OutputPlugin: pass config_param reference

24 files changed, 159 insertions, 156 deletions

diff --git a/src/ConfigData.hxx b/src/ConfigData.hxx
index 5e13d073c..d6b024b9b 100644
--- a/src/ConfigData.hxx
+++ b/src/ConfigData.hxx
@@ -80,6 +80,15 @@ struct config_param {
 
 	config_param &operator=(const config_param &) = delete;
 
+	/**
+	 * Determine if this is a "null" instance, i.e. an empty
+	 * object that was synthesized and not loaded from a
+	 * configuration file.
+	 */
+	bool IsNull() const {
+		return line == unsigned(-1);
+	}
+
 	gcc_nonnull_all
 	void AddBlockParam(const char *_name, const char *_value,
 			   int _line=-1) {
diff --git a/src/OutputAll.cxx b/src/OutputAll.cxx
index a73afbbb6..2e721efa3 100644
--- a/src/OutputAll.cxx
+++ b/src/OutputAll.cxx
@@ -109,16 +109,23 @@ audio_output_all_init(struct player_control *pc)
 	num_audio_outputs = audio_output_config_count();
 	audio_outputs = g_new(struct audio_output *, num_audio_outputs);
 
+	const config_param empty;
+
 	for (i = 0; i < num_audio_outputs; i++)
 	{
 		unsigned int j;
 
 		param = config_get_next_param(CONF_AUDIO_OUTPUT, param);
+		if (param == nullptr) {
+			/* only allow param to be nullptr if there
+			   just one audio output */
+			assert(i == 0);
+			assert(num_audio_outputs == 1);
 
-		/* only allow param to be NULL if there just one audioOutput */
-		assert(param || (num_audio_outputs == 1));
+			param = &empty;
+		}
 
-		struct audio_output *output = audio_output_new(param, pc, &error);
+		struct audio_output *output = audio_output_new(*param, pc, &error);
 		if (output == NULL) {
 			if (param != NULL)
 				MPD_ERROR("line %i: %s",
diff --git a/src/OutputInit.cxx b/src/OutputInit.cxx
index cef4755c6..4ba33be1d 100644
--- a/src/OutputInit.cxx
+++ b/src/OutputInit.cxx
@@ -75,16 +75,17 @@ audio_output_detect(GError **error)
  * This handles the deprecated options mixer_type (global) and
  * mixer_enabled, if the mixer_type setting is not configured.
  */
+gcc_pure
 static enum mixer_type
-audio_output_mixer_type(const struct config_param *param)
+audio_output_mixer_type(const config_param &param)
 {
 	/* read the local "mixer_type" setting */
-	const char *p = config_get_block_string(param, "mixer_type", NULL);
+	const char *p = param.GetBlockValue("mixer_type");
 	if (p != NULL)
 		return mixer_type_parse(p);
 
 	/* try the local "mixer_enabled" setting next (deprecated) */
-	if (!config_get_block_bool(param, "mixer_enabled", true))
+	if (!param.GetBlockValue("mixer_enabled", true))
 		return MIXER_TYPE_NONE;
 
 	/* fall back to the global "mixer_type" setting (also
@@ -95,7 +96,7 @@ audio_output_mixer_type(const struct config_param *param)
 
 static Mixer *
 audio_output_load_mixer(struct audio_output *ao,
-			const struct config_param *param,
+			const config_param &param,
 			const struct mixer_plugin *plugin,
 			Filter &filter_chain,
 			GError **error_r)
@@ -111,7 +112,7 @@ audio_output_load_mixer(struct audio_output *ao,
 		if (plugin == NULL)
 			return NULL;
 
-		return mixer_new(plugin, ao, param, error_r);
+		return mixer_new(plugin, ao, &param, error_r);
 
 	case MIXER_TYPE_SOFTWARE:
 		mixer = mixer_new(&software_mixer_plugin, NULL, NULL, NULL);
@@ -129,7 +130,7 @@ audio_output_load_mixer(struct audio_output *ao,
 bool
 ao_base_init(struct audio_output *ao,
 	     const struct audio_output_plugin *plugin,
-	     const struct config_param *param, GError **error_r)
+	     const config_param &param, GError **error_r)
 {
 	assert(ao != NULL);
 	assert(plugin != NULL);
@@ -140,19 +141,15 @@ ao_base_init(struct audio_output *ao,
 
 	GError *error = NULL;
 
-	if (param) {
-		const char *p;
-
-		ao->name = config_get_block_string(param, AUDIO_OUTPUT_NAME,
-						   NULL);
+	if (!param.IsNull()) {
+		ao->name = param.GetBlockValue(AUDIO_OUTPUT_NAME);
 		if (ao->name == NULL) {
 			g_set_error(error_r, output_quark(), 0,
 				    "Missing \"name\" configuration");
 			return false;
 		}
 
-		p = config_get_block_string(param, AUDIO_OUTPUT_FORMAT,
-						 NULL);
+		const char *p = param.GetBlockValue(AUDIO_OUTPUT_FORMAT);
 		if (p != NULL) {
 			bool success =
 				audio_format_parse(ao->config_audio_format,
@@ -168,9 +165,9 @@ ao_base_init(struct audio_output *ao,
 	}
 
 	ao->plugin = plugin;
-	ao->tags = config_get_block_bool(param, "tags", true);
-	ao->always_on = config_get_block_bool(param, "always_on", false);
-	ao->enabled = config_get_block_bool(param, "enabled", true);
+	ao->tags = param.GetBlockValue("tags", true);
+	ao->always_on = param.GetBlockValue("always_on", false);
+	ao->enabled = param.GetBlockValue("enabled", true);
 	ao->really_enabled = false;
 	ao->open = false;
 	ao->pause = false;
@@ -194,7 +191,7 @@ ao_base_init(struct audio_output *ao,
 	}
 
 	filter_chain_parse(*ao->filter,
-	                   config_get_block_string(param, AUDIO_FILTERS, ""),
+			   param.GetBlockValue(AUDIO_FILTERS, ""),
 	                   &error
 	);
 
