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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.SystemClock;
     28 import android.os.TokenWatcher;
     29 import android.os.UpdateLock;
     30 import android.os.UserHandle;
     31 import android.util.Slog;
     32 
     33 import java.io.FileDescriptor;
     34 import java.io.PrintWriter;
     35 
     36 public class UpdateLockService extends IUpdateLock.Stub {
     37     static final boolean DEBUG = false;
     38     static final String TAG = "UpdateLockService";
     39 
     40     // signatureOrSystem required to use update locks
     41     static final String PERMISSION = "android.permission.UPDATE_LOCK";
     42 
     43     Context mContext;
     44     LockWatcher mLocks;
     45 
     46     class LockWatcher extends TokenWatcher {
     47         LockWatcher(Handler h, String tag) {
     48             super(h, tag);
     49         }
     50 
     51         public void acquired() {
     52             if (DEBUG) {
     53                 Slog.d(TAG, "first acquire; broadcasting convenient=false");
     54             }
     55             sendLockChangedBroadcast(false);
     56         }
     57         public void released() {
     58             if (DEBUG) {
     59                 Slog.d(TAG, "last release; broadcasting convenient=true");
     60             }
     61             sendLockChangedBroadcast(true);
     62         }
     63     }
     64 
     65     UpdateLockService(Context context) {
     66         mContext = context;
     67         mLocks = new LockWatcher(new Handler(), "UpdateLocks");
     68 
     69         // Consider just-booting to be a reasonable time to allow
     70         // interruptions for update installation etc.
     71         sendLockChangedBroadcast(true);
     72     }
     73 
     74     void sendLockChangedBroadcast(boolean state) {
     75         // Safe early during boot because this broadcast only goes to registered receivers.
     76         long oldIdent = Binder.clearCallingIdentity();
     77         try {
     78             Intent intent = new Intent(UpdateLock.UPDATE_LOCK_CHANGED)
     79                     .putExtra(UpdateLock.NOW_IS_CONVENIENT, state)
     80                     .putExtra(UpdateLock.TIMESTAMP, System.currentTimeMillis())
     81                     .addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);
     82             mContext.sendStickyBroadcastAsUser(intent, UserHandle.ALL);
     83         } finally {
     84             Binder.restoreCallingIdentity(oldIdent);
     85         }
     86     }
     87 
     88     @Override
     89     public void acquireUpdateLock(IBinder token, String tag) throws RemoteException {
     90         if (DEBUG) {
     91             Slog.d(TAG, "acquire(" + token + ") by " + makeTag(tag));
     92         }
     93 
     94         mContext.enforceCallingOrSelfPermission(PERMISSION, "acquireUpdateLock");
     95         mLocks.acquire(token, makeTag(tag));
     96     }
     97 
     98     @Override
     99     public void releaseUpdateLock(IBinder token) throws RemoteException {
    100         if (DEBUG) {
    101             Slog.d(TAG, "release(" + token + ')');
    102         }
    103 
    104         mContext.enforceCallingOrSelfPermission(PERMISSION, "releaseUpdateLock");
    105         mLocks.release(token);
    106     };
    107 
    108     private String makeTag(String tag) {
    109         return "{tag=" + tag
    110                 + " uid=" + Binder.getCallingUid()
    111                 + " pid=" + Binder.getCallingPid() + '}';
    112     }
    113 
    114     @Override
    115     public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
    116         if (mContext.checkCallingOrSelfPermission(android.Manifest.permission.DUMP)
    117                 != PackageManager.PERMISSION_GRANTED) {
    118             pw.println("Permission Denial: can't dump update lock service from from pid="
    119                     + Binder.getCallingPid()
    120                     + ", uid=" + Binder.getCallingUid());
    121             return;
    122         }
    123 
    124         mLocks.dump(pw);
    125     }
    126 }
    127