input_stream: non-blocking I/O

NEWS

@@ -5,6 +5,7 @@ ver 0.17 (2011/??/??)
 * input:
   - cdio_paranoia: new input plugin to play audio CDs
   - curl: enable CURLOPT_NETRC
+  - curl: non-blocking I/O
   - soup: new input plugin based on libsoup
   - ffmpeg: support libavformat 0.7
 * decoder:

src/archive/bz2_archive_plugin.c

@@ -114,7 +114,11 @@ bz2_open(const char *pathname, GError **error_r)
 	refcount_init(&context->ref);
 
 	//open archive
-	context->istream = input_stream_open(pathname, error_r);
+	static GStaticMutex mutex = G_STATIC_MUTEX_INIT;
+	context->istream = input_stream_open(pathname,
+					     g_static_mutex_get_mutex(&mutex),
+					     NULL,
+					     error_r);
 	if (context->istream == NULL) {
 		g_free(context);
 		return NULL;
@@ -169,12 +173,15 @@ bz2_close(struct archive_file *file)
 /* single archive handling */
 
 static struct input_stream *
-bz2_open_stream(struct archive_file *file, const char *path, GError **error_r)
+bz2_open_stream(struct archive_file *file, const char *path,
+		GMutex *mutex, GCond *cond,
+		GError **error_r)
 {
 	struct bz2_archive_file *context = (struct bz2_archive_file *) file;
 	struct bz2_input_stream *bis = g_new(struct bz2_input_stream, 1);
 
-	input_stream_init(&bis->base, &bz2_inputplugin, path);
+	input_stream_init(&bis->base, &bz2_inputplugin, path,
+			  mutex, cond);
 
 	bis->archive = context;
 

src/archive/iso9660_archive_plugin.c

@@ -173,15 +173,17 @@ struct iso9660_input_stream {
 };
 
 static struct input_stream *
-iso9660_archive_open_stream(struct archive_file *file,
-		const char *pathname, GError **error_r)
+iso9660_archive_open_stream(struct archive_file *file, const char *pathname,
+			    GMutex *mutex, GCond *cond,
+			    GError **error_r)
 {
 	struct iso9660_archive_file *context =
 		(struct iso9660_archive_file *)file;
 	struct iso9660_input_stream *iis;
 
 	iis = g_new(struct iso9660_input_stream, 1);
-	input_stream_init(&iis->base, &iso9660_input_plugin, pathname);
+	input_stream_init(&iis->base, &iso9660_input_plugin, pathname,
+			  mutex, cond);
 
 	iis->archive = context;
 	iis->statbuf = iso9660_ifs_stat_translate(context->iso, pathname);

src/archive/zzip_archive_plugin.c

@@ -135,14 +135,17 @@ struct zzip_input_stream {
 
 static struct input_stream *
 zzip_archive_open_stream(struct archive_file *file,
-			 const char *pathname, GError **error_r)
+			 const char *pathname,
+			 GMutex *mutex, GCond *cond,
+			 GError **error_r)
 {
 	struct zzip_archive *context = (struct zzip_archive *) file;
 	struct zzip_input_stream *zis;
 	ZZIP_STAT z_stat;
 
 	zis = g_new(struct zzip_input_stream, 1);
-	input_stream_init(&zis->base, &zzip_input_plugin, pathname);
+	input_stream_init(&zis->base, &zzip_input_plugin, pathname,
+			  mutex, cond);
 
 	zis->archive = context;
 	zis->file = zzip_file_open(context->dir, pathname, 0);

src/archive_plugin.c

@@ -81,12 +81,14 @@ archive_file_scan_next(struct archive_file *file)
 }
 
 struct input_stream *
-archive_file_open_stream(struct archive_file *file,
-			 const char *path, GError **error_r)
+archive_file_open_stream(struct archive_file *file, const char *path,
+			 GMutex *mutex, GCond *cond,
+			 GError **error_r)
 {
 	assert(file != NULL);
 	assert(file->plugin != NULL);
 	assert(file->plugin->open_stream != NULL);
 
-	return file->plugin->open_stream(file, path, error_r);
+	return file->plugin->open_stream(file, path, mutex, cond,
+					 error_r);
 }

src/archive_plugin.h

@@ -73,6 +73,7 @@ struct archive_plugin {
 	 */
 	struct input_stream *(*open_stream)(struct archive_file *af,
 					    const char *path,
+					    GMutex *mutex, GCond *cond,
 					    GError **error_r);
 
 	/**
@@ -101,7 +102,8 @@ char *
 archive_file_scan_next(struct archive_file *file);
 
 struct input_stream *
-archive_file_open_stream(struct archive_file *file,
-			 const char *path, GError **error_r);
+archive_file_open_stream(struct archive_file *file, const char *path,
+			 GMutex *mutex, GCond *cond,
+			 GError **error_r);
 
 #endif

src/decoder/audiofile_decoder_plugin.c

@@ -53,7 +53,7 @@ audiofile_file_read(AFvirtualfile *vfile, void *data, size_t length)
 	GError *error = NULL;
 	size_t nbytes;
 
-	nbytes = input_stream_read(is, data, length, &error);
+	nbytes = input_stream_lock_read(is, data, length, &error);
 	if (nbytes == 0 && error != NULL) {
 		g_warning("%s", error->message);
 		g_error_free(error);
@@ -90,7 +90,7 @@ audiofile_file_seek(AFvirtualfile *vfile, long offset, int is_relative)
 {
 	struct input_stream *is = (struct input_stream *) vfile->closure;
 	int whence = (is_relative ? SEEK_CUR : SEEK_SET);
-	if (input_stream_seek(is, offset, whence, NULL)) {
+	if (input_stream_lock_seek(is, offset, whence, NULL)) {
 		return is->offset;
 	} else {
 		return -1;

src/decoder/faad_decoder_plugin.c

@@ -205,7 +205,7 @@ faad_song_duration(struct decoder_buffer *buffer, struct input_stream *is)
 		/* obtain the duration from the ADTS header */
 		float song_length = adts_song_duration(buffer);
 
-		input_stream_seek(is, tagsize, SEEK_SET, NULL);
+		input_stream_lock_seek(is, tagsize, SEEK_SET, NULL);
 
 		data = decoder_buffer_read(buffer, &length);
 		if (data != NULL)
@@ -406,7 +406,7 @@ faad_stream_decode(struct decoder *mpd_decoder, struct input_stream *is)
 	faacDecSetConfiguration(decoder, config);
 
 	while (!decoder_buffer_is_full(buffer) &&
-	       !input_stream_eof(is) &&
+	       !input_stream_lock_eof(is) &&
 	       decoder_get_command(mpd_decoder) == DECODE_COMMAND_NONE) {
 		adts_find_frame(buffer);
 		decoder_buffer_fill(buffer);

src/decoder/ffmpeg_decoder_plugin.c

@@ -105,7 +105,7 @@ mpd_ffmpeg_stream_seek(void *opaque, int64_t pos, int whence)
 	if (whence == AVSEEK_SIZE)
 		return stream->input->size;
 
-	if (!input_stream_seek(stream->input, pos, whence, NULL))
+	if (!input_stream_lock_seek(stream->input, pos, whence, NULL))
 		return -1;
 
 	return stream->input->offset;
@@ -320,7 +320,8 @@ ffmpeg_probe(struct decoder *decoder, struct input_stream *is)
 
 	unsigned char *buffer = g_malloc(BUFFER_SIZE);
 	size_t nbytes = decoder_read(decoder, is, buffer, BUFFER_SIZE);
-	if (nbytes <= PADDING || !input_stream_seek(is, 0, SEEK_SET, NULL)) {
+	if (nbytes <= PADDING ||
+	    !input_stream_lock_seek(is, 0, SEEK_SET, NULL)) {
 		g_free(buffer);
 		return NULL;
 	}

src/decoder/flac_decoder_plugin.c

@@ -50,7 +50,7 @@ flac_read_cb(G_GNUC_UNUSED const FLAC__StreamDecoder *fd,
 
 	if (r == 0) {
 		if (decoder_get_command(data->decoder) != DECODE_COMMAND_NONE ||
-		    input_stream_eof(data->input_stream))
+		    input_stream_lock_eof(data->input_stream))
 			return FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
 		else
 			return FLAC__STREAM_DECODER_READ_STATUS_ABORT;
@@ -68,7 +68,8 @@ flac_seek_cb(G_GNUC_UNUSED const FLAC__StreamDecoder *fd,
 	if (!data->input_stream->seekable)
 		return FLAC__STREAM_DECODER_SEEK_STATUS_UNSUPPORTED;
 
-	if (!input_stream_seek(data->input_stream, offset, SEEK_SET, NULL))
+	if (!input_stream_lock_seek(data->input_stream, offset, SEEK_SET,
+				    NULL))
 		return FLAC__STREAM_DECODER_SEEK_STATUS_ERROR;
 
 	return FLAC__STREAM_DECODER_SEEK_STATUS_OK;
@@ -109,7 +110,7 @@ flac_eof_cb(G_GNUC_UNUSED const FLAC__StreamDecoder *fd, void *fdata)
 
 	return (decoder_get_command(data->decoder) != DECODE_COMMAND_NONE &&
 		decoder_get_command(data->decoder) != DECODE_COMMAND_SEEK) ||
-		input_stream_eof(data->input_stream);
+		input_stream_lock_eof(data->input_stream);
 }
 
 static void
@@ -449,7 +450,7 @@ oggflac_decode(struct decoder *decoder, struct input_stream *input_stream)
 
 	/* rewind the stream, because ogg_stream_type_detect() has
 	   moved it */
-	input_stream_seek(input_stream, 0, SEEK_SET, NULL);
+	input_stream_lock_seek(input_stream, 0, SEEK_SET, NULL);
 
 	flac_decode_internal(decoder, input_stream, true);
 }

src/decoder/mad_decoder_plugin.c

@@ -168,7 +168,7 @@ mp3_data_init(struct mp3_data *data, struct decoder *decoder,
 
 static bool mp3_seek(struct mp3_data *data, long offset)
 {
-	if (!input_stream_seek(data->input_stream, offset, SEEK_SET, NULL))
+	if (!input_stream_lock_seek(data->input_stream, offset, SEEK_SET, NULL))
 		return false;
 
 	mad_stream_buffer(&data->stream, data->input_buffer, 0);

src/decoder/modplug_decoder_plugin.c

@@ -62,7 +62,7 @@ static GByteArray *mod_loadfile(struct decoder *decoder, struct input_stream *is
 	while (true) {
 		ret = decoder_read(decoder, is, data, MODPLUG_READ_BLOCK);
 		if (ret == 0) {
-			if (input_stream_eof(is))
+			if (input_stream_lock_eof(is))
 				/* end of file */
 				break;
 

src/decoder/mp4ff_decoder_plugin.c

@@ -102,7 +102,8 @@ mp4_seek(void *user_data, uint64_t position)
 {
 	struct mp4ff_input_stream *mis = user_data;
 
