| /* |
| * Copyright (C) 2012 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.server.os; |
| |
| import android.content.pm.PackageManager; |
| import android.os.Binder; |
| import android.os.ISchedulingPolicyService; |
| import android.os.Process; |
| |
| /** |
| * The implementation of the scheduling policy service interface. |
| * |
| * @hide |
| */ |
| public class SchedulingPolicyService extends ISchedulingPolicyService.Stub { |
| |
| private static final String TAG = "SchedulingPolicyService"; |
| |
| // Minimum and maximum values allowed for requestPriority parameter prio |
| private static final int PRIORITY_MIN = 1; |
| private static final int PRIORITY_MAX = 3; |
| |
| public SchedulingPolicyService() { |
| } |
| |
| public int requestPriority(int pid, int tid, int prio) { |
| //Log.i(TAG, "requestPriority(pid=" + pid + ", tid=" + tid + ", prio=" + prio + ")"); |
| |
| // Verify that caller is mediaserver, priority is in range, and that the |
| // callback thread specified by app belongs to the app that called mediaserver. |
| // Once we've verified that the caller is mediaserver, we can trust the pid but |
| // we can't trust the tid. No need to explicitly check for pid == 0 || tid == 0, |
| // since if not the case then the getThreadGroupLeader() test will also fail. |
| if (Binder.getCallingUid() != Process.MEDIA_UID || prio < PRIORITY_MIN || |
| prio > PRIORITY_MAX || Process.getThreadGroupLeader(tid) != pid) { |
| return PackageManager.PERMISSION_DENIED; |
| } |
| try { |
| // make good use of our CAP_SYS_NICE capability |
| Process.setThreadGroup(tid, Binder.getCallingPid() == pid ? |
| Process.THREAD_GROUP_AUDIO_SYS : Process.THREAD_GROUP_AUDIO_APP); |
| // must be in this order or it fails the schedulability constraint |
| Process.setThreadScheduler(tid, Process.SCHED_FIFO, prio); |
| } catch (RuntimeException e) { |
| return PackageManager.PERMISSION_DENIED; |
| } |
| return PackageManager.PERMISSION_GRANTED; |
| } |
| |
| } |