output: use bool for return values and flags

Don't return 0/-1 on success/error, but true/false.  Instead of int,
use bool for storing flags.

21 files changed, 162 insertions, 153 deletions

diff --git a/src/audio.c b/src/audio.c
index 0eff63f8f..f4f0ffe14 100644
--- a/src/audio.c
+++ b/src/audio.c
@@ -247,9 +247,9 @@ static void syncAudioDeviceStates(void)
 	}
 }
 
-int playAudio(const char *buffer, size_t length)
+bool playAudio(const char *buffer, size_t length)
 {
-	int ret = -1, err;
+	bool ret = false;
 	unsigned int i;
 
 	/* no partial frames allowed */
@@ -262,8 +262,8 @@ int playAudio(const char *buffer, size_t length)
 			audio_output_play(&audioOutputArray[i],
 					  buffer, length);
 
-	while (1) {
-		int finished = 1;
+	while (true) {
+		bool finished = true;
 
 		for (i = 0; i < audioOutputArraySize; ++i) {
 			struct audio_output *ao = &audioOutputArray[i];
@@ -272,16 +272,16 @@ int playAudio(const char *buffer, size_t length)
 				continue;
 
 			if (audio_output_command_is_finished(ao)) {
-				err = audio_output_get_result(ao);
-				if (!err)
-					ret = 0;
-				else if (err < 0)
+				bool success = audio_output_get_result(ao);
+				if (success)
+					ret = true;
+				else
 					/* device should already be
 					   closed if the play func
 					   returned an error */
 					audioDeviceStates[i] = true;
 			} else {
-				finished = 0;
+				finished = false;
 				audio_output_signal(ao);
 			}
 		}
@@ -295,13 +295,13 @@ int playAudio(const char *buffer, size_t length)
 	return ret;
 }
 
-int openAudioDevice(const struct audio_format *audioFormat)
+bool openAudioDevice(const struct audio_format *audioFormat)
 {
-	int ret = -1;
+	bool ret = false;
 	unsigned int i;
 
 	if (!audioOutputArray)
-		return -1;
+		return false;
 
 	if (audioFormat != NULL)
 		input_audio_format = *audioFormat;
@@ -310,10 +310,10 @@ int openAudioDevice(const struct audio_format *audioFormat)
 
 	for (i = 0; i < audioOutputArraySize; ++i) {
 		if (audioOutputArray[i].open)
-			ret = 0;
+			ret = true;
 	}
 
-	if (ret != 0)
+	if (!ret)
 		/* close all devices if there was an error */
 		closeAudioDevice();
 
diff --git a/src/audio.h b/src/audio.h
index 9140afd58..c6f6cbde0 100644
--- a/src/audio.h
+++ b/src/audio.h
@@ -42,9 +42,9 @@ void initAudioDriver(void);
 
 void finishAudioDriver(void);
 
-int openAudioDevice(const struct audio_format *audioFormat);
+bool openAudioDevice(const struct audio_format *audioFormat);
 
-int playAudio(const char *playChunk, size_t size);
+bool playAudio(const char *playChunk, size_t size);
 
 void audio_output_pause_all(void);
 
diff --git a/src/output/alsa_plugin.c b/src/output/alsa_plugin.c
index e812e49fc..2d4f9c239 100644
--- a/src/output/alsa_plugin.c
+++ b/src/output/alsa_plugin.c
@@ -125,7 +125,7 @@ static void alsa_finishDriver(void *data)
 	freeAlsaData(ad);
 }
 
-static int alsa_testDefault(void)
+static bool alsa_testDefault(void)
 {
 	snd_pcm_t *handle;
 
@@ -134,11 +134,11 @@ static int alsa_testDefault(void)
 	if (ret) {
 		WARNING("Error opening default ALSA device: %s\n",
 			snd_strerror(-ret));
-		return -1;
+		return false;
 	} else
 		snd_pcm_close(handle);
 
-	return 0;
+	return true;
 }
 
 static snd_pcm_format_t get_bitformat(const struct audio_format *af)
@@ -152,7 +152,7 @@ static snd_pcm_format_t get_bitformat(const struct audio_format *af)
 	return SND_PCM_FORMAT_UNKNOWN;
 }
 
-static int alsa_openDevice(void *data, struct audio_format *audioFormat)
+static bool alsa_openDevice(void *data, struct audio_format *audioFormat)
 {
 	AlsaData *ad = data;
 	snd_pcm_format_t bitformat;
@@ -318,7 +318,7 @@ configure_hw:
 	      "%u Hz\n", ad->device, audioFormat->bits,
 	      channels, sample_rate);
 