-	return input_stream_seek(mis->input_stream, position, SEEK_SET, NULL)
+	return input_stream_lock_seek(mis->input_stream, position, SEEK_SET,
+				      NULL)
 		? 0 : -1;
 }
 

src/decoder/mpcdec_decoder_plugin.c

@@ -61,7 +61,7 @@ mpc_seek_cb(cb_first_arg, mpc_int32_t offset)
 {
 	struct mpc_decoder_data *data = (struct mpc_decoder_data *) cb_data;
 
-	return input_stream_seek(data->is, offset, SEEK_SET, NULL);
+	return input_stream_lock_seek(data->is, offset, SEEK_SET, NULL);
 }
 
 static mpc_int32_t

src/decoder/pcm_decoder_plugin.c

@@ -52,7 +52,7 @@ pcm_stream_decode(struct decoder *decoder, struct input_stream *is)
 		size_t nbytes = decoder_read(decoder, is,
 					     buffer, sizeof(buffer));
 
-		if (nbytes == 0 && input_stream_eof(is))
+		if (nbytes == 0 && input_stream_lock_eof(is))
 			break;
 
 		cmd = nbytes > 0
@@ -62,7 +62,8 @@ pcm_stream_decode(struct decoder *decoder, struct input_stream *is)
 		if (cmd == DECODE_COMMAND_SEEK) {
 			goffset offset = (goffset)(time_to_size *
 						   decoder_seek_where(decoder));
-			if (input_stream_seek(is, offset, SEEK_SET, &error)) {
+			if (input_stream_lock_seek(is, offset, SEEK_SET,
+						   &error)) {
 				decoder_command_finished(decoder);
 			} else {
 				g_warning("seeking failed: %s", error->message);

src/decoder/sndfile_decoder_plugin.c

@@ -40,7 +40,7 @@ sndfile_vio_seek(sf_count_t offset, int whence, void *user_data)
 	struct input_stream *is = user_data;
 	bool success;
 
-	success = input_stream_seek(is, offset, whence, NULL);
+	success = input_stream_lock_seek(is, offset, whence, NULL);
 	if (!success)
 		return -1;
 
@@ -54,7 +54,7 @@ sndfile_vio_read(void *ptr, sf_count_t count, void *user_data)
 	GError *error = NULL;
 	size_t nbytes;
 
-	nbytes = input_stream_read(is, ptr, count, &error);
+	nbytes = input_stream_lock_read(is, ptr, count, &error);
 	if (nbytes == 0 && error != NULL) {
 		g_warning("%s", error->message);
 		g_error_free(error);

src/decoder/vorbis_decoder_plugin.c

@@ -80,7 +80,7 @@ static int ogg_seek_cb(void *data, ogg_int64_t offset, int whence)
 
 	return vis->seekable &&
 		(!vis->decoder || decoder_get_command(vis->decoder) != DECODE_COMMAND_STOP) &&
-		input_stream_seek(vis->input_stream, offset, whence, NULL)
+		input_stream_lock_seek(vis->input_stream, offset, whence, NULL)
 		? 0 : -1;
 }
 
@@ -290,7 +290,7 @@ vorbis_stream_decode(struct decoder *decoder,
 
 	/* rewind the stream, because ogg_stream_type_detect() has
 	   moved it */
-	input_stream_seek(input_stream, 0, SEEK_SET, NULL);
+	input_stream_lock_seek(input_stream, 0, SEEK_SET, NULL);
 
 	if (!vorbis_is_open(&vis, &vf, decoder, input_stream))
 		return;

src/decoder/wavpack_decoder_plugin.c

@@ -390,13 +390,15 @@ wavpack_input_get_pos(void *id)
 static int
 wavpack_input_set_pos_abs(void *id, uint32_t pos)
 {
-	return input_stream_seek(wpin(id)->is, pos, SEEK_SET, NULL) ? 0 : -1;
+	return input_stream_lock_seek(wpin(id)->is, pos, SEEK_SET, NULL)
+		? 0 : -1;
 }
 
 static int
 wavpack_input_set_pos_rel(void *id, int32_t delta, int mode)
 {
-	return input_stream_seek(wpin(id)->is, delta, mode, NULL) ? 0 : -1;
+	return input_stream_lock_seek(wpin(id)->is, delta, mode, NULL)
+		? 0 : -1;
 }
 
 static int
@@ -447,6 +449,7 @@ wavpack_input_init(struct wavpack_input *isp, struct decoder *decoder,
 
 static struct input_stream *
 wavpack_open_wvc(struct decoder *decoder, const char *uri,
+		 GMutex *mutex, GCond *cond,
 		 struct wavpack_input *wpi)
 {
 	struct input_stream *is_wvc;
@@ -462,7 +465,7 @@ wavpack_open_wvc(struct decoder *decoder, const char *uri,
 		return false;
 
 	wvc_url = g_strconcat(uri, "c", NULL);
-	is_wvc = input_stream_open(wvc_url, NULL);
+	is_wvc = input_stream_open(wvc_url, mutex, cond, NULL);
 	g_free(wvc_url);
 
 	if (is_wvc == NULL)
@@ -499,7 +502,8 @@ wavpack_streamdecode(struct decoder * decoder, struct input_stream *is)
 	struct wavpack_input isp, isp_wvc;
 	bool can_seek = is->seekable;
 
-	is_wvc = wavpack_open_wvc(decoder, is->uri, &isp_wvc);
+	is_wvc = wavpack_open_wvc(decoder, is->uri, is->mutex, is->cond,
+				  &isp_wvc);
 	if (is_wvc != NULL) {
 		open_flags |= OPEN_WVC;
 		can_seek &= is_wvc->seekable;

src/decoder_api.c

@@ -183,8 +183,19 @@ size_t decoder_read(struct decoder *decoder,
 	if (length == 0)
 		return 0;
 
-	if (decoder_check_cancel_read(decoder))
-		return 0;
+	input_stream_lock(is);
+
+	while (true) {
+		if (decoder_check_cancel_read(decoder)) {
+			input_stream_unlock(is);
+			return 0;
+		}
+
+		if (input_stream_available(is))
+			break;
+
+		g_cond_wait(is->cond, is->mutex);
+	}
 
 	nbytes = input_stream_read(is, buffer, length, &error);
 	assert(nbytes == 0 || error == NULL);
@@ -195,6 +206,8 @@ size_t decoder_read(struct decoder *decoder,
 		g_error_free(error);
 	}
 
+	input_stream_unlock(is);
+
 	return nbytes;
 }
 
@@ -241,7 +254,7 @@ update_stream_tag(struct decoder *decoder, struct input_stream *is)
 	struct tag *tag;
 
 	tag = is != NULL
-		? input_stream_tag(is)
+		? input_stream_lock_tag(is)
 		: NULL;
 	if (tag == NULL) {
 		tag = decoder->song_tag;

src/decoder_thread.c

@@ -41,18 +41,6 @@
 #undef G_LOG_DOMAIN
 #define G_LOG_DOMAIN "decoder_thread"
 
-static enum decoder_command
-decoder_lock_get_command(struct decoder_control *dc)
-{
-	enum decoder_command command;
-
-	decoder_lock(dc);
-	command = dc->command;
-	decoder_unlock(dc);
-
-	return command;
-}
-
 /**
  * Marks the current decoder command as "finished" and notifies the
  * player thread.
@@ -86,7 +74,7 @@ decoder_input_stream_open(struct decoder_control *dc, const char *uri)
 	GError *error = NULL;
 	struct input_stream *is;
 
-	is = input_stream_open(uri, &error);
+	is = input_stream_open(uri, dc->mutex, dc->cond, &error);
 	if (is == NULL) {
 		if (error != NULL) {
 			g_warning("%s", error->message);
@@ -99,19 +87,27 @@ decoder_input_stream_open(struct decoder_control *dc, const char *uri)
 	/* wait for the input stream to become ready; its metadata
 	   will be available then */
 
+	decoder_lock(dc);
+
+	input_stream_update(is);
 	while (!is->ready &&
-	       decoder_lock_get_command(dc) != DECODE_COMMAND_STOP) {
-		int ret;
+	       dc->command != DECODE_COMMAND_STOP) {
+		decoder_wait(dc);
 
-		ret = input_stream_buffer(is, &error);
-		if (ret < 0) {
-			input_stream_close(is);
-			g_warning("%s", error->message);
-			g_error_free(error);
-			return NULL;
-		}
+		input_stream_update(is);
 	}
 
+	if (!input_stream_check(is, &error)) {
+		decoder_unlock(dc);
+
+		g_warning("%s", error->message);
+		g_error_free(error);
+
+		return NULL;
+	}
+
+	decoder_unlock(dc);
+
 	return is;
 }
 
@@ -132,11 +128,11 @@ decoder_stream_decode(const struct decoder_plugin *plugin,
 	if (decoder->dc->command == DECODE_COMMAND_STOP)
 		return true;
 
-	decoder_unlock(decoder->dc);
-
 	/* rewind the stream, so each plugin gets a fresh start */
 	input_stream_seek(input_stream, 0, SEEK_SET, NULL);
 
+	decoder_unlock(decoder->dc);
+
 	decoder_plugin_stream_decode(plugin, decoder, input_stream);
 
 	decoder_lock(decoder->dc);

src/input/archive_input_plugin.c

@@ -34,7 +34,9 @@
  * plugin and gzip fetches file from disk
  */
 static struct input_stream *
-input_archive_open(const char *pathname, GError **error_r)
+input_archive_open(const char *pathname,
+		   GMutex *mutex, GCond *cond,
+		   GError **error_r)
 {
 	const struct archive_plugin *arplug;
 	struct archive_file *file;
@@ -65,7 +67,8 @@ input_archive_open(const char *pathname, GError **error_r)
 		return NULL;
 
 	//setup fileops
-	is = archive_file_open_stream(file, filename, error_r);
+	is = archive_file_open_stream(file, filename, mutex, cond,
+				      error_r);
 	archive_file_close(file);
 	g_free(pname);
 

src/input/cdio_paranoia_input_plugin.c

@@ -149,7 +149,9 @@ cdio_detect_device(void)
 }
 
 static struct input_stream *
-input_cdio_open(const char *uri, GError **error_r)
+input_cdio_open(const char *uri,
+		GMutex *mutex, GCond *cond,
+		GError **error_r)
 {
 	struct input_cdio_paranoia *i;
 
@@ -158,7 +160,8 @@ input_cdio_open(const char *uri, GError **error_r)
 		return NULL;
 
 	i = g_new(struct input_cdio_paranoia, 1);
-	input_stream_init(&i->base, &input_plugin_cdio_paranoia, uri);
+	input_stream_init(&i->base, &input_plugin_cdio_paranoia, uri,
+			  mutex, cond);
 
 	/* initialize everything (should be already) */
 	i->drv = NULL;

src/input/curl_input_plugin.c

@@ -81,9 +81,6 @@ struct input_curl {
 	/** the curl handles */
 	CURL *easy;
 
-	GMutex *mutex;
-	GCond *cond;
-
 	/** the GMainLoop source used to poll all CURL file
 	    descriptors */
 	GSource *source;
@@ -433,11 +430,11 @@ input_curl_abort_all_requests(GError *error)
 
 		input_curl_easy_free(c);
 
