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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 com.android.internal.util.DumpUtils;
     33 
     34 import java.io.FileDescriptor;
     35 import java.io.PrintWriter;
     36 
     37 public class UpdateLockService extends IUpdateLock.Stub {
     38     static final boolean DEBUG = false;
     39     static final String TAG = "UpdateLockService";
     40 
     41     // signatureOrSystem required to use update locks
     42     static final String PERMISSION = "android.permission.UPDATE_LOCK";
     43 
     44     Context mContext;
     45     LockWatcher mLocks;
     46 
     47     class LockWatcher extends TokenWatcher {
     48         LockWatcher(Handler h, String tag) {
     49             super(h, tag);
     50         }
     51 
     52         public void acquired() {
     53             if (DEBUG) {
     54                 Slog.d(TAG, "first acquire; broadcasting convenient=false");
     55             }
     56             sendLockChangedBroadcast(false);
     57         }
     58         public void released() {
     59             if (DEBUG) {
     60                 Slog.d(TAG, "last release; broadcasting convenient=true");
     61             }
     62             sendLockChangedBroadcast(true);
     63         }
     64     }
     65 
     66     UpdateLockService(Context context) {
     67         mContext = context;
     68         mLocks = new LockWatcher(new Handler(), "UpdateLocks");
     69 
     70         // Consider just-booting to be a reasonable time to allow
     71         // interruptions for update installation etc.
     72         sendLockChangedBroadcast(true);
     73     }
     74 
     75     void sendLockChangedBroadcast(boolean state) {
     76         // Safe early during boot because this broadcast only goes to registered receivers.
     77         long oldIdent = Binder.clearCallingIdentity();
     78         try {
     79             Intent intent = new Intent(UpdateLock.UPDATE_LOCK_CHANGED)
     80                     .putExtra(UpdateLock.NOW_IS_CONVENIENT, state)
     81                     .putExtra(UpdateLock.TIMESTAMP, System.currentTimeMillis())
     82                     .addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);
     83             mContext.sendStickyBroadcastAsUser(intent, UserHandle.ALL);
     84         } finally {
     85             Binder.restoreCallingIdentity(oldIdent);
     86         }
     87     }
     88 
     89     @Override
     90     public void acquireUpdateLock(IBinder token, String tag) throws RemoteException {
     91         if (DEBUG) {
     92             Slog.d(TAG, "acquire(" + token + ") by " + makeTag(tag));
     93         }
     94 
     95         mContext.enforceCallingOrSelfPermission(PERMISSION, "acquireUpdateLock");
     96         mLocks.acquire(token, makeTag(tag));
     97     }
     98 
     99     @Override
    100     public void releaseUpdateLock(IBinder token) throws RemoteException {
    101         if (DEBUG) {
    102             Slog.d(TAG, "release(" + token + ')');
    103         }
    104 
    105         mContext.enforceCallingOrSelfPermission(PERMISSION, "releaseUpdateLock");
    106         mLocks.release(token);
    107     };
    108 
    109     private String makeTag(String tag) {
    110         return "{tag=" + tag
    111                 + " uid=" + Binder.getCallingUid()
    112                 + " pid=" + Binder.getCallingPid() + '}';
    113     }
    114 
    115     @Override
    116     public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
    117         if (!DumpUtils.checkDumpPermission(mContext, TAG, pw)) return;
    118         mLocks.dump(pw);
    119     }
    120 }
    121