metadata: Add metadata API

Metadata allows apps to attach properties to objects that can be
read by other apps.
Not complete yet, properties should be removed when the object is
removed.

src/modules/module-metadata.c

@@ -0,0 +1,185 @@
+/* PipeWire
+ *
+ * Copyright © 2019 Wim Taymans
+ *
+ * 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 <string.h>
+#include <stdio.h>
+#include <errno.h>
+#include <dlfcn.h>
+
+#include "config.h"
+
+#include <spa/utils/result.h>
+
+#include <pipewire/pipewire.h>
+#include <extensions/metadata.h>
+
+#define NAME "metadata"
+
+static const struct spa_dict_item module_props[] = {
+	{ PW_KEY_MODULE_AUTHOR, "Wim Taymans <wim.taymans@gmail.com>" },
+	{ PW_KEY_MODULE_DESCRIPTION, "Allow clients to create metadata store" },
+	{ PW_KEY_MODULE_VERSION, PACKAGE_VERSION },
+};
+
+
+void * pw_metadata_new(struct pw_core *core, struct pw_resource *resource,
+		   struct pw_properties *properties);
+
+struct pw_proxy *pw_remote_metadata_export(struct pw_remote *remote,
+		uint32_t type, struct pw_properties *props, void *object, size_t user_data_size);
+
+int pw_protocol_native_ext_metadata_init(struct pw_core *core);
+
+struct factory_data {
+	struct pw_factory *this;
+
+	struct pw_module *module;
+	struct spa_hook module_listener;
+
+	struct pw_export_type export_metadata;
+};
+
+static void *create_object(void *_data,
+			   struct pw_resource *resource,
+			   uint32_t type,
+			   uint32_t version,
+			   struct pw_properties *properties,
+			   uint32_t new_id)
+{
+	void *result;
+	struct pw_resource *metadata_resource;
+	struct pw_client *client = pw_resource_get_client(resource);
+	int res;
+
+	metadata_resource = pw_resource_new(client, new_id, PW_PERM_RWX, type, version, 0);
+	if (metadata_resource == NULL) {
+		res = -errno;
+		goto error_resource;
+	}
+
+	pw_log_debug(".");
+	result = pw_metadata_new(pw_client_get_core(client), metadata_resource, properties);
+	if (result == NULL) {
+		res = -errno;
+		goto error_node;
+	}
+	pw_log_debug(".");
+	return result;
+
+error_resource:
+	pw_log_error("can't create resource: %s", spa_strerror(res));
+	pw_resource_error(resource, res, "can't create resource: %s", spa_strerror(res));
+	goto error_exit;
+error_node:
+	pw_log_error("can't create metadata: %s", spa_strerror(res));
+	pw_resource_error(resource, res, "can't create metadata: %s", spa_strerror(res));
+	goto error_exit_free;
+
+error_exit_free:
+	pw_resource_destroy(metadata_resource);
+error_exit:
+	errno = -res;
+	return NULL;
+}
+
+static const struct pw_factory_implementation impl_factory = {
+	PW_VERSION_FACTORY_IMPLEMENTATION,
+	.create_object = create_object,
+};
+
+static void module_destroy(void *data)
+{
+	struct factory_data *d = data;
+
+	spa_hook_remove(&d->module_listener);
+
+	spa_list_remove(&d->export_metadata.link);
+
+	pw_factory_destroy(d->this);
+}
+
+static void module_registered(void *data)
+{
+	struct factory_data *d = data;
+	struct pw_module *module = d->module;
+	struct pw_factory *factory = d->this;
+	struct spa_dict_item items[1];
+	char id[16];
+	int res;
+
+	snprintf(id, sizeof(id), "%d", pw_global_get_id(pw_module_get_global(module)));
+	items[0] = SPA_DICT_ITEM_INIT(PW_KEY_MODULE_ID, id);
+	pw_factory_update_properties(factory, &SPA_DICT_INIT(items, 1));
+
+	if ((res = pw_factory_register(factory, NULL)) < 0) {
+		pw_log_error(NAME" %p: can't register factory: %s", factory, spa_strerror(res));
+	}
+}
+
+static const struct pw_module_events module_events = {
+	PW_VERSION_MODULE_EVENTS,
+	.destroy = module_destroy,
+	.registered = module_registered,
+};
+
+SPA_EXPORT
+int pipewire__module_init(struct pw_module *module, const char *args)
+{
+	struct pw_core *core = pw_module_get_core(module);
+	struct pw_factory *factory;
+	struct factory_data *data;
+	int res;
+
+	if ((res = pw_protocol_native_ext_metadata_init(core)) < 0)
+		return res;
+
+	factory = pw_factory_new(core,
+				 "metadata",
+				 PW_TYPE_INTERFACE_Metadata,
+				 PW_VERSION_METADATA,
+				 NULL,
+				 sizeof(*data));
+	if (factory == NULL)
+		return -errno;
+
+	data = pw_factory_get_user_data(factory);
+	data->this = factory;
+	data->module = module;
+
+	pw_log_debug("module %p: new", module);
+
+	pw_factory_set_implementation(factory,
+				      &impl_factory,
+				      data);
+
+	data->export_metadata.type = PW_TYPE_INTERFACE_Metadata;
+	data->export_metadata.func = pw_remote_metadata_export;
+	pw_core_register_export_type(core, &data->export_metadata);
+
+	pw_module_add_listener(module, &data->module_listener, &module_events, data);
+
+	pw_module_update_properties(module, &SPA_DICT_INIT_ARRAY(module_props));
+
+	return 0;
+}