1 /*
2  * Copyright (C) 2018 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 android.os;
18 
19 import android.content.pm.ApplicationInfo;
20 import android.util.Log;
21 
22 import com.android.internal.annotations.GuardedBy;
23 
24 /**
25  * AppZygote is responsible for interfacing with an application-specific zygote.
26  *
27  * Application zygotes can pre-load app-specific code and data, and this interface can
28  * be used to spawn isolated services from such an application zygote.
29  *
30  * Note that we'll have only one instance of this per application / uid combination.
31  *
32  * @hide
33  */
34 public class AppZygote {
35     private static final String LOG_TAG = "AppZygote";
36 
37     // UID of the Zygote itself
38     private final int mZygoteUid;
39 
40     // First UID/GID of the range the AppZygote can setuid()/setgid() to
41     private final int mZygoteUidGidMin;
42 
43     // Last UID/GID of the range the AppZygote can setuid()/setgid() to
44     private final int mZygoteUidGidMax;
45 
46     private final Object mLock = new Object();
47 
48     /**
49      * Instance that maintains the socket connection to the zygote. This is {@code null} if the
50      * zygote is not running or is not connected.
51      */
52     @GuardedBy("mLock")
53     private ChildZygoteProcess mZygote;
54 
55     private final ApplicationInfo mAppInfo;
56 
AppZygote(ApplicationInfo appInfo, int zygoteUid, int uidGidMin, int uidGidMax)57     public AppZygote(ApplicationInfo appInfo, int zygoteUid, int uidGidMin, int uidGidMax) {
58         mAppInfo = appInfo;
59         mZygoteUid = zygoteUid;
60         mZygoteUidGidMin = uidGidMin;
61         mZygoteUidGidMax = uidGidMax;
62     }
63 
64     /**
65      * Returns the zygote process associated with this app zygote.
66      * Creates the process if it's not already running.
67      */
getProcess()68     public ChildZygoteProcess getProcess() {
69         synchronized (mLock) {
70             if (mZygote != null) return mZygote;
71 
72             connectToZygoteIfNeededLocked();
73             return mZygote;
74         }
75     }
76 
77     /**
78      * Stops the Zygote and kills the zygote process.
79      */
stopZygote()80     public void stopZygote() {
81         synchronized (mLock) {
82             stopZygoteLocked();
83         }
84     }
85 
getAppInfo()86     public ApplicationInfo getAppInfo() {
87         return mAppInfo;
88     }
89 
90     @GuardedBy("mLock")
stopZygoteLocked()91     private void stopZygoteLocked() {
92         if (mZygote != null) {
93             // Close the connection and kill the zygote process. This will not cause
94             // child processes to be killed by itself.
95             mZygote.close();
96             Process.killProcess(mZygote.getPid());
97             mZygote = null;
98         }
99     }
100 
101     @GuardedBy("mLock")
connectToZygoteIfNeededLocked()102     private void connectToZygoteIfNeededLocked() {
103         String abi = mAppInfo.primaryCpuAbi != null ? mAppInfo.primaryCpuAbi :
104                 Build.SUPPORTED_ABIS[0];
105         try {
106             mZygote = Process.ZYGOTE_PROCESS.startChildZygote(
107                     "com.android.internal.os.AppZygoteInit",
108                     mAppInfo.processName + "_zygote",
109                     mZygoteUid,
110                     mZygoteUid,
111                     null,  // gids
112                     0,  // runtimeFlags
113                     "app_zygote",  // seInfo
114                     abi,  // abi
115                     abi, // acceptedAbiList
116                     null, // instructionSet
117                     mZygoteUidGidMin,
118                     mZygoteUidGidMax);
119 
120             ZygoteProcess.waitForConnectionToZygote(mZygote.getPrimarySocketAddress());
121             // preload application code in the zygote
122             Log.i(LOG_TAG, "Starting application preload.");
123             mZygote.preloadApp(mAppInfo, abi);
124             Log.i(LOG_TAG, "Application preload done.");
125         } catch (Exception e) {
126             Log.e(LOG_TAG, "Error connecting to app zygote", e);
127             stopZygoteLocked();
128         }
129     }
130 }
131