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);
+}