CODEWITHSUNDEEP
phpinclude
user3186555
user3186555

Reputation:

PHP self-including loop (concept)

I have a curiosity. What happens if a PHP script includes itself?

The reason I ask is that I have a php file that generates the contents for all of my site's <head> tags. That includes the site's 404 error page head tag.

If the php file that generates these head tags is accessed directly it "pretends" to not exist by including the 404 error page, which sends 404 status back to the client.

This is what the filesystem looks like:

/
  .htaccess <- (apache 404 handling)
  404.php <- 404 error page
  head.php <- '<head>' generator
  ...

404.php contains:

<?php
    header("HTTP/1.0 404 Not Found");
?>
<html>
    <head>
<?php
    $key = true;
    include dirname(__FILE__) . "/head.php";
?>
    </head>
    <body>
        lul. dead.
    </body>
</html>

head.php contains:

<?php
    if(isset($key) && $key===true){
        //code to generate <head> content
    }else{
        include dirname(__FILE__) . "/404.php";
    }
?>

$key tells head.php that it was included by another php file and not requested over URL.

So, to sum up, if I directly request head.php from my web browser (not accessing it via php includes, just via http request) it should:

(a) realize that the request was not an include from another php file, then
(b) include 404.php, which
(c) sends a 404 status on line 2 of 404.php and, then,
(d) includes head.php.

Therefore, eventually head.php will include head.php.

does this happen?

Upvotes: 0

Views: 529

Answers (1)

user3186555
user3186555

Reputation:

Yes, it does.

NOTE: However, an internal server error can occur. For example:

include.php:

<?php
    if(!isset($s)){
        $s = 0;
    }
    if($s<10){
        include "include.php";
        $s++;
    }
?>
test

This script produces an internal server error. I did not check to see how many times a file can be self-included before the error occurs, but apparently 10 times is (or is more than) enough times to cause the error.

Either that or a PHP script can not directly include itself. It has to do so through including a separate script which includes the original script

Upvotes: 1

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