import_request_variables

描述

bool import_request_variables ( string types [, string prefix] )

将 GET／POST／Cookie 变量导入到全局作用域中。如果你禁止了 register_globals，但又想用到一些全局变量，那么此函数就很有用。

你可以使用 types 参数指定需要导入的变量。可以用字母‘G’、‘P’和‘C’分别表示 GET、POST 和 Cookie。这些字母不区分大小写，所以你可以使用‘g’、‘p’和‘c’的任何组合。POST 包含了通过 POST 方法上传的文件信息。注意这些字母的顺序，当使用“gp”时，POST 变量将使用相同的名字覆盖 GET 变量。任何 GPC 以外的字母都将被忽略。

prefix 参数作为变量名的前缀，置于所有被导入到全局作用域的变量之前。所以如果你有个名为“userid”的 GET 变量，同时提供了“pref_”作为前缀，那么你将获得一个名为 $pref_userid 的全局变量。

如果你对导入其它全局变量（例如 SERVER 变量）感兴趣，请考虑使用 extract()。

注: 虽然 prefix 参数是可选的，但如果不指定前缀，或者指定一个空字符串作为前缀，你将获得一个 E_NOTICE 级别的错误。使用默认错误报告级别是不显示注意（Notice）级别的错误的。


<?php
// 此处将导入 GET 和 POST 变量
// 使用“rvar_”作为前缀
import_request_variables("gP", "rvar_");

echo $rvar_foo;
?>

参见 $_REQUEST、register_globals、预定义变量和 extract()。

add a note User Contributed Notes

samb06 at gmail dot com
16-May-2006 07:09


What i do is have a small script in my header file that takes an array called $input, and loops through the array to extract variables. that way the security hole can be closed, as you specify what variables you would like extracted



$input = array('name' => null, 'age' => 26) ;



// 26 is the default age, if $_GET['age'] is empty or not set



function extract_get()

    {

        global $input ;

        

        if ($input)

            {

                foreach ($input as $k => $v)

                    {

                        if ($_GET[$k] == '' or $_GET[$k] == NULL)

                            {

                                $GLOBALS[$k] = $v ;

                            }

                        else

                            {

                                $GLOBALS = $_GET[$k] ;

                            }

                    }

            }

    }

jason
09-Jul-2005 03:35


reply to ceo AT l-i-e DOT com:



I don't think it's a risk, as all of your request variables will be tagged with the prefix. As long as you don't prefix any of your internal variables with the same, you should be fine.



If someone tries to access an uninitiated security-related variable like $admin_level through request data, it will get imported as $RV_admin_level.

nexxer at rogers dot com
11-Feb-2005 02:47


PHP5 seems to have fixed that, in the sense that import_request_variables("g") works like extract($_GET). It doesn't seem to be passing a reference to the global, but instead creating a copy of it as expected

cornflake4 at gmx dot at
11-Jan-2005 06:52


oops, a typo in my comment:



The last line in the second example (the on using the extract() function) should read:



echo $_GET['var']; # prints 1, so $_GET has been unchanged

cornflake4 at gmx dot at
10-Jan-2005 01:39


Beware:



import_request_variables() does not copy the request variables into local scope variables. Instead, it copies the *reference* to the request variable content to local variables Important implication: any change to the local variable means a changes to the respective request variable, too!



This is a clear difference to extract($_GET) which copies the content of the request variables into local variables.



To shed some light on the implication, consider this (assuming the query string "...&var=1"):



echo $_GET['var']; # prints: 1

import_request_variables();

echo $var; # prints 1

$var = 2;

echo $_GET['var']; # prints 2 !!!!



So, $_GET has changed as well!



On the other hand:



echo $_GET['var']; # prints: 1

extract($_GET);

echo $var; # prints 1

$var = 2;

echo $_GET['var']; # prints 2 !!!!



Because of this, I recommend NOT using import_request_variables(), but extract($_GET); extract($_POST); extract($_COOKIE); instead, since this combination bears not these unexspected side effects.



PS: not to mention that you have to reconsider your coding style if any need to import_request_variables arises at all!

ceo AT l-i-e DOT com
11-Dec-2004 04:56


Call me crazy, but it seems to me that if you use this function, even WITH the prefix, then you might as well just turn register_globals back on...



Sooner or later, somebody will find a "hole" with your prefixed variables in an un-initialized variable.



Better to import precisely the variables you need, and initialize anything else properly.

brian at enchanter dot net
07-Dec-2004 09:19


import_request_variables does *not* read from the $_GET, $_POST, or $_COOKIE arrays - it reads the data directly from what was submitted. This is an important distinction if, for example, the server has magic_quotes turned on and you massage the data to run stripslashes on it; if you then use import_request_variables, your variables will still have slashes in them.



In other words: even if you say $_GET=""; $_POST=""; then use import_request_variables, it'll still get all the request data.



If you change the contents of $_GET and you then want to bring this data into global variables, use extract($_GET, EXTR_PREFIX_ALL, "myprefix") instead.

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