牛骨文教育服务平台(让学习变的简单)

文件位置:Location: ./system/core/Common.php

CodeIgniter 使用了一些全局定义的函数来完成操作,在任何情况下你都能够使用这些函数。使用他们不需要载入任何类库或辅助函数。

这些函数主要用于加载基类和执行请求。

1、 第一个函数is_php 

判断当前php版本是否大于指定的php版本,有些地方需要用到这个函数

2、 判断文件夹是否有可写权限is_really_writable()

因为函数is_writable()在window和unix中并不可靠,所以要对它进行重新封装

在Windows平台,is_writable()函数在实际没有文件写权限时也返回真。那是因为,只有文件有只读属性时,操作系统才向PHP报告为假。

在unix中当safe_mode为开启状态下也是不可靠的。

这个函数依靠对文件的先行写入来判断是否真的具有写权限。

3、 类注册器load_class()

这是一个单例模式的函数,如果请求的类没有找到会将它设置为一个静态变量,如果以前存在就直接返回。

4、 is_loaded(); 追踪已经加载的类,这个函数被load_class 调用

5、 get_config(); 加载主配置文件

6、 config_item() 返回指定的配置项

7、 show_error错误处理程序

这个函数调用异常处理类并且使用application/errors/error_general.php模板来显示错误

8、 show_404 404页面处理程序 

这个函数和show_error函数相似使用application/errors/error_404.php模板来显示的。

9、 log_message(‘级别’, ‘消息’) 记录错误日志

这个函数可以让你将消息写入记录文件中。你必须在第一个参数中选择三个“级别“中的任何一个, 指明它是那一类消息(调试 debug, 错误 error, 信息info)。 第二个参数是消息本身。

他会调用system/libraries/log.php 进行处理

如果这个config_item("log_threshold") 为0 则不进行任何处理,也就不会记录错误日志了

10、set_status_header   设置http状态头

11、_exception_handler   异常处理程序

12、remove_invisible_characters  去除看不见的字

符  这个函数能防止在ASCII字符之间插入空字符,如Javascript. 

13、html_escape 把一些预定义的字符转换为 HTML 实体

它接受字符串和数组。有助于防止跨站脚本攻击(XSS)。

文件源码:

<?php  if ( ! defined("BASEPATH")) exit("No direct script access allowed");
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.1.6 or newer
 *
 * @package		CodeIgniter
 * @author		ExpressionEngine Dev Team
 * @copyright	Copyright (c) 2008 - 2011, EllisLab, Inc.
 * @license		http://codeigniter.com/user_guide/license.html
 * @link		http://codeigniter.com
 * @since		Version 1.0
 * @filesource
 */

// ------------------------------------------------------------------------

/**
 * Common Functions
 *
 * Loads the base classes and executes 执行 the request.
 *
 * @package		CodeIgniter
 * @subpackage	codeigniter
 * @category	Common Functions
 * @author		ExpressionEngine Dev Team
 * @link		http://codeigniter.com/user_guide/
 */

// ------------------------------------------------------------------------

/**
* Determines  if the current version of PHP is greater 较大的 then the supplied 提供的 value
*
* Since there are a few 很少的 places where we conditionally 有条件的 test for PHP > 5
* we"ll set a static variable.
*
* @access	public
* @param	string
* @return	bool	TRUE if the current version is $version or higher
*/
if ( ! function_exists("is_php"))
{
	function is_php($version = "5.0.0")
	{
		static $_is_php;
		$version = (string)$version;

		if ( ! isset($_is_php[$version]))
		{
			$_is_php[$version] = (version_compare(PHP_VERSION, $version) < 0) ? FALSE : TRUE;
		}

		return $_is_php[$version];
	}
}

// ------------------------------------------------------------------------

/**
 * Tests for file writability 可写性
 *
 * is_writable() returns TRUE on Windows servers when you really can"t write to
 * the file, based on the read-only attribute.  is_writable() is also unreliable 不可靠的
 * on Unix servers if safe_mode is on.
 *
 * @access	private
 * @return	void
 */
if ( ! function_exists("is_really_writable"))
{
	function is_really_writable($file)
	{
		// If we"re on a Unix server with safe_mode off we call is_writable
		if (DIRECTORY_SEPARATOR == "/" AND @ini_get("safe_mode") == FALSE)
		{
			return is_writable($file);
		}

