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      1 /*
      2  * Copyright (C) 2012 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;
     18 
     19 import android.content.Context;
     20 import android.content.Intent;
     21 import android.content.pm.PackageManager;
     22 import android.os.Binder;
     23 import android.os.Handler;
     24 import android.os.IBinder;
     25 import android.os.IUpdateLock;
     26 import android.os.RemoteException;
     27 import android.os.TokenWatcher;
     28 import android.os.UpdateLock;
     29 import android.os.UserHandle;
     30 import android.util.Slog;
     31 
     32 import java.io.FileDescriptor;
     33 import java.io.PrintWriter;
     34 
     35 public class UpdateLockService extends IUpdateLock.Stub {
     36     static final boolean DEBUG = false;
     37     static final String TAG = "UpdateLockService";
     38 
     39     // signatureOrSystem required to use update locks
     40     static final String PERMISSION = "android.permission.UPDATE_LOCK";
     41 
     42     Context mContext;
     43     LockWatcher mLocks;
     44 
     45     class LockWatcher extends TokenWatcher {
     46         LockWatcher(Handler h, String tag) {
     47             super(h, tag);
     48         }
     49 
     50         public void acquired() {
     51             if (DEBUG) {
     52                 Slog.d(TAG, "first acquire; broadcasting convenient=false");
     53             }
     54             sendLockChangedBroadcast(false);
     55         }
     56         public void released() {
     57             if (DEBUG) {
     58                 Slog.d(TAG, "last release; broadcasting convenient=true");
     59             }
     60             sendLockChangedBroadcast(true);
     61         }
     62     }
     63 
     64     UpdateLockService(Context context) {
     65         mContext = context;
     66         mLocks = new LockWatcher(new Handler(), "UpdateLocks");
     67 
     68         // Consider just-booting to be a reasonable time to allow
     69         // interruptions for update installation etc.
     70         sendLockChangedBroadcast(true);
     71     }
     72 
     73     void sendLockChangedBroadcast(boolean state) {
     74         // Safe early during boot because this broadcast only goes to registered receivers.
     75         long oldIdent = Binder.clearCallingIdentity();
     76         try {
     77             Intent intent = new Intent(UpdateLock.UPDATE_LOCK_CHANGED)
     78                     .putExtra(UpdateLock.NOW_IS_CONVENIENT, state)
     79                     .putExtra(UpdateLock.TIMESTAMP, System.currentTimeMillis())
     80                     .addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);
     81             mContext.sendStickyBroadcastAsUser(intent, UserHandle.ALL);
     82         } finally {
     83             Binder.restoreCallingIdentity(oldIdent);
     84         }
     85     }
     86 
     87     @Override
     88     public void acquireUpdateLock(IBinder token, String tag) throws RemoteException {
     89         if (DEBUG) {
     90             Slog.d(TAG, "acquire(" + token + ") by " + makeTag(tag));
     91         }
     92 
     93         mContext.enforceCallingOrSelfPermission(PERMISSION, "acquireUpdateLock");
     94         mLocks.acquire(token, makeTag(tag));
     95     }
     96 
     97     @Override
     98     public void releaseUpdateLock(IBinder token) throws RemoteException {
     99         if (DEBUG) {
    100             Slog.d(TAG, "release(" + token + ')');
    101         }
    102 
    103         mContext.enforceCallingOrSelfPermission(PERMISSION, "releaseUpdateLock");
    104         mLocks.release(token);
    105     };
    106 
    107     private String makeTag(String tag) {
    108         return "{tag=" + tag
    109                 + " uid=" + Binder.getCallingUid()
    110                 + " pid=" + Binder.getCallingPid() + '}';
    111     }
    112 
    113     @Override
    114     public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
    115         if (mContext.checkCallingOrSelfPermission(android.Manifest.permission.DUMP)
    116                 != PackageManager.PERMISSION_GRANTED) {
    117             pw.println("Permission Denial: can't dump update lock service from from pid="
    118                     + Binder.getCallingPid()
    119                     + ", uid=" + Binder.getCallingUid());
    120             return;
    121         }
    122 
    123         mLocks.dump(pw);
    124     }
    125 }
    126