-		g_mutex_lock(c->mutex);
+		g_mutex_lock(c->base.mutex);
 		c->postponed_error = g_error_copy(error);
 		c->base.ready = true;
-		g_cond_broadcast(c->cond);
-		g_mutex_unlock(c->mutex);
+		g_cond_broadcast(c->base.cond);
+		g_mutex_unlock(c->base.mutex);
 	}
 
 	g_error_free(error);
@@ -457,7 +454,7 @@ input_curl_request_done(struct input_curl *c, CURLcode result, long status)
 	assert(c->easy == NULL);
 	assert(c->postponed_error == NULL);
 
-	g_mutex_lock(c->mutex);
+	g_mutex_lock(c->base.mutex);
 
 	if (result != CURLE_OK) {
 		c->postponed_error = g_error_new(curl_quark(), result,
@@ -470,8 +467,8 @@ input_curl_request_done(struct input_curl *c, CURLcode result, long status)
 	}
 
 	c->base.ready = true;
-	g_cond_broadcast(c->cond);
-	g_mutex_unlock(c->mutex);
+	g_cond_broadcast(c->base.cond);
+	g_mutex_unlock(c->base.mutex);
 }
 
 static void
@@ -763,9 +760,6 @@ input_curl_free(struct input_curl *c)
 
 	g_queue_free(c->buffers);
 
-	g_mutex_free(c->mutex);
-	g_cond_free(c->cond);
-
 	if (c->postponed_error != NULL)
 		g_error_free(c->postponed_error);
 
@@ -779,15 +773,12 @@ input_curl_check(struct input_stream *is, GError **error_r)
 {
 	struct input_curl *c = (struct input_curl *)is;
 
-	g_mutex_lock(c->mutex);
-
 	bool success = c->postponed_error == NULL;
 	if (!success) {
 		g_propagate_error(error_r, c->postponed_error);
 		c->postponed_error = NULL;
 	}
 
-	g_mutex_unlock(c->mutex);
 	return success;
 }
 
@@ -805,7 +796,7 @@ static bool
 fill_buffer(struct input_curl *c, GError **error_r)
 {
 	while (c->easy != NULL && g_queue_is_empty(c->buffers))
-		g_cond_wait(c->cond, c->mutex);
+		g_cond_wait(c->base.cond, c->base.mutex);
 
 	if (c->postponed_error != NULL) {
 		g_propagate_error(error_r, c->postponed_error);
@@ -906,6 +897,15 @@ copy_icy_tag(struct input_curl *c)
 	c->tag = tag;
 }
 
+static bool
+input_curl_available(struct input_stream *is)
+{
+	struct input_curl *c = (struct input_curl *)is;
+
+	return c->postponed_error != NULL || c->easy == NULL ||
+		!g_queue_is_empty(c->buffers);
+}
+
 static size_t
 input_curl_read(struct input_stream *is, void *ptr, size_t size,
 		GError **error_r)
@@ -915,16 +915,12 @@ input_curl_read(struct input_stream *is, void *ptr, size_t size,
 	size_t nbytes = 0;
 	char *dest = ptr;
 
-	g_mutex_lock(c->mutex);
-
 	do {
 		/* fill the buffer */
 
 		success = fill_buffer(c, error_r);
-		if (!success) {
-			g_mutex_unlock(c->mutex);
+		if (!success)
 			return 0;
-		}
 
 		/* send buffer contents */
 
@@ -944,14 +940,12 @@ input_curl_read(struct input_stream *is, void *ptr, size_t size,
 
 #if LIBCURL_VERSION_NUM >= 0x071200
 	if (c->paused && curl_total_buffer_size(c) < CURL_RESUME_AT) {
-		g_mutex_unlock(c->mutex);
+		g_mutex_unlock(c->base.mutex);
 		io_thread_call(input_curl_resume, c);
-		g_mutex_lock(c->mutex);
+		g_mutex_lock(c->base.mutex);
 	}
 #endif
 
-	g_mutex_unlock(c->mutex);
-
 	return nbytes;
 }
 
@@ -968,33 +962,7 @@ input_curl_eof(G_GNUC_UNUSED struct input_stream *is)
 {
 	struct input_curl *c = (struct input_curl *)is;
 
-	g_mutex_lock(c->mutex);
-	bool eof = c->easy == NULL && g_queue_is_empty(c->buffers);
-	g_mutex_unlock(c->mutex);
-
-	return eof;
-}
-
-static int
-input_curl_buffer(struct input_stream *is, GError **error_r)
-{
-	struct input_curl *c = (struct input_curl *)is;
-
-	g_mutex_lock(c->mutex);
-
-	int result;
-	if (c->postponed_error != NULL) {
-		g_propagate_error(error_r, c->postponed_error);
-		c->postponed_error = NULL;
-		result = -1;
-	} else if (g_queue_is_empty(c->buffers))
-		result = 0;
-	else
-		result = 1;
-
-	g_mutex_unlock(c->mutex);
-
-	return result;
+	return c->easy == NULL && g_queue_is_empty(c->buffers);
 }
 
 /** called by curl when new data is available */
@@ -1092,12 +1060,12 @@ input_curl_writefunction(void *ptr, size_t size, size_t nmemb, void *stream)
 	if (size == 0)
 		return 0;
 
-	g_mutex_lock(c->mutex);
+	g_mutex_lock(c->base.mutex);
 
 #if LIBCURL_VERSION_NUM >= 0x071200
 	if (curl_total_buffer_size(c) + size >= CURL_MAX_BUFFERED) {
 		c->paused = true;
-		g_mutex_unlock(c->mutex);
+		g_mutex_unlock(c->base.mutex);
 		return CURL_WRITEFUNC_PAUSE;
 	}
 #endif
@@ -1108,11 +1076,10 @@ input_curl_writefunction(void *ptr, size_t size, size_t nmemb, void *stream)
 	memcpy(buffer->data, ptr, size);
 
 	g_queue_push_tail(c->buffers, buffer);
-
 	c->base.ready = true;
 
-	g_cond_broadcast(c->cond);
-	g_mutex_unlock(c->mutex);
+	g_cond_broadcast(c->base.cond);
+	g_mutex_unlock(c->base.mutex);
 
 	return size;
 }
@@ -1219,8 +1186,6 @@ input_curl_seek(struct input_stream *is, goffset offset, int whence,
 
 	/* check if we can fast-forward the buffer */
 
-	g_mutex_lock(c->mutex);
-
 	while (offset > is->offset && !g_queue_is_empty(c->buffers)) {
 		struct buffer *buffer;
 		size_t length;
@@ -1238,13 +1203,13 @@ input_curl_seek(struct input_stream *is, goffset offset, int whence,
 		is->offset += length;
 	}
 
-	g_mutex_unlock(c->mutex);
-
 	if (offset == is->offset)
 		return true;
 
 	/* close the old connection and open a new one */
 
+	g_mutex_unlock(c->base.mutex);
+
 	input_curl_easy_free_indirect(c);
 	input_curl_flush_buffers(c);
 
@@ -1272,36 +1237,35 @@ input_curl_seek(struct input_stream *is, goffset offset, int whence,
 	if (!input_curl_easy_add_indirect(c, error_r))
 		return false;
 
-	g_mutex_lock(c->mutex);
+	g_mutex_lock(c->base.mutex);
 
 	while (!c->base.ready)
-		g_cond_wait(c->cond, c->mutex);
+		g_cond_wait(c->base.cond, c->base.mutex);
 
 	if (c->postponed_error != NULL) {
 		g_propagate_error(error_r, c->postponed_error);
 		c->postponed_error = NULL;
-		g_mutex_unlock(c->mutex);
 		return false;
 	}
 
-	g_mutex_unlock(c->mutex);
-
 	return true;
 }
 
 static struct input_stream *
-input_curl_open(const char *url, GError **error_r)
+input_curl_open(const char *url, GMutex *mutex, GCond *cond,
+		GError **error_r)
 {
+	assert(mutex != NULL);
+	assert(cond != NULL);
+
 	struct input_curl *c;
 
 	if (strncmp(url, "http://", 7) != 0)
 		return NULL;
 
 	c = g_new0(struct input_curl, 1);
-	input_stream_init(&c->base, &input_plugin_curl, url);
-
-	c->mutex = g_mutex_new();
-	c->cond = g_cond_new();
+	input_stream_init(&c->base, &input_plugin_curl, url,
+			  mutex, cond);
 
 	c->url = g_strdup(url);
 	c->buffers = g_queue_new();
@@ -1337,7 +1301,7 @@ const struct input_plugin input_plugin_curl = {
 	.close = input_curl_close,
 	.check = input_curl_check,
 	.tag = input_curl_tag,
-	.buffer = input_curl_buffer,
+	.available = input_curl_available,
 	.read = input_curl_read,
 	.eof = input_curl_eof,
 	.seek = input_curl_seek,

src/input/despotify_input_plugin.c

@@ -97,7 +97,9 @@ static void callback(G_GNUC_UNUSED struct despotify_session* ds,
 
 
 static struct input_stream *
-input_despotify_open(const char *url, G_GNUC_UNUSED GError **error_r)
+input_despotify_open(const char *url,
+		     GMutex *mutex, GCond *cond,
+		     G_GNUC_UNUSED GError **error_r)
 {
 	struct input_despotify *ctx;
 	struct despotify_session *session;
@@ -131,7 +133,8 @@ input_despotify_open(const char *url, G_GNUC_UNUSED GError **error_r)
 		return NULL;
 	}
 
-	input_stream_init(&ctx->base, &input_plugin_despotify, url);
+	input_stream_init(&ctx->base, &input_plugin_despotify, url,
+			  mutex, cond);
 	ctx->session = session;
 	ctx->track = track;
 	ctx->tag = mpd_despotify_tag_from_track(track);

src/input/ffmpeg_input_plugin.c

@@ -74,7 +74,9 @@ input_ffmpeg_init(G_GNUC_UNUSED const struct config_param *param,
 }
 
 static struct input_stream *
-input_ffmpeg_open(const char *uri, GError **error_r)
+input_ffmpeg_open(const char *uri,
+		  GMutex *mutex, GCond *cond,
+		  GError **error_r)
 {
 	struct input_ffmpeg *i;
 
@@ -87,7 +89,8 @@ input_ffmpeg_open(const char *uri, GError **error_r)
 		return NULL;
 
 	i = g_new(struct input_ffmpeg, 1);
-	input_stream_init(&i->base, &input_plugin_ffmpeg, uri);
+	input_stream_init(&i->base, &input_plugin_ffmpeg, uri,
+			  mutex, cond);
 
