if no audioOutput specified, we no attempt to detect if there exists a usable oss or alsa device

src/audio.c

@@ -79,7 +79,9 @@ void initAudioDriver() {
 		myAudioDevicesEnabled[i] = 1;
 	}
 
-	while((param = getNextConfigParam(CONF_AUDIO_OUTPUT, param))) {
+	param = getNextConfigParam(CONF_AUDIO_OUTPUT, param);
+
+	do {
 		if(audioOutputArraySize == AUDIO_MAX_DEVICES) {
 			ERROR("only up to 255 audio output devices are "
 					"supported");
@@ -93,12 +95,12 @@ void initAudioDriver() {
 	
 		audioOutputArray[i] = newAudioOutput(param);
 
-		if(!audioOutputArray[i]) {
+		if(!audioOutputArray[i] && param) {
 			ERROR("problems configuring output device defined at "
 					"line %i\n", param->line);
 			exit(EXIT_FAILURE);
 		}
-	}
+	} while((param = getNextConfigParam(CONF_AUDIO_OUTPUT, param)));
 }
 
 void getOutputAudioFormat(AudioFormat * inAudioFormat, 

src/audioOutput.c

@@ -48,13 +48,64 @@ AudioOutput * newAudioOutput(ConfigParam * param) {
 	char * name = NULL;
 	char * format = NULL;
 	char * type = NULL;
-	BlockParam * bp;
+	BlockParam * bp = NULL;
+	AudioOutputPlugin * plugin = NULL;
 
+	if(param) {
 		getBlockParam(AUDIO_OUTPUT_NAME, name, 1);
 		getBlockParam(AUDIO_OUTPUT_TYPE, type, 1);
 
-	if(findInList(audioOutputPluginList, type, &data)) {
-		AudioOutputPlugin * plugin = (AudioOutputPlugin *) data;
+		if(!findInList(audioOutputPluginList, type, &data)) {
+			ERROR("couldn't find audio output plugin for type "
+					"\"%s\" at line %i\n", type, 
+					param->line);
+			exit(EXIT_FAILURE);
+		}
+
+		plugin = (AudioOutputPlugin *) data;
+	
+		if(format) {
+			ret->convertAudioFormat = 1;
+
+			if(0 != parseAudioConfig(&ret->reqAudioFormat, format))
+			{
+	        		ERROR("error parsing format at line %i\n", 
+						bp->line);
+	        		exit(EXIT_FAILURE);
+	        	}
+		}
+	}
+	else {
+		ListNode * node = audioOutputPluginList->firstNode;
+
+		WARNING("No \"%s\" defined in config file\n", 
+				CONF_AUDIO_OUTPUT);
+		WARNING("Attempt to detect audio output device\n");
+
+		while(node) {
+			plugin = (AudioOutputPlugin *) node->data;
+			if(plugin->testDefaultDeviceFunc) {
+				WARNING("Attempting to detect a %s audio "
+						"device\n", plugin->name);
+				if(plugin->testDefaultDeviceFunc() == 0) {
+					WARNING("Successfully detected a %s "
+							"audio device\n",
+							plugin->name);
+					break;
+				}
+			}
+			node = node->nextNode;
+		}
+
+		if(!node) {
+			WARNING("Unable to detect an audio device\n");
+			return NULL;
+		}
+
+		name = "default detected output";
+		type = plugin->name;
+	}
+
 	ret = malloc(sizeof(AudioOutput));
 	ret->name = strdup(name);
 	ret->type = strdup(type);
@@ -75,29 +126,10 @@ AudioOutput * newAudioOutput(ConfigParam * param) {
 	memset(&ret->outAudioFormat, 0, sizeof(AudioFormat));
 	memset(&ret->reqAudioFormat, 0, sizeof(AudioFormat));
 
-		getBlockParam(AUDIO_OUTPUT_FORMAT, format, 0);
-
-		if(format) {
-			ret->convertAudioFormat = 1;
-
-			if(0 != parseAudioConfig(&ret->reqAudioFormat, format))
-			{
-		        	ERROR("error parsing format at line %i\n", 
-						bp->line);
-		        	exit(EXIT_FAILURE);
-		        }
-		}
-
 	if(plugin->initDriverFunc(ret, param) != 0) {
 		free(ret);
 		ret = NULL;
 	}
-	}
-	else {
-		ERROR("couldn't find audio output plugin for type \"%s\" at "
-				"line %i\n", type, param->line);
-		exit(EXIT_FAILURE);
-	}
 
 	return ret;
 }

src/audioOutput.h

@@ -28,6 +28,8 @@
 
 typedef struct _AudioOutput AudioOutput;
 
+typedef int (* AudioOutputTestDefaultDeviceFunc) ();
+
 typedef int (* AudioOutputInitDriverFunc) (AudioOutput * audioOutput, 
 		ConfigParam * param);
 
@@ -71,6 +73,7 @@ struct _AudioOutput {
 typedef struct _AudioOutputPlugin {
 	char * name;
 
+	AudioOutputTestDefaultDeviceFunc testDefaultDeviceFunc;
         AudioOutputInitDriverFunc initDriverFunc;
         AudioOutputFinishDriverFunc finishDriverFunc;
         AudioOutputOpenDeviceFunc openDeviceFunc;

src/audioOutputs/audioOutput_alsa.c

@@ -69,7 +69,10 @@ static void freeAlsaData(AlsaData * ad) {
 }
 
 static int alsa_initDriver(AudioOutput * audioOutput, ConfigParam * param) {
-	BlockParam * bp = getBlockParam(param, "device");
+	BlockParam * bp = NULL;
+
+	if(param) bp = getBlockParam(param, "device");
+
 	AlsaData * ad = newAlsaData();
 	
 	audioOutput->data = ad;
@@ -85,6 +88,23 @@ static void alsa_finishDriver(AudioOutput * audioOutput) {
 	freeAlsaData(ad);
 }
 