-	return 0;
+	return true;
 
 error:
 	if (cmd) {
@@ -332,7 +332,7 @@ fail:
 	if (ad->pcmHandle)
 		snd_pcm_close(ad->pcmHandle);
 	ad->pcmHandle = NULL;
-	return -1;
+	return false;
 }
 
 static int alsa_errorRecovery(AlsaData * ad, int err)
@@ -393,7 +393,8 @@ static void alsa_closeDevice(void *data)
 	}
 }
 
-static int alsa_playAudio(void *data, const char *playChunk, size_t size)
+static bool
+alsa_playAudio(void *data, const char *playChunk, size_t size)
 {
 	AlsaData *ad = data;
 	int ret;
@@ -412,7 +413,7 @@ static int alsa_playAudio(void *data, const char *playChunk, size_t size)
 				      "error: %s\n", ad->device,
 				      snd_strerror(-errno));
 				alsa_closeDevice(ad);
-				return -1;
+				return false;
 			}
 			continue;
 		}
@@ -421,7 +422,7 @@ static int alsa_playAudio(void *data, const char *playChunk, size_t size)
 		size -= ret;
 	}
 
-	return 0;
+	return true;
 }
 
 const struct audio_output_plugin alsaPlugin = {
diff --git a/src/output/ao_plugin.c b/src/output/ao_plugin.c
index b5cebc93b..d2c7dab6e 100644
--- a/src/output/ao_plugin.c
+++ b/src/output/ao_plugin.c
@@ -168,8 +168,8 @@ static void audioOutputAo_closeDevice(void *data)
 	}
 }
 
-static int audioOutputAo_openDevice(void *data,
-				    struct audio_format *audio_format)
+static bool
+audioOutputAo_openDevice(void *data, struct audio_format *audio_format)
 {
 	ao_sample_format format;
 	AoData *ad = (AoData *)data;
@@ -186,9 +186,9 @@ static int audioOutputAo_openDevice(void *data,
 	ad->device = ao_open_live(ad->driverId, &format, ad->options);
 
 	if (ad->device == NULL)
-		return -1;
+		return false;
 
-	return 0;
+	return true;
 }
 
 /**
@@ -208,13 +208,14 @@ static int ao_play_deconst(ao_device *device, const void *output_samples,
 	return ao_play(device, u.out, num_bytes);
 }
 
-static int audioOutputAo_play(void *data, const char *playChunk, size_t size)
+static bool
+audioOutputAo_play(void *data, const char *playChunk, size_t size)
 {
 	AoData *ad = (AoData *)data;
 	size_t chunk_size;
 
 	if (ad->device == NULL)
-		return -1;
+		return false;
 
 	while (size > 0) {
 		chunk_size = (size_t)ad->writeSize > size
@@ -224,14 +225,14 @@ static int audioOutputAo_play(void *data, const char *playChunk, size_t size)
 			audioOutputAo_error();
 			ERROR("closing audio device due to write error\n");
 			audioOutputAo_closeDevice(ad);
-			return -1;
+			return false;
 		}
 
 		playChunk += chunk_size;
 		size -= chunk_size;
 	}
 
-	return 0;
+	return true;
 }
 
 const struct audio_output_plugin aoPlugin = {
diff --git a/src/output/fifo_plugin.c b/src/output/fifo_plugin.c
index cd83177f8..fe85d6644 100644
--- a/src/output/fifo_plugin.c
+++ b/src/output/fifo_plugin.c
@@ -128,17 +128,17 @@ static int checkFifo(FifoData *fd)
 	return 0;
 }
 
-static int openFifo(FifoData *fd)
+static bool openFifo(FifoData *fd)
 {
 	if (checkFifo(fd) < 0)
-		return -1;
+		return false;
 
 	fd->input = open(fd->path, O_RDONLY|O_NONBLOCK);
 	if (fd->input < 0) {
 		ERROR("Could not open FIFO \"%s\" for reading: %s\n",
 		      fd->path, strerror(errno));
 		closeFifo(fd);
-		return -1;
+		return false;
 	}
 
 	fd->output = open(fd->path, O_WRONLY|O_NONBLOCK);
@@ -146,10 +146,10 @@ static int openFifo(FifoData *fd)
 		ERROR("Could not open FIFO \"%s\" for writing: %s\n",
 		      fd->path, strerror(errno));
 		closeFifo(fd);
-		return -1;
+		return false;
 	}
 
-	return 0;
+	return true;
 }
 
 static void *fifo_initDriver(mpd_unused struct audio_output *ao,
@@ -175,7 +175,7 @@ static void *fifo_initDriver(mpd_unused struct audio_output *ao,
 	fd = newFifoData();
 	fd->path = path;
 
-	if (openFifo(fd) < 0) {
+	if (!openFifo(fd)) {
 		freeFifoData(fd);
 		return NULL;
 	}
@@ -191,7 +191,7 @@ static void fifo_finishDriver(void *data)
 	freeFifoData(fd);
 }
 
