Is there a way to find out which FILE used require_once?

Question

Let's say I have the following situation:

File1.php:

<?php
require_once('init.php');
...
?>

File2.php:

<?php
require_once('init.php');
...
?>

init.php:

<?php
magic_function_which_tells_me_which_file_parsed_this_file();
...
?>

I know this is a long-shot, but is there a way to know from within init.php which file included init.php it in the current execution?

Answer 1

You are able to use debug_backtrace to find the caller even without functions:

test1.php

<?php
echo 'test1';
include 'test2.php';

test2.php

<?php
echo 'test2';
print_r(debug_backtrace());

Output

ABCArray
(
[0] => Array
    (
        [file] => /tmp/b.php
        [line] => 3
        [function] => include
    )

[1] => Array
    (
        [file] => /tmp/a.php
        [line] => 3
        [args] => Array
            (
                [0] => /tmp/b.php
            )

        [function] => include
    )
)

Anyways, I'd not recommend using it because it can be a noticeable performance drag when used excessively.