Implements hook_field_access().
function field_test_field_access($op, $field, $entity_type, $entity, $account) {
if ($field['field_name'] == "field_no_{$op}_access") {
return FALSE;
}
// Only grant view access to test_view_field fields when the user has
// 'view test_view_field content' permission.
if ($field['field_name'] == 'test_view_field' && $op == 'view' && !user_access('view test_view_field content')) {
return FALSE;
}
return TRUE;
}