Index: modules/node/node.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.module,v
retrieving revision 1.947.2.22
diff -u -p -r1.947.2.22 node.module
--- modules/node/node.module	3 Mar 2010 21:36:37 -0000	1.947.2.22
+++ modules/node/node.module	19 Mar 2010 04:52:00 -0000
@@ -2125,6 +2125,10 @@ function _node_access_where_sql($op = 'v
  * access module should implement hook_node_grants() to provide a grant
  * list for the user.
  *
+ * After the default grants have been loaded, we allow modules to alter
+ * the grants array by reference. This hook allows for complex business
+ * logic to be applied when integrating multiple node access modules.
+ *
  * @param $op
  *   The operation that the user is trying to perform.
  * @param $account
@@ -2140,7 +2144,12 @@ function node_access_grants($op, $accoun
     $account = $GLOBALS['user'];
   }
 
-  return array_merge(array('all' => array(0)), module_invoke_all('node_grants', $account, $op));
+  // Fetch node access grants from other modules.
+  $grants = module_invoke_all('node_grants', $account, $op);
+  // Allow modules to alter the assigned grants.
+  drupal_alter('node_grants', $grants, $account, $op);
+
+  return array_merge(array('all' => array(0)), $grants);
 }
 
 /**
@@ -2188,6 +2197,12 @@ function node_db_rewrite_sql($query, $pr
  * called by modules whenever something other than a node_save causes
  * the permissions on a node to change.
  *
+ * After the default grants have been loaded, we allow modules to alter
+ * the grants array by reference. This hook allows for complex business
+ * logic to be applied when integrating multiple node access modules.
+ *
+ * @see hook_node_access_records()
+ *
  * This function is the only function that should write to the node_access
  * table.
  *
@@ -2196,6 +2211,9 @@ function node_db_rewrite_sql($query, $pr
  */
 function node_access_acquire_grants($node) {
   $grants = module_invoke_all('node_access_records', $node);
+  // Let modules alter the grants.
+  drupal_alter('node_access_records', $grants, $node);
+  // If no grants are set, then use the default grant.
   if (empty($grants)) {
     $grants[] = array('realm' => 'all', 'gid' => 0, 'grant_view' => 1, 'grant_update' => 0, 'grant_delete' => 0);
   }