 #if LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(53,1,0)
 	int ret = avio_open(&i->h, uri, AVIO_FLAG_READ);

src/input/file_input_plugin.c

@@ -46,7 +46,9 @@ file_quark(void)
 }
 
 static struct input_stream *
-input_file_open(const char *filename, GError **error_r)
+input_file_open(const char *filename,
+		GMutex *mutex, GCond *cond,
+		GError **error_r)
 {
 	int fd, ret;
 	struct stat st;
@@ -85,7 +87,8 @@ input_file_open(const char *filename, GError **error_r)
 #endif
 
 	fis = g_new(struct file_input_stream, 1);
-	input_stream_init(&fis->base, &input_plugin_file, filename);
+	input_stream_init(&fis->base, &input_plugin_file, filename,
+			  mutex, cond);
 
 	fis->base.size = st.st_size;
 	fis->base.seekable = true;

src/input/mms_input_plugin.c

@@ -46,7 +46,9 @@ mms_quark(void)
 }
 
 static struct input_stream *
-input_mms_open(const char *url, GError **error_r)
+input_mms_open(const char *url,
+	       GMutex *mutex, GCond *cond,
+	       GError **error_r)
 {
 	struct input_mms *m;
 
@@ -57,7 +59,8 @@ input_mms_open(const char *url, GError **error_r)
 		return NULL;
 
 	m = g_new(struct input_mms, 1);
-	input_stream_init(&m->base, &input_plugin_mms, url);
+	input_stream_init(&m->base, &input_plugin_mms, url,
+			  mutex, cond);
 
 	m->mms = mmsx_connect(NULL, NULL, url, 128 * 1024);
 	if (m->mms == NULL) {

src/input/rewind_input_plugin.c

@@ -132,16 +132,12 @@ input_rewind_tag(struct input_stream *is)
 	return input_stream_tag(r->input);
 }
 
-static int
-input_rewind_buffer(struct input_stream *is, GError **error_r)
+static bool
+input_rewind_available(struct input_stream *is)
 {
 	struct input_rewind *r = (struct input_rewind *)is;
 
-	int ret = input_stream_buffer(r->input, error_r);
-	if (ret < 0 || !reading_from_buffer(r))
-		copy_attributes(r);
-
-	return ret;
+	return input_stream_available(r->input);
 }
 
 static size_t
@@ -232,7 +228,7 @@ static const struct input_plugin rewind_input_plugin = {
 	.check = input_rewind_check,
 	.update = input_rewind_update,
 	.tag = input_rewind_tag,
-	.buffer = input_rewind_buffer,
+	.available = input_rewind_available,
 	.read = input_rewind_read,
 	.eof = input_rewind_eof,
 	.seek = input_rewind_seek,
@@ -251,7 +247,8 @@ input_rewind_open(struct input_stream *is)
 		return is;
 
 	c = g_new(struct input_rewind, 1);
-	input_stream_init(&c->base, &rewind_input_plugin, is->uri);
+	input_stream_init(&c->base, &rewind_input_plugin, is->uri,
+			  is->mutex, is->cond);
 	c->tail = 0;
 	c->input = is;
 

src/input/soup_input_plugin.c

@@ -46,9 +46,6 @@ static SoupSession *soup_session;
 struct input_soup {
 	struct input_stream base;
 
-	GMutex *mutex;
-	GCond *cond;
-
 	SoupMessage *msg;
 
 	GQueue *buffers;
@@ -124,14 +121,14 @@ input_soup_session_callback(G_GNUC_UNUSED SoupSession *session,
 	assert(msg == s->msg);
 	assert(!s->completed);
 
-	g_mutex_lock(s->mutex);
+	g_mutex_lock(s->base.mutex);
 
 	s->base.ready = true;
 	s->alive = false;
 	s->completed = true;
 
-	g_cond_broadcast(s->cond);
-	g_mutex_unlock(s->mutex);
+	g_cond_broadcast(s->base.cond);
+	g_mutex_unlock(s->base.mutex);
 }
 
 static void
@@ -140,7 +137,7 @@ input_soup_got_headers(SoupMessage *msg, gpointer user_data)
 	struct input_soup *s = user_data;
 
 	if (!SOUP_STATUS_IS_SUCCESSFUL(msg->status_code)) {
-		g_mutex_lock(s->mutex);
+		g_mutex_lock(s->base.mutex);
 
 		if (s->postponed_error == NULL)
 			s->postponed_error =
@@ -148,7 +145,7 @@ input_soup_got_headers(SoupMessage *msg, gpointer user_data)
 					    "got HTTP status %d",
 					    msg->status_code);
 
-		g_mutex_unlock(s->mutex);
+		g_mutex_unlock(s->base.mutex);
 
 		soup_session_cancel_message(soup_session, msg,
 					    SOUP_STATUS_CANCELLED);
@@ -157,10 +154,10 @@ input_soup_got_headers(SoupMessage *msg, gpointer user_data)
 
 	soup_message_body_set_accumulate(msg->response_body, false);
 
-	g_mutex_lock(s->mutex);
+	g_mutex_lock(s->base.mutex);
 	s->base.ready = true;
-	g_cond_broadcast(s->cond);
-	g_mutex_unlock(s->mutex);
+	g_cond_broadcast(s->base.cond);
+	g_mutex_unlock(s->base.mutex);
 }
 
 static void
@@ -170,7 +167,7 @@ input_soup_got_chunk(SoupMessage *msg, SoupBuffer *chunk, gpointer user_data)
 
 	assert(msg == s->msg);
 
-	g_mutex_lock(s->mutex);
+	g_mutex_lock(s->base.mutex);
 
 	g_queue_push_tail(s->buffers, soup_buffer_copy(chunk));
 	s->total_buffered += chunk->length;
@@ -180,8 +177,8 @@ input_soup_got_chunk(SoupMessage *msg, SoupBuffer *chunk, gpointer user_data)
 		soup_session_pause_message(soup_session, msg);
 	}
 
-	g_cond_broadcast(s->cond);
-	g_mutex_unlock(s->mutex);
+	g_cond_broadcast(s->base.cond);
+	g_mutex_unlock(s->base.mutex);
 }
 
 static void
@@ -191,14 +188,14 @@ input_soup_got_body(G_GNUC_UNUSED SoupMessage *msg, gpointer user_data)
 
 	assert(msg == s->msg);
 
-	g_mutex_lock(s->mutex);
+	g_mutex_lock(s->base.mutex);
 
 	s->base.ready = true;
 	s->eof = true;
 	s->alive = false;
 
-	g_cond_broadcast(s->cond);
-	g_mutex_unlock(s->mutex);
+	g_cond_broadcast(s->base.cond);
+	g_mutex_unlock(s->base.mutex);
 }
 
 static bool
@@ -216,7 +213,7 @@ input_soup_wait_data(struct input_soup *s)
 
 		assert(s->current_consumed == 0);
 
-		g_cond_wait(s->cond, s->mutex);
+		g_cond_wait(s->base.cond, s->base.mutex);
 	}
 }
 
@@ -232,16 +229,16 @@ input_soup_queue(gpointer data)
 }
 
 static struct input_stream *
-input_soup_open(const char *uri, G_GNUC_UNUSED GError **error_r)
+input_soup_open(const char *uri,
+		GMutex *mutex, GCond *cond,
+		G_GNUC_UNUSED GError **error_r)
 {
 	if (strncmp(uri, "http://", 7) != 0)
 		return NULL;
 
 	struct input_soup *s = g_new(struct input_soup, 1);
-	input_stream_init(&s->base, &input_plugin_soup, uri);
-
-	s->mutex = g_mutex_new();
-	s->cond = g_cond_new();
+	input_stream_init(&s->base, &input_plugin_soup, uri,
+			  mutex, cond);
 
 	s->buffers = g_queue_new();
 	s->current_consumed = 0;
@@ -288,25 +285,22 @@ input_soup_close(struct input_stream *is)
 {
 	struct input_soup *s = (struct input_soup *)is;
 
-	g_mutex_lock(s->mutex);
+	g_mutex_lock(s->base.mutex);
 
 	if (!s->completed) {
 		/* the messages's session callback hasn't been invoked
 		   yet; cancel it and wait for completion */
 
-		g_mutex_unlock(s->mutex);
+		g_mutex_unlock(s->base.mutex);
 
 		io_thread_call(input_soup_cancel, s);
 
-		g_mutex_lock(s->mutex);
+		g_mutex_lock(s->base.mutex);
 		while (!s->completed)
-			g_cond_wait(s->cond, s->mutex);
+			g_cond_wait(s->base.cond, s->base.mutex);
 	}
 
-	g_mutex_unlock(s->mutex);
-
-	g_mutex_free(s->mutex);
-	g_cond_free(s->cond);
+	g_mutex_unlock(s->base.mutex);
 
 	SoupBuffer *buffer;
 	while ((buffer = g_queue_pop_head(s->buffers)) != NULL)
@@ -325,54 +319,21 @@ input_soup_check(struct input_stream *is, GError **error_r)
 {
 	struct input_soup *s = (struct input_soup *)is;
 
-	g_mutex_lock(s->mutex);
-
 	bool success = s->postponed_error == NULL;
 	if (!success) {
 		g_propagate_error(error_r, s->postponed_error);
 		s->postponed_error = NULL;
 	}
 
-	g_mutex_unlock(s->mutex);
 	return success;
 }
 
-static int
-input_soup_buffer(struct input_stream *is, GError **error_r)
+static bool
+input_soup_available(struct input_stream *is)
 {
 	struct input_soup *s = (struct input_soup *)is;
 
-	g_mutex_lock(s->mutex);
-
-	if (s->pause) {
-		if (s->total_buffered >= SOUP_MAX_BUFFERED) {
-			g_mutex_unlock(s->mutex);
-			return 1;
-		}
-
-		s->pause = false;
-		soup_session_unpause_message(soup_session, s->msg);
-	}
-
-
-	bool success = input_soup_wait_data(s);
-
-	if (!success) {
-		if (s->postponed_error != NULL) {
-			g_propagate_error(error_r, s->postponed_error);
-			s->postponed_error = NULL;
-		} else
-			g_set_error_literal(error_r, soup_quark(), 0,
-					    "HTTP failure");
-	}
-
-	g_mutex_unlock(s->mutex);
-
-	if (!success) {
-		return -1;
-	}
-
-	return 1;
+	return s->eof || !s->alive || !g_queue_is_empty(s->buffers);
 }
 
 static size_t
@@ -381,8 +342,6 @@ input_soup_read(struct input_stream *is, void *ptr, size_t size,
 {
 	struct input_soup *s = (struct input_soup *)is;
 
-	g_mutex_lock(s->mutex);
-
 	if (!input_soup_wait_data(s)) {
 		assert(!s->alive);
 
@@ -392,8 +351,6 @@ input_soup_read(struct input_stream *is, void *ptr, size_t size,
 		} else
 			g_set_error_literal(error_r, soup_quark(), 0,
 					    "HTTP failure");
-
-		g_mutex_unlock(s->mutex);
 		return 0;
 	}
 
@@ -442,7 +399,6 @@ input_soup_read(struct input_stream *is, void *ptr, size_t size,
 	size_t nbytes = p - p0;
 	s->base.offset += nbytes;
 
