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 {
LockWatcher(Handler h, String tag)48         LockWatcher(Handler h, String tag) {
49             super(h, tag);
50         }
51 
acquired()52         public void acquired() {
53             if (DEBUG) {
54                 Slog.d(TAG, "first acquire; broadcasting convenient=false");
55             }
56             sendLockChangedBroadcast(false);
57         }
released()58         public void released() {
59             if (DEBUG) {
60                 Slog.d(TAG, "last release; broadcasting convenient=true");
61             }
62             sendLockChangedBroadcast(true);
63         }
64     }
65 
UpdateLockService(Context context)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 
sendLockChangedBroadcast(boolean state)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
acquireUpdateLock(IBinder token, String tag)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
releaseUpdateLock(IBinder token)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 
makeTag(String tag)109     private String makeTag(String tag) {
110         return "{tag=" + tag
111                 + " uid=" + Binder.getCallingUid()
112                 + " pid=" + Binder.getCallingPid() + '}';
113     }
114 
115     @Override
dump(FileDescriptor fd, PrintWriter pw, String[] args)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