@@ -219,25 +216,24 @@ ao_base_init(struct audio_output *ao,
 }
 
 static bool
-audio_output_setup(struct audio_output *ao, const struct config_param *param,
+audio_output_setup(struct audio_output *ao, const config_param &param,
 		   GError **error_r)
 {
 
 	/* create the replay_gain filter */
 
 	const char *replay_gain_handler =
-		config_get_block_string(param, "replay_gain_handler",
-					"software");
+		param.GetBlockValue("replay_gain_handler", "software");
 
 	if (strcmp(replay_gain_handler, "none") != 0) {
 		ao->replay_gain_filter = filter_new(&replay_gain_filter_plugin,
-						    param, NULL);
+						    &param, NULL);
 		assert(ao->replay_gain_filter != NULL);
 
 		ao->replay_gain_serial = 0;
 
 		ao->other_replay_gain_filter = filter_new(&replay_gain_filter_plugin,
-							  param, NULL);
+							  &param, NULL);
 		assert(ao->other_replay_gain_filter != NULL);
 
 		ao->other_replay_gain_serial = 0;
@@ -284,16 +280,16 @@ audio_output_setup(struct audio_output *ao, const struct config_param *param,
 }
 
 struct audio_output *
-audio_output_new(const struct config_param *param,
+audio_output_new(const config_param &param,
 		 struct player_control *pc,
 		 GError **error_r)
 {
 	const struct audio_output_plugin *plugin;
 
-	if (param) {
+	if (!param.IsNull()) {
 		const char *p;
 
-		p = config_get_block_string(param, AUDIO_OUTPUT_TYPE, NULL);
+		p = param.GetBlockValue(AUDIO_OUTPUT_TYPE);
 		if (p == NULL) {
 			g_set_error(error_r, output_quark(), 0,
 				    "Missing \"type\" configuration");
diff --git a/src/OutputInternal.hxx b/src/OutputInternal.hxx
index b23ec95b6..20e48279f 100644
--- a/src/OutputInternal.hxx
+++ b/src/OutputInternal.hxx
@@ -261,14 +261,14 @@ audio_output_command_is_finished(const struct audio_output *ao)
 }
 
 struct audio_output *
-audio_output_new(const struct config_param *param,
+audio_output_new(const config_param &param,
 		 struct player_control *pc,
 		 GError **error_r);
 
 bool
 ao_base_init(struct audio_output *ao,
 	     const struct audio_output_plugin *plugin,
-	     const struct config_param *param, GError **error_r);
+	     const config_param &param, GError **error_r);
 
 void
 ao_base_finish(struct audio_output *ao);
diff --git a/src/OutputPlugin.cxx b/src/OutputPlugin.cxx
index 00901aad2..7ac97cab9 100644
--- a/src/OutputPlugin.cxx
+++ b/src/OutputPlugin.cxx
@@ -23,7 +23,7 @@
 
 struct audio_output *
 ao_plugin_init(const struct audio_output_plugin *plugin,
-	       const struct config_param *param,
+	       const config_param &param,
 	       GError **error)
 {
 	assert(plugin != NULL);
diff --git a/src/OutputPlugin.hxx b/src/OutputPlugin.hxx
index 4e19ffcfb..5be476b68 100644
--- a/src/OutputPlugin.hxx
+++ b/src/OutputPlugin.hxx
@@ -55,7 +55,7 @@ struct audio_output_plugin {
 	 * @return NULL on error, or an opaque pointer to the plugin's
 	 * data
 	 */
-	struct audio_output *(*init)(const struct config_param *param,
+	struct audio_output *(*init)(const config_param &param,
 				     GError **error);
 
 	/**
@@ -168,7 +168,7 @@ ao_plugin_test_default_device(const struct audio_output_plugin *plugin)
 gcc_malloc
 struct audio_output *
 ao_plugin_init(const struct audio_output_plugin *plugin,
-	       const struct config_param *param,
+	       const config_param &param,
 	       GError **error);
 
 void
diff --git a/src/output/AlsaOutputPlugin.cxx b/src/output/AlsaOutputPlugin.cxx
index 0e70babb6..b26a3e1df 100644
--- a/src/output/AlsaOutputPlugin.cxx
+++ b/src/output/AlsaOutputPlugin.cxx
@@ -37,9 +37,7 @@
 
 static const char default_device[] = "default";
 
-enum {
-	MPD_ALSA_BUFFER_TIME_US = 500000,
-};
+static constexpr unsigned MPD_ALSA_BUFFER_TIME_US = 500000;
 
 #define MPD_ALSA_RETRY_NR 5
 
@@ -117,7 +115,7 @@ struct AlsaOutput {
 	AlsaOutput():mode(0), writei(snd_pcm_writei) {
 	}
 
-	bool Init(const config_param *param, GError **error_r) {
+	bool Init(const config_param &param, GError **error_r) {
 		return ao_base_init(&base, &alsa_output_plugin,
 				    param, error_r);
 	}
@@ -143,36 +141,36 @@ alsa_device(const AlsaOutput *ad)
 }
 
 static void
-alsa_configure(AlsaOutput *ad, const struct config_param *param)
+alsa_configure(AlsaOutput *ad, const config_param &param)
 {
-	ad->device = config_get_block_string(param, "device", "");
+	ad->device = param.GetBlockValue("device", "");
 
-	ad->use_mmap = config_get_block_bool(param, "use_mmap", false);
+	ad->use_mmap = param.GetBlockValue("use_mmap", false);
 
-	ad->dsd_usb = config_get_block_bool(param, "dsd_usb", false);
+	ad->dsd_usb = param.GetBlockValue("dsd_usb", false);
 