-	g_mutex_unlock(s->mutex);
 	return nbytes;
 }
 
@@ -462,7 +418,7 @@ const struct input_plugin input_plugin_soup = {
 	.open = input_soup_open,
 	.close = input_soup_close,
 	.check = input_soup_check,
-	.buffer = input_soup_buffer,
+	.available = input_soup_available,
 	.read = input_soup_read,
 	.eof = input_soup_eof,
 };

src/input_internal.c

@@ -25,7 +25,7 @@
 
 void
 input_stream_init(struct input_stream *is, const struct input_plugin *plugin,
-		  const char *uri)
+		  const char *uri, GMutex *mutex, GCond *cond)
 {
 	assert(is != NULL);
 	assert(plugin != NULL);
@@ -33,6 +33,8 @@ input_stream_init(struct input_stream *is, const struct input_plugin *plugin,
 
 	is->plugin = plugin;
 	is->uri = g_strdup(uri);
+	is->mutex = mutex;
+	is->cond = cond;
 	is->ready = false;
 	is->seekable = false;
 	is->size = -1;
@@ -49,3 +51,23 @@ input_stream_deinit(struct input_stream *is)
 	g_free(is->uri);
 	g_free(is->mime);
 }
+
+void
+input_stream_signal_client(struct input_stream *is)
+{
+	if (is->cond != NULL)
+		g_cond_broadcast(is->cond);
+}
+
+void
+input_stream_set_ready(struct input_stream *is)
+{
+	g_mutex_lock(is->mutex);
+
+	if (!is->ready) {
+		is->ready = true;
+		input_stream_signal_client(is);
+	}
+
+	g_mutex_unlock(is->mutex);
+}

src/input_internal.h

@@ -22,14 +22,22 @@
 
 #include "check.h"
 
+#include <glib.h>
+
 struct input_stream;
 struct input_plugin;
 
 void
 input_stream_init(struct input_stream *is, const struct input_plugin *plugin,
-		  const char *uri);
+		  const char *uri, GMutex *mutex, GCond *cond);
 
 void
 input_stream_deinit(struct input_stream *is);
 
+void
+input_stream_signal_client(struct input_stream *is);
+
+void
+input_stream_set_ready(struct input_stream *is);
+
 #endif

src/input_plugin.h

@@ -48,7 +48,9 @@ struct input_plugin {
 	 */
 	void (*finish)(void);
 
-	struct input_stream *(*open)(const char *uri, GError **error_r);
+	struct input_stream *(*open)(const char *uri,
+				     GMutex *mutex, GCond *cond,
+				     GError **error_r);
 	void (*close)(struct input_stream *is);
 
 	/**
@@ -66,7 +68,17 @@ struct input_plugin {
 	void (*update)(struct input_stream *is);
 
 	struct tag *(*tag)(struct input_stream *is);
-	int (*buffer)(struct input_stream *is, GError **error_r);
+
+	/**
+	 * Returns true if the next read operation will not block:
+	 * either data is available, or end-of-stream has been
+	 * reached, or an error has occurred.
+	 *
+	 * If this method is unimplemented, then it is assumed that
+	 * reading will never block.
+	 */
+	bool (*available)(struct input_stream *is);
+
 	size_t (*read)(struct input_stream *is, void *ptr, size_t size,
 		       GError **error_r);
 	bool (*eof)(struct input_stream *is);

src/input_stream.c

@@ -33,10 +33,13 @@ input_quark(void)
 }
 
 struct input_stream *
-input_stream_open(const char *url, GError **error_r)
+input_stream_open(const char *url,
+		  GMutex *mutex, GCond *cond,
+		  GError **error_r)
 {
 	GError *error = NULL;
 
+	assert(mutex != NULL);
 	assert(error_r == NULL || *error_r == NULL);
 
 	for (unsigned i = 0; input_plugins[i] != NULL; ++i) {
@@ -46,7 +49,7 @@ input_stream_open(const char *url, GError **error_r)
 		if (!input_plugins_enabled[i])
 			continue;
 
-		is = plugin->open(url, &error);
+		is = plugin->open(url, mutex, cond, &error);
 		if (is != NULL) {
 			assert(is->plugin != NULL);
 			assert(is->plugin->close != NULL);
@@ -87,26 +90,108 @@ input_stream_update(struct input_stream *is)
 		is->plugin->update(is);
 }
 
+void
+input_stream_wait_ready(struct input_stream *is)
+{
+	assert(is != NULL);
+	assert(is->mutex != NULL);
+	assert(is->cond != NULL);
+
+	while (true) {
+		input_stream_update(is);
+		if (is->ready)
+			break;
+
+		g_cond_wait(is->cond, is->mutex);
+	}
+}
+
+void
+input_stream_lock_wait_ready(struct input_stream *is)
+{
+	assert(is != NULL);
+	assert(is->mutex != NULL);
+	assert(is->cond != NULL);
+
+	g_mutex_lock(is->mutex);
+	input_stream_wait_ready(is);
+	g_mutex_unlock(is->mutex);
+}
+
 bool
 input_stream_seek(struct input_stream *is, goffset offset, int whence,
 		  GError **error_r)
 {
+	assert(is != NULL);
+	assert(is->plugin != NULL);
+
 	if (is->plugin->seek == NULL)
 		return false;
 
 	return is->plugin->seek(is, offset, whence, error_r);
 }
 
+bool
+input_stream_lock_seek(struct input_stream *is, goffset offset, int whence,
+		       GError **error_r)
+{
+	assert(is != NULL);
+	assert(is->plugin != NULL);
+
+	if (is->plugin->seek == NULL)
+		return false;
+
+	if (is->mutex == NULL)
+		/* no locking */
+		return input_stream_seek(is, offset, whence, error_r);
+
+	g_mutex_lock(is->mutex);
+	bool success = input_stream_seek(is, offset, whence, error_r);
+	g_mutex_unlock(is->mutex);
+	return success;
+}
+
 struct tag *
 input_stream_tag(struct input_stream *is)
 {
 	assert(is != NULL);
+	assert(is->plugin != NULL);
 
 	return is->plugin->tag != NULL
 		? is->plugin->tag(is)
 		: NULL;
 }
 
+struct tag *
+input_stream_lock_tag(struct input_stream *is)
+{
+	assert(is != NULL);
+	assert(is->plugin != NULL);
+
+	if (is->plugin->tag == NULL)
+		return false;
+
+	if (is->mutex == NULL)
+		/* no locking */
+		return input_stream_tag(is);
+
+	g_mutex_lock(is->mutex);
+	struct tag *tag = input_stream_tag(is);
+	g_mutex_unlock(is->mutex);
+	return tag;
+}
+
+bool
+input_stream_available(struct input_stream *is)
+{
+	assert(is != NULL);
+	assert(is->plugin != NULL);
+
+	return is->plugin->available != NULL
+		? is->plugin->available(is)
+		: true;
+}
+
 size_t
 input_stream_read(struct input_stream *is, void *ptr, size_t size,
 		  GError **error_r)
@@ -117,6 +202,23 @@ input_stream_read(struct input_stream *is, void *ptr, size_t size,
 	return is->plugin->read(is, ptr, size, error_r);
 }
 
+size_t
+input_stream_lock_read(struct input_stream *is, void *ptr, size_t size,
+		       GError **error_r)
+{
+	assert(ptr != NULL);
+	assert(size > 0);
+
+	if (is->mutex == NULL)
+		/* no locking */
+		return input_stream_read(is, ptr, size, error_r);
+
+	g_mutex_lock(is->mutex);
+	size_t nbytes = input_stream_read(is, ptr, size, error_r);
+	g_mutex_unlock(is->mutex);
+	return nbytes;
+}
+
 void input_stream_close(struct input_stream *is)
 {
 	is->plugin->close(is);
@@ -127,11 +229,19 @@ bool input_stream_eof(struct input_stream *is)
 	return is->plugin->eof(is);
 }
 
-int
-input_stream_buffer(struct input_stream *is, GError **error_r)
+bool
+input_stream_lock_eof(struct input_stream *is)
 {
-	if (is->plugin->buffer == NULL)
-		return 0;
+	assert(is != NULL);
+	assert(is->plugin != NULL);
+
+	if (is->mutex == NULL)
+		/* no locking */
+		return input_stream_eof(is);
 
-	return is->plugin->buffer(is, error_r);
+	g_mutex_lock(is->mutex);
+	bool eof = input_stream_eof(is);
+	g_mutex_unlock(is->mutex);
+	return eof;
 }
+

src/input_stream.h

@@ -46,6 +46,26 @@ struct input_stream {
 	char *uri;
 
 	/**
+	 * A mutex that protects the mutable attributes of this object
+	 * and its implementation.  It must be locked before calling
+	 * any of the public methods.
+	 *
+	 * This object is allocated by the client, and the client is
+	 * responsible for freeing it.
+	 */
+	GMutex *mutex;
+
+	/**
+	 * A cond that gets signalled when the state of this object
+	 * changes from the I/O thread.  The client of this object may
+	 * wait on it.  Optional, may be NULL.
+	 *
+	 * This object is allocated by the client, and the client is
+	 * responsible for freeing it.
+	 */
+	GCond *cond;
+
+	/**
 	 * indicates whether the stream is ready for reading and
 	 * whether the other attributes in this struct are valid
 	 */
@@ -76,20 +96,43 @@ struct input_stream {
  * Opens a new input stream.  You may not access it until the "ready"
  * flag is set.
  *
+ * @param mutex a mutex that is used to protect this object; must be
+ * locked before calling any of the public methods
+ * @param cond a cond that gets signalled when the state of
+ * this object changes; may be NULL if the caller doesn't want to get
+ * notifications
  * @return an #input_stream object on success, NULL on error
  */
-gcc_nonnull(1)
+gcc_nonnull(1, 2)
 G_GNUC_MALLOC
 struct input_stream *
-input_stream_open(const char *uri, GError **error_r);
+input_stream_open(const char *uri,
+		  GMutex *mutex, GCond *cond,
+		  GError **error_r);
 
 /**
  * Close the input stream and free resources.
+ *
+ * The caller must not lock the mutex.
  */
 gcc_nonnull(1)
 void
 input_stream_close(struct input_stream *is);
 
+gcc_nonnull(1)
+static inline void
+input_stream_lock(struct input_stream *is)
+{
+	g_mutex_lock(is->mutex);
+}
+
+gcc_nonnull(1)
+static inline void
+input_stream_unlock(struct input_stream *is)
+{
+	g_mutex_unlock(is->mutex);
+}
+
 /**
  * Check for errors that may have occurred in the I/O thread.
  *
@@ -108,9 +151,28 @@ void
 input_stream_update(struct input_stream *is);
 
 /**
+ * Wait until the stream becomes ready.
+ *
+ * The caller must lock the mutex.
+ */
+gcc_nonnull(1)
+void
+input_stream_wait_ready(struct input_stream *is);
+
+/**
+ * Wrapper for input_stream_wait_locked() which locks and unlocks the
+ * mutex; the caller must not be holding it already.
+ */
+gcc_nonnull(1)
+void
+input_stream_lock_wait_ready(struct input_stream *is);
+
+/**
  * Seeks to the specified position in the stream.  This will most
  * likely fail if the "seekable" flag is false.
  *
+ * The caller must lock the mutex.
+ *
  * @param is the input_stream object
  * @param offset the relative offset
  * @param whence the base of the seek, one of SEEK_SET, SEEK_CUR, SEEK_END
@@ -121,15 +183,37 @@ input_stream_seek(struct input_stream *is, goffset offset, int whence,
 		  GError **error_r);
 
