Drupal 7 replaces the old
hook_access() function with
hook_node_access(). This change was one of the many improvements to come from a work session at DrupalCON Szeged in 2008, and credit goes to Larry Garfield (Crell) for implementing these changes.
hook_node_access() allows any module to have a say in how node access is handled. It does not require database storage, or the use of the rest of the Node Access API. Further, it may be applied to any of the four basic CRUD operations.
The hook passes three parameters:
$node, the complete node object being acted upon, or a node type string in the case of the Create operation.
$op, the operation being performed.
$account, the user requesting access to the node for this action. ...