-static int fifo_openDevice(void *data,
+static bool fifo_openDevice(void *data,
 			   struct audio_format *audio_format)
 {
 	FifoData *fd = (FifoData *)data;
@@ -201,7 +201,7 @@ static int fifo_openDevice(void *data,
 
 	fd->timer = timer_new(audio_format);
 
-	return 0;
+	return true;
 }
 
 static void fifo_closeDevice(void *data)
@@ -231,8 +231,8 @@ static void fifo_dropBufferedAudio(void *data)
 	}
 }
 
-static int fifo_playAudio(void *data,
-			  const char *playChunk, size_t size)
+static bool
+fifo_playAudio(void *data, const char *playChunk, size_t size)
 {
 	FifoData *fd = (FifoData *)data;
 	size_t offset = 0;
@@ -260,14 +260,14 @@ static int fifo_playAudio(void *data,
 			ERROR("Closing FIFO output \"%s\" due to write error: "
 			      "%s\n", fd->path, strerror(errno));
 			fifo_closeDevice(fd);
-			return -1;
+			return false;
 		}
 
 		size -= bytes;
 		offset += bytes;
 	}
 
-	return 0;
+	return true;
 }
 
 const struct audio_output_plugin fifoPlugin = {
diff --git a/src/output/jack_plugin.c b/src/output/jack_plugin.c
index 7f10db976..1e6c81b75 100644
--- a/src/output/jack_plugin.c
+++ b/src/output/jack_plugin.c
@@ -242,10 +242,10 @@ mpd_jack_init(struct audio_output *ao,
 	return jd;
 }
 
-static int
+static bool
 mpd_jack_test_default_device(void)
 {
-	return 0;
+	return true;
 }
 
 static int
@@ -328,7 +328,7 @@ mpd_jack_connect(struct jack_data *jd, struct audio_format *audio_format)
 	return 1;
 }
 
-static int
+static bool
 mpd_jack_open(void *data, struct audio_format *audio_format)
 {
 	struct jack_data *jd = data;
@@ -337,12 +337,12 @@ mpd_jack_open(void *data, struct audio_format *audio_format)
 
 	if (jd->client == NULL && mpd_jack_connect(jd, audio_format) < 0) {
 		mpd_jack_client_free(jd);
-		return -1;
+		return false;
 	}
 
 	set_audioformat(jd, audio_format);
 
-	return 0;
+	return true;
 }
 
 static void
@@ -422,7 +422,7 @@ mpd_jack_write_samples(struct jack_data *jd, const void *src,
 	}
 }
 
-static int
+static bool
 mpd_jack_play(void *data, const char *buff, size_t size)
 {
 	struct jack_data *jd = data;
@@ -433,7 +433,7 @@ mpd_jack_play(void *data, const char *buff, size_t size)
 		ERROR("Refusing to play, because there is no client thread.\n");
 		mpd_jack_client_free(jd);
 		audio_output_closed(jd->ao);
-		return 0;
+		return true;
 	}
 
 	assert(size % frame_size == 0);
@@ -462,7 +462,7 @@ mpd_jack_play(void *data, const char *buff, size_t size)
 
 	}
 
-	return 0;
+	return true;
 }
 
 const struct audio_output_plugin jackPlugin = {
diff --git a/src/output/mvp_plugin.c b/src/output/mvp_plugin.c
index 94f4f0ea7..9a56e7943 100644
--- a/src/output/mvp_plugin.c
+++ b/src/output/mvp_plugin.c
@@ -81,7 +81,7 @@ static unsigned pcmfrequencies[][3] = {
 static const unsigned numfrequencies =
 	sizeof(pcmfrequencies) / sizeof(pcmfrequencies[0]);
 
-static int mvp_testDefault(void)
+static bool mvp_testDefault(void)
 {
 	int fd;
 
@@ -89,13 +89,13 @@ static int mvp_testDefault(void)
 
 	if (fd) {
 		close(fd);
-		return 0;
+		return true;
 	}
 
 	WARNING("Error opening PCM device \"/dev/adec_pcm\": %s\n",
 		strerror(errno));
 
-	return -1;
+	return false;
 }
 
 static void *mvp_initDriver(mpd_unused struct audio_output *audio_output,
@@ -178,7 +178,8 @@ static int mvp_setPcmParams(MvpData * md, unsigned long rate, int channels,
 	return 0;
 }
 
