//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;
