraries文件夹中寻中类名文件,找到了实例化后放进$_classes 中,当调用&load_class时,会取出全部的$_classes数组。

if ( ! function_exists('load_class'))
{
/**
* Class registry
*
* This function acts as a singleton. If the requested class does not
* exist it is instantiated and set to a static variable. If it has
* previously been instantiated the variable is returned.
*
* @param string the class name being requested
* @param string the directory where the class should be found
* @param mixed an optional argument to pass to the class constructor
* @return object
*/
function &load_class($class, $directory = 'libraries', $param = NULL)
{
static $_classes = array();


// Does the class exist? If so, we're done...
if (isset($_classes[$class]))
{
return $_classes[$class];
}


$name = FALSE;


// Look for the class first in the local application/libraries folder
// then in the native system/libraries folder
foreach (array(APPPATH, BASEPATH) as $path)
{
if (file_exists($path.$directory.'/'.$class.'.php'))
{
$name = 'CI_'.$class;


if (class_exists($name, FALSE) === FALSE)
{
require_once($path.$directory.'/'.$class.'.php');
}


break;
}
}


// Is the request a class extension? If so we load it too
if (file_exists(APPPATH.$directory.'/'.config_item('subclass_prefix').$class.'.php'))
{
$name = config_item('subclass_prefix').$class;


if (class_exists($name, FALSE) === FALSE)
{
require_once(APPPATH.$directory.'/'.$name.'.php');
}
}


// Did we find the class?
if ($name === FALSE)
{
// Note: We use exit() rather than show_error() in order to avoid a
// self-referencing loop with the Exceptions class
set_status_header(503);
echo 'Unable to locate the specified class: '.$class.'.php';
exit(5); // EXIT_UNK_CLASS
}


// Keep track of what we just loaded
is_loaded($class);


$_classes[$class] = isset($param)
? new $name($param)
: new $name();
return $_classes[$class];
}
}

4)ls_loaded——记录哪些类被记载了

if ( ! function_exists('is_loaded'))
{
  /**
   * Keeps track of which libraries have been loaded. This function is
   * called by the load_class() function above
   *
   * @param string
   * @return  array
   */
  function &is_loaded($class = '')
  {
    static $_is_loaded = array();


    if ($class !== '')
    {
      $_is_loaded[strtolower($class)] = $class;
    }


    return $_is_loaded;
  }
}

5) &get_config ——加载配置文件

if ( ! function_exists('get_config'))
{
  /**
   * Loads the main config.php file
   *
   * This function lets us grab the config file even if the Config class
   * hasn't been instantiated yet
   *
   * @param array
   * @return  array
   */
  function &get_config(Array $replace = array())
  {
    static $config;


    if (empty($config))
    {
      $file_path = APPPATH.'config/config.php';
      $found = FALSE;
      if (file_exists($file_path))
      {
        $found = TRUE;
        require($file_path);
      }


      // Is the config file in the environment folder?
      if (file_exists($file_path = APPPATH.'config/'.ENVIRONMENT.'/config.php'))
      {
        require($file_path);
      }
      elseif ( ! $found)
      {
        set_status_header(503);
        echo 'The configuration file does not exist.';
        exit(3); // EXIT_CONFIG
      }


      // Does the $config array exist in the file?
      if ( ! isset($config) OR ! is_array($config))
      {
        set_status_header(503);
        echo 'Your config file does not appear to be formatted correctly.';
        exit(3); // EXIT_CONFIG
      }
    }

    //动态修改config里面的值
    // Are any values being dynamically added or replaced?
    foreach ($replace as $key => $val)
    {
      $config[$key] = $val;
    }


    return $config;
  }
}

6)config_item  ——将配置文件赋值给一个静态数组,并返回。

if ( ! function_exists('config_item'))
{
  /**
   * Returns the specified config item
   *
   * @param string
   * @return  mixed
   */
  function config_item($item)
  {
    static $_config;


    if (empty($_config))
    {
      // references cannot be directly assigned to static variables, so we use an array
      $_config[0] =& get_config();
    }