-	ad->buffer_time = config_get_block_unsigned(param, "buffer_time",
-			MPD_ALSA_BUFFER_TIME_US);
-	ad->period_time = config_get_block_unsigned(param, "period_time", 0);
+	ad->buffer_time = param.GetBlockValue("buffer_time",
+					      MPD_ALSA_BUFFER_TIME_US);
+	ad->period_time = param.GetBlockValue("period_time", 0u);
 
 #ifdef SND_PCM_NO_AUTO_RESAMPLE
-	if (!config_get_block_bool(param, "auto_resample", true))
+	if (!param.GetBlockValue("auto_resample", true))
 		ad->mode |= SND_PCM_NO_AUTO_RESAMPLE;
 #endif
 
 #ifdef SND_PCM_NO_AUTO_CHANNELS
-	if (!config_get_block_bool(param, "auto_channels", true))
+	if (!param.GetBlockValue("auto_channels", true))
 		ad->mode |= SND_PCM_NO_AUTO_CHANNELS;
 #endif
 
 #ifdef SND_PCM_NO_AUTO_FORMAT
-	if (!config_get_block_bool(param, "auto_format", true))
+	if (!param.GetBlockValue("auto_format", true))
 		ad->mode |= SND_PCM_NO_AUTO_FORMAT;
 #endif
 }
 
 static struct audio_output *
-alsa_init(const struct config_param *param, GError **error_r)
+alsa_init(const config_param &param, GError **error_r)
 {
 	AlsaOutput *ad = new AlsaOutput();
 
diff --git a/src/output/AoOutputPlugin.cxx b/src/output/AoOutputPlugin.cxx
index d25a30973..db7b9a360 100644
--- a/src/output/AoOutputPlugin.cxx
+++ b/src/output/AoOutputPlugin.cxx
@@ -42,7 +42,7 @@ struct AoOutput {
 	ao_option *options;
 	ao_device *device;
 
-	bool Initialize(const config_param *param, GError **error_r) {
+	bool Initialize(const config_param &param, GError **error_r) {
 		return ao_base_init(&base, &ao_output_plugin, param,
 				    error_r);
 	}
@@ -51,7 +51,7 @@ struct AoOutput {
 		ao_base_finish(&base);
 	}
 
-	bool Configure(const config_param *param, GError **error_r);
+	bool Configure(const config_param &param, GError **error_r);
 };
 
 static inline GQuark
@@ -95,20 +95,20 @@ ao_output_error(GError **error_r)
 }
 
 inline bool
-AoOutput::Configure(const config_param *param, GError **error_r)
+AoOutput::Configure(const config_param &param, GError **error_r)
 {
 	const char *value;
 
 	options = nullptr;
 
-	write_size = config_get_block_unsigned(param, "write_size", 1024);
+	write_size = param.GetBlockValue("write_size", 1024u);
 
 	if (ao_output_ref == 0) {
 		ao_initialize();
 	}
 	ao_output_ref++;
 
-	value = config_get_block_string(param, "driver", "default");
+	value = param.GetBlockValue("driver", "default");
 	if (0 == strcmp(value, "default"))
 		driver = ao_default_driver_id();
 	else
@@ -129,9 +129,9 @@ AoOutput::Configure(const config_param *param, GError **error_r)
 	}
 
 	g_debug("using ao driver \"%s\" for \"%s\"\n", ai->short_name,
-		config_get_block_string(param, "name", nullptr));
+		param.GetBlockValue("name", nullptr));
 
-	value = config_get_block_string(param, "options", nullptr);
+	value = param.GetBlockValue("options", nullptr);
 	if (value != nullptr) {
 		gchar **_options = g_strsplit(value, ";", 0);
 
@@ -158,7 +158,7 @@ AoOutput::Configure(const config_param *param, GError **error_r)
 }
 
 static struct audio_output *
-ao_output_init(const config_param *param, GError **error_r)
+ao_output_init(const config_param &param, GError **error_r)
 {
 	AoOutput *ad = new AoOutput();
 
diff --git a/src/output/FifoOutputPlugin.cxx b/src/output/FifoOutputPlugin.cxx
index a0d07c702..50062988c 100644
--- a/src/output/FifoOutputPlugin.cxx
+++ b/src/output/FifoOutputPlugin.cxx
@@ -53,7 +53,7 @@ struct FifoOutput {
 		g_free(path);
 	}
 
-	bool Initialize(const config_param *param, GError **error_r) {
+	bool Initialize(const config_param &param, GError **error_r) {
 		return ao_base_init(&base, &fifo_output_plugin, param,
 				    error_r);
 	}
@@ -186,10 +186,10 @@ fifo_open(FifoOutput *fd, GError **error_r)
 }
 
 static struct audio_output *
-fifo_output_init(const config_param *param, GError **error_r)
+fifo_output_init(const config_param &param, GError **error_r)
 {
 	GError *error = nullptr;
-	char *path = config_dup_block_path(param, "path", &error);
+	char *path = param.DupBlockPath("path", &error);
 	if (!path) {
 		if (error != nullptr)
 			g_propagate_error(error_r, error);
diff --git a/src/output/HttpdInternal.hxx b/src/output/HttpdInternal.hxx
index 8bc0c130e..e8a37e033 100644
--- a/src/output/HttpdInternal.hxx
+++ b/src/output/HttpdInternal.hxx
@@ -123,7 +123,7 @@ struct HttpdOutput final : private ServerSocket {
 	HttpdOutput(EventLoop &_loop);
 	~HttpdOutput();
 
