content: /*
   * Copyright (C) 2018 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;
  
  import android.content.pm.ApplicationInfo;
  import android.util.Log;
  
  import com.android.internal.annotations.GuardedBy;
  
  /**
   * AppZygote is responsible for interfacing with an application-specific zygote.
   *
   * Application zygotes can pre-load app-specific code and data, and this interface can
   * be used to spawn isolated services from such an application zygote.
   *
   * Note that we'll have only one instance of this per application / uid combination.
   *
   * @hide
   */
  public class AppZygote {
      private static final String LOG_TAG = "AppZygote";
  
      // UID of the Zygote itself
      private final int mZygoteUid;
  
      // First UID/GID of the range the AppZygote can setuid()/setgid() to
      private final int mZygoteUidGidMin;
  
      // Last UID/GID of the range the AppZygote can setuid()/setgid() to
      private final int mZygoteUidGidMax;
  
      private final Object mLock = new Object();
  
      /**
       * Instance that maintains the socket connection to the zygote. This is {@code null} if the
       * zygote is not running or is not connected.
       */
      @GuardedBy("mLock")
      private ChildZygoteProcess mZygote;
  
      private final ApplicationInfo mAppInfo;
  
      public AppZygote(ApplicationInfo appInfo, int zygoteUid, int uidGidMin, int uidGidMax) {
          mAppInfo = appInfo;
          mZygoteUid = zygoteUid;
          mZygoteUidGidMin = uidGidMin;
          mZygoteUidGidMax = uidGidMax;
      }
  
      /**
       * Returns the zygote process associated with this app zygote.
       * Creates the process if it's not already running.
       */
      public ChildZygoteProcess getProcess() {
          synchronized (mLock) {
              if (mZygote != null) return mZygote;
  
              connectToZygoteIfNeededLocked();
              return mZygote;
          }
      }
  
      /**
       * Stops the Zygote and kills the zygote process.
       */
      public void stopZygote() {
          synchronized (mLock) {
              stopZygoteLocked();
          }
      }
  
      public ApplicationInfo getAppInfo() {
          return mAppInfo;
      }
  
      @GuardedBy("mLock")
      private void stopZygoteLocked() {
          if (mZygote != null) {
              mZygote.close();
              // use killProcessGroup() here, so we kill all untracked children as well.
              Process.killProcessGroup(mZygoteUid, mZygote.getPid());
              mZygote = null;
          }
      }
  
      @GuardedBy("mLock")
      private void connectToZygoteIfNeededLocked() {
          String abi = mAppInfo.primaryCpuAbi != null ? mAppInfo.primaryCpuAbi :
                  Build.SUPPORTED_ABIS[0];
          try {
              mZygote = Process.ZYGOTE_PROCESS.startChildZygote(
                      "com.android.internal.os.AppZygoteInit",
                      mAppInfo.processName + "_zygote",
                      mZygoteUid,
                      mZygoteUid,
                      null,  // gids
                      0,  // runtimeFlags
                      "app_zygote",  // seInfo
                      abi,  // abi
                      abi, // acceptedAbiList
                      null, // instructionSet
                      mZygoteUidGidMin,
                      mZygoteUidGidMax);
  
              ZygoteProcess.waitForConnectionToZygote(mZygote.getPrimarySocketAddress());
              // preload application code in the zygote
              Log.i(LOG_TAG, "Starting application preload.");
              mZygote.preloadApp(mAppInfo, abi);
              Log.i(LOG_TAG, "Application preload done.");
          } catch (Exception e) {
              Log.e(LOG_TAG, "Error connecting to app zygote", e);
              stopZygoteLocked();
          }
      }
  }
  