+static int alsa_testDefault()
+{
+	snd_pcm_t * handle;
+
+	int ret = snd_pcm_open(&handle, "default", SND_PCM_STREAM_PLAYBACK, 
+					           SND_PCM_NONBLOCK);
+	
+	if(ret) {
+		WARNING("Error opening default alsa device: %s\n",
+				snd_strerror(-ret));
+		return -1;
+	}
+	else snd_pcm_close(handle);
+
+	return 0;
+}
+
 static int alsa_openDevice(AudioOutput * audioOutput) 
 {
 	AlsaData * ad = audioOutput->data;
@@ -313,6 +333,7 @@ static int alsa_playAudio(AudioOutput * audioOutput, char * playChunk,
 AudioOutputPlugin alsaPlugin =
 {
 	"alsa",
+	alsa_testDefault,
 	alsa_initDriver,
 	alsa_finishDriver,
 	alsa_openDevice,
@@ -332,6 +353,7 @@ AudioOutputPlugin alsaPlugin =
 	NULL,
 	NULL,
 	NULL,
+	NULL,
 	NULL /* sendMetadataFunc */
 };
 

src/audioOutputs/audioOutput_ao.c

@@ -237,6 +237,7 @@ static int audioOutputAo_play(AudioOutput * audioOutput, char * playChunk,
 AudioOutputPlugin aoPlugin = 
 {
 	"ao",
+	NULL,
 	audioOutputAo_initDriver,
 	audioOutputAo_finishDriver,
 	audioOutputAo_openDevice,
@@ -259,6 +260,7 @@ AudioOutputPlugin aoPlugin =
 	NULL,
 	NULL,
 	NULL,
+	NULL,
 	NULL
 };
 

src/audioOutputs/audioOutput_oss.c

@@ -291,10 +291,38 @@ static int oss_statDevice(char * device, int * stErrno) {
 	return 0;
 }
 
+static int oss_testDefault() {
+	int fd;
+
+	fd = open("/dev/sound/dsp", O_WRONLY);
+
+	if(fd) {
+		close(fd);
+		return 0;
+	}
+
+	WARNING("Error opening OSS device \"/dev/sound/dsp\": %s\n",
+			strerror(errno));
+
+	fd = open("/dev/dsp", O_WRONLY);
+
+	if(fd) {
+		close(fd);
+		return 0;
+	}
+
+	WARNING("Error opening OSS device \"/dev/dsp\": %s\n",
+			strerror(errno));
+
+	return -1;
+}
+
 static int oss_initDriver(AudioOutput * audioOutput, ConfigParam * param) {
-	BlockParam * bp = getBlockParam(param, "device");
-	OssData * od = newOssData();
+	BlockParam * bp = NULL;
 
+	if(param) bp = getBlockParam(param, "device");
+
+	OssData * od = newOssData();
 	audioOutput->data = od;
 
 	if(!bp) {
@@ -307,8 +335,14 @@ static int oss_initDriver(AudioOutput * audioOutput, ConfigParam * param) {
 		if(ret[0] == 0) od->device = strdup("/dev/sound/dsp");
 		else if(ret[1] == 0) od->device = strdup("/dev/dsp");
 		else {
+			if(param) {
 				ERROR("Error trying to open default OSS device "
 					"specified at line %i\n", param->line);
+			}
+			else {
+				ERROR("Error trying to open default OSS "
+						"device\n");
+			}
 
 			if(ret[0] == ret[1] == OSS_STAT_DOESN_T_EXIST) {
 				ERROR("Neither /dev/dsp nor /dev/sound/dsp "
@@ -501,6 +535,7 @@ static int oss_playAudio(AudioOutput * audioOutput, char * playChunk,
 AudioOutputPlugin ossPlugin =
 {
 	"oss",
+	oss_testDefault,
 	oss_initDriver,
 	oss_finishDriver,
 	oss_openDevice,
@@ -521,6 +556,7 @@ AudioOutputPlugin ossPlugin =
 	NULL,
 	NULL,
 	NULL,
+	NULL,
 	NULL /* sendMetadataFunc */
 };
 

src/audioOutputs/audioOutput_shout.c

@@ -597,6 +597,7 @@ static void myShout_setTag(AudioOutput * audioOutput, MpdTag * tag) {
 AudioOutputPlugin shoutPlugin = 
 {
 	"shout",
+	NULL,
 	myShout_initDriver,
 	myShout_finishDriver,
 	myShout_openDevice,
@@ -617,6 +618,7 @@ AudioOutputPlugin shoutPlugin =
 	NULL,
 	NULL,
 	NULL,
+	NULL,
 	NULL
 };
 

src/log.c

@@ -68,9 +68,12 @@ void bufferWarning(char * format, ... ) {
 
 	va_end(arglist);
 }
+
 void flushWarningLog() {
 	char * s;
 
+	DEBUG("flushing warning messages\n");
+
 	if(warningBuffer == NULL) return;
 
 	s = strtok(warningBuffer, "\n");

src/main.c

@@ -357,8 +357,8 @@ void setupLogOutput(Options * options, FILE * out, FILE * err) {
                 }
 
                 myfprintfStdLogMode(out, err);
-                flushWarningLog();
         }
+        flushWarningLog();
 
         /* lets redirect stdin to dev null as a work around for libao bug */
         {