diff --git a/include/cutils/multiuser.h b/include/cutils/multiuser.h
new file mode 100644
index 0000000..191d80c
--- /dev/null
+++ b/include/cutils/multiuser.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __CUTILS_MULTIUSER_H
+#define __CUTILS_MULTIUSER_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// NOTE: keep in sync with android.os.UserId
+
+#define MULTIUSER_APP_PER_USER_RANGE 100000
+
+typedef uid_t userid_t;
+typedef uid_t appid_t;
+
+extern userid_t getUserId(uid_t uid);
+extern appid_t getAppId(uid_t uid);
+extern uid_t getUid(userid_t userId, appid_t appId);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __CUTILS_MULTIUSER_H */
diff --git a/libcutils/Android.mk b/libcutils/Android.mk
index 5c227b6..6d525ba 100644
--- a/libcutils/Android.mk
+++ b/libcutils/Android.mk
@@ -50,7 +50,8 @@
 	threads.c \
 	sched_policy.c \
 	iosched_policy.c \
-	str_parms.c
+	str_parms.c \
+	multiuser.c
 
 commonHostSources := \
         ashmem-host.c
diff --git a/libcutils/multiuser.c b/libcutils/multiuser.c
new file mode 100644
index 0000000..be9304d
--- /dev/null
+++ b/libcutils/multiuser.c
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <cutils/multiuser.h>
+
+userid_t getUserId(uid_t uid) {
+    return uid / MULTIUSER_APP_PER_USER_RANGE;
+}
+
+appid_t getAppId(uid_t uid) {
+    return uid % MULTIUSER_APP_PER_USER_RANGE;
+}
+
+uid_t getUid(userid_t userId, appid_t appId) {
+    return userId * MULTIUSER_APP_PER_USER_RANGE + (appId % MULTIUSER_APP_PER_USER_RANGE);
+}