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      1 /*
      2  * Copyright (C) 2015 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.pm;
     18 
     19 import android.app.EphemeralResolverService;
     20 import android.app.IEphemeralResolver;
     21 import android.content.ComponentName;
     22 import android.content.Context;
     23 import android.content.Intent;
     24 import android.content.ServiceConnection;
     25 import android.content.pm.EphemeralResolveInfo;
     26 import android.os.Build;
     27 import android.os.Bundle;
     28 import android.os.IBinder;
     29 import android.os.IRemoteCallback;
     30 import android.os.RemoteException;
     31 import android.os.SystemClock;
     32 import android.os.UserHandle;
     33 import android.util.TimedRemoteCaller;
     34 
     35 import java.io.FileDescriptor;
     36 import java.io.PrintWriter;
     37 import java.util.ArrayList;
     38 import java.util.List;
     39 import java.util.concurrent.TimeoutException;
     40 
     41 /**
     42  * Represents a remote ephemeral resolver. It is responsible for binding to the remote
     43  * service and handling all interactions in a timely manner.
     44  * @hide
     45  */
     46 final class EphemeralResolverConnection {
     47     // This is running in a critical section and the timeout must be sufficiently low
     48     private static final long BIND_SERVICE_TIMEOUT_MS =
     49             ("eng".equals(Build.TYPE)) ? 300 : 200;
     50 
     51     private final Object mLock = new Object();
     52     private final GetEphemeralResolveInfoCaller mGetEphemeralResolveInfoCaller =
     53             new GetEphemeralResolveInfoCaller();
     54     private final ServiceConnection mServiceConnection = new MyServiceConnection();
     55     private final Context mContext;
     56     /** Intent used to bind to the service */
     57     private final Intent mIntent;
     58 
     59     private volatile boolean mBindRequested;
     60     private IEphemeralResolver mRemoteInstance;
     61 
     62     public EphemeralResolverConnection(Context context, ComponentName componentName) {
     63         mContext = context;
     64         mIntent = new Intent(Intent.ACTION_RESOLVE_EPHEMERAL_PACKAGE).setComponent(componentName);
     65     }
     66 
     67     public final List<EphemeralResolveInfo> getEphemeralResolveInfoList(
     68             int hashPrefix[], int prefixMask) {
     69         throwIfCalledOnMainThread();
     70         try {
     71             return mGetEphemeralResolveInfoCaller.getEphemeralResolveInfoList(
     72                     getRemoteInstanceLazy(), hashPrefix, prefixMask);
     73         } catch (RemoteException re) {
     74         } catch (TimeoutException te) {
     75         } finally {
     76             synchronized (mLock) {
     77                 mLock.notifyAll();
     78             }
     79         }
     80         return null;
     81     }
     82 
     83     public void dump(FileDescriptor fd, PrintWriter pw, String prefix) {
     84         synchronized (mLock) {
     85             pw.append(prefix).append("bound=")
     86                     .append((mRemoteInstance != null) ? "true" : "false").println();
     87 
     88             pw.flush();
     89 
     90             try {
     91                 getRemoteInstanceLazy().asBinder().dump(fd, new String[] { prefix });
     92             } catch (TimeoutException te) {
     93                 /* ignore */
     94             } catch (RemoteException re) {
     95                 /* ignore */
     96             }
     97         }
     98     }
     99 
    100     private IEphemeralResolver getRemoteInstanceLazy() throws TimeoutException {
    101         synchronized (mLock) {
    102             if (mRemoteInstance != null) {
    103                 return mRemoteInstance;
    104             }
    105             bindLocked();
    106             return mRemoteInstance;
    107         }
    108     }
    109 
    110     private void bindLocked() throws TimeoutException {
    111         if (mRemoteInstance != null) {
    112             return;
    113         }
    114 
    115         if (!mBindRequested) {
    116             mBindRequested = true;
    117             mContext.bindServiceAsUser(mIntent, mServiceConnection,
    118                     Context.BIND_AUTO_CREATE | Context.BIND_FOREGROUND_SERVICE, UserHandle.SYSTEM);
    119         }
    120 
    121         final long startMillis = SystemClock.uptimeMillis();
    122         while (true) {
    123             if (mRemoteInstance != null) {
    124                 break;
    125             }
    126             final long elapsedMillis = SystemClock.uptimeMillis() - startMillis;
    127             final long remainingMillis = BIND_SERVICE_TIMEOUT_MS - elapsedMillis;
    128             if (remainingMillis <= 0) {
    129                 throw new TimeoutException("Didn't bind to resolver in time.");
    130             }
    131             try {
    132                 mLock.wait(remainingMillis);
    133             } catch (InterruptedException ie) {
    134                 /* ignore */
    135             }
    136         }
    137 
    138         mLock.notifyAll();
    139     }
    140 
    141     private void throwIfCalledOnMainThread() {
    142         if (Thread.currentThread() == mContext.getMainLooper().getThread()) {
    143             throw new RuntimeException("Cannot invoke on the main thread");
    144         }
    145     }
    146 
    147     private final class MyServiceConnection implements ServiceConnection {
    148         @Override
    149         public void onServiceConnected(ComponentName name, IBinder service) {
    150             synchronized (mLock) {
    151                 mRemoteInstance = IEphemeralResolver.Stub.asInterface(service);
    152                 mLock.notifyAll();
    153             }
    154         }
    155 
    156         @Override
    157         public void onServiceDisconnected(ComponentName name) {
    158             synchronized (mLock) {
    159                 mRemoteInstance = null;
    160             }
    161         }
    162     }
    163 
    164     private static final class GetEphemeralResolveInfoCaller
    165             extends TimedRemoteCaller<List<EphemeralResolveInfo>> {
    166         private final IRemoteCallback mCallback;
    167 
    168         public GetEphemeralResolveInfoCaller() {
    169             super(TimedRemoteCaller.DEFAULT_CALL_TIMEOUT_MILLIS);
    170             mCallback = new IRemoteCallback.Stub() {
    171                     @Override
    172                     public void sendResult(Bundle data) throws RemoteException {
    173                         final ArrayList<EphemeralResolveInfo> resolveList =
    174                                 data.getParcelableArrayList(
    175                                         EphemeralResolverService.EXTRA_RESOLVE_INFO);
    176                         int sequence =
    177                                 data.getInt(EphemeralResolverService.EXTRA_SEQUENCE, -1);
    178                         onRemoteMethodResult(resolveList, sequence);
    179                     }
    180             };
    181         }
    182 
    183         public List<EphemeralResolveInfo> getEphemeralResolveInfoList(
    184                 IEphemeralResolver target, int hashPrefix[], int prefixMask)
    185                         throws RemoteException, TimeoutException {
    186             final int sequence = onBeforeRemoteCall();
    187             target.getEphemeralResolveInfoList(mCallback, hashPrefix, prefixMask, sequence);
    188             return getResultTimed(sequence);
    189         }
    190     }
    191 }
    192