    return isset($_config[0][$item]) ? $_config[0][$item] : NULL;
  }
}

7)&get_mimes—— 返回mime types

if ( ! function_exists('get_mimes'))
{
  /**
   * Returns the MIME types array from config/mimes.php
   *
   * @return  array
   */
  function &get_mimes()
  {
    static $_mimes;


    if (empty($_mimes))
    {
      $_mimes = file_exists(APPPATH.'config/mimes.php')
        ? include(APPPATH.'config/mimes.php')
        : array();


      if (file_exists(APPPATH.'config/'.ENVIRONMENT.'/mimes.php'))
      {
        $_mimes = array_merge($_mimes, include(APPPATH.'config/'.ENVIRONMENT.'/mimes.php'));
      }
    }


    return $_mimes;
  }
}

8) is_https——判断是不是https链接

if ( ! function_exists('is_https'))
{
  /**
   * Is HTTPS?
   *
   * Determines if the application is accessed via an encrypted
   * (HTTPS) connection.
   *
   * @return  bool
   */
  function is_https()
  {
    if ( ! empty($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) !== 'off')
    {
      return TRUE;
    }
    elseif (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && strtolower($_SERVER['HTTP_X_FORWARDED_PROTO']) === 'https')
    {
      return TRUE;
    }
    elseif ( ! empty($_SERVER['HTTP_FRONT_END_HTTPS']) && strtolower($_SERVER['HTTP_FRONT_END_HTTPS']) !== 'off')
    {
      return TRUE;
    }


    return FALSE;
  }
}

9) is_cli  ——判断请求是不是命令行模式

if ( ! function_exists('is_cli'))
{


  /**
   * Is CLI?
   *
   * Test to see if a request was made from the command line.
   *
   * @return  bool
   */
  function is_cli()
  {
    return (PHP_SAPI === 'cli' OR defined('STDIN'));
  }
}

10)show_error——展示错误信息

if ( ! function_exists('show_error'))
{
  /**
   * Error Handler
   *
   * This function lets us invoke the exception class and
   * display errors using the standard error template located
   * in application/views/errors/error_general.php
   * This function will send the error page directly to the
   * browser and exit.
   *

  * 该函数援引异常类,将错误通过application/views/errors/error_general.php标准模板展示出来,并直接显示在浏览器上并终止程序

   * @param string
   * @param int
   * @param string
   * @return  void
   */
  function show_error($message, $status_code = 500, $heading = 'An Error Was Encountered')
  {
    $status_code = abs($status_code);
    if ($status_code < 100)
    {
      $exit_status = $status_code + 9; // 9 is EXIT__AUTO_MIN
      $status_code = 500;
    }
    else
    {
      $exit_status = 1; // EXIT_ERROR
    }


    $_error =& load_class('Exceptions', 'core');

    //调用异常类Exception里面的show_error方法
    echo $_error->show_error($heading, $message, 'error_general', $status_code);
    exit($exit_status);
  }
}

11)show_404——展示404错误

if ( ! function_exists('show_404'))
{
   /**
    * 404 Page Handler
    *
    * This function is similar to the show_error() function above
    * However, instead of the standard error template it displays
    * 404 errors.
    *
    * @param   string
    * @param   bool
    * @return  void
    */
   function show_404($page = '', $log_error = TRUE)
   {
      $_error =& load_class('Exceptions', 'core');
      $_error->show_404($page, $log_error);
      exit(4); // EXIT_UNKNOWN_FILE
   }
}


12)log_message——记录日志

if ( ! function_exists('log_message'))
{
/**
* Error Logging Interface
*
* We use this as a simple mechanism to access the logging
* class and send messages to be logged.
*
* @param string the error level: 'error', 'debug' or 'info'
* @param string the error message
* @return void
*/
function log_message($level, $message)
{
static $_log;


if ($_log === NULL)
{
// references cannot be directly assigned to static variables, so we use an array
$_log[0] =& load_class('Log', 'core');
}


$_log[0]->write_log($level, $message);
}
}


13)set_status_header——设置http s

if ( ! function_exists('set_status_header'))
{
/**
* Set HTTP Status Header
*
* @param int the status code
* @param string
* @return void
*/
function set_status_header($code = 200, $text = '')
{
if (is_cli())
{
return;
}


if (empty($code) OR ! is_numeric($code))
{
show_error('Status codes must be numeric', 500);
}


if (empty($text))
{
is_int($code) OR $code = (int) $code;
$stati = array(
100 => 'Continue',
101 => 'Switching Protocols',


200 => 'OK',
201 => 'Created',
202 => 'Accepted',
203 => 'Non-Authoritative Information',
204 => 'No Content',
205 => 'Reset Content',
206 => 'Partial Content',


300 => 'Multiple Choices',
301 => 'Moved Permanently',
302 => 'Found',
303 => 'See Other',
304 => 'Not Modified',
305 => 'Use Proxy',
307 => 'Temporary Redirect',


400 => 'Bad Request',
401 => 'Unauthorized',
402 => 'Payment Required',
403 => 'Forbidden',
404 => 'Not Found',
405 => 'Method Not Allowed',
406 => 'Not Acceptable',
407 => 'Proxy Authentication Required',
408 => 'Request Timeout',
409 => 'Conflict',
410 => 'Gone',
411 => 'Length Required',
412 => 'Precondition Failed',
413 => 'Request Entity Too Large',
414 => 'Request-URI Too Long',
415 => 'Unsupported Media Type',
416 => 'Requested Range Not Satisfiable',
417 => 'Expectation Failed',
422 => 'Unprocessable Entity',
426 => 'Upgrade Required',
428 => 'Precondition Required',
429 => 'Too Many Requests',
431 => 'Request Header Fields Too Large',


500 => 'Internal Server Error',
501 => 'Not Implemented',
502 => 'Bad Gateway',
503 => 'Service Unavailable',
504 => 'Gateway Timeout',
505 => 'HTTP Version Not Supported',
511 => 'Network Authentication Required',
);


if (isset($stati[$code]))
{
$text = $stati[$code];
}
else
{
show_error('No status text available. Please check your status code number or supply your own message text.', 500);
}
}


if (strpos(PHP_SAPI, 'cgi') === 0)
{
header('Status: '.$code.' '.$text, TRUE);
return;
}


$server_protocol = (isset($_SERVER['SERVER_PROTOCOL']) && in_array($_SERVER['SERVER_PROTOCOL'], array('HTTP/1.0', 'HTTP/1.1', 'HTTP/2'), TRUE))
? $_SERVER['SERVER_PROTOCOL'] : 'HTTP/1.1';
header($server_protocol.' '.$code.' '.$text, TRUE, $code);
}
}


14)_exception_handler——display_errors is On 用于测试或者开发环境处理异常

if ( ! function_exists('_exception_handler'))
{
/**
* Exception Handler
*
* Sends uncaught exceptions to the logger and displays them
* only if display_errors is On so that they don't show up in
* production environments.
*
* @param Exception $exception
* @return void
*/
function _exception_handler($exception)
{
$_error =& load_class('Exceptions', 'core');
$_error->log_exception('error', 'Exception: '.$exception->getMessage(), $exception->getFile(), $exception->getLine());


is_cli() OR set_status_header(500);
// Should we display the error?
if (str_ireplace(array('off', 'none', 'no', 'false', 'null'), '', ini_get('display_errors')))
{
$_error->show_exception($exception);
}


exit(1); // EXIT_ERROR
}
}


15)_shutdown_handler——关闭错误处理

if ( ! function_exists('_shutdown_handler'))
{
/**
* Shutdown Handler
*
* This is the shutdown handler that is declared at the top
* of CodeIgniter.php. The main reason we use this is to simulate
* a complete custom exception handler.
*
* E_STRICT is purposively neglected because such events may have
* been caught. Duplication or none? None is preferred for now.
*
* @link http://insomanic.me.uk/post/229851073/php-trick-catching-fatal-errors-e-error-with-a
* @return void
*/
function _shutdown_handler()
{
$last_error = error_get_last();
if (isset($last_error) &&
($last_error['type'] & (E_ERROR | E_PARSE | E_CORE_ERROR | E_CORE_WARNING | E_COMPILE_ERROR | E_COMPILE_WARNING)))
{
_error_handler($last_error['type'], $last_error['message'], $last_error['file'], $last_error['line']);
}
}
}


