1 files changed, 49 insertions, 0 deletions
diff --git a/fs/sdcardfs/multiuser.h b/fs/sdcardfs/multiuser.h
new file mode 100644
index 000000000000..52bc20080904
--- /dev/null
+++ b/fs/sdcardfs/multiuser.h
@@ -0,0 +1,49 @@
+/*
+ * fs/sdcardfs/multiuser.h
+ *
+ * Copyright (c) 2013 Samsung Electronics Co. Ltd
+ *   Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun,
+ *               Sunghwan Yun, Sungjong Seo
+ *
+ * This program has been developed as a stackable file system based on
+ * the WrapFS which written by
+ *
+ * Copyright (c) 1998-2011 Erez Zadok
+ * Copyright (c) 2009     Shrikar Archak
+ * Copyright (c) 2003-2011 Stony Brook University
+ * Copyright (c) 2003-2011 The Research Foundation of SUNY
+ *
+ * This file is dual licensed.  It may be redistributed and/or modified
+ * under the terms of the Apache 2.0 License OR version 2 of the GNU
+ * General Public License.
+ */
+
+#define AID_USER_OFFSET     100000 /* offset for uid ranges for each user */
+#define AID_APP_START        10000 /* first app user */
+#define AID_APP_END          19999 /* last app user */
+#define AID_CACHE_GID_START  20000 /* start of gids for apps to mark cached data */
+#define AID_EXT_GID_START    30000 /* start of gids for apps to mark external data */
+#define AID_SHARED_GID_START 50000 /* start of gids for apps in each user to share */
+
+typedef uid_t userid_t;
+typedef uid_t appid_t;
+
+static inline uid_t multiuser_get_uid(userid_t user_id, appid_t app_id) {
+    return (user_id * AID_USER_OFFSET) + (app_id % AID_USER_OFFSET);
+}
+
+static inline gid_t multiuser_get_cache_gid(userid_t user_id, appid_t app_id) {
+    if (app_id >= AID_APP_START && app_id <= AID_APP_END) {
+        return multiuser_get_uid(user_id, (app_id - AID_APP_START) + AID_CACHE_GID_START);
+    } else {
+        return -1;
+    }
+}
+
+static inline gid_t multiuser_get_ext_gid(userid_t user_id, appid_t app_id) {
+    if (app_id >= AID_APP_START && app_id <= AID_APP_END) {
+        return multiuser_get_uid(user_id, (app_id - AID_APP_START) + AID_EXT_GID_START);
+    } else {
+        return -1;
+    }
+}