		// For windows servers and safe_mode "on" installations we"ll actually
		// write a file then read it.  Bah...
		if (is_dir($file))
		{
			$file = rtrim($file, "/")."/".md5(mt_rand(1,100).mt_rand(1,100));

			if (($fp = @fopen($file, FOPEN_WRITE_CREATE)) === FALSE)
			{
				return FALSE;
			}

			fclose($fp);
			@chmod($file, DIR_WRITE_MODE);
			@unlink($file);
			return TRUE;
		}
		elseif ( ! is_file($file) OR ($fp = @fopen($file, FOPEN_WRITE_CREATE)) === FALSE)
		{
			return FALSE;
		}

		fclose($fp);
		return TRUE;
	}
}

// ------------------------------------------------------------------------

/**
* Class registry
*
* This function acts as 扮演一个 a singleton.单例模式  If the requested class does not
* exist it is instantiated and set to a static variable.  If it has
* previously 以前 been instantiated the variable is returned.
*
* @access	public
* @param	string	the class name being requested
* @param	string	the directory where the class should be found
* @param	string	the class name prefix
* @return	object
*/
if ( ! function_exists("load_class"))
{
	function &load_class($class, $directory = "libraries", $prefix = "CI_")
	{
		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 = $prefix.$class;

				if (class_exists($name) === FALSE)
				{
					require($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($name) === FALSE)
			{
				require(APPPATH.$directory."/".config_item("subclass_prefix").$class.".php");
			}
		}

		// Did we find the class?
		if ($name === FALSE)
		{
			// Note: We use exit() rather then show_error() in order to avoid a
			// self-referencing loop with the Excptions class
			exit("Unable to locate the specified class: ".$class.".php");
		}

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

		$_classes[$class] = new $name();
		return $_classes[$class];
	}
}

// --------------------------------------------------------------------

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

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

		return $_is_loaded;
	}
}

// ------------------------------------------------------------------------

/**
* Loads the main config.php file
*
* This function lets us grab 获取 the config file even 甚至 if the Config class
* hasn"t been instantiated yet
*
* @access	private
* @return	array
*/
if ( ! function_exists("get_config"))
{
	function &get_config($replace = array())
	{
		static $_config;

		if (isset($_config))
		{
			return $_config[0];
		}

		// Is the config file in the environment folder?
		if ( ! defined("ENVIRONMENT") OR ! file_exists($file_path = APPPATH."config/".ENVIRONMENT."/config.php"))
		{
			$file_path = APPPATH."config/config.php";
		}

		// Fetch 取得、拿来 the config file
		if ( ! file_exists($file_path))
		{
			exit("The configuration file does not exist.");
		}

		require($file_path);

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

		// Are any values being dynamically replaced?
		if (count($replace) > 0)
		{
			foreach ($replace as $key => $val)
			{
				if (isset($config[$key]))
				{
					$config[$key] = $val;
				}
			}
		}

		return $_config[0] =& $config;
	}
}

// ------------------------------------------------------------------------

/**
* Returns the specified 指定的 config item
*
* @access	public
* @return	mixed
*/
if ( ! function_exists("config_item"))
{
	function config_item($item)
	{
		static $_config_item = array();

		if ( ! isset($_config_item[$item]))
		{
			$config =& get_config();

			if ( ! isset($config[$item]))
			{
				return FALSE;
			}
			$_config_item[$item] = $config[$item];
		}

		return $_config_item[$item];
	}
}

// ------------------------------------------------------------------------

/**
* Error Handler 处理器、处理程序
*
* This function lets us invoke 调用 the exception 异常 class and
* display errors using the standard 标准 error template located 地处、处于
* in application/errors/errors.php
* This function will send the error page directly to the
* browser and exit.
*
* @access	public
* @return	void
*/
if ( ! function_exists("show_error"))
{
	function show_error($message, $status_code = 500, $heading = "An Error Was Encountered")
	{
		$_error =& load_class("Exceptions", "core");
		echo $_error->show_error($heading, $message, "error_general", $status_code);
		exit;
	}
}

// ------------------------------------------------------------------------

/**
* 404 Page Handler
*
* This function is similar 相似的类似的 to the show_error() function above在。。。上面
* However 然而、但是, instead 代替、反而、更换 of the standard 标准、规格、标准版 error 
* template it displays
* 404 errors.
*
* @access	public
* @return	void
*/
if ( ! function_exists("show_404"))
{
	function show_404($page = "", $log_error = TRUE)
	{
		$_error =& load_class("Exceptions", "core");
		$_error->show_404($page, $log_error);
		exit;
	}
}