-static int mvp_openDevice(void *data, struct audio_format *audioFormat)
+static bool
+mvp_openDevice(void *data, struct audio_format *audioFormat)
 {
 	MvpData *md = data;
 	long long int stc = 0;
@@ -186,24 +187,24 @@ static int mvp_openDevice(void *data, struct audio_format *audioFormat)
 
 	if ((md->fd = open("/dev/adec_pcm", O_RDWR | O_NONBLOCK)) < 0) {
 		ERROR("Error opening /dev/adec_pcm: %s\n", strerror(errno));
-		return -1;
+		return false;
 	}
 	if (ioctl(md->fd, MVP_SET_AUD_SRC, 1) < 0) {
 		ERROR("Error setting audio source: %s\n", strerror(errno));
-		return -1;
+		return false;
 	}
 	if (ioctl(md->fd, MVP_SET_AUD_STREAMTYPE, 0) < 0) {
 		ERROR("Error setting audio streamtype: %s\n", strerror(errno));
-		return -1;
+		return false;
 	}
 	if (ioctl(md->fd, MVP_SET_AUD_FORMAT, &mix) < 0) {
 		ERROR("Error setting audio format: %s\n", strerror(errno));
-		return -1;
+		return false;
 	}
 	ioctl(md->fd, MVP_SET_AUD_STC, &stc);
 	if (ioctl(md->fd, MVP_SET_AUD_BYPASS, 1) < 0) {
 		ERROR("Error setting audio streamtype: %s\n", strerror(errno));
-		return -1;
+		return false;
 	}
 #ifdef WORDS_BIGENDIAN
 	mvp_setPcmParams(md, audioFormat->sample_rate, audioFormat->channels,
@@ -213,7 +214,7 @@ static int mvp_openDevice(void *data, struct audio_format *audioFormat)
 			 1, audioFormat->bits);
 #endif
 	md->audio_format = *audioFormat;
-	return 0;
+	return true;
 }
 
 static void mvp_closeDevice(void *data)
@@ -235,7 +236,8 @@ static void mvp_dropBufferedAudio(void *data)
 	}
 }
 
-static int mvp_playAudio(void *data, const char *playChunk, size_t size)
+static bool
+mvp_playAudio(void *data, const char *playChunk, size_t size)
 {
 	MvpData *md = data;
 	ssize_t ret;
@@ -252,12 +254,12 @@ static int mvp_playAudio(void *data, const char *playChunk, size_t size)
 			ERROR("closing mvp PCM device due to write error: "
 			      "%s\n", strerror(errno));
 			mvp_closeDevice(md);
-			return -1;
+			return false;
 		}
 		playChunk += ret;
 		size -= ret;
 	}
-	return 0;
+	return true;
 }
 
 const struct audio_output_plugin mvpPlugin = {
diff --git a/src/output/null_plugin.c b/src/output/null_plugin.c
index ff3a9833c..bef2ff924 100644
--- a/src/output/null_plugin.c
+++ b/src/output/null_plugin.c
@@ -33,13 +33,13 @@ static void *null_initDriver(mpd_unused struct audio_output *audioOutput,
 	return nd;
 }
 
-static int null_openDevice(void *data,
-			   struct audio_format *audio_format)
+static bool
+null_openDevice(void *data, struct audio_format *audio_format)
 {
 	struct null_data *nd = data;
 
 	nd->timer = timer_new(audio_format);
-	return 0;
+	return true;
 }
 
 static void null_closeDevice(void *data)
@@ -52,8 +52,8 @@ static void null_closeDevice(void *data)
 	}
 }
 
-static int null_playAudio(void *data,
-			  mpd_unused const char *playChunk, size_t size)
+static bool
+null_playAudio(void *data, mpd_unused const char *playChunk, size_t size)
 {
 	struct null_data *nd = data;
 	Timer *timer = nd->timer;
@@ -65,7 +65,7 @@ static int null_playAudio(void *data,
 
 	timer_add(timer, size);
 
-	return 0;
+	return true;
 }
 
 static void null_dropBufferedAudio(void *data)
diff --git a/src/output/oss_plugin.c b/src/output/oss_plugin.c
index 2992368d9..26bc1b3aa 100644
--- a/src/output/oss_plugin.c
+++ b/src/output/oss_plugin.c
@@ -322,20 +322,20 @@ static int oss_statDevice(const char *device, int *stErrno)
 
 static const char *default_devices[] = { "/dev/sound/dsp", "/dev/dsp" };
 
-static int oss_testDefault(void)
+static bool oss_testDefault(void)
 {
 	int fd, i;
 
 	for (i = ARRAY_SIZE(default_devices); --i >= 0; ) {
 		if ((fd = open(default_devices[i], O_WRONLY)) >= 0) {
 			xclose(fd);
-			return 0;
+			return true;
 		}
 		WARNING("Error opening OSS device \"%s\": %s\n",
 		        default_devices[i], strerror(errno));
 	}
 
-	return -1;
+	return false;
 }
 
 static void *oss_open_default(ConfigParam *param)
@@ -438,7 +438,7 @@ static void oss_close(OssData * od)
 	od->fd = -1;
 }
 