-	bool Configure(const config_param *param, GError **error_r);
+	bool Configure(const config_param &param, GError **error_r);
 
 	bool Bind(GError **error_r);
 	void Unbind();
diff --git a/src/output/HttpdOutputPlugin.cxx b/src/output/HttpdOutputPlugin.cxx
index 462dd3429..21774bac9 100644
--- a/src/output/HttpdOutputPlugin.cxx
+++ b/src/output/HttpdOutputPlugin.cxx
@@ -91,18 +91,17 @@ HttpdOutput::Unbind()
 }
 
 inline bool
-HttpdOutput::Configure(const config_param *param, GError **error_r)
+HttpdOutput::Configure(const config_param &param, GError **error_r)
 {
 	/* read configuration */
-	name = config_get_block_string(param, "name", "Set name in config");
-	genre = config_get_block_string(param, "genre", "Set genre in config");
-	website = config_get_block_string(param, "website",
-					  "Set website in config");
+	name = param.GetBlockValue("name", "Set name in config");
+	genre = param.GetBlockValue("genre", "Set genre in config");
+	website = param.GetBlockValue("website", "Set website in config");
 
-	guint port = config_get_block_unsigned(param, "port", 8000);
+	guint port = param.GetBlockValue("port", 8000u);
 
 	const char *encoder_name =
-		config_get_block_string(param, "encoder", "vorbis");
+		param.GetBlockValue("encoder", "vorbis");
 	const auto encoder_plugin = encoder_plugin_get(encoder_name);
 	if (encoder_plugin == NULL) {
 		g_set_error(error_r, httpd_output_quark(), 0,
@@ -110,12 +109,11 @@ HttpdOutput::Configure(const config_param *param, GError **error_r)
 		return false;
 	}
 
-	clients_max = config_get_block_unsigned(param,"max_clients", 0);
+	clients_max = param.GetBlockValue("max_clients", 0u);
 
 	/* set up bind_to_address */
 
-	const char *bind_to_address =
-		config_get_block_string(param, "bind_to_address", NULL);
+	const char *bind_to_address = param.GetBlockValue("bind_to_address");
 	bool success = bind_to_address != NULL &&
 		strcmp(bind_to_address, "any") != 0
 		? AddHost(bind_to_address, port, error_r)
@@ -125,7 +123,7 @@ HttpdOutput::Configure(const config_param *param, GError **error_r)
 
 	/* initialize encoder */
 
-	encoder = encoder_init(*encoder_plugin, param, error_r);
+	encoder = encoder_init(*encoder_plugin, &param, error_r);
 	if (encoder == nullptr)
 		return false;
 
@@ -138,7 +136,7 @@ HttpdOutput::Configure(const config_param *param, GError **error_r)
 }
 
 static struct audio_output *
-httpd_output_init(const struct config_param *param,
+httpd_output_init(const struct config_param &param,
 		  GError **error_r)
 {
 	HttpdOutput *httpd = new HttpdOutput(*main_loop);
diff --git a/src/output/JackOutputPlugin.cxx b/src/output/JackOutputPlugin.cxx
index 6c9ee9335..241857d82 100644
--- a/src/output/JackOutputPlugin.cxx
+++ b/src/output/JackOutputPlugin.cxx
@@ -82,7 +82,7 @@ struct JackOutput {
 	 */
 	bool pause;
 
-	bool Initialize(const config_param *param, GError **error_r) {
+	bool Initialize(const config_param &param, GError **error_r) {
 		return ao_base_init(&base, &jack_output_plugin, param,
 				    error_r);
 	}
@@ -323,7 +323,7 @@ parse_port_list(int line, const char *source, char **dest, GError **error_r)
 }
 
 static struct audio_output *
-mpd_jack_init(const config_param *param, GError **error_r)
+mpd_jack_init(const config_param &param, GError **error_r)
 {
 	JackOutput *jd = new JackOutput();
 
@@ -336,7 +336,7 @@ mpd_jack_init(const config_param *param, GError **error_r)
 
 	jd->options = JackNullOption;
 
-	jd->name = config_get_block_string(param, "client_name", nullptr);
+	jd->name = param.GetBlockValue("client_name", nullptr);
 	if (jd->name != nullptr)
 		jd->options = jack_options_t(jd->options | JackUseExactName);
 	else
@@ -344,35 +344,35 @@ mpd_jack_init(const config_param *param, GError **error_r)
 		   care about the JackUseExactName option */
 		jd->name = "Music Player Daemon";
 
-	jd->server_name = config_get_block_string(param, "server_name", nullptr);
+	jd->server_name = param.GetBlockValue("server_name", nullptr);
 	if (jd->server_name != nullptr)
 		jd->options = jack_options_t(jd->options | JackServerName);
 
-	if (!config_get_block_bool(param, "autostart", false))
+	if (!param.GetBlockValue("autostart", false))
 		jd->options = jack_options_t(jd->options | JackNoStartServer);
 
 	/* configure the source ports */
 
-	value = config_get_block_string(param, "source_ports", "left,right");
-	jd->num_source_ports = parse_port_list(param->line, value,
+	value = param.GetBlockValue("source_ports", "left,right");
+	jd->num_source_ports = parse_port_list(param.line, value,
 					       jd->source_ports, error_r);
 	if (jd->num_source_ports == 0)
 		return nullptr;
 
 	/* configure the destination ports */
 
-	value = config_get_block_string(param, "destination_ports", nullptr);
+	value = param.GetBlockValue("destination_ports", nullptr);
 	if (value == nullptr) {
 		/* compatibility with MPD < 0.16 */
-		value = config_get_block_string(param, "ports", nullptr);
+		value = param.GetBlockValue("ports", nullptr);
 		if (value != nullptr)
 			g_warning("deprecated option 'ports' in line %d",
-				  param->line);
+				  param.line);
 	}
 
 	if (value != nullptr) {
 		jd->num_destination_ports =
-			parse_port_list(param->line, value,
+			parse_port_list(param.line, value,
 					jd->destination_ports, error_r);
 		if (jd->num_destination_ports == 0)
 			return nullptr;
@@ -385,10 +385,9 @@ mpd_jack_init(const config_param *param, GError **error_r)
 		g_warning("number of source ports (%u) mismatches the "
 			  "number of destination ports (%u) in line %d",
 			  jd->num_source_ports, jd->num_destination_ports,
-			  param->line);
+			  param.line);
 