 /**
+ * Wrapper for input_stream_seek() which locks and unlocks the
+ * mutex; the caller must not be holding it already.
+ */
+gcc_nonnull(1)
+bool
+input_stream_lock_seek(struct input_stream *is, goffset offset, int whence,
+		       GError **error_r);
+
+/**
  * Returns true if the stream has reached end-of-file.
+ *
+ * The caller must lock the mutex.
  */
 gcc_nonnull(1)
 G_GNUC_PURE
 bool input_stream_eof(struct input_stream *is);
 
 /**
+ * Wrapper for input_stream_eof() which locks and unlocks the mutex;
+ * the caller must not be holding it already.
+ */
+gcc_nonnull(1)
+G_GNUC_PURE
+bool
+input_stream_lock_eof(struct input_stream *is);
+
+/**
  * Reads the tag from the stream.
  *
+ * The caller must lock the mutex.
+ *
  * @return a tag object which must be freed with tag_free(), or NULL
  * if the tag has not changed since the last call
  */
@@ -139,20 +223,32 @@ struct tag *
 input_stream_tag(struct input_stream *is);
 
 /**
- * Reads some of the stream into its buffer.  The following return
- * codes are defined: -1 = error, 1 = something was buffered, 0 =
- * nothing was buffered.
+ * Wrapper for input_stream_tag() which locks and unlocks the
+ * mutex; the caller must not be holding it already.
+ */
+gcc_nonnull(1)
+G_GNUC_MALLOC
+struct tag *
+input_stream_lock_tag(struct input_stream *is);
+
+/**
+ * Returns true if the next read operation will not block: either data
+ * is available, or end-of-stream has been reached, or an error has
+ * occurred.
  *
- * The semantics of this function are not well-defined, and it will
- * eventually be removed.
+ * The caller must lock the mutex.
  */
 gcc_nonnull(1)
-int input_stream_buffer(struct input_stream *is, GError **error_r);
+G_GNUC_PURE
+bool
+input_stream_available(struct input_stream *is);
 
 /**
  * Reads data from the stream into the caller-supplied buffer.
  * Returns 0 on error or eof (check with input_stream_eof()).
  *
+ * The caller must lock the mutex.
+ *
  * @param is the input_stream object
  * @param ptr the buffer to read into
  * @param size the maximum number of bytes to read
@@ -163,4 +259,13 @@ size_t
 input_stream_read(struct input_stream *is, void *ptr, size_t size,
 		  GError **error_r);
 
+/**
+ * Wrapper for input_stream_tag() which locks and unlocks the
+ * mutex; the caller must not be holding it already.
+ */
+gcc_nonnull(1, 2)
+size_t
+input_stream_lock_read(struct input_stream *is, void *ptr, size_t size,
+		       GError **error_r);
+
 #endif

src/playlist/asx_playlist_plugin.c

@@ -233,7 +233,8 @@ asx_open_stream(struct input_stream *is)
 					     &parser, asx_parser_destroy);
 
 	while (true) {
-		nbytes = input_stream_read(is, buffer, sizeof(buffer), &error);
+		nbytes = input_stream_lock_read(is, buffer, sizeof(buffer),
+						&error);
 		if (nbytes == 0) {
 			if (error != NULL) {
 				g_markup_parse_context_free(context);

src/playlist/cue_playlist_plugin.c

@@ -41,7 +41,8 @@ struct cue_playlist {
 };
 
 static struct playlist_provider *
-cue_playlist_open_uri(const char *uri)
+cue_playlist_open_uri(const char *uri,
+		      G_GNUC_UNUSED GMutex *mutex, G_GNUC_UNUSED GCond *cond)
 {
 	struct cue_playlist *playlist;
 	FILE *file;

src/playlist/despotify_playlist_plugin.c

@@ -110,7 +110,8 @@ despotify_playlist_finish(void)
 
 
 static struct playlist_provider *
-despotify_playlist_open_uri(const char *url)
+despotify_playlist_open_uri(const char *url, G_GNUC_UNUSED GMutex *mutex,
+			    G_GNUC_UNUSED GCond *cond)
 {
 	struct despotify_playlist *ctx;
 	struct despotify_session *session;

src/playlist/flac_playlist_plugin.c

@@ -45,7 +45,8 @@ struct flac_playlist {
 };
 
 static struct playlist_provider *
-flac_playlist_open_uri(const char *uri)
+flac_playlist_open_uri(const char *uri,
+		       G_GNUC_UNUSED GMutex *mutex, G_GNUC_UNUSED GCond *cond)
 {
 	if (!g_path_is_absolute(uri))
 		/* only local files supported */

src/playlist/lastfm_playlist_plugin.c

@@ -83,15 +83,14 @@ lastfm_finish(void)
  * @return data fetched, or NULL on error. Must be freed with g_free.
  */
 static char *
-lastfm_get(const char *url)
+lastfm_get(const char *url, GMutex *mutex, GCond *cond)
 {
 	struct input_stream *input_stream;
 	GError *error = NULL;
-	int ret;
 	char buffer[4096];
 	size_t length = 0, nbytes;
 
-	input_stream = input_stream_open(url, &error);
+	input_stream = input_stream_open(url, mutex, cond, &error);
 	if (input_stream == NULL) {
 		if (error != NULL) {
 			g_warning("%s", error->message);
@@ -101,15 +100,9 @@ lastfm_get(const char *url)
 		return NULL;
 	}
 
-	while (!input_stream->ready) {
-		ret = input_stream_buffer(input_stream, &error);
-		if (ret < 0) {
-			input_stream_close(input_stream);
-			g_warning("%s", error->message);
-			g_error_free(error);
-			return NULL;
-		}
-	}
+	g_mutex_lock(mutex);
+
+	input_stream_wait_ready(input_stream);
 
 	do {
 		nbytes = input_stream_read(input_stream, buffer + length,
@@ -124,6 +117,7 @@ lastfm_get(const char *url)
 				break;
 
 			/* I/O error */
+			g_mutex_unlock(mutex);
 			input_stream_close(input_stream);
 			return NULL;
 		}
@@ -131,6 +125,8 @@ lastfm_get(const char *url)
 		length += nbytes;
 	} while (length < sizeof(buffer));
 
+	g_mutex_unlock(mutex);
+
 	input_stream_close(input_stream);
 	return g_strndup(buffer, length);
 }
@@ -162,7 +158,7 @@ lastfm_find(const char *response, const char *name)
 }
 
 static struct playlist_provider *
-lastfm_open_uri(const char *uri)
+lastfm_open_uri(const char *uri, GMutex *mutex, GCond *cond)
 {
 	struct lastfm_playlist *playlist;
 	GError *error = NULL;
@@ -175,7 +171,7 @@ lastfm_open_uri(const char *uri)
 			"username=", lastfm_config.user, "&"
 			"passwordmd5=", lastfm_config.md5, "&"
 			"debug=0&partner=", NULL);
-	response = lastfm_get(p);
+	response = lastfm_get(p, mutex, cond);
 	g_free(p);
 	if (response == NULL)
 		return NULL;
@@ -207,7 +203,7 @@ lastfm_open_uri(const char *uri)
 				NULL);
 		g_free(escaped_uri);
 
-		response = lastfm_get(p);
+		response = lastfm_get(p, mutex, cond);
 		g_free(response);
 		g_free(p);
 
@@ -229,7 +225,7 @@ lastfm_open_uri(const char *uri)
 			NULL);
 	g_free(session);
 
-	playlist->is = input_stream_open(p, &error);
+	playlist->is = input_stream_open(p, mutex, cond, &error);
 	g_free(p);
 
 	if (playlist->is == NULL) {
@@ -243,26 +239,17 @@ lastfm_open_uri(const char *uri)
 		return NULL;
 	}
 
-	while (!playlist->is->ready) {
-		int ret = input_stream_buffer(playlist->is, &error);
-		if (ret < 0) {
-			input_stream_close(playlist->is);
-			g_free(playlist);
-			g_warning("%s", error->message);
-			g_error_free(error);
-			return NULL;
-		}
+	g_mutex_lock(mutex);
 
-		if (ret == 0)
-			/* nothing was buffered - wait */
-			g_usleep(10000);
-	}
+	input_stream_wait_ready(playlist->is);
 
 	/* last.fm does not send a MIME type, we have to fake it here
 	   :-( */
 	g_free(playlist->is->mime);
 	playlist->is->mime = g_strdup("application/xspf+xml");
 
+	g_mutex_unlock(mutex);
+
 	/* parse the XSPF playlist */
 
 	playlist->xspf = playlist_list_open_stream(playlist->is, NULL);

src/playlist/pls_playlist_plugin.c

@@ -115,7 +115,8 @@ pls_open_stream(struct input_stream *is)
 	GString *kf_data = g_string_new("");
 
 	do {
-		nbytes = input_stream_read(is, buffer, sizeof(buffer), &error);
+		nbytes = input_stream_lock_read(is, buffer, sizeof(buffer),
+						&error);
 		if (nbytes == 0) {
 			if (error != NULL) {
 				g_string_free(kf_data, TRUE);

src/playlist/rss_playlist_plugin.c

@@ -231,7 +231,8 @@ rss_open_stream(struct input_stream *is)
 					     &parser, rss_parser_destroy);
 
 	while (true) {
-		nbytes = input_stream_read(is, buffer, sizeof(buffer), &error);
+		nbytes = input_stream_lock_read(is, buffer, sizeof(buffer),
+						&error);
 		if (nbytes == 0) {
 			if (error != NULL) {
 				g_markup_parse_context_free(context);

src/playlist/xspf_playlist_plugin.c

@@ -253,7 +253,8 @@ xspf_open_stream(struct input_stream *is)
 					     &parser, xspf_parser_destroy);
 
 	while (true) {
-		nbytes = input_stream_read(is, buffer, sizeof(buffer), &error);
+		nbytes = input_stream_lock_read(is, buffer, sizeof(buffer),
+						&error);
 		if (nbytes == 0) {
 			if (error != NULL) {
 				g_markup_parse_context_free(context);

src/playlist_any.c

@@ -27,18 +27,20 @@
 #include <assert.h>
 
 static struct playlist_provider *
-playlist_open_remote(const char *uri, struct input_stream **is_r)
+playlist_open_remote(const char *uri, GMutex *mutex, GCond *cond,
+		     struct input_stream **is_r)
 {
 	assert(uri_has_scheme(uri));
 
-	struct playlist_provider *playlist = playlist_list_open_uri(uri);
+	struct playlist_provider *playlist =
+		playlist_list_open_uri(uri, mutex, cond);
 	if (playlist != NULL) {
 		*is_r = NULL;
 		return playlist;
 	}
 
 	GError *error = NULL;
-	struct input_stream *is = input_stream_open(uri, &error);
+	struct input_stream *is = input_stream_open(uri, mutex, cond, &error);
 	if (is == NULL) {
 		if (error != NULL) {
 			g_warning("Failed to open %s: %s",
@@ -60,9 +62,10 @@ playlist_open_remote(const char *uri, struct input_stream **is_r)
 }
 
 struct playlist_provider *
-playlist_open_any(const char *uri, struct input_stream **is_r)
+playlist_open_any(const char *uri, GMutex *mutex, GCond *cond,
+		  struct input_stream **is_r)
 {
 	return uri_has_scheme(uri)
-		? playlist_open_remote(uri, is_r)
-		: playlist_mapper_open(uri, is_r);
+		? playlist_open_remote(uri, mutex, cond, is_r)
+		: playlist_mapper_open(uri, mutex, cond, is_r);
 }

src/playlist_any.h

@@ -20,7 +20,7 @@
 #ifndef MPD_PLAYLIST_ANY_H
 #define MPD_PLAYLIST_ANY_H
 
-#include <stdbool.h>
+#include <glib.h>
 
 struct playlist_provider;
 struct input_stream;
@@ -35,6 +35,7 @@ struct input_stream;
  * freed
  */
 struct playlist_provider *
-playlist_open_any(const char *uri, struct input_stream **is_r);
+playlist_open_any(const char *uri, GMutex *mutex, GCond *cond,
+		  struct input_stream **is_r);
 
 #endif

src/playlist_list.c

@@ -119,7 +119,8 @@ playlist_list_global_finish(void)
 }
 
 static struct playlist_provider *
-playlist_list_open_uri_scheme(const char *uri, bool *tried)
+playlist_list_open_uri_scheme(const char *uri, GMutex *mutex, GCond *cond,
+			      bool *tried)
 {
 	char *scheme;
 	struct playlist_provider *playlist = NULL;
@@ -138,7 +139,8 @@ playlist_list_open_uri_scheme(const char *uri, bool *tried)
 		if (playlist_plugins_enabled[i] && plugin->open_uri != NULL &&
 		    plugin->schemes != NULL &&
 		    string_array_contains(plugin->schemes, scheme)) {
-			playlist = playlist_plugin_open_uri(plugin, uri);
+			playlist = playlist_plugin_open_uri(plugin, uri,
+							    mutex, cond);
 			if (playlist != NULL)
 				break;
 
@@ -151,7 +153,8 @@ playlist_list_open_uri_scheme(const char *uri, bool *tried)
 }
 
 static struct playlist_provider *
-playlist_list_open_uri_suffix(const char *uri, const bool *tried)
+playlist_list_open_uri_suffix(const char *uri, GMutex *mutex, GCond *cond,
+			      const bool *tried)
 {
 	const char *suffix;
 	struct playlist_provider *playlist = NULL;
@@ -168,7 +171,8 @@ playlist_list_open_uri_suffix(const char *uri, const bool *tried)
 		if (playlist_plugins_enabled[i] && !tried[i] &&
 		    plugin->open_uri != NULL && plugin->suffixes != NULL &&
 		    string_array_contains(plugin->suffixes, suffix)) {
-			playlist = playlist_plugin_open_uri(plugin, uri);
+			playlist = playlist_plugin_open_uri(plugin, uri,
+							    mutex, cond);
 			if (playlist != NULL)
 				break;
 		}
@@ -178,7 +182,7 @@ playlist_list_open_uri_suffix(const char *uri, const bool *tried)
 }
 
 struct playlist_provider *
-playlist_list_open_uri(const char *uri)
+playlist_list_open_uri(const char *uri, GMutex *mutex, GCond *cond)
 {
 	struct playlist_provider *playlist;
 	/** this array tracks which plugins have already been tried by
@@ -189,9 +193,10 @@ playlist_list_open_uri(const char *uri)
 
 	memset(tried, false, sizeof(tried));
 
-	playlist = playlist_list_open_uri_scheme(uri, tried);
+	playlist = playlist_list_open_uri_scheme(uri, mutex, cond, tried);
 	if (playlist == NULL)
-		playlist = playlist_list_open_uri_suffix(uri, tried);
+		playlist = playlist_list_open_uri_suffix(uri, mutex, cond,
+							 tried);
 
 	return playlist;
 }
@@ -278,16 +283,7 @@ playlist_list_open_stream(struct input_stream *is, const char *uri)
 	const char *suffix;
 	struct playlist_provider *playlist;
 
-	GError *error = NULL;
-	while (!is->ready) {
-		int ret = input_stream_buffer(is, &error);
-		if (ret < 0) {
-			input_stream_close(is);
-			g_warning("%s", error->message);
-			g_error_free(error);
-			return NULL;
-		}
-	}
+	input_stream_lock_wait_ready(is);
 
 	if (is->mime != NULL) {
 		playlist = playlist_list_open_stream_mime(is);
@@ -322,7 +318,8 @@ playlist_suffix_supported(const char *suffix)
 }
 
 struct playlist_provider *
-playlist_list_open_path(const char *path_fs, struct input_stream **is_r)
+playlist_list_open_path(const char *path_fs, GMutex *mutex, GCond *cond,
+			struct input_stream **is_r)
 {
 	GError *error = NULL;
 	const char *suffix;
@@ -335,7 +332,7 @@ playlist_list_open_path(const char *path_fs, struct input_stream **is_r)
 	if (suffix == NULL || !playlist_suffix_supported(suffix))
 		return NULL;
 
-	is = input_stream_open(path_fs, &error);
+	is = input_stream_open(path_fs, mutex, cond, &error);
 	if (is == NULL) {
 		if (error != NULL) {
 			g_warning("%s", error->message);
@@ -345,15 +342,7 @@ playlist_list_open_path(const char *path_fs, struct input_stream **is_r)
 		return NULL;
 	}
 
-	while (!is->ready) {
-		int ret = input_stream_buffer(is, &error);
-		if (ret < 0) {
-			input_stream_close(is);
-			g_warning("%s", error->message);
-			g_error_free(error);
-			return NULL;
-		}
-	}
+	input_stream_lock_wait_ready(is);
 
 	playlist = playlist_list_open_stream_suffix(is, suffix);
 	if (playlist != NULL)

src/playlist_list.h

@@ -20,6 +20,8 @@
 #ifndef MPD_PLAYLIST_LIST_H
 #define MPD_PLAYLIST_LIST_H
 
+#include <glib.h>
+
 #include <stdbool.h>
 
 struct playlist_provider;
@@ -41,7 +43,7 @@ playlist_list_global_finish(void);
  * Opens a playlist by its URI.
  */
 struct playlist_provider *
-playlist_list_open_uri(const char *uri);
+playlist_list_open_uri(const char *uri, GMutex *mutex, GCond *cond);
 
 /**
  * Opens a playlist from an input stream.
@@ -69,6 +71,7 @@ playlist_suffix_supported(const char *suffix);
  * @return a playlist, or NULL on error
  */
 struct playlist_provider *
-playlist_list_open_path(const char *path_fs, struct input_stream **is_r);
+playlist_list_open_path(const char *path_fs, GMutex *mutex, GCond *cond,
+			struct input_stream **is_r);
 
 #endif

src/playlist_mapper.c

@@ -27,15 +27,16 @@
 #include <assert.h>
 
 static struct playlist_provider *
-playlist_open_path(const char *path_fs, struct input_stream **is_r)
+playlist_open_path(const char *path_fs, GMutex *mutex, GCond *cond,
+		   struct input_stream **is_r)
 {
 	struct playlist_provider *playlist;
 
-	playlist = playlist_list_open_uri(path_fs);
+	playlist = playlist_list_open_uri(path_fs, mutex, cond);
 	if (playlist != NULL)
 		*is_r = NULL;
 	else
-		playlist = playlist_list_open_path(path_fs, is_r);
+		playlist = playlist_list_open_path(path_fs, mutex, cond, is_r);
 
 	return playlist;
 }
@@ -44,7 +45,8 @@ playlist_open_path(const char *path_fs, struct input_stream **is_r)
  * Load a playlist from the configured playlist directory.
  */
 static struct playlist_provider *
-playlist_open_in_playlist_dir(const char *uri, struct input_stream **is_r)
+playlist_open_in_playlist_dir(const char *uri, GMutex *mutex, GCond *cond,
+			      struct input_stream **is_r)
 {
 	char *path_fs;
 
@@ -56,7 +58,8 @@ playlist_open_in_playlist_dir(const char *uri, struct input_stream **is_r)
 
 	path_fs = g_build_filename(playlist_directory_fs, uri, NULL);
 
-	struct playlist_provider *playlist = playlist_open_path(path_fs, is_r);
+	struct playlist_provider *playlist =
+		playlist_open_path(path_fs, mutex, cond, is_r);
 	g_free(path_fs);
 
 	return playlist;
@@ -66,7 +69,8 @@ playlist_open_in_playlist_dir(const char *uri, struct input_stream **is_r)
  * Load a playlist from the configured music directory.
  */
 static struct playlist_provider *
-playlist_open_in_music_dir(const char *uri, struct input_stream **is_r)
+playlist_open_in_music_dir(const char *uri, GMutex *mutex, GCond *cond,
+			   struct input_stream **is_r)
 {
 	char *path_fs;
 
@@ -76,25 +80,28 @@ playlist_open_in_music_dir(const char *uri, struct input_stream **is_r)
 	if (path_fs == NULL)
 		return NULL;
 
-	struct playlist_provider *playlist = playlist_open_path(path_fs, is_r);
+	struct playlist_provider *playlist =
+		playlist_open_path(path_fs, mutex, cond, is_r);
 	g_free(path_fs);
 
 	return playlist;
 }
 
 struct playlist_provider *
-playlist_mapper_open(const char *uri, struct input_stream **is_r)
+playlist_mapper_open(const char *uri, GMutex *mutex, GCond *cond,
+		     struct input_stream **is_r)
 {
 	struct playlist_provider *playlist;
 
 	if (spl_valid_name(uri)) {
-		playlist = playlist_open_in_playlist_dir(uri, is_r);
+		playlist = playlist_open_in_playlist_dir(uri, mutex, cond,
+							 is_r);
 		if (playlist != NULL)
 			return playlist;
 	}
 
 	if (uri_safe_local(uri)) {
-		playlist = playlist_open_in_music_dir(uri, is_r);
+		playlist = playlist_open_in_music_dir(uri, mutex, cond, is_r);
 		if (playlist != NULL)
 			return playlist;
 	}

src/playlist_mapper.h

@@ -20,6 +20,8 @@
 #ifndef MPD_PLAYLIST_MAPPER_H
 #define MPD_PLAYLIST_MAPPER_H
 
+#include <glib.h>
+
 struct input_stream;
 
 /**
@@ -31,6 +33,7 @@ struct input_stream;
  * freed
  */
 struct playlist_provider *
-playlist_mapper_open(const char *uri, struct input_stream **is_r);
+playlist_mapper_open(const char *uri, GMutex *mutex, GCond *cond,
+		     struct input_stream **is_r);
 
