2 files changed, 120 insertions, 1 deletions
diff --git a/core/java/android/os/Binder.java b/core/java/android/os/Binder.java
index 24569fa..577fc43 100644
--- a/core/java/android/os/Binder.java
+++ b/core/java/android/os/Binder.java
@@ -49,6 +49,7 @@ public class Binder implements IBinder {
     private static final boolean FIND_POTENTIAL_LEAKS = false;
     private static final String TAG = "Binder";
 
+    /* mObject is used by native code, do not remove or rename */
     private int mObject;
     private IInterface mOwner;
     private String mDescriptor;
@@ -70,7 +71,35 @@ public class Binder implements IBinder {
      * incoming transaction, then its own uid is returned.
      */
     public static final native int getCallingUid();
-    
+
+    /**
+     * Return the original ID of the user assigned to the process that sent you the current
+     * transaction that is being processed. This uid can be used with higher-level system services
+     * to determine its identity and check permissions. If the current thread is not currently
+     * executing an incoming transaction, then its own uid is returned.
+     * <p/>
+     * This value cannot be reset by calls to {@link #clearCallingIdentity()}.
+     * @hide
+     */
+    public static final int getOrigCallingUid() {
+        if (UserId.MU_ENABLED) {
+            return getOrigCallingUidNative();
+        } else {
+            return getCallingUid();
+        }
+    }
+
+    private static final native int getOrigCallingUidNative();
+
+    /**
+     * Utility function to return the user id of the calling process.
+     * @return userId of the calling process, extracted from the callingUid
+     * @hide
+     */
+    public static final int getOrigCallingUser() {
+        return UserId.getUserId(getOrigCallingUid());
+    }
+
     /**
      * Reset the identity of the incoming IPC on the current thread.  This can
      * be useful if, while handling an incoming call, you will be calling
diff --git a/core/java/android/os/UserId.java b/core/java/android/os/UserId.java
new file mode 100644
index 0000000..4124d51
--- /dev/null
+++ b/core/java/android/os/UserId.java
@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2011 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.
+ */
+
+package android.os;
+
+/**
+ * @hide
+ */
+public final class UserId {
+    /**
+     * Range of IDs allocated for a user.
+     *
+     * @hide
+     */
+    public static final int PER_USER_RANGE = 100000;
+
+    public static final int USER_ALL = -1;
+
+    /**
+     * Enable multi-user related side effects. Set this to false if there are problems with single
+     * user usecases.
+     * */
+    public static final boolean MU_ENABLED = true;
+
+    /**
+     * Checks to see if the user id is the same for the two uids, i.e., they belong to the same
+     * user.
+     * @hide
+     */
+    public static final boolean isSameUser(int uid1, int uid2) {
+        return getUserId(uid1) == getUserId(uid2);
+    }
+
+    /**
+     * Checks to see if both uids are referring to the same app id, ignoring the user id part of the
+     * uids.
+     * @param uid1 uid to compare
+     * @param uid2 other uid to compare
+     * @return whether the appId is the same for both uids
+     * @hide
+     */
+    public static final boolean isSameApp(int uid1, int uid2) {
+        return getAppId(uid1) == getAppId(uid2);
+    }
+
+    /**
+     * Returns the user id for a given uid.
+     * @hide
+     */
+    public static final int getUserId(int uid) {
+        if (MU_ENABLED) {
+            return uid / PER_USER_RANGE;
+        } else {
+            return 0;
+        }
+    }
+
+    /**
+     * Returns the uid that is composed from the userId and the appId.
+     * @hide
+     */
+    public static final int getUid(int userId, int appId) {
+        if (MU_ENABLED) {
+            return userId * PER_USER_RANGE + (appId % PER_USER_RANGE);
+        } else {
+            return appId;
+        }
+    }
+
+    /**
+     * Returns the app id (or base uid) for a given uid, stripping out the user id from it.
+     * @hide
+     */
+    public static final int getAppId(int uid) {
+        return uid % PER_USER_RANGE;
+    }
+}