-static int oss_open(OssData *od)
+static bool oss_open(OssData *od)
 {
 	int tmp;
 
@@ -486,23 +486,24 @@ static int oss_open(OssData *od)
 		goto fail;
 	}
 
-	return 0;
+	return true;
 
 fail:
 	oss_close(od);
-	return -1;
+	return false;
 }
 
-static int oss_openDevice(void *data,
-			  struct audio_format *audioFormat)
+static bool
+oss_openDevice(void *data, struct audio_format *audioFormat)
 {
-	int ret;
+	bool ret;
 	OssData *od = data;
 
 	od->audio_format = *audioFormat;
 
-	if ((ret = oss_open(od)) < 0)
-		return ret;
+	ret = oss_open(od);
+	if (!ret)
+		return false;
 
 	*audioFormat = od->audio_format;
 
@@ -531,15 +532,15 @@ static void oss_dropBufferedAudio(void *data)
 	}
 }
 
-static int oss_playAudio(void *data,
-			 const char *playChunk, size_t size)
+static bool
+oss_playAudio(void *data, const char *playChunk, size_t size)
 {
 	OssData *od = data;
 	ssize_t ret;
 
 	/* reopen the device since it was closed by dropBufferedAudio */
 	if (od->fd < 0 && oss_open(od) < 0)
-		return -1;
+		return false;
 
 	while (size > 0) {
 		ret = write(od->fd, playChunk, size);
@@ -549,13 +550,13 @@ static int oss_playAudio(void *data,
 			ERROR("closing oss device \"%s\" due to write error: "
 			      "%s\n", od->device, strerror(errno));
 			oss_closeDevice(od);
-			return -1;
+			return false;
 		}
 		playChunk += ret;
 		size -= ret;
 	}
 
-	return 0;
+	return true;
 }
 
 const struct audio_output_plugin ossPlugin = {
diff --git a/src/output/osx_plugin.c b/src/output/osx_plugin.c
index a3f67fa68..a31a6e736 100644
--- a/src/output/osx_plugin.c
+++ b/src/output/osx_plugin.c
@@ -49,7 +49,7 @@ static OsxData *newOsxData()
 	return ret;
 }
 
-static int osx_testDefault()
+static bool osx_testDefault()
 {
 	/*AudioUnit au;
 	   ComponentDescription desc;
@@ -74,7 +74,7 @@ static int osx_testDefault()
 
 	   CloseComponent(au); */
 
-	return 0;
+	return true;
 }
 
 static int osx_initDriver(struct audio_output *audioOutput,
@@ -212,8 +212,9 @@ static OSStatus osx_render(void *vdata,
 	return 0;
 }
 
-static int osx_openDevice(struct audio_output *audioOutput,
-			  struct audio_format *audioFormat)
+static bool
+osx_openDevice(struct audio_output *audioOutput,
+	       struct audio_format *audioFormat)
 {
 	OsxData *od = (OsxData *) audioOutput->data;
 	ComponentDescription desc;
@@ -230,18 +231,18 @@ static int osx_openDevice(struct audio_output *audioOutput,
 	comp = FindNextComponent(NULL, &desc);
 	if (comp == 0) {
 		ERROR("Error finding OS X component\n");
-		return -1;
+		return false;
 	}
 
 	if (OpenAComponent(comp, &od->au) != noErr) {
 		ERROR("Unable to open OS X component\n");
-		return -1;
+		return false;
 	}
 
 	if (AudioUnitInitialize(od->au) != 0) {
 		CloseComponent(od->au);
 		ERROR("Unable to initialize OS X audio unit\n");
-		return -1;
+		return false;
 	}
 
 	callback.inputProc = osx_render;
@@ -253,7 +254,7 @@ static int osx_openDevice(struct audio_output *audioOutput,
 		AudioUnitUninitialize(od->au);
 		CloseComponent(od->au);
 		ERROR("unable to set callback for OS X audio unit\n");
-		return -1;
+		return false;
 	}
 
 	streamDesc.mSampleRate = audioFormat->sample_rate;
@@ -275,7 +276,7 @@ static int osx_openDevice(struct audio_output *audioOutput,
 		AudioUnitUninitialize(od->au);
 		CloseComponent(od->au);
 		ERROR("Unable to set format on OS X device\n");
-		return -1;
+		return false;
 	}
 
 	/* create a buffer of 1s */
@@ -286,11 +287,11 @@ static int osx_openDevice(struct audio_output *audioOutput,
 	od->pos = 0;
 	od->len = 0;
 
