PHP reliably determine path of caller file

Question

I have a file which will be included in a parent, so-to-speak, file. I need to reliably determine the path of the parent file from within the child file.

My first thought was $_SERVER['SCRIPT_FILENAME'] but that can be easily manipulated from the parent file.

Next thing I thought of was getcwd() but that will not always work, apache always provides the directory of the executed script but if it is run from cli or cron that is not the case.

If I can not trust the parent file, what is a secure way of determining its location from inside the file that is to be included?

Use the Constant `__FILE__` bind this value to an $variable in the parent and then you have it in the include. — JustOnUnderMillions, Oct 06 '16 at 15:33
@JustOnUnderMillions I can't trust the parent file, `$variable` can be anything. — php_nub_qq, Oct 06 '16 at 15:34
*"If I can not trust the parent file"* - if you cannot trust the file, how can you be sure it will include your script without modifications? This seems pointless to me. — Shira, Oct 06 '16 at 15:36
As side note, in modern oop code, mostly `include` is only used for `autoloading`. — JustOnUnderMillions, Oct 06 '16 at 15:38
Take a look at the answer with the most upvotes: http://stackoverflow.com/questions/1318608/php-get-parent-script-name — cOle2, Oct 06 '16 at 15:38

score 2 · Answer 1 · answered Oct 06 '16 at 15:32

Offhand, can't find anything that'll directly give you the "parent" path in an include chain, but you CAN use debug_backtrace():

./z.php

<?php
include('y/y.php');

./y/y.php

<?php
var_dump(debug_backtrace());

And then:

$ php z.php
array(1) {
  [0]=>
  array(3) {
    ["file"]=>
    string(44) "/home/marc/z/z.php"
    ["line"]=>
    int(3)
    ["function"]=>
    string(7) "include"
  }

}

PHP reliably determine path of caller file

1 Answers1