output: make "struct audio_output" opaque for output plugins

We have eliminated direct accesses to the audio_output struct from
the all output plugins.  Make it opaque for them, and move its real
declaration to output_internal.h, similar to decoder_internal.h.

Pass the opaque structure to plugin.init() only, which will return the
plugin's data pointer on success, and NULL on failure.  This data
pointer will be passed to all other methods instead of the
audio_output struct.

1 files changed, 15 insertions, 18 deletions

diff --git a/src/audioOutputs/audioOutput_alsa.c b/src/audioOutputs/audioOutput_alsa.c
index b6d00f176..98a7155d3 100644
--- a/src/audioOutputs/audioOutput_alsa.c
+++ b/src/audioOutputs/audioOutput_alsa.c
@@ -72,9 +72,9 @@ static void freeAlsaData(AlsaData * ad)
 	free(ad);
 }
 
-static int alsa_initDriver(struct audio_output *audioOutput,
-			   mpd_unused const struct audio_format *audio_format,
-			   ConfigParam * param)
+static void *alsa_initDriver(mpd_unused struct audio_output *ao,
+			     mpd_unused const struct audio_format *audio_format,
+			     ConfigParam * param)
 {
 	/* no need for pthread_once thread-safety when reading config */
 	static int free_global_registered;
@@ -98,14 +98,13 @@ static int alsa_initDriver(struct audio_output *audioOutput,
 		if ((bp = getBlockParam(param, "period_time")))
 			ad->period_time = atoi(bp->value);
 	}
-	audioOutput->data = ad;
 
-	return 0;
+	return ad;
 }
 
-static void alsa_finishDriver(struct audio_output *audioOutput)
+static void alsa_finishDriver(void *data)
 {
-	AlsaData *ad = audioOutput->data;
+	AlsaData *ad = data;
 
 	freeAlsaData(ad);
 }
@@ -137,10 +136,9 @@ static snd_pcm_format_t get_bitformat(const struct audio_format *af)
 	return SND_PCM_FORMAT_UNKNOWN;
 }
 
-static int alsa_openDevice(struct audio_output *audioOutput,
-			   struct audio_format *audioFormat)
+static int alsa_openDevice(void *data, struct audio_format *audioFormat)
 {
-	AlsaData *ad = audioOutput->data;
+	AlsaData *ad = data;
 	snd_pcm_format_t bitformat;
 	snd_pcm_hw_params_t *hwparams;
 	snd_pcm_sw_params_t *swparams;
@@ -351,16 +349,16 @@ static int alsa_errorRecovery(AlsaData * ad, int err)
 	return err;
 }
 
-static void alsa_dropBufferedAudio(struct audio_output *audioOutput)
+static void alsa_dropBufferedAudio(void *data)
 {
-	AlsaData *ad = audioOutput->data;
+	AlsaData *ad = data;
 
 	alsa_errorRecovery(ad, snd_pcm_drop(ad->pcmHandle));
 }
 
-static void alsa_closeDevice(struct audio_output *audioOutput)
+static void alsa_closeDevice(void *data)
 {
-	AlsaData *ad = audioOutput->data;
+	AlsaData *ad = data;
 
 	if (ad->pcmHandle) {
 		if (snd_pcm_state(ad->pcmHandle) == SND_PCM_STATE_RUNNING) {
@@ -371,10 +369,9 @@ static void alsa_closeDevice(struct audio_output *audioOutput)
 	}
 }
 
-static int alsa_playAudio(struct audio_output *audioOutput,
-			  const char *playChunk, size_t size)
+static int alsa_playAudio(void *data, const char *playChunk, size_t size)
 {
-	AlsaData *ad = audioOutput->data;
+	AlsaData *ad = data;
 	int ret;
 
 	size /= ad->sampleSize;
@@ -395,7 +392,7 @@ static int alsa_playAudio(struct audio_output *audioOutput,
 				ERROR("closing ALSA device \"%s\" due to write "
 				      "error: %s\n", ad->device,
 				      snd_strerror(-errno));
-				alsa_closeDevice(audioOutput);
+				alsa_closeDevice(ad);
 				return -1;
 			}
 			continue;