--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cms/drupal/modules/file/file.api.php	Fri Sep 08 12:04:06 2017 +0200
@@ -0,0 +1,60 @@
+<?php
+
+/**
+ * @file
+ * Hooks for file module.
+ */
+
+/**
+ * Control download access to files.
+ *
+ * The hook is typically implemented to limit access based on the entity the
+ * file is referenced, e.g., only users with access to a node should be allowed
+ * to download files attached to that node.
+ *
+ * @param array $file_item
+ *   The array of information about the file to check access for.
+ * @param $entity_type
+ *   The type of $entity; for example, 'node' or 'user'.
+ * @param $entity
+ *   The $entity to which $file is referenced.
+ *
+ * @return
+ *   TRUE is access should be allowed by this entity or FALSE if denied. Note
+ *   that denial may be overridden by another entity controller, making this
+ *   grant permissive rather than restrictive.
+ *
+ * @see hook_field_access().
+ */
+function hook_file_download_access($file_item, $entity_type, $entity) {
+  if ($entity_type == 'node') {
+    return node_access('view', $entity);
+  }
+}
+
+/**
+ * Alter the access rules applied to a file download.
+ *
+ * Entities that implement file management set the access rules for their
+ * individual files. Module may use this hook to create custom access rules
+ * for file downloads.
+ *
+ * @see hook_file_download_access().
+ *
+ * @param $grants
+ *   An array of grants gathered by hook_file_download_access(). The array is
+ *   keyed by the module that defines the entity type's access control; the
+ *   values are Boolean grant responses for each module.
+ * @param array $file_item
+ *   The array of information about the file to alter access for.
+ * @param $entity_type
+ *   The type of $entity; for example, 'node' or 'user'.
+ * @param $entity
+ *   The $entity to which $file is referenced.
+ */
+function hook_file_download_access_alter(&$grants, $file_item, $entity_type, $entity) {
+  // For our example module, we always enforce the rules set by node module.
+  if (isset($grants['node'])) {
+    $grants = array('node' => $grants['node']);
+  }
+}