sdk/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 "precomp.h"
  12
  13 HANDLE EntrypointMutexes[SOUND_DEVICE_TYPES];
  14
  15 /*
  16     Creates a set of mutexes which are used for the purpose of guarding the
  17     device-type specific module entry-points. If any of these fail creation,
  18     all of them will be destroyed and the failure reported.
  19 */
  20 MMRESULT
  21 InitEntrypointMutexes()
  22 {
  23     UCHAR i;
  24     MMRESULT Result = MMSYSERR_NOERROR;
  25
  26     /* Blank all entries ni the table first */
  27     for ( i = 0; i < SOUND_DEVICE_TYPES; ++ i )
  28     {
  29         EntrypointMutexes[i] = NULL;
  30     }
  31
  32     /* Now create the mutexes */
  33     for ( i = 0; i < SOUND_DEVICE_TYPES; ++ i )
  34     {
  35         EntrypointMutexes[i] = CreateMutex(NULL, FALSE, NULL);
  36
  37         if ( ! EntrypointMutexes[i] )
  38         {
  39             Result = Win32ErrorToMmResult(GetLastError());
  40
  41             /* Clean up any mutexes we successfully created */
  42             CleanupEntrypointMutexes();
  43             break;
  44         }
  45     }
  46
  47     return Result;
  48 }
  49
  50 /*
  51     Cleans up any of the entry-point guard mutexes. This will only close the
  52     handles of mutexes which have been created, making it safe for use as a
  53     cleanup routine even within the InitEntrypointMutexes routine above.
  54 */
  55 VOID
  56 CleanupEntrypointMutexes()
  57 {
  58     UCHAR i;
  59
  60     /* Only clean up a mutex if it actually exists */
  61     for ( i = 0; i < SOUND_DEVICE_TYPES; ++ i )
  62     {
  63         if ( EntrypointMutexes[i] )
  64         {
  65             CloseHandle(EntrypointMutexes[i]);
  66             EntrypointMutexes[i] = NULL;
  67         }
  68     }
  69 }
  70
  71 /*
  72     Grabs an entry-point mutex.
  73 */
  74 VOID
  75 AcquireEntrypointMutex(
  76     IN  MMDEVICE_TYPE DeviceType)
  77 {
  78     UCHAR i;
  79
  80     SND_ASSERT( IS_VALID_SOUND_DEVICE_TYPE(DeviceType) );
  81     i = SOUND_DEVICE_TYPE_TO_INDEX(DeviceType);
  82
  83     SND_ASSERT( EntrypointMutexes[i] );
  84
  85     WaitForSingleObject(EntrypointMutexes[i], INFINITE);
  86 }
  87
  88 /*
  89     Releases an entry-point mutex.
  90 */
  91 VOID
  92 ReleaseEntrypointMutex(
  93     IN  MMDEVICE_TYPE DeviceType)
  94 {
  95     UCHAR i;
  96
  97     SND_ASSERT( IS_VALID_SOUND_DEVICE_TYPE(DeviceType) );
  98     i = SOUND_DEVICE_TYPE_TO_INDEX(DeviceType);
  99
 100     SND_ASSERT( EntrypointMutexes[i] );
 101
 102     ReleaseMutex(EntrypointMutexes[i]);
 103 }