get the permission must the user have to access to the 'Access denied ' page

Question

i'm working on a drupal 7 online payment module ,

and i need to know if there is a Drupal 7 function that can track (each time and for all the users) if 'the logging online user' is requesting an 'Access denied ' page , and then get the permission must the user have to access to that page

PS: i'm creating a drupal payment module , the payment will be by roles , for exemple ( user1 can create 'Blog content type' just if he has the permission on that, if not i i need to know which 'Access denied ' page he is in and it's role so i can show him a message to buy this role depending on the price in the database) all what i need is the string permission of the page

thanks in advance ^_^

Answer 1

The only answer I can think of is to roll this functionality yourself with some coding in a custom module.

You probably want to use Chain Menu Access and the drupal API function user_role_permissions.

You can use the chain menu access api to put a fired-last menu access check that does some comparisons over previous access checks and Roles:

<?php
  chain_menu_access_chain($menu, 'an/existing/path', '_mymodule_new_access_callback_check_permissions_to_roles');
?>

Then use the drupal api user_role_permissions to see what Role has X permission that was failed in a parent-chained access callback. You could store that for example in the users $_SESSION data. Then write a custom 404 page that shows them purchase options.