1 /*
2  * Copyright 2020 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 
17 package com.android.server.timezonedetector;
18 
19 import android.annotation.UserIdInt;
20 import android.app.ActivityManager;
21 import android.os.Binder;
22 import android.os.UserHandle;
23 
24 /**
25  * An interface to wrap various difficult-to-intercept calls that services make to access / manage
26  * caller identity, e.g. {@link Binder#clearCallingIdentity()}.
27  */
28 public interface CallerIdentityInjector {
29 
30     /** A singleton for the real implementation of {@link CallerIdentityInjector}. */
31     CallerIdentityInjector REAL = new Real();
32 
33     /**
34      * A {@link ActivityManager#handleIncomingUser} call. This can be used to map the abstract
35      * user ID value USER_CURRENT to the actual user ID.
36      */
resolveUserId(@serIdInt int userId, String debugInfo)37     @UserIdInt int resolveUserId(@UserIdInt int userId, String debugInfo);
38 
39     /** A {@link UserHandle#getCallingUserId()} call. */
getCallingUserId()40     @UserIdInt int getCallingUserId();
41 
42     /** A {@link Binder#clearCallingIdentity()} call. */
clearCallingIdentity()43     long clearCallingIdentity();
44 
45     /** A {@link Binder#restoreCallingIdentity(long)} ()} call. */
restoreCallingIdentity(long token)46     void restoreCallingIdentity(long token);
47 
48     /** The real implementation of {@link CallerIdentityInjector}. */
49     class Real implements CallerIdentityInjector {
50 
Real()51         protected Real() {
52         }
53 
54         @Override
resolveUserId(@serIdInt int userId, String debugName)55         public int resolveUserId(@UserIdInt int userId, String debugName) {
56             return ActivityManager.handleIncomingUser(Binder.getCallingPid(),
57                     Binder.getCallingUid(), userId, false, false, debugName, null);
58         }
59 
60         @Override
getCallingUserId()61         public int getCallingUserId() {
62             return UserHandle.getCallingUserId();
63         }
64 
65         @Override
clearCallingIdentity()66         public long clearCallingIdentity() {
67             return Binder.clearCallingIdentity();
68         }
69 
70         @Override
restoreCallingIdentity(long token)71         public void restoreCallingIdentity(long token) {
72             Binder.restoreCallingIdentity(token);
73         }
74     }
75 }
76