get_home_path fails in headless mode.

[fishpig]

The core get_home_path function is incorrect when in a headless mode and siteurl and home are different.

The easy fix for this is to just add a filter to the return value so that we can return ABSPATH

[ruchirj]

To call this function you need to do this.

Note that get_home_path() is declared in wp-admin/includes/file.php which is not included by default, except on admin pages when wp-admin/includes/admin.php has been included.

Ensure get_home_path() is declared.
require_once ABSPATH . 'wp-admin/includes/file.php';

$home_path = get_home_path();