lib/drivers/sound/mmebuddy/reentrancy.c

   1 /*
   2  * PROJECT:     ReactOS Sound System "MME Buddy" Library
   3  * LICENSE:     GPL - See COPYING in the top level directory
   4  * FILE:        lib/sound/mmebuddy/reentrancy.c
   5  *
   6  * PURPOSE:     Provides entry-point mutex guards.
   7  *
   8  * PROGRAMMERS: Andrew Greenwood (silverblade@reactos.org)
   9 */
  10
  11 #include <windows.h>
  12 #include <mmsystem.h>
  13 #include <mmddk.h>
  14 #include <ntddsnd.h>
  15 #include <sndtypes.h>
  16 #include <mmebuddy.h>
  17
  18 HANDLE EntrypointMutexes[SOUND_DEVICE_TYPES];
  19
  20 /*
  21     Creates a set of mutexes which are used for the purpose of guarding the
  22     device-type specific module entry-points. If any of these fail creation,
  23     all of them will be destroyed and the failure reported.
  24 */
  25 MMRESULT
  26 InitEntrypointMutexes()
  27 {
  28     UCHAR i;
  29     MMRESULT Result = MMSYSERR_NOERROR;
  30
  31     /* Blank all entries ni the table first */
  32     for ( i = 0; i < SOUND_DEVICE_TYPES; ++ i )
  33     {
  34         EntrypointMutexes[i] = NULL;
  35     }
  36
  37     /* Now create the mutexes */
  38     for ( i = 0; i < SOUND_DEVICE_TYPES; ++ i )
  39     {
  40         EntrypointMutexes[i] = CreateMutex(NULL, FALSE, NULL);
  41
  42         if ( ! EntrypointMutexes[i] )
  43         {
  44             Result = Win32ErrorToMmResult(GetLastError());
  45
  46             /* Clean up any mutexes we successfully created */
  47             CleanupEntrypointMutexes();
  48             break;
  49         }
  50     }
  51
  52     return Result;
  53 }
  54
  55 /*
  56     Cleans up any of the entry-point guard mutexes. This will only close the
  57     handles of mutexes which have been created, making it safe for use as a
  58     cleanup routine even within the InitEntrypointMutexes routine above.
  59 */
  60 VOID
  61 CleanupEntrypointMutexes()
  62 {
  63     UCHAR i;
  64
  65     /* Only clean up a mutex if it actually exists */
  66     for ( i = 0; i < SOUND_DEVICE_TYPES; ++ i )
  67     {
  68         if ( EntrypointMutexes[i] )
  69         {
  70             CloseHandle(EntrypointMutexes[i]);
  71             EntrypointMutexes[i] = NULL;
  72         }
  73     }
  74 }
  75
  76 /*
  77     Grabs an entry-point mutex.
  78 */
  79 VOID
  80 AcquireEntrypointMutex(
  81     IN  MMDEVICE_TYPE DeviceType)
  82 {
  83     UCHAR i;
  84
  85     SND_ASSERT( IS_VALID_SOUND_DEVICE_TYPE(DeviceType) );
  86     i = SOUND_DEVICE_TYPE_TO_INDEX(DeviceType);
  87
  88     SND_ASSERT( EntrypointMutexes[i] );
  89
  90     WaitForSingleObject(EntrypointMutexes[i], INFINITE);
  91 }
  92
  93 /*
  94     Releases an entry-point mutex.
  95 */
  96 VOID
  97 ReleaseEntrypointMutex(
  98     IN  MMDEVICE_TYPE DeviceType)
  99 {
 100     UCHAR i;
 101
 102     SND_ASSERT( IS_VALID_SOUND_DEVICE_TYPE(DeviceType) );
 103     i = SOUND_DEVICE_TYPE_TO_INDEX(DeviceType);
 104
 105     SND_ASSERT( EntrypointMutexes[i] );
 106
 107     ReleaseMutex(EntrypointMutexes[i]);
 108 }