-	return 0;
+	return true;
 }
 
-static int osx_play(struct audio_output *audioOutput,
-		    const char *playChunk, size_t size)
+static bool
+osx_play(struct audio_output *audioOutput, const char *playChunk, size_t size)
 {
 	OsxData *od = (OsxData *) audioOutput->data;
 	size_t bytesToCopy;
@@ -304,7 +305,7 @@ static int osx_play(struct audio_output *audioOutput,
 		err = AudioOutputUnitStart(od->au);
 		if (err) {
 			ERROR("unable to start audio output: %i\n", err);
-			return -1;
+			return false;
 		}
 	}
 
@@ -345,7 +346,7 @@ static int osx_play(struct audio_output *audioOutput,
 	pthread_mutex_unlock(&od->mutex);
 
 	/* DEBUG("osx_play: leave\n"); */
-	return 0;
+	return true;
 }
 
 const struct audio_output_plugin osxPlugin = {
diff --git a/src/output/pulse_plugin.c b/src/output/pulse_plugin.c
index 2104fe81e..c6849dbc6 100644
--- a/src/output/pulse_plugin.c
+++ b/src/output/pulse_plugin.c
@@ -86,7 +86,7 @@ static void pulse_finish(void *data)
 	pulse_free_data(pd);
 }
 
-static int pulse_test_default_device(void)
+static bool pulse_test_default_device(void)
 {
 	pa_simple *s;
 	pa_sample_spec ss;
@@ -101,15 +101,15 @@ static int pulse_test_default_device(void)
 	if (!s) {
 		g_message("Cannot connect to default PulseAudio server: %s\n",
 			  pa_strerror(error));
-		return -1;
+		return false;
 	}
 
 	pa_simple_free(s);
 
-	return 0;
+	return true;
 }
 
-static int
+static bool
 pulse_open(void *data, struct audio_format *audio_format)
 {
 	struct pulse_data *pd = data;
@@ -121,7 +121,7 @@ pulse_open(void *data, struct audio_format *audio_format)
 
 	if (pd->num_connect_attempts != 0 &&
 	    (t - pd->last_connect_attempt) < CONN_ATTEMPT_INTERVAL)
-		return -1;
+		return false;
 
 	pd->num_connect_attempts++;
 	pd->last_connect_attempt = t;
@@ -143,7 +143,7 @@ pulse_open(void *data, struct audio_format *audio_format)
 			  "\"%s\" (attempt %i): %s\n",
 			  audio_output_get_name(pd->ao),
 			  pd->num_connect_attempts, pa_strerror(error));
-		return -1;
+		return false;
 	}
 
 	pd->num_connect_attempts = 0;
@@ -154,7 +154,7 @@ pulse_open(void *data, struct audio_format *audio_format)
 		audio_format->bits,
 		audio_format->channels, audio_format->sample_rate);
 
-	return 0;
+	return true;
 }
 
 static void pulse_cancel(void *data)
@@ -179,8 +179,8 @@ static void pulse_close(void *data)
 	}
 }
 
-static int pulse_play(void *data,
-			   const char *playChunk, size_t size)
+static bool
+pulse_play(void *data, const char *playChunk, size_t size)
 {
 	struct pulse_data *pd = data;
 	int error;
@@ -191,10 +191,10 @@ static int pulse_play(void *data,
 			  audio_output_get_name(pd->ao),
 			  pa_strerror(error));
 		pulse_close(pd);
-		return -1;
+		return false;
 	}
 
-	return 0;
+	return true;
 }
 
 const struct audio_output_plugin pulse_plugin = {
diff --git a/src/output/shout_plugin.c b/src/output/shout_plugin.c
index dd909bdae..7bd806d36 100644
--- a/src/output/shout_plugin.c
+++ b/src/output/shout_plugin.c
@@ -354,7 +354,7 @@ static void close_shout_conn(struct shout_data * sd)
 		      shout_get_error(sd->shout_conn));
 	}
 
-	sd->opened = 0;
+	sd->opened = false;
 }
 
 static void my_shout_finish_driver(void *data)
@@ -465,27 +465,27 @@ static int open_shout_conn(void *data)
 	write_page(sd);
 
 	sd->shout_error = 0;
-	sd->opened = 1;
+	sd->opened = true;
 	sd->tag_to_send = 1;
 	sd->conn_attempts = 0;
 
 	return 0;
 }
 
-static int my_shout_open_device(void *data,
+static bool my_shout_open_device(void *data,
 				struct audio_format *audio_format)
 {
 	struct shout_data *sd = (struct shout_data *)data;
 
 	if (!sd->opened && open_shout_conn(sd) < 0)
-		return -1;
+		return false;
 
 	if (sd->timer)
 		timer_free(sd->timer);
 
 	sd->timer = timer_new(audio_format);
 
-	return 0;
+	return true;
 }
 
 static void send_metadata(struct shout_data * sd)
@@ -508,8 +508,8 @@ static void send_metadata(struct shout_data * sd)
 	sd->tag_to_send = 0;
 }
 
