base/services/audiosrv/pnp_list_lock.c

   1 /*
   2  * PROJECT:          ReactOS
   3  * LICENSE:          GPL - See COPYING in the top level directory
   4  * FILE:             base/services/audiosrv/list_lock.c
   5  * PURPOSE:          Audio Service Plug and Play list locking mechanism
   6  * COPYRIGHT:        Copyright 2007 Andrew Greenwood
   7  */
   8
   9 #include "audiosrv.h"
  10
  11 static HANDLE audio_device_list_lock = NULL;
  12
  13 BOOL
  14 InitializeAudioDeviceListLock()
  15 {
  16     /* The security stuff is to make sure the mutex can be grabbed by
  17        other processes - is this the best idea though ??? */
  18
  19     SECURITY_DESCRIPTOR security_descriptor;
  20     SECURITY_ATTRIBUTES security;
  21
  22     InitializeSecurityDescriptor(&security_descriptor, SECURITY_DESCRIPTOR_REVISION);
  23     SetSecurityDescriptorDacl(&security_descriptor, TRUE, 0, FALSE);
  24
  25     security.nLength = sizeof(SECURITY_ATTRIBUTES);
  26     security.lpSecurityDescriptor = &security_descriptor;
  27     security.bInheritHandle = FALSE;
  28
  29     audio_device_list_lock = CreateMutex(&security,
  30                                          FALSE,
  31                                          AUDIO_LIST_LOCK_NAME);
  32
  33     return ( audio_device_list_lock != NULL );
  34 }
  35
  36 VOID
  37 KillAudioDeviceListLock()
  38 {
  39     CloseHandle(audio_device_list_lock);
  40     audio_device_list_lock = NULL;
  41 }
  42
  43 VOID
  44 LockAudioDeviceList()
  45 {
  46     assert( audio_device_list_lock != NULL );
  47     WaitForSingleObject(audio_device_list_lock, INFINITE);
  48 }
  49
  50 VOID
  51 UnlockAudioDeviceList()
  52 {
  53     assert( audio_device_list_lock != NULL );
  54     ReleaseMutex(audio_device_list_lock);
  55 }
  56