-	jd->ringbuffer_size =
-		config_get_block_unsigned(param, "ringbuffer_size", 32768);
+	jd->ringbuffer_size = param.GetBlockValue("ringbuffer_size", 32768u);
 
 	jack_set_error_function(mpd_jack_error);
 
diff --git a/src/output/NullOutputPlugin.cxx b/src/output/NullOutputPlugin.cxx
index 814a9d2e2..0ce32fbda 100644
--- a/src/output/NullOutputPlugin.cxx
+++ b/src/output/NullOutputPlugin.cxx
@@ -31,7 +31,7 @@ struct NullOutput {
 
 	Timer *timer;
 
-	bool Initialize(const config_param *param, GError **error_r) {
+	bool Initialize(const config_param &param, GError **error_r) {
 		return ao_base_init(&base, &null_output_plugin, param,
 				    error_r);
 	}
@@ -42,7 +42,7 @@ struct NullOutput {
 };
 
 static struct audio_output *
-null_init(const config_param *param, GError **error_r)
+null_init(const config_param &param, GError **error_r)
 {
 	NullOutput *nd = new NullOutput();
 
@@ -51,7 +51,7 @@ null_init(const config_param *param, GError **error_r)
 		return nullptr;
 	}
 
-	nd->sync = config_get_block_bool(param, "sync", true);
+	nd->sync = param.GetBlockValue("sync", true);
 
 	return &nd->base;
 }
diff --git a/src/output/OSXOutputPlugin.cxx b/src/output/OSXOutputPlugin.cxx
index afe8e064d..6e42b2518 100644
--- a/src/output/OSXOutputPlugin.cxx
+++ b/src/output/OSXOutputPlugin.cxx
@@ -65,9 +65,9 @@ osx_output_test_default_device(void)
 }
 
 static void
-osx_output_configure(OSXOutput *oo, const struct config_param *param)
+osx_output_configure(OSXOutput *oo, const config_param &param)
 {
-	const char *device = config_get_block_string(param, "device", NULL);
+	const char *device = param.GetBlockValue("device");
 
 	if (device == NULL || 0 == strcmp(device, "default")) {
 		oo->component_subtype = kAudioUnitSubType_DefaultOutput;
@@ -85,7 +85,7 @@ osx_output_configure(OSXOutput *oo, const struct config_param *param)
 }
 
 static struct audio_output *
-osx_output_init(const struct config_param *param, GError **error_r)
+osx_output_init(const config_param &param, GError **error_r)
 {
 	OSXOutput *oo = new OSXOutput();
 	if (!ao_base_init(&oo->base, &osx_output_plugin, param, error_r)) {
diff --git a/src/output/OpenALOutputPlugin.cxx b/src/output/OpenALOutputPlugin.cxx
index 81c75f6c4..1864052fa 100644
--- a/src/output/OpenALOutputPlugin.cxx
+++ b/src/output/OpenALOutputPlugin.cxx
@@ -49,7 +49,7 @@ struct OpenALOutput {
 	ALenum format;
 	ALuint frequency;
 
-	bool Initialize(const config_param *param, GError **error_r) {
+	bool Initialize(const config_param &param, GError **error_r) {
 		return ao_base_init(&base, &openal_output_plugin, param,
 				    error_r);
 	}
@@ -140,10 +140,9 @@ openal_setup_context(OpenALOutput *od,
 }
 
 static struct audio_output *
-openal_init(const config_param *param, GError **error_r)
+openal_init(const config_param &param, GError **error_r)
 {
-	const char *device_name = config_get_block_string(param, "device", nullptr);
-
+	const char *device_name = param.GetBlockValue("device");
 	if (device_name == nullptr) {
 		device_name = alcGetString(nullptr, ALC_DEFAULT_DEVICE_SPECIFIER);
 	}
diff --git a/src/output/OssOutputPlugin.cxx b/src/output/OssOutputPlugin.cxx
index 49b02386b..2ef0edd67 100644
--- a/src/output/OssOutputPlugin.cxx
+++ b/src/output/OssOutputPlugin.cxx
@@ -80,7 +80,7 @@ struct OssOutput {
 
 	OssOutput():fd(-1), device(nullptr) {}
 
-	bool Initialize(const config_param *param, GError **error_r) {
+	bool Initialize(const config_param &param, GError **error_r) {
 		return ao_base_init(&base, &oss_output_plugin, param,
 				    error_r);
 	}
@@ -160,11 +160,12 @@ oss_open_default(GError **error)
 	int err[G_N_ELEMENTS(default_devices)];
 	enum oss_stat ret[G_N_ELEMENTS(default_devices)];
 
+	const config_param empty;
 	for (int i = G_N_ELEMENTS(default_devices); --i >= 0; ) {
 		ret[i] = oss_stat_device(default_devices[i], &err[i]);
 		if (ret[i] == OSS_STAT_NO_ERROR) {
 			OssOutput *od = new OssOutput();
-			if (!od->Initialize(nullptr, error)) {
+			if (!od->Initialize(empty, error)) {
 				delete od;
 				return NULL;
 			}
@@ -201,9 +202,9 @@ oss_open_default(GError **error)
 }
 
 static struct audio_output *
-oss_output_init(const config_param *param, GError **error_r)
+oss_output_init(const config_param &param, GError **error_r)
 {
-	const char *device = config_get_block_string(param, "device", NULL);
+	const char *device = param.GetBlockValue("device");
 	if (device != NULL) {
 		OssOutput *od = new OssOutput();
 		if (!od->Initialize(param, error_r)) {
diff --git a/src/output/PipeOutputPlugin.cxx b/src/output/PipeOutputPlugin.cxx
index f76dd04c1..f485f1554 100644
--- a/src/output/PipeOutputPlugin.cxx
+++ b/src/output/PipeOutputPlugin.cxx
@@ -30,7 +30,7 @@ struct PipeOutput {
 	char *cmd;
 	FILE *fh;
 
