pulse-server: add module-always-sink

It just loads/unloads libpipewire-module-fallback-sink.

src/modules/meson.build

@@ -239,6 +239,7 @@ pipewire_module_protocol_pulse_sources = [
   'module-protocol-pulse/stream.c',
   'module-protocol-pulse/utils.c',
   'module-protocol-pulse/volume.c',
+  'module-protocol-pulse/modules/module-always-sink.c',
   'module-protocol-pulse/modules/module-combine-sink.c',
   'module-protocol-pulse/modules/module-echo-cancel.c',
   'module-protocol-pulse/modules/module-ladspa-sink.c',

src/modules/module-protocol-pulse/module.c

@@ -260,6 +260,7 @@ bool module_args_parse_bool(const char *v)
 #include "modules/registry.h"
 
 static const struct module_info module_list[] = {
+	{ "module-always-sink", create_module_always_sink, },
 	{ "module-combine-sink", create_module_combine_sink, },
 	{ "module-echo-cancel", create_module_echo_cancel, },
 	{ "module-ladspa-sink", create_module_ladspa_sink, },

src/modules/module-protocol-pulse/modules/module-always-sink.c

@@ -0,0 +1,136 @@
+/* PipeWire
+ *
+ * Copyright © 2022 Wim Taymans <wim.taymans@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <pipewire/pipewire.h>
+
+#include "../module.h"
+
+#define NAME "always-sink"
+
+PW_LOG_TOPIC_STATIC(mod_topic, "mod." NAME);
+#define PW_LOG_TOPIC_DEFAULT mod_topic
+
+struct module_always_sink_data {
+	struct module *module;
+
+	struct pw_impl_module *mod;
+	struct spa_hook mod_listener;
+};
+
+static void module_destroy(void *data)
+{
+	struct module_always_sink_data *d = data;
+	spa_hook_remove(&d->mod_listener);
+	d->mod = NULL;
+	module_schedule_unload(d->module);
+}
+
+static const struct pw_impl_module_events module_events = {
+	PW_VERSION_IMPL_MODULE_EVENTS,
+	.destroy = module_destroy
+};
+
+static int module_always_sink_load(struct client *client, struct module *module)
+{
+	struct module_always_sink_data *data = module->user_data;
+	FILE *f;
+	char *args;
+	const char *str;
+	size_t size;
+
+	f = open_memstream(&args, &size);
+	fprintf(f, "{");
+	if ((str = pw_properties_get(module->props, "sink_name")) != NULL)
+		fprintf(f, " sink.name = \"%s\"", str);
+	fprintf(f, " }");
+	fclose(f);
+
+	data->mod = pw_context_load_module(module->impl->context,
+			"libpipewire-module-fallback-sink",
+			args, NULL);
+	free(args);
+
+	if (data->mod == NULL)
+		return -errno;
+
+	pw_impl_module_add_listener(data->mod,
+			&data->mod_listener,
+			&module_events, data);
+	return 0;
+}
+
+static int module_always_sink_unload(struct module *module)
+{
+	struct module_always_sink_data *d = module->user_data;
+
+	if (d->mod) {
+		spa_hook_remove(&d->mod_listener);
+		pw_impl_module_destroy(d->mod);
+		d->mod = NULL;
+	}
+	return 0;
+}
+
+static const struct module_methods module_always_sink_methods = {
+	VERSION_MODULE_METHODS,
+	.load = module_always_sink_load,
+	.unload = module_always_sink_unload,
+};
+
+static const struct spa_dict_item module_always_sink_info[] = {
+	{ PW_KEY_MODULE_AUTHOR, "Pauli Virtanen <pav@iki.fi>" },
+	{ PW_KEY_MODULE_DESCRIPTION, "Always keeps at least one sink loaded even if it's a null one" },
+	{ PW_KEY_MODULE_USAGE,  "sink_name=<name of sink>" },
+	{ PW_KEY_MODULE_VERSION, PACKAGE_VERSION },
+};
+
+struct module *create_module_always_sink(struct impl *impl, const char *argument)
+{
+	struct module *module;
+	struct pw_properties *props = NULL;
+	int res;
+
+	PW_LOG_TOPIC_INIT(mod_topic);
+
+	props = pw_properties_new_dict(&SPA_DICT_INIT_ARRAY(module_always_sink_info));
+	if (props == NULL) {
+		res = -EINVAL;
+		goto out;
+	}
+	if (argument)
+		module_args_add_props(props, argument);
+
+	module = module_new(impl, &module_always_sink_methods, sizeof(struct module_always_sink_data));
+	if (module == NULL) {
+		res = -errno;
+		goto out;
+	}
+	module->props = props;
+
+	return module;
+out:
+	pw_properties_free(props);
+	errno = -res;
+	return NULL;
+}

src/modules/module-protocol-pulse/modules/registry.h

@@ -28,6 +28,7 @@
 
 struct impl;
 
+struct module *create_module_always_sink(struct impl *impl, const char *argument);
 struct module *create_module_combine_sink(struct impl *impl, const char *argument);
 struct module *create_module_echo_cancel(struct impl *impl, const char *argument);
 struct module *create_module_ladspa_sink(struct impl *impl, const char *argument);