pulse-server: pass FILE to message handlers

Use `open_memstream()` to create a FILE stream and pass
that to message handlers to store their response. This allows
the `open_memstream()` calls and related error handling to be
removed from the message handlers.

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

@@ -9,6 +9,8 @@
 extern "C" {
 #endif
 
+#include <stdio.h>
+
 #include <spa/utils/defs.h>
 #include <spa/pod/pod.h>
 
@@ -69,7 +71,7 @@ struct pw_manager_object {
 	struct pw_proxy *proxy;
 	char *message_object_path;
 	int (*message_handler)(struct pw_manager *m, struct pw_manager_object *o,
-	                       const char *message, const char *params, char **response);
+	                       const char *message, const char *params, FILE *response);
 
 	void *info;
 	struct spa_param_info *params;

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

@@ -3,6 +3,7 @@
 /* SPDX-License-Identifier: MIT */
 
 #include <stdint.h>
+#include <stdio.h>
 
 #include <regex.h>
 
@@ -20,7 +21,7 @@
 #include "manager.h"
 #include "message-handler.h"
 
-static int bluez_card_object_message_handler(struct pw_manager *m, struct pw_manager_object *o, const char *message, const char *params, char **response)
+static int bluez_card_object_message_handler(struct pw_manager *m, struct pw_manager_object *o, const char *message, const char *params, FILE *response)
 {
 	struct transport_codec_info codecs[64];
 	uint32_t n_codecs, active;
@@ -60,66 +61,53 @@ static int bluez_card_object_message_handler(struct pw_manager *m, struct pw_man
 
 		pw_device_set_param((struct pw_device *)o->proxy,
 				SPA_PARAM_Props, 0, param);
-		return 0;
 	} else if (spa_streq(message, "list-codecs")) {
 		uint32_t i;
-		FILE *r;
-		size_t size;
 		bool first = true;
 
-		r = open_memstream(response, &size);
+		fputc('[', response);
-		if (r == NULL)
-			return -errno;
-
-		fputc('[', r);
 		for (i = 0; i < n_codecs; ++i) {
 			const char *desc = codecs[i].description;
-			fprintf(r, "%s{\"name\":\"%d\",\"description\":\"%s\"}",
+			fprintf(response, "%s{\"name\":\"%d\",\"description\":\"%s\"}",
 					first ? "" : ",",
 					(int)codecs[i].id, desc ