CodeIgniter框架原始碼分析第一篇comnon.php
index.php 定義一些基本的路徑及環境資訊（預設development）
一. 載入程式——core/CodeIgniter.php
1.constants.php——定義框架常量
例如：
defined('SHOW_DEBUG_BACKTRACE') OR define('SHOW_DEBUG_BACKTRACE', TRUE);——設定列印php執行時的錯誤資訊
2.core/comnon.php——載入全域性函式
1) is_php
判斷php的版本是否等於或者大於給定的值。
2）is_really_writeable
判斷檔案是否有可寫許可權。true——可寫，false——不可寫
3) load_class——類註冊函式
定義了一個static $_classes = array();
如果用&load_class方式呼叫，實際上指向了$_classes的記憶體地址。
該函式首先在application/libraries 資料夾中尋找類名檔案，再在system/libraries資料夾中尋中類名檔案，找到了例項化後放進$_classes 中，當呼叫&load_class時，會取出全部的$_classes陣列。
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
stringthe class name being requested
* @param
stringthe directory where the class should be found
* @param
mixedan 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——記錄哪些類被記載了
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 ——載入配置檔案
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($config))
{
set_status_header(503);
echo 'Your config file does not appear to be formatted correctly.';
exit(3); // EXIT_CONFIG
}
}
//動態修改config裡面的值
// Are any values being dynamically added or replaced?
foreach ($replace as $key => $val)
{
$config[$key] = $val;
}
return $config;
}
}
6）config_item ——將配置檔案賦值給一個靜態陣列，並返回。
if ( ! function_exists('config_item'))
{
/**
* Returns the specified config item
*
* @param string
* @return mixed
*/
function config_item($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 $_mimes;
}
}
8) is_https——判斷是不是https連結
if ( ! function_exists('is_https'))
{
/**
* Is HTTPS?
*
* Determines if the application is accessed via an encrypted
* (HTTPS) connection.
*
* @return bool
*/
function is_https()
{
if ( ! empty($_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($_SERVER['HTTP_FRONT_END_HTTPS']) !== 'off')
{
return TRUE;
}
return FALSE;
}
}
9) is_cli ——判斷請求是不是命令列模式
if ( ! function_exists('is_cli'))
{
/**
* Is CLI?
*
* Test to see if a request was made from the command line.
*
* @return bool
*/
function is_cli()
{
return (PHP_SAPI === 'cli' OR defined('STDIN'));
}
}
10）show_error——展示錯誤資訊
if ( ! function_exists('show_error'))
{
/**
* Error Handler
*
* This function lets us invoke the exception class and
* display errors using the standard error template located
* in application/views/errors/error_general.php
* This function will send the error page directly to the
* browser and exit.
*
＊ 該函式援引異常類，將錯誤通過application/views/errors/error_general.php標準模板展示出來，並直接顯示在瀏覽器上並終止程式
* @param string
* @param int
* @param string
* @return void
*/
function show_error($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');
//呼叫異常類Exception裡面的show_error方法
echo $_error->show_error($heading, $message, 'error_general', $status_code);
exit($exit_status);
}
}
11)show_404——展示404錯誤
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, $log_error);
exit(4); // EXIT_UNKNOWN_FILE
}
}
12)log_message——記錄日誌
if ( ! function_exists('log_message'))
{
/**
* Error Logging Interface
*
* We use this as a simple mechanism to access the logging
* class and send messages to be logged.
*
* @param
stringthe error level: 'error', 'debug' or 'info'
* @param
stringthe error message
* @return
void
*/
function log_message($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, $message);
}
}
13）set_status_header——設定http s
if ( ! function_exists('set_status_header'))
{
/**
* Set HTTP Status Header
*
* @param
intthe status code
* @param
string
* @return
void
*/
function set_status_header($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, $code);
}
}
14）_exception_handler——display_errors is On 用於測試或者開發環境處理異常
if ( ! function_exists('_exception_handler'))
{
/**
* Exception Handler
*
* Sends uncaught exceptions to the logger and displays them
* only if display_errors is On so that they don't show up in
* production environments.
*
* @param
Exception$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——關閉錯誤處理
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'], $last_error['line']);
}
}
}
16）remove_invisible_characters——移除字串中不可見字元
if ( ! function_exists('remove_invisible_characters'))
{
/**
* Remove Invisible Characters
*
* This prevents sandwiching null characters
* between ascii characters, like Java\0script.
*
* @param
string
* @param
bool
* @return
string
*/
function remove_invisible_characters($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 $str;
}
}
17) html_escape —— html程式碼轉碼原樣輸出
if ( ! function_exists('html_escape'))
{
/**
* Returns HTML escaped variable.
*
* @param
mixed$var
The input string or array of strings to be escaped.
* @param
bool$double_encode$double_encode set to FALSE prevents escaping twice.
* @return
mixedThe 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'), $double_encode);
}
}
18）_stringify_attributes —— 轉換字串、陣列、物件為字串
if ( ! function_exists('_stringify_attributes')){
/**
* Stringify attributes for use in HTML tags.
*
* Helper function used to convert a string, array, or object
* of attributes to a string.
*
* @param mixedstring, array, object
* @param bool
* @return string
*/
function _stringify_attributes($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($atts, ',');
}
}
19）function_usable——檢查suhosin擴充套件，返回fasle
if ( ! function_exists('function_usable'))
{
/**
* Function usable
*
* Executes a function_exists() check, and if the Suhosin PHP
* extension is loaded - checks whether the function that is
* checked might be disabled in there as well.
*
* This is useful as function_exists() will return FALSE for
* functions disabled via the *disable_functions* php.ini
* setting, but not for *suhosin.executor.func.blacklist* and
* *suhosin.executor.disable_eval*. These settings will just
* terminate script execution if a disabled function is executed.
*
* The above described behavior turned out to be a bug in Suhosin,
* but even though a fix was committed for 0.9.34 on 2012-02-12,
* that version is yet to be released. This function will therefore
* be just temporary, but would probably be kept for a few years.
*
* @link
http://www.hardened-php.net/suhosin/
* @param
string$function_nameFunction to check for
* @return
boolTRUE 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;
}
}