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 <windows.h>
  10 #include <assert.h>
  11 #include <audiosrv/audiosrv.h>
  12
  13 static HANDLE audio_device_list_lock = NULL;
  14
  15 BOOL
  16 InitializeAudioDeviceListLock()
  17 {
  18     /* The security stuff is to make sure the mutex can be grabbed by
  19        other processes - is this the best idea though ??? */
  20
  21     SECURITY_DESCRIPTOR security_descriptor;
  22     SECURITY_ATTRIBUTES security;
  23
  24     InitializeSecurityDescriptor(&security_descriptor, SECURITY_DESCRIPTOR_REVISION);
  25     SetSecurityDescriptorDacl(&security_descriptor, TRUE, 0, FALSE);
  26
  27     security.nLength = sizeof(SECURITY_ATTRIBUTES);
  28     security.lpSecurityDescriptor = &security_descriptor;
  29     security.bInheritHandle = FALSE;
  30
  31     audio_device_list_lock = CreateMutex(&security,
  32                                          FALSE,
  33                                          AUDIO_LIST_LOCK_NAME);
  34
  35     return ( audio_device_list_lock != NULL );
  36 }
  37
  38 VOID
  39 KillAudioDeviceListLock()
  40 {
  41     CloseHandle(audio_device_list_lock);
  42     audio_device_list_lock = NULL;
  43 }
  44
  45 VOID
  46 LockAudioDeviceList()
  47 {
  48     assert( audio_device_list_lock != NULL );
  49     WaitForSingleObject(audio_device_list_lock, INFINITE);
  50 }
  51
  52 VOID
  53 UnlockAudioDeviceList()
  54 {
  55     assert( audio_device_list_lock != NULL );
  56     ReleaseMutex(audio_device_list_lock);
  57 }
  58