-static int my_shout_play(void *data,
-			 const char *chunk, size_t size)
+static bool
+my_shout_play(void *data, const char *chunk, size_t size)
 {
 	struct shout_data *sd = (struct shout_data *)data;
 	int status;
@@ -526,24 +526,24 @@ static int my_shout_play(void *data,
 		status = open_shout_conn(sd);
 		if (status < 0) {
 			my_shout_close_device(sd);
-			return -1;
+			return false;
 		} else if (status > 0) {
 			timer_sync(sd->timer);
-			return 0;
+			return true;
 		}
 	}
 
 	if (sd->encoder->encode_func(sd, chunk, size)) {
 		my_shout_close_device(sd);
-		return -1;
+		return false;
 	}
 
 	if (write_page(sd) < 0) {
 		my_shout_close_device(sd);
-		return -1;
+		return false;
 	}
 
-	return 0;
+	return true;
 }
 
 static void my_shout_pause(void *data)
diff --git a/src/output/shout_plugin.h b/src/output/shout_plugin.h
index ae7d23b03..2ddde22ae 100644
--- a/src/output/shout_plugin.h
+++ b/src/output/shout_plugin.h
@@ -65,7 +65,7 @@ struct shout_data {
 	float quality;
 	int bitrate;
 
-	int opened;
+	bool opened;
 
 	struct tag *tag;
 	int tag_to_send;
diff --git a/src/output_api.c b/src/output_api.c
index 3d3230376..7737fc9d7 100644
--- a/src/output_api.c
+++ b/src/output_api.c
@@ -30,7 +30,7 @@ void audio_output_closed(struct audio_output *ao)
 {
 	assert(ao->open);
 
-	ao->open = 0;
+	ao->open = false;
 }
 
 bool audio_output_is_pending(const struct audio_output *ao)
diff --git a/src/output_api.h b/src/output_api.h
index 11d4620f6..fb0844cd8 100644
--- a/src/output_api.h
+++ b/src/output_api.h
@@ -45,7 +45,7 @@ struct audio_output_plugin {
 	 * Test if this plugin can provide a default output, in case
 	 * none has been configured.  This method is optional.
 	 */
-	int (*test_default_device)(void);
+	bool (*test_default_device)(void);
 
 	/**
 	 * Configure and initialize the device, but do not open it
@@ -73,12 +73,12 @@ struct audio_output_plugin {
 	 * @param audio_format the audio format in which data is going
 	 * to be delivered; may be modified by the plugin
 	 */
-	int (*open)(void *data, struct audio_format *audio_format);
+	bool (*open)(void *data, struct audio_format *audio_format);
 
 	/**
 	 * Play a chunk of audio data.
 	 */
-	int (*play)(void *data, const char *playChunk, size_t size);
+	bool (*play)(void *data, const char *playChunk, size_t size);
 
 	/**
 	 * Pause the device.  If supported, it may perform a special
diff --git a/src/output_control.c b/src/output_control.c
index 15b4eb19c..9193e92eb 100644
--- a/src/output_control.c
+++ b/src/output_control.c
@@ -51,14 +51,15 @@ static void ao_command_async(struct audio_output *ao,
 	notify_signal(&ao->notify);
 }
 
-int audio_output_open(struct audio_output *audioOutput,
-		      const struct audio_format *audioFormat)
+bool
+audio_output_open(struct audio_output *audioOutput,
+		  const struct audio_format *audioFormat)
 {
-	int ret = 0;
+	bool ret = true;
 
 	if (audioOutput->open &&
 	    audio_format_equals(audioFormat, &audioOutput->inAudioFormat)) {
-		return 0;
+		return true;
 	}
 
 	audioOutput->inAudioFormat = *audioFormat;
diff --git a/src/output_control.h b/src/output_control.h
index 275e58aa9..b2b9a6c64 100644
--- a/src/output_control.h
+++ b/src/output_control.h
@@ -22,6 +22,7 @@
 #include "conf.h"
 
 #include <stddef.h>
+#include <stdbool.h>
 
 struct audio_output;
 struct audio_output_plugin;
@@ -29,8 +30,10 @@ struct audio_format;
 struct tag;
 
 int audio_output_init(struct audio_output *, ConfigParam * param);
-int audio_output_open(struct audio_output *audioOutput,
-		      const struct audio_format *audioFormat);
+
+bool
+audio_output_open(struct audio_output *audioOutput,
+		  const struct audio_format *audioFormat);
 