-	bool Initialize(const config_param *param, GError **error_r) {
+	bool Initialize(const config_param &param, GError **error_r) {
 		return ao_base_init(&base, &pipe_output_plugin, param,
 				    error_r);
 	}
@@ -39,7 +39,7 @@ struct PipeOutput {
 		ao_base_finish(&base);
 	}
 
-	bool Configure(const config_param *param, GError **error_r);
+	bool Configure(const config_param &param, GError **error_r);
 };
 
 /**
@@ -52,9 +52,9 @@ pipe_output_quark(void)
 }
 
 inline bool
-PipeOutput::Configure(const config_param *param, GError **error_r)
+PipeOutput::Configure(const config_param &param, GError **error_r)
 {
-	cmd = config_dup_block_string(param, "command", nullptr);
+	cmd = param.DupBlockString("command");
 	if (cmd == nullptr) {
 		g_set_error(error_r, pipe_output_quark(), 0,
 			    "No \"command\" parameter specified");
@@ -65,7 +65,7 @@ PipeOutput::Configure(const config_param *param, GError **error_r)
 }
 
 static struct audio_output *
-pipe_output_init(const config_param *param, GError **error_r)
+pipe_output_init(const config_param &param, GError **error_r)
 {
 	PipeOutput *pd = new PipeOutput();
 
diff --git a/src/output/PulseOutputPlugin.cxx b/src/output/PulseOutputPlugin.cxx
index 65526c8fb..f59c8d76e 100644
--- a/src/output/PulseOutputPlugin.cxx
+++ b/src/output/PulseOutputPlugin.cxx
@@ -344,7 +344,7 @@ pulse_output_setup_context(PulseOutput *po, GError **error_r)
 }
 
 static struct audio_output *
-pulse_output_init(const struct config_param *param, GError **error_r)
+pulse_output_init(const config_param &param, GError **error_r)
 {
 	PulseOutput *po;
 
@@ -356,9 +356,9 @@ pulse_output_init(const struct config_param *param, GError **error_r)
 		return nullptr;
 	}
 
-	po->name = config_get_block_string(param, "name", "mpd_pulse");
-	po->server = config_get_block_string(param, "server", nullptr);
-	po->sink = config_get_block_string(param, "sink", nullptr);
+	po->name = param.GetBlockValue("name", "mpd_pulse");
+	po->server = param.GetBlockValue("server");
+	po->sink = param.GetBlockValue("sink");
 
 	po->mixer = nullptr;
 	po->mainloop = nullptr;
@@ -923,10 +923,10 @@ pulse_output_pause(struct audio_output *ao)
 static bool
 pulse_output_test_default_device(void)
 {
-	PulseOutput *po;
 	bool success;
 
-	po = (PulseOutput *)pulse_output_init(nullptr, nullptr);
+	const config_param empty;
+	PulseOutput *po = (PulseOutput *)pulse_output_init(empty, nullptr);
 	if (po == nullptr)
 		return false;
 
diff --git a/src/output/RecorderOutputPlugin.cxx b/src/output/RecorderOutputPlugin.cxx
index 2e77463f0..8da6d88f2 100644
--- a/src/output/RecorderOutputPlugin.cxx
+++ b/src/output/RecorderOutputPlugin.cxx
@@ -57,7 +57,7 @@ struct RecorderOutput {
 	 */
 	char buffer[32768];
 
-	bool Initialize(const config_param *param, GError **error_r) {
+	bool Initialize(const config_param &param, GError **error_r) {
 		return ao_base_init(&base, &recorder_output_plugin, param,
 				    error_r);
 	}
@@ -66,7 +66,7 @@ struct RecorderOutput {
 		ao_base_finish(&base);
 	}
 
-	bool Configure(const config_param *param, GError **error_r);
+	bool Configure(const config_param &param, GError **error_r);
 
 	bool WriteToFile(const void *data, size_t length, GError **error_r);
 
@@ -86,12 +86,12 @@ recorder_output_quark(void)
 }
 
 inline bool
-RecorderOutput::Configure(const config_param *param, GError **error_r)
+RecorderOutput::Configure(const config_param &param, GError **error_r)
 {
 	/* read configuration */
 
 	const char *encoder_name =
-		config_get_block_string(param, "encoder", "vorbis");
+		param.GetBlockValue("encoder", "vorbis");
 	const auto encoder_plugin = encoder_plugin_get(encoder_name);
 	if (encoder_plugin == nullptr) {
 		g_set_error(error_r, recorder_output_quark(), 0,
@@ -99,7 +99,7 @@ RecorderOutput::Configure(const config_param *param, GError **error_r)
 		return false;
 	}
 
-	path = config_get_block_string(param, "path", nullptr);
+	path = param.GetBlockValue("path");
 	if (path == nullptr) {
 		g_set_error(error_r, recorder_output_quark(), 0,
 			    "'path' not configured");
@@ -108,7 +108,7 @@ RecorderOutput::Configure(const config_param *param, GError **error_r)
 
 	/* initialize encoder */
 
-	encoder = encoder_init(*encoder_plugin, param, error_r);
+	encoder = encoder_init(*encoder_plugin, &param, error_r);
 	if (encoder == nullptr)
 		return false;
 