16)remove_invisible_characters——移除字符串中不可见字符

if ( ! function_exists('remove_invisible_characters'))
{
/**
* Remove Invisible Characters
*
* This prevents sandwiching null characters
* between ascii characters, like Java\0script.
*
* @param string
* @param bool
* @return string
*/
function remove_invisible_characters($str, $url_encoded = TRUE)
{
$non_displayables = array();


// every control character except newline (dec 10),
// carriage return (dec 13) and horizontal tab (dec 09)
if ($url_encoded)
{
$non_displayables[] = '/%0[0-8bcef]/i';// url encoded 00-08, 11, 12, 14, 15
$non_displayables[] = '/%1[0-9a-f]/i';// url encoded 16-31
$non_displayables[] = '/%7f/i';// url encoded 127
}


$non_displayables[] = '/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]+/S';// 00-08, 11, 12, 14-31, 127


do
{
$str = preg_replace($non_displayables, '', $str, -1, $count);
}
while ($count);


return $str;
}
}


17) html_escape —— html代码转码原样输出

if ( ! function_exists('html_escape'))
{
/**
* Returns HTML escaped variable.
*
* @param mixed $var The input string or array of strings to be escaped.
* @param bool $double_encode$double_encode set to FALSE prevents escaping twice.
* @return mixed The escaped string or array of strings as a result.
*/
function html_escape($var, $double_encode = TRUE)
{
if (empty($var))
{
return $var;
}


if (is_array($var))
{
foreach (array_keys($var) as $key)
{
$var[$key] = html_escape($var[$key], $double_encode);
}


return $var;
}


return htmlspecialchars($var, ENT_QUOTES, config_item('charset'), $double_encode);
}
}


18)_stringify_attributes —— 转换字符串、数组、对象为字符串

if ( ! function_exists('_stringify_attributes'))
{
/**
* Stringify attributes for use in HTML tags.
*
* Helper function used to convert a string, array, or object
* of attributes to a string.
*
* @param mixed string, array, object
* @param bool
* @return string
*/
function _stringify_attributes($attributes, $js = FALSE)
{
$atts = NULL;


if (empty($attributes))
{
return $atts;
}


if (is_string($attributes))
{
return ' '.$attributes;
}


$attributes = (array) $attributes;


foreach ($attributes as $key => $val)
{
$atts .= ($js) ? $key.'='.$val.',' : ' '.$key.'="'.$val.'"';
}


return rtrim($atts, ',');
}

}


19)function_usable——检查suhosin扩展,返回fasle

if ( ! function_exists('function_usable'))
{
/**
* Function usable
*
* Executes a function_exists() check, and if the Suhosin PHP
* extension is loaded - checks whether the function that is
* checked might be disabled in there as well.
*
* This is useful as function_exists() will return FALSE for
* functions disabled via the *disable_functions* php.ini
* setting, but not for *suhosin.executor.func.blacklist* and
* *suhosin.executor.disable_eval*. These settings will just
* terminate script execution if a disabled function is executed.
*
* The above described behavior turned out to be a bug in Suhosin,
* but even though a fix was committed for 0.9.34 on 2012-02-12,
* that version is yet to be released. This function will therefore
* be just temporary, but would probably be kept for a few years.
*
* @link http://www.hardened-php.net/suhosin/
* @param string $function_nameFunction to check for
* @return bool TRUE if the function exists and is safe to call,
* FALSE otherwise.
*/
function function_usable($function_name)
{
static $_suhosin_func_blacklist;


if (function_exists($function_name))
{
if ( ! isset($_suhosin_func_blacklist))
{
$_suhosin_func_blacklist = extension_loaded('suhosin')
? explode(',', trim(ini_get('suhosin.executor.func.blacklist')))
: array();
}


return ! in_array($function_name, $_suhosin_func_blacklist, TRUE);
}


return FALSE;
}
}