/services/java/com/android/server/UpdateLockService.java

  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.SystemClock;
 28import android.os.TokenWatcher;
 29import android.os.UpdateLock;
 30import android.os.UserHandle;
 31import android.util.Slog;
 32
 33import java.io.FileDescriptor;
 34import java.io.PrintWriter;
 35
 36public 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}