 #endif

src/playlist_plugin.h

@@ -20,6 +20,8 @@
 #ifndef MPD_PLAYLIST_PLUGIN_H
 #define MPD_PLAYLIST_PLUGIN_H
 
+#include <glib.h>
+
 #include <stdbool.h>
 #include <stddef.h>
 
@@ -64,7 +66,8 @@ struct playlist_plugin {
 	 * Opens the playlist on the specified URI.  This URI has
 	 * either matched one of the schemes or one of the suffixes.
 	 */
-	struct playlist_provider *(*open_uri)(const char *uri);
+	struct playlist_provider *(*open_uri)(const char *uri,
+					      GMutex *mutex, GCond *cond);
 
 	/**
 	 * Opens the playlist in the specified input stream.  It has
@@ -110,9 +113,10 @@ playlist_plugin_finish(const struct playlist_plugin *plugin)
 }
 
 static inline struct playlist_provider *
-playlist_plugin_open_uri(const struct playlist_plugin *plugin, const char *uri)
+playlist_plugin_open_uri(const struct playlist_plugin *plugin, const char *uri,
+			 GMutex *mutex, GCond *cond)
 {
-	return plugin->open_uri(uri);
+	return plugin->open_uri(uri, mutex, cond);
 }
 
 static inline struct playlist_provider *

src/playlist_print.c

@@ -171,10 +171,17 @@ playlist_provider_print(struct client *client, const char *uri,
 bool
 playlist_file_print(struct client *client, const char *uri, bool detail)
 {
+	GMutex *mutex = g_mutex_new();
+	GCond *cond = g_cond_new();
+
 	struct input_stream *is;
-	struct playlist_provider *playlist = playlist_open_any(uri, &is);
-	if (playlist == NULL)
+	struct playlist_provider *playlist =
+		playlist_open_any(uri, mutex, cond, &is);
+	if (playlist == NULL) {
+		g_cond_free(cond);
+		g_mutex_free(mutex);
 		return false;
+	}
 
 	playlist_provider_print(client, uri, playlist, detail);
 	playlist_plugin_close(playlist);
@@ -182,5 +189,8 @@ playlist_file_print(struct client *client, const char *uri, bool detail)
 	if (is != NULL)
 		input_stream_close(is);
 
+	g_cond_free(cond);
+	g_mutex_free(mutex);
+
 	return true;
 }

src/playlist_queue.c

@@ -59,10 +59,17 @@ playlist_open_into_queue(const char *uri,
 			 struct playlist *dest, struct player_control *pc,
 			 bool secure)
 {
+	GMutex *mutex = g_mutex_new();
+	GCond *cond = g_cond_new();
+
 	struct input_stream *is;
-	struct playlist_provider *playlist = playlist_open_any(uri, &is);
-	if (playlist == NULL)
+	struct playlist_provider *playlist =
+		playlist_open_any(uri, mutex, cond, &is);
+	if (playlist == NULL) {
+		g_cond_free(cond);
+		g_mutex_free(mutex);
 		return PLAYLIST_RESULT_NO_SUCH_LIST;
+	}
 
 	enum playlist_result result =
 		playlist_load_into_queue(uri, playlist, dest, pc, secure);
@@ -71,5 +78,8 @@ playlist_open_into_queue(const char *uri,
 	if (is != NULL)
 		input_stream_close(is);
 
+	g_cond_free(cond);
+	g_mutex_free(mutex);
+
 	return result;
 }

src/song_update.c

@@ -131,6 +131,9 @@ song_file_update(struct song *song)
 
 	song->mtime = st.st_mtime;
 
+	GMutex *mutex = NULL;
+	GCond *cond;
+
 	do {
 		/* load file tag */
 		song->tag = decoder_plugin_tag_dup(plugin, path_fs);
@@ -141,8 +144,12 @@ song_file_update(struct song *song)
 		if (plugin->stream_tag != NULL) {
 			/* open the input_stream (if not already
 			   open) */
-			if (is == NULL)
-				is = input_stream_open(path_fs, NULL);
+			if (is == NULL) {
+				mutex = g_mutex_new();
+				cond = g_cond_new();
+				is = input_stream_open(path_fs, mutex, cond,
+						       NULL);
+			}
 
 			/* now try the stream_tag() method */
 			if (is != NULL) {
@@ -151,7 +158,7 @@ song_file_update(struct song *song)
 				if (song->tag != NULL)
 					break;
 
-				input_stream_seek(is, 0, SEEK_SET, NULL);
+				input_stream_lock_seek(is, 0, SEEK_SET, NULL);
 			}
 		}
 
@@ -161,6 +168,11 @@ song_file_update(struct song *song)
 	if (is != NULL)
 		input_stream_close(is);
 
+	if (mutex != NULL) {
+		g_cond_free(cond);
+		g_mutex_free(mutex);
+	}
+
 	if (song->tag != NULL && tag_is_empty(song->tag))
 		song->tag = tag_fallback(path_fs, song->tag);
 

src/text_input_stream.c

@@ -68,8 +68,8 @@ text_input_stream_read(struct text_input_stream *tis)
 	do {
 		dest = fifo_buffer_write(tis->buffer, &length);
 		if (dest != NULL) {
-			nbytes = input_stream_read(tis->is, dest, length,
-						   &error);
+			nbytes = input_stream_lock_read(tis->is, dest, length,
+							&error);
 			if (nbytes > 0)
 				fifo_buffer_append(tis->buffer, nbytes);
 			else if (error != NULL) {

test/dump_playlist.c

@@ -92,11 +92,14 @@ int main(int argc, char **argv)
 
 	/* open the playlist */
 
-	playlist = playlist_list_open_uri(uri);
+	GMutex *mutex = g_mutex_new();
+	GCond *cond = g_cond_new();
+
+	playlist = playlist_list_open_uri(uri, mutex, cond);
 	if (playlist == NULL) {
 		/* open the stream and wait until it becomes ready */
 
-		is = input_stream_open(uri, &error);
+		is = input_stream_open(uri, mutex, cond, &error);
 		if (is == NULL) {
 			if (error != NULL) {
 				g_warning("%s", error->message);
@@ -106,19 +109,7 @@ int main(int argc, char **argv)
 			return 2;
 		}
 
-		while (!is->ready) {
-			int ret = input_stream_buffer(is, &error);
-			if (ret < 0) {
-				/* error */
-				g_warning("%s", error->message);
-				g_error_free(error);
-				return 2;
-			}
-
-			if (ret == 0)
-				/* nothing was buffered - wait */
-				g_usleep(10000);
-		}
+		input_stream_lock_wait_ready(is);
 
 		/* open the playlist */
 
@@ -157,6 +148,10 @@ int main(int argc, char **argv)
 	playlist_plugin_close(playlist);
 	if (is != NULL)
 		input_stream_close(is);
+
+	g_cond_free(cond);
+	g_mutex_free(mutex);
+
 	playlist_list_global_finish();
 	input_stream_global_finish();
 	io_thread_deinit();

test/read_tags.c

@@ -91,7 +91,7 @@ decoder_read(G_GNUC_UNUSED struct decoder *decoder,
 	     struct input_stream *is,
 	     void *buffer, size_t length)
 {
-	return input_stream_read(is, buffer, length, NULL);
+	return input_stream_lock_read(is, buffer, length, NULL);
 }
 
 void
@@ -193,7 +193,11 @@ int main(int argc, char **argv)
 
 	tag = decoder_plugin_tag_dup(plugin, path);
 	if (tag == NULL && plugin->stream_tag != NULL) {
-		struct input_stream *is = input_stream_open(path, &error);
+		GMutex *mutex = g_mutex_new();
+		GCond *cond = g_cond_new();
+
+		struct input_stream *is =
+			input_stream_open(path, mutex, cond, &error);
 
 		if (is == NULL) {
 			g_printerr("Failed to open %s: %s\n",
@@ -204,6 +208,9 @@ int main(int argc, char **argv)
 
 		tag = decoder_plugin_stream_tag(plugin, is);
 		input_stream_close(is);
+
+		g_cond_free(cond);
+		g_mutex_free(mutex);
 	}
 
 	decoder_plugin_deinit_all();

test/run_decoder.c

@@ -112,7 +112,7 @@ decoder_read(G_GNUC_UNUSED struct decoder *decoder,
 	     struct input_stream *is,
 	     void *buffer, size_t length)
 {
-	return input_stream_read(is, buffer, length, NULL);
+	return input_stream_lock_read(is, buffer, length, NULL);
 }
 
 void
@@ -209,8 +209,11 @@ int main(int argc, char **argv)
 		decoder_plugin_file_decode(decoder.plugin, &decoder,
 					   decoder.uri);
 	} else if (decoder.plugin->stream_decode != NULL) {
+		GMutex *mutex = g_mutex_new();
+		GCond *cond = g_cond_new();
+
 		struct input_stream *is =
-			input_stream_open(decoder.uri, &error);
+			input_stream_open(decoder.uri, mutex, cond, &error);
 		if (is == NULL) {
 			if (error != NULL) {
 				g_warning("%s", error->message);
@@ -224,6 +227,9 @@ int main(int argc, char **argv)
 		decoder_plugin_stream_decode(decoder.plugin, &decoder, is);
 
 		input_stream_close(is);
+
+		g_cond_free(cond);
+		g_mutex_free(mutex);
 	} else {
 		g_printerr("Decoder plugin is not usable\n");
 		return 1;

test/run_input.c

@@ -53,20 +53,17 @@ dump_input_stream(struct input_stream *is)
 	size_t num_read;
 	ssize_t num_written;
 
+	g_mutex_lock(is->mutex);
+
 	/* wait until the stream becomes ready */
 
-	while (!is->ready) {
-		int ret = input_stream_buffer(is, &error);
-		if (ret < 0) {
-			/* error */
-			g_warning("%s", error->message);
-			g_error_free(error);
-			return 2;
-		}
+	input_stream_wait_ready(is);
 
-		if (ret == 0)
-			/* nothing was buffered - wait */
-			g_usleep(10000);
+	if (!input_stream_check(is, &error)) {
+		g_warning("%s", error->message);
+		g_error_free(error);
+		g_mutex_unlock(is->mutex);
+		return EXIT_FAILURE;
 	}
 
 	/* print meta data */
@@ -103,9 +100,12 @@ dump_input_stream(struct input_stream *is)
 	if (!input_stream_check(is, &error)) {
 		g_warning("%s", error->message);
 		g_error_free(error);
+		g_mutex_unlock(is->mutex);
 		return EXIT_FAILURE;
 	}
 
+	g_mutex_unlock(is->mutex);
+
 	return 0;
 }
 
@@ -149,7 +149,10 @@ int main(int argc, char **argv)
 
 	/* open the stream and dump it */
 
-	is = input_stream_open(argv[1], &error);
+	GMutex *mutex = g_mutex_new();
+	GCond *cond = g_cond_new();
+
+	is = input_stream_open(argv[1], mutex, cond, &error);
 	if (is != NULL) {
 		ret = dump_input_stream(is);
 		input_stream_close(is);
@@ -162,6 +165,9 @@ int main(int argc, char **argv)
 		ret = 2;
 	}
 
+	g_cond_free(cond);
+	g_mutex_free(mutex);
+
 	/* deinitialize everything */
 
 	input_stream_global_finish();