 /**
  * Wakes up the audio output thread.  This is part of a workaround for
diff --git a/src/output_init.c b/src/output_init.c
index ebfbf137e..16b4dfb73 100644
--- a/src/output_init.c
+++ b/src/output_init.c
@@ -67,7 +67,7 @@ int audio_output_init(struct audio_output *ao, ConfigParam * param)
 			if (plugin->test_default_device) {
 				WARNING("Attempting to detect a %s audio "
 					"device\n", plugin->name);
-				if (plugin->test_default_device() == 0) {
+				if (plugin->test_default_device()) {
 					WARNING("Successfully detected a %s "
 						"audio device\n", plugin->name);
 					break;
@@ -85,7 +85,7 @@ int audio_output_init(struct audio_output *ao, ConfigParam * param)
 
 	ao->name = name;
 	ao->plugin = plugin;
-	ao->open = 0;
+	ao->open = false;
 
 	ao->convBuffer = NULL;
 	ao->convBufferLen = 0;
diff --git a/src/output_internal.h b/src/output_internal.h
index fc146546a..d3f650086 100644
--- a/src/output_internal.h
+++ b/src/output_internal.h
@@ -43,7 +43,7 @@ struct audio_output {
 	/**
 	 * Is the device (already) open and functional?
 	 */
-	int open;
+	bool open;
 
 	/**
 	 * The audio_format in which audio data is received from the
@@ -98,9 +98,9 @@ struct audio_output {
 	} args;
 
 	/**
-	 * Result value of the command.  Generally, "0" means success.
+	 * Result value of the command.  true means success.
 	 */
-	int result;
+	bool result;
 };
 
 /**
@@ -109,19 +109,19 @@ struct audio_output {
  */
 extern struct notify audio_output_client_notify;
 
-static inline int
+static inline bool
 audio_output_is_open(const struct audio_output *ao)
 {
 	return ao->open;
 }
 
-static inline int
+static inline bool
 audio_output_command_is_finished(const struct audio_output *ao)
 {
 	return ao->command == AO_COMMAND_NONE;
 }
 
-static inline int
+static inline bool
 audio_output_get_result(const struct audio_output *ao)
 {
 	return ao->result;
diff --git a/src/output_thread.c b/src/output_thread.c
index e2f360d9b..f03520013 100644
--- a/src/output_thread.c
+++ b/src/output_thread.c
@@ -74,7 +74,7 @@ static void ao_pause(struct audio_output *ao)
 	} else {
 		/* pause is not supported - simply close the device */
 		ao->plugin->close(ao->data);
-		ao->open = 0;
+		ao->open = false;
 		ao_command_finished(ao);
 	}
 }
@@ -94,8 +94,8 @@ static void *audio_output_task(void *arg)
 						      &ao->outAudioFormat);
 
 			assert(!ao->open);
-			if (ao->result == 0)
-				ao->open = 1;
+			if (ao->result == true)
+				ao->open = true;
 
 			ao_command_finished(ao);
 			break;
@@ -103,7 +103,7 @@ static void *audio_output_task(void *arg)
 		case AO_COMMAND_CLOSE:
 			assert(ao->open);
 			ao->plugin->close(ao->data);
-			ao->open = 0;
+			ao->open = false;
 			ao_command_finished(ao);
 			break;
 
diff --git a/src/player_thread.c b/src/player_thread.c
index 35796d95d..0275b680a 100644
--- a/src/player_thread.c
+++ b/src/player_thread.c
@@ -156,7 +156,7 @@ static void processDecodeInput(struct player *player)
 			audio_output_pause_all();
 			pc.state = PLAYER_STATE_PAUSE;
 		} else {
-			if (openAudioDevice(NULL) >= 0) {
+			if (openAudioDevice(NULL)) {
 				pc.state = PLAYER_STATE_PLAY;
 			} else {
 				char tmp[MPD_PATH_MAX];
@@ -215,8 +215,7 @@ static int playChunk(ob_chunk * chunk,
 	pcm_volume(chunk->data, chunk->chunkSize,
 		   format, pc.softwareVolume);
 
-	if (playAudio(chunk->data,
-		      chunk->chunkSize) < 0)
+	if (!playAudio(chunk->data, chunk->chunkSize))
 		return -1;
 
 	pc.totalPlayTime += sizeToTime * chunk->chunkSize;
@@ -288,7 +287,7 @@ static void do_play(void)
 			else if (!decoder_is_starting()) {
 				/* the decoder is ready and ok */
 				player.decoder_starting = false;
-				if(openAudioDevice(&(ob.audioFormat))<0) {
+				if (!openAudioDevice(&ob.audioFormat)) {
 					char tmp[MPD_PATH_MAX];
 					assert(dc.next_song == NULL || dc.next_song->url != NULL);
 					pc.errored_song = dc.next_song;
@@ -439,7 +438,7 @@ static void do_play(void)
 			unsigned num_frames = CHUNK_SIZE / frame_size;
 
 			/*DEBUG("waiting for decoded audio, play silence\n");*/
-			if (playAudio(silence, num_frames * frame_size) < 0)
+			if (!playAudio(silence, num_frames * frame_size))
 				break;
 		}
 	}