UserHandle.java revision f02b60aa4f367516f40cf3d60fffae0c6fe3e1b8 
1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.os;
18
19/**
20 * Representation of a user on the device.
21 * @hide
22 */
23public final class UserHandle {
24    /**
25     * Range of IDs allocated for a user.
26     *
27     * @hide
28     */
29    public static final int PER_USER_RANGE = 100000;
30
31    /** A user id to indicate all users on the device */
32    public static final int USER_ALL = -1;
33
34    /** A user id to indicate the currently active user */
35    public static final int USER_CURRENT = -2;
36
37    /** A user id constant to indicate the "owner" user of the device */
38    public static final int USER_OWNER = 0;
39
40    /**
41     * Enable multi-user related side effects. Set this to false if there are problems with single
42     * user usecases.
43     * */
44    public static final boolean MU_ENABLED = true;
45
46    /**
47     * Checks to see if the user id is the same for the two uids, i.e., they belong to the same
48     * user.
49     * @hide
50     */
51    public static final boolean isSameUser(int uid1, int uid2) {
52        return getUserId(uid1) == getUserId(uid2);
53    }
54
55    /**
56     * Checks to see if both uids are referring to the same app id, ignoring the user id part of the
57     * uids.
58     * @param uid1 uid to compare
59     * @param uid2 other uid to compare
60     * @return whether the appId is the same for both uids
61     * @hide
62     */
63    public static final boolean isSameApp(int uid1, int uid2) {
64        return getAppId(uid1) == getAppId(uid2);
65    }
66
67    public static final boolean isIsolated(int uid) {
68        uid = getAppId(uid);
69        return uid >= Process.FIRST_ISOLATED_UID && uid <= Process.LAST_ISOLATED_UID;
70    }
71
72    public static boolean isApp(int uid) {
73        if (uid > 0) {
74            uid = UserHandle.getAppId(uid);
75            return uid >= Process.FIRST_APPLICATION_UID && uid <= Process.LAST_APPLICATION_UID;
76        } else {
77            return false;
78        }
79    }
80
81    /**
82     * Returns the user id for a given uid.
83     * @hide
84     */
85    public static final int getUserId(int uid) {
86        if (MU_ENABLED) {
87            return uid / PER_USER_RANGE;
88        } else {
89            return 0;
90        }
91    }
92
93    public static final int getCallingUserId() {
94        return getUserId(Binder.getCallingUid());
95    }
96
97    /**
98     * Returns the uid that is composed from the userId and the appId.
99     * @hide
100     */
101    public static final int getUid(int userId, int appId) {
102        if (MU_ENABLED) {
103            return userId * PER_USER_RANGE + (appId % PER_USER_RANGE);
104        } else {
105            return appId;
106        }
107    }
108
109    /**
110     * Returns the app id (or base uid) for a given uid, stripping out the user id from it.
111     * @hide
112     */
113    public static final int getAppId(int uid) {
114        return uid % PER_USER_RANGE;
115    }
116
117    /**
118     * Returns the user id of the current process
119     * @return user id of the current process
120     */
121    public static final int myUserId() {
122        return getUserId(Process.myUid());
123    }
124}
125