materio-base-d7/sites/all/modules/contrib/users/user_role_field/user_role_field.module

<?php

/**
 * Hook into field edit form, user registration form and profile2 forms.
 */
function user_role_field_form_alter(&$form, $form_state, $form_id) {
  if (isset($form['instance']) && ($form['instance']['entity_type']['#value'] == 'user' || $form['instance']['entity_type']['#value'] == 'profile2') && $form_id == 'field_ui_field_edit_form' && isset($form['field'])) {
    module_load_include('inc', 'user_role_field', 'user_role_field.admin');
    return _user_role_field_field_settings_form_alter($form, $form_state, $form_id);
  }
}

/**
 * Custom permissions.
 */
function user_role_field_permission() {
  return array(
    'administer user field roles' => array(
      'title' => t('Administer user field roles'),
      'description' => t('Manage user field roles.'),
    ),
  );
}

function _user_role_field_roles($field) {
  return (isset($field['settings']['user_role_field']) && is_array($field['settings']['user_role_field']) ? array_filter($field['settings']['user_role_field']) : array());
}

/*
 * Make sure only appropriate roles have access
 */
function user_role_field_field_access($op, $field, $obj_type, $object, $account) {
  // We only handle user fields and profile2 fields
  if (($obj_type != 'user') && ($obj_type != 'profile2'))
    return true;

  // Admin user can see all fields when creating a new user.
  if (arg(2) == 'create' && arg(0) == 'admin' && user_access ('administer permissions'))
    return true;

  // If the object type is profile2, we need to load the user owning profile2 object
  if ($obj_type == 'profile2' && !empty($object->uid))
    $object = user_load ($object->uid);

  // Ignore the request if roles have not been enabled for this field.
  $roles = _user_role_field_roles ($field);
  if (empty($roles)) {
    return true;
  }

  // If the user object doesn't have the roles property, we get here through
  // the views module for example. In that case we want the data to display.
  // To revisit in case there are other cases.
  if (!isset ($object->roles))
      return true;

  $matching_roles = array_intersect_key ($object->roles, $roles);
  return !empty ($matching_roles);
}