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
17package com.android.server;
18
19import android.content.Context;
20import android.content.Intent;
21import android.content.pm.PackageManager;
22import android.os.Binder;
23import android.os.Handler;
24import android.os.IBinder;
25import android.os.IUpdateLock;
26import android.os.RemoteException;
27import android.os.TokenWatcher;
28import android.os.UpdateLock;
29import android.os.UserHandle;
30import android.util.Slog;
31
32import java.io.FileDescriptor;
33import java.io.PrintWriter;
34
35public 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