@@ -116,7 +116,7 @@ RecorderOutput::Configure(const config_param *param, GError **error_r)
 }
 
 static audio_output *
-recorder_output_init(const config_param *param, GError **error_r)
+recorder_output_init(const config_param &param, GError **error_r)
 {
 	RecorderOutput *recorder = new RecorderOutput();
 
diff --git a/src/output/RoarOutputPlugin.cxx b/src/output/RoarOutputPlugin.cxx
index bf2bf1789..36f7c395b 100644
--- a/src/output/RoarOutputPlugin.cxx
+++ b/src/output/RoarOutputPlugin.cxx
@@ -108,19 +108,19 @@ roar_output_set_volume(RoarOutput *roar, unsigned volume)
 }
 
 static void
-roar_configure(RoarOutput *self, const struct config_param *param)
+roar_configure(RoarOutput *self, const config_param &param)
 {
-	self->host = config_dup_block_string(param, "server", nullptr);
-	self->name = config_dup_block_string(param, "name", "MPD");
+	self->host = param.DupBlockString("server", nullptr);
+	self->name = param.DupBlockString("name", "MPD");
 
-	const char *role = config_get_block_string(param, "role", "music");
+	const char *role = param.GetBlockValue("role", "music");
 	self->role = role != nullptr
 		? roar_str2role(role)
 		: ROAR_ROLE_MUSIC;
 }
 
 static struct audio_output *
-roar_init(const struct config_param *param, GError **error_r)
+roar_init(const config_param &param, GError **error_r)
 {
 	RoarOutput *self = new RoarOutput();
 
diff --git a/src/output/ShoutOutputPlugin.cxx b/src/output/ShoutOutputPlugin.cxx
index fbad24ec8..1f307eafc 100644
--- a/src/output/ShoutOutputPlugin.cxx
+++ b/src/output/ShoutOutputPlugin.cxx
@@ -35,7 +35,7 @@
 #undef G_LOG_DOMAIN
 #define G_LOG_DOMAIN "shout"
 
-#define DEFAULT_CONN_TIMEOUT  2
+static constexpr unsigned DEFAULT_CONN_TIMEOUT = 2;
 
 struct ShoutOutput final {
 	struct audio_output base;
@@ -66,7 +66,7 @@ struct ShoutOutput final {
 			shout_free(shout_conn);
 	}
 
-	bool Initialize(const config_param *param, GError **error_r) {
+	bool Initialize(const config_param &param, GError **error_r) {
 		return ao_base_init(&base, &shout_output_plugin, param,
 				    error_r);
 	}
@@ -75,7 +75,7 @@ struct ShoutOutput final {
 		ao_base_finish(&base);
 	}
 
-	bool Configure(const config_param *param, GError **error_r);
+	bool Configure(const config_param &param, GError **error_r);
 };
 
 static int shout_init_count;
@@ -102,18 +102,18 @@ shout_encoder_plugin_get(const char *name)
 
 gcc_pure
 static const char *
-require_block_string(const struct config_param *param, const char *name)
+require_block_string(const config_param &param, const char *name)
 {
-	const char *value = config_get_block_string(param, name, nullptr);
+	const char *value = param.GetBlockValue(name);
 	if (value == nullptr)
 		MPD_ERROR("no \"%s\" defined for shout device defined at line " \
-			  "%i\n", name, param->line);			\
+			  "%i\n", name, param.line);
 
 	return value;
 }
 
 inline bool
-ShoutOutput::Configure(const config_param *param, GError **error_r)
+ShoutOutput::Configure(const config_param &param, GError **error_r)
 {
 
 	const AudioFormat audio_format = base.config_audio_format;
@@ -125,8 +125,7 @@ ShoutOutput::Configure(const config_param *param, GError **error_r)
 
 	const char *host = require_block_string(param, "host");
 	const char *mount = require_block_string(param, "mount");
-
-	unsigned port = config_get_block_unsigned(param, "port", 0);
+	unsigned port = param.GetBlockValue("port", 0u);
 	if (port == 0) {
 		g_set_error(error_r, shout_output_quark(), 0,
 			    "shout port must be configured");
@@ -136,11 +135,11 @@ ShoutOutput::Configure(const config_param *param, GError **error_r)
 	const char *passwd = require_block_string(param, "password");
 	const char *name = require_block_string(param, "name");
 
-	bool is_public = config_get_block_bool(param, "public", false);
+	bool is_public = param.GetBlockValue("public", false);
 
-	const char *user = config_get_block_string(param, "user", "source");
+	const char *user = param.GetBlockValue("user", "source");
 
-	const char *value = config_get_block_string(param, "quality", nullptr);
+	const char *value = param.GetBlockValue("quality");
 	if (value != nullptr) {
 		char *test;
 		quality = strtod(value, &test);
@@ -149,18 +148,18 @@ ShoutOutput::Configure(const config_param *param, GError **error_r)
 			g_set_error(error_r, shout_output_quark(), 0,
 				    "shout quality \"%s\" is not a number in the "
 				    "range -1 to 10, line %i",
-				    value, param->line);
+				    value, param.line);
 			return false;
 		}
 
-		if (config_get_block_string(param, "bitrate", nullptr) != nullptr) {
+		if (param.GetBlockValue("bitrate") != nullptr) {
 			g_set_error(error_r, shout_output_quark(), 0,
 				    "quality and bitrate are "
 				    "both defined");
 			return false;
 		}
 	} else {
-		value = config_get_block_string(param, "bitrate", nullptr);
+		value = param.GetBlockValue("bitrate");
 		if (value == nullptr) {
 			g_set_error(error_r, shout_output_quark(), 0,
 				    "neither bitrate nor quality defined");
@@ -177,8 +176,7 @@ ShoutOutput::Configure(const config_param *param, GError **error_r)
 		}
 	}
 
-	const char *encoding = config_get_block_string(param, "encoding",
-						       "ogg");
+	const char *encoding = param.GetBlockValue("encoding", "ogg");
 	const auto encoder_plugin = shout_encoder_plugin_get(encoding);
 	if (encoder_plugin == nullptr) {
 		g_set_error(error_r, shout_output_quark(), 0,
@@ -187,7 +185,7 @@ ShoutOutput::Configure(const config_param *param, GError **error_r)
 		return false;
 	}
 
