Don't destroy voice when it is output to other voices

include/FAudio.h

@@ -1064,6 +1064,11 @@ FAUDIOAPI void FAudioVoice_GetOutputMatrix(
 /* Removes this voice from the audio graph and frees memory. */
 FAUDIOAPI void FAudioVoice_DestroyVoice(FAudioVoice *voice);
 
+/*
+ * Returns S_OK on success and E_FAIL if voice could not be destroyed (e. g., because it is in use).
+ */
+FAUDIOAPI uint32_t FAudioVoice_DestroyVoiceSafeEXT(FAudioVoice *voice);
+
 /* FAudioSourceVoice Interface */
 
 /* Starts processing for a source voice.

src/FAudio.c

@@ -2265,11 +2265,71 @@ void FAudioVoice_GetOutputMatrix(
 	LOG_API_EXIT(voice->audio)
 }
 
-void FAudioVoice_DestroyVoice(FAudioVoice *voice)
+static uint32_t check_for_sends_to_voice(FAudioVoice *voice)
 {
+	FAudio *audio = voice->audio;
+	uint32_t ret = 0;
+	FAudioSourceVoice *source;
+	FAudioSubmixVoice *submix;
+	LinkedList *list;
 	uint32_t i;
+
+	FAudio_PlatformLockMutex(audio->sourceLock);
+	list = audio->sources;
+	while (list != NULL)
+	{
+		source = (FAudioSourceVoice*) list->entry;
+		for (i = 0; i < source->sends.SendCount; i += 1)
+			if (source->sends.pSends[i].pOutputVoice == voice)
+			{
+				ret = 0x80004005; /* E_FAIL */
+				break;
+			}
+		if (ret)
+			break;
+		list = list->next;
+	}
+	FAudio_PlatformUnlockMutex(audio->sourceLock);
+
+	if (ret)
+		return ret;
+
+	FAudio_PlatformLockMutex(audio->submixLock);
+	list = audio->submixes;
+	while (list != NULL)
+	{
+		submix = (FAudioSubmixVoice*) list->entry;
+		for (i = 0; i < submix->sends.SendCount; i += 1)
+			if (submix->sends.pSends[i].pOutputVoice == voice)
+			{
+				ret = 0x80004005; /* E_FAIL */
+				break;
+			}
+		if (ret)
+			break;
+		list = list->next;
+	}
+	FAudio_PlatformUnlockMutex(audio->submixLock);
+
+	return ret;
+}
+
+uint32_t FAudioVoice_DestroyVoiceSafeEXT(FAudioVoice *voice)
+{
+	uint32_t i, ret;
 	LOG_API_ENTER(voice->audio)
 
+	if ((ret = check_for_sends_to_voice(voice)))
+	{
+		LOG_ERROR(
+			voice->audio,
+			"Voice %p is an output for other voice(s)",
+			voice
+		)
+		LOG_API_EXIT(voice->audio)
+		return ret;
+	}
+
 	/* TODO: Check for dependencies and remove from audio graph first! */
 	FAudio_OPERATIONSET_ClearAllForVoice(voice);
 
@@ -2443,6 +2503,12 @@ void FAudioVoice_DestroyVoice(FAudioVoice *voice)
 	LOG_API_EXIT(voice->audio)
 	FAudio_Release(voice->audio);
 	voice->audio->pFree(voice);
+	return 0;
+}
+
+void FAudioVoice_DestroyVoice(FAudioVoice *voice)
+{
+	FAudioVoice_DestroyVoiceSafeEXT(voice);
 }
 
 /* FAudioSourceVoice Interface */