pulse-server: Implement module load and unload

Implement a minimal version of the LOAD_MODULE and UNLOAD_MODULE
stream commands. The only supported module for now is the null
sink.

Modules are stored on a per-client bases, so that when clients
are disconnected, the modules they loaded is removed too.

This is enough to allow GNOME Network Displays to register a sink.

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

@@ -0,0 +1,203 @@
+/* PipeWire
+ *
+ * Copyright © 2020 Georges Basile Stavracas Neto
+ *
+ * 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.
+ */
+
+struct module;
+
+typedef void (*module_loaded_cb)(struct module *module, int error, void *userdata);
+
+struct module_events {
+	void (*removed) (void *data, struct module *module);
+	void (*error) (void *data);
+};
+
+struct module {
+	struct spa_list link;           /**< link in client modules */
+	struct pw_proxy *proxy;
+	struct spa_hook listener;
+	struct client *client;
+	struct message *reply;
+
+	module_loaded_cb cb;
+	void *cb_data;
+
+	struct module_events *events;
+	void *events_data;
+
+	uint32_t idx;
+};
+
+static void module_proxy_removed(void *data)
+{
+	struct module *module = data;
+
+	if (module->events)
+		module->events->removed(module->events_data, module);
+
+	pw_proxy_destroy(module->proxy);
+}
+
+static void module_proxy_destroy(void *data)
+{
+	struct module *module = data;
+	pw_log_info(NAME" %p: proxy %p destroy", module, module->proxy);
+	spa_hook_remove(&module->listener);
+	free(module);
+}
+
+static void module_proxy_bound(void *data, uint32_t global_id)
+{
+	struct module *module = data;
+
+	pw_log_info(NAME" module %p proxy %p bound", module, module->proxy);
+
+	module->idx = global_id;
+
+	if (module->cb)
+		module->cb(module, 0, module->cb_data);
+}
+
+static void module_proxy_error(void *data, int seq, int res, const char *message)
+{
+	struct module *module = data;
+	struct impl *impl = module->client->impl;
+
+	pw_log_info(NAME" %p module %p error %d", impl, module, res);
+
+	module->idx = 0;
+
+	if (module->cb)
+		module->cb(module, res, module->cb_data);
+
+	pw_proxy_destroy(module->proxy);
+}
+
+static int load_null_sink_module(struct client *client, struct module *module, struct pw_properties *props)
+{
+	static const struct pw_proxy_events proxy_events = {
+		.removed = module_proxy_removed,
+		.bound = module_proxy_bound,
+		.error = module_proxy_error,
+		.destroy = module_proxy_destroy,
+	};
+
+	module->proxy = pw_core_create_object(client->core,
+                                "adapter",
+                                PW_TYPE_INTERFACE_Node,
+                                PW_VERSION_NODE,
+                                props ? &props->dict : NULL, 0);
+	if (module->proxy == NULL)
+		return -errno;
+
+	pw_proxy_add_listener(module->proxy, &module->listener, &proxy_events, module);
+	return 0;
+}
+
+static void add_props(struct pw_properties *props, const char *str)
+{
+	char *s = strdup(str), *p = s, *e, f;
+	const char *k, *v;
+
+	while (*p) {
+		e = strchr(p, '=');
+		if (e == NULL)
+			break;
+		*e = '\0';
+		k = p;
+		p = e+1;
+
+		if (*p == '\"') {
+			p++;
+			f = '\"';
+		} else {
+			f = ' ';
+		}
+		e = strchr(p, f);
+		if (e == NULL)
+			break;
+		*e = '\0';
+		v = p;
+		p = e + 1;
+		pw_properties_set(props, k, v);
+	}
+	free(s);
+}
+
+static int load_module(struct client *client, const char *name, const char *argument, module_loaded_cb cb, void *data)
+{
+	struct module *module = NULL;
+	int res = -ENOENT;
+
+	if (strcmp(name, "module-null-sink") == 0) {
+		struct pw_properties *props = NULL;
+		const char *str;
+
+		props = pw_properties_new_string(argument);
+		if (props == NULL) {
+			res = -EINVAL;
+			goto out;
+		}
+		if ((str = pw_properties_get(props, "sink_name")) != NULL) {
+			pw_properties_set(props, "node.name", str);
+			pw_properties_set(props, "sink_name", NULL);
+		} else {
+			pw_properties_set(props, "node.name", "null");
+		}
+		if ((str = pw_properties_get(props, "sink_properties")) != NULL) {
+			add_props(props, str);
+			pw_properties_set(props, "sink_properties", NULL);
+		}
+		if ((str = pw_properties_get(props, "device.description")) != NULL) {
+			pw_properties_set(props, "node.description", str);
+			pw_properties_set(props, "device.description", NULL);
+		}
+		pw_properties_set(props, "factory.name", "support.null-audio-sink");
+
+		module = calloc(1, sizeof(struct module));
+		module->client = client;
+		module->cb = cb;
+		module->cb_data = data;
+
+		if ((res = load_null_sink_module(client, module, props)) < 0)
+			goto out;
+	}
+
+out:
+	if (res < 0) {
+		free(module);
+		module = NULL;
+	}
+
+	return res;
+}
+
+static void module_add_listener(struct module *module, struct module_events *events, void *userdata)
+{
+	module->events = events;
+	module->events_data = userdata;
+}
+
+static void unload_module(struct module *module)
+{
+	pw_proxy_destroy(module->proxy);
+}

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

@@ -111,6 +111,7 @@ struct client {
 	struct spa_list out_messages;
 
 	struct spa_list operations;
+	struct spa_list modules;
 
 	unsigned int disconnecting:1;
 };
@@ -190,6 +191,7 @@ struct impl {
 };
 
