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      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 
     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      */
     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      */
     80     public void stopZygote() {
     81         synchronized (mLock) {
     82             stopZygoteLocked();
     83         }
     84     }
     85 
     86     public ApplicationInfo getAppInfo() {
     87         return mAppInfo;
     88     }
     89 
     90     @GuardedBy("mLock")
     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")
    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