-	encoder = encoder_init(*encoder_plugin, param, error_r);
+	encoder = encoder_init(*encoder_plugin, &param, error_r);
 	if (encoder == nullptr)
 		return false;
 
@@ -198,7 +196,7 @@ ShoutOutput::Configure(const config_param *param, GError **error_r)
 		shout_format = SHOUT_FORMAT_OGG;
 
 	unsigned protocol;
-	value = config_get_block_string(param, "protocol", nullptr);
+	value = param.GetBlockValue("protocol");
 	if (value != nullptr) {
 		if (0 == strcmp(value, "shoutcast") &&
 		    0 != strcmp(encoding, "mp3")) {
@@ -240,24 +238,23 @@ ShoutOutput::Configure(const config_param *param, GError **error_r)
 	}
 
 	/* optional paramters */
-	timeout = config_get_block_unsigned(param, "timeout",
-					    DEFAULT_CONN_TIMEOUT);
+	timeout = param.GetBlockValue("timeout", DEFAULT_CONN_TIMEOUT);
 
-	value = config_get_block_string(param, "genre", nullptr);
+	value = param.GetBlockValue("genre");
 	if (value != nullptr && shout_set_genre(shout_conn, value)) {
 		g_set_error(error_r, shout_output_quark(), 0,
 			    "%s", shout_get_error(shout_conn));
 		return false;
 	}
 
-	value = config_get_block_string(param, "description", nullptr);
+	value = param.GetBlockValue("description");
 	if (value != nullptr && shout_set_description(shout_conn, value)) {
 		g_set_error(error_r, shout_output_quark(), 0,
 			    "%s", shout_get_error(shout_conn));
 		return false;
 	}
 
-	value = config_get_block_string(param, "url", nullptr);
+	value = param.GetBlockValue("url");
 	if (value != nullptr && shout_set_url(shout_conn, value)) {
 		g_set_error(error_r, shout_output_quark(), 0,
 			    "%s", shout_get_error(shout_conn));
@@ -290,7 +287,7 @@ ShoutOutput::Configure(const config_param *param, GError **error_r)
 }
 
 static struct audio_output *
-my_shout_init_driver(const config_param *param, GError **error_r)
+my_shout_init_driver(const config_param &param, GError **error_r)
 {
 	ShoutOutput *sd = new ShoutOutput();
 	if (!sd->Initialize(param, error_r)) {
diff --git a/src/output/SolarisOutputPlugin.cxx b/src/output/SolarisOutputPlugin.cxx
index 81c793e21..074eae728 100644
--- a/src/output/SolarisOutputPlugin.cxx
+++ b/src/output/SolarisOutputPlugin.cxx
@@ -61,7 +61,7 @@ struct SolarisOutput {
 
 	int fd;
 
-	bool Initialize(const config_param *param, GError **error_r) {
+	bool Initialize(const config_param &param, GError **error_r) {
 		return ao_base_init(&base, &solaris_output_plugin, param,
 				    error_r);
 	}
@@ -90,7 +90,7 @@ solaris_output_test_default_device(void)
 }
 
 static struct audio_output *
-solaris_output_init(const config_param *param, GError **error_r)
+solaris_output_init(const config_param &param, GError **error_r)
 {
 	SolarisOutput *so = new SolarisOutput();
 	if (!so->Initialize(param, error_r)) {
@@ -98,7 +98,7 @@ solaris_output_init(const config_param *param, GError **error_r)
 		return nullptr;
 	}
 
-	so->device = config_get_block_string(param, "device", "/dev/audio");
+	so->device = param.GetBlockValue("device", "/dev/audio");
 
 	return &so->base;
 }
diff --git a/src/output/WinmmOutputPlugin.cxx b/src/output/WinmmOutputPlugin.cxx
index de6927bd2..d02b52c58 100644
--- a/src/output/WinmmOutputPlugin.cxx
+++ b/src/output/WinmmOutputPlugin.cxx
@@ -114,7 +114,7 @@ fail:
 }
 
 static struct audio_output *
-winmm_output_init(const struct config_param *param, GError **error_r)
+winmm_output_init(const config_param &param, GError **error_r)
 {
 	WinmmOutput *wo = new WinmmOutput();
 	if (!ao_base_init(&wo->base, &winmm_output_plugin, param, error_r)) {
@@ -122,7 +122,7 @@ winmm_output_init(const struct config_param *param, GError **error_r)
 		return nullptr;
 	}
 
-	const char *device = config_get_block_string(param, "device", nullptr);
+	const char *device = param.GetBlockValue("device");
 	if (!get_device_id(device, &wo->device_id, error_r)) {
 		ao_base_finish(&wo->base);
 		g_free(wo);
diff --git a/test/run_output.cxx b/test/run_output.cxx
index 34879c657..fbdeebcb6 100644
--- a/test/run_output.cxx
+++ b/test/run_output.cxx
@@ -76,8 +76,7 @@ find_named_config_block(ConfigOption option, const char *name)
 	const struct config_param *param = NULL;
 
 	while ((param = config_get_next_param(option, param)) != NULL) {
-		const char *current_name =
-			config_get_block_string(param, "name", NULL);
+		const char *current_name = param->GetBlockValue("name");
 		if (current_name != NULL && strcmp(current_name, name) == 0)
 			return param;
 	}
@@ -104,7 +103,7 @@ load_audio_output(const char *name)
 	static struct player_control dummy_player_control(32, 4);
 
 	struct audio_output *ao =
-		audio_output_new(param, &dummy_player_control, &error);
+		audio_output_new(*param, &dummy_player_control, &error);
 	if (ao == NULL) {
 		g_printerr("%s\n", error->message);
 		g_error_free(error);