 #include "collect.c"
+#include "module.c"
 
 struct command {
 	const char *name;
@@ -3694,6 +3696,117 @@ static int do_kill(struct client *client, uint32_t command, uint32_t tag, struct
 	return reply_simple_ack(client, tag);
 }
 
+struct load_module_data {
+	struct client *client;
+	uint32_t tag;
+};
+
+static struct load_module_data *load_module_data_new(struct client *client, uint32_t tag)
+{
+	struct load_module_data *data = calloc(1, sizeof(struct load_module_data));
+	data->client = client;
+	data->tag = tag;
+	return data;
+}
+
+static void on_module_removed(void *data, struct module *module)
+{
+	struct client *client = data;
+
+	pw_log_info(NAME" %p: client %p: module %d unloaded", client->impl, client, module->idx);
+
+	spa_list_remove(&module->link);
+}
+
+static void on_module_error(void *data)
+{
+	struct client *client = data;
+
+	pw_log_info(NAME" %p: client %p: error loading module", client->impl, client);
+}
+
+static void on_module_loaded(struct module *module, int error, void *data)
+{
+	struct load_module_data *d = data;
+	struct message *reply;
+	struct client *client;
+	uint32_t tag;
+	int res;
+
+	struct module_events listener = {
+		on_module_removed,
+		on_module_error,
+	};
+
+	client = d->client;
+	tag = d->tag;
+	free(d);
+
+	if (error < 0) {
+		pw_log_warn(NAME" %p: client %p: error loading module", client->impl, client);
+		reply_error (client, COMMAND_LOAD_MODULE, tag, error);
+		return;
+	}
+
+	spa_list_append(&client->modules, &module->link);
+	module_add_listener(module, &listener, client);
+
+	pw_log_info(NAME" %p: client %p: module %d loaded", client->impl, client, module->idx);
+
+	reply = reply_new(client, tag);
+	message_put(reply,
+		TAG_U32, module->idx,
+		TAG_INVALID);
+	if ((res = send_message(client, reply)) < 0)
+		reply_error(client, COMMAND_LOAD_MODULE, tag, res);
+}
+
+static int do_load_module(struct client *client, uint32_t command, uint32_t tag, struct message *m)
+{
+	struct load_module_data *data;
+	struct impl *impl = client->impl;
+	const char *name, *argument;
+	int res;
+
+	if ((res = message_get(m,
+			TAG_STRING, &name,
+			TAG_STRING, &argument,
+			TAG_INVALID)) < 0)
+		return -EPROTO;
+
+	pw_log_info(NAME" %p: %s name:%s argument:%s", impl, commands[command].name, name, argument);
+
+	data = load_module_data_new(client, tag);
+	res = load_module(client, name, argument, on_module_loaded, data);
+	return res;
+}
+
+static int do_unload_module(struct client *client, uint32_t command, uint32_t tag, struct message *m)
+{
+	struct impl *impl = client->impl;
+	struct module *module;
+	uint32_t module_idx;
+	int res;
+
+	if ((res = message_get(m,
+			TAG_U32, &module_idx,
+			TAG_INVALID)) < 0)
+		return -EPROTO;
+
+	pw_log_info(NAME" %p: %s id:%u", impl, commands[command].name, module_idx);
+
+	spa_list_for_each(module, &client->modules, link) {
+		if (module->idx == module_idx)
+			break;
+	}
+
+	if (module == NULL)
+		return -ENOENT;
+
+	unload_module(module);
+	return reply_simple_ack(client, tag);
+}
+
 static const struct command commands[COMMAND_MAX] =
 {
 	[COMMAND_ERROR] = { "ERROR", },
@@ -3761,8 +3874,8 @@ static const struct command commands[COMMAND_MAX] =
 	[COMMAND_KILL_SINK_INPUT] = { "KILL_SINK_INPUT", do_kill, },
 	[COMMAND_KILL_SOURCE_OUTPUT] = { "KILL_SOURCE_OUTPUT", do_kill, },
 
-	[COMMAND_LOAD_MODULE] = { "LOAD_MODULE", do_error_access, },
+	[COMMAND_LOAD_MODULE] = { "LOAD_MODULE", do_load_module, },
-	[COMMAND_UNLOAD_MODULE] = { "UNLOAD_MODULE", do_error_access, },
+	[COMMAND_UNLOAD_MODULE] = { "UNLOAD_MODULE", do_unload_module, },
 
 	/* Obsolete */
 	[COMMAND_ADD_AUTOLOAD___OBSOLETE] = { "ADD_AUTOLOAD___OBSOLETE", do_error_access, },
@@ -3865,6 +3978,7 @@ static void client_free(struct client *client)
 {
 	struct impl *impl = client->impl;
 	struct message *msg;
+	struct module *module, *tmp;
 
 	pw_log_info(NAME" %p: client %p free", impl, client);
 	spa_list_remove(&client->link);
@@ -3872,6 +3986,8 @@ static void client_free(struct client *client)
 	pw_map_for_each(&client->streams, client_free_stream, client);
 	pw_map_clear(&client->streams);
 
+	spa_list_for_each_safe(module, tmp, &client->modules, link)
+		unload_module(module);
 	spa_list_consume(msg, &client->free_messages, link)
 		message_free(client, msg, true, true);
 	spa_list_consume(msg, &client->out_messages, link)
@@ -4124,6 +4240,7 @@ on_connect(void *data, int fd, uint32_t mask)
 	spa_list_init(&client->free_messages);
 	spa_list_init(&client->out_messages);
 	spa_list_init(&client->operations);
+	spa_list_init(&client->modules);
 
 	client->props = pw_properties_new(
 			PW_KEY_CLIENT_API, "pipewire-pulse",