// ------------------------------------------------------------------------

/**
* Error Logging Interface 界面
*
* We use this as a simple mechanism 机制、原理 to access 接近、进入、通道 the logging
* class and send messages to be logged.
*
* @access	public
* @return	void
*/
if ( ! function_exists("log_message"))
{
	function log_message($level = "error", $message, $php_error = FALSE)
	{
		static $_log;

		if (config_item("log_threshold") == 0)
		{
			return;
		}

		$_log =& load_class("Log");
		$_log->write_log($level, $message, $php_error);
	}
}

// ------------------------------------------------------------------------

/**
 * Set HTTP Status Header
 *
 * @access	public
 * @param	int		the status code
 * @param	string
 * @return	void
 */
if ( ! function_exists("set_status_header"))
{
	function set_status_header($code = 200, $text = "")
	{
		$stati = array(
							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",
							304	=> "Not Modified",
							305	=> "Use Proxy",
							307	=> "Temporary Redirect",

							400	=> "Bad Request",
							401	=> "Unauthorized",
							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",

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

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

		if (isset($stati[$code]) AND $text == "")
		{
			$text = $stati[$code];
		}

		if ($text == "")
		{
			show_error("No status text available.  Please check your status code number or supply your own message text.", 500);
		}

		$server_protocol = (isset($_SERVER["SERVER_PROTOCOL"])) ? $_SERVER["SERVER_PROTOCOL"] : FALSE;

		if (substr(php_sapi_name(), 0, 3) == "cgi")
		{
			header("Status: {$code} {$text}", TRUE);
		}
		elseif ($server_protocol == "HTTP/1.1" OR $server_protocol == "HTTP/1.0")
		{
			header($server_protocol." {$code} {$text}", TRUE, $code);
		}
		else
		{
			header("HTTP/1.1 {$code} {$text}", TRUE, $code);
		}
	}
}

// --------------------------------------------------------------------

/**
* Exception Handler
*
* This is the custom 自定义的 exception handler that is declaired at the top
* of Codeigniter.php.  The main reason 原因、理由 we use this is to permit 许可
* PHP errors to be logged in our own log files since the user may
* not have access 接近、进入 to server logs. Since this function
* effectively 有效地 intercepts 拦截 PHP errors, however,但是 we also need
* to display errors based on the current error_reporting level.
* We do that with the use of a PHP error template.
*
* @access	private
* @return	void
*/
if ( ! function_exists("_exception_handler"))
{
	function _exception_handler($severity, $message, $filepath, $line)
	{
		 // We don"t bother 打扰、麻烦 with "strict" 严格地 notices since they tend 倾向于 to fill up
		 // the log file with excess information that isn"t normally very helpful.
		 // For example, if you are running PHP 5 and you use version 4 style
		 // class functions (without prefixes like "public", "private", etc.)
		 // you"ll get notices telling you that these have been deprecated.
		if ($severity == E_STRICT)
		{
			return;
		}

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

		// Should we display the error? We"ll get the current error_reporting
		// level and add its bits with the severity bits to find out.
		if (($severity & error_reporting()) == $severity)
		{
			$_error->show_php_error($severity, $message, $filepath, $line);
		}

		// Should we log the error?  No?  We"re done...
		if (config_item("log_threshold") == 0)
		{
			return;
		}

		$_error->log_exception($severity, $message, $filepath, $line);
	}
}

// --------------------------------------------------------------------

/**
 * Remove Invisible 无形的,看不见的 Characters
 *
 * This prevents sandwiching 夹层 null characters
 * between ascii characters, like Javascript.
 *
 * @access	public
 * @param	string
 * @return	string
 */
if ( ! function_exists("remove_invisible_characters"))
{
	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]/";	// url encoded 00-08, 11, 12, 14, 15
			$non_displayables[] = "/%1[0-9a-f]/";	// url encoded 16-31
		}
		
		$non_displayables[] = "/[x00-x08x0Bx0Cx0E-x1Fx7F]+/S";	// 00-08, 11, 12, 14-31, 127

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

		return $str;
	}
}

// ------------------------------------------------------------------------

/**
* Returns HTML escaped variable
*
* @access	public
* @param	mixed
* @return	mixed
*/
if ( ! function_exists("html_escape"))
{
	function html_escape($var)
	{
		if (is_array($var))
		{
			return array_map("html_escape", $var);
		}
		else
		{
			return htmlspecialchars($var, ENT_QUOTES, config_item("charset"));
		}
	}
}

/* End of file Common.php */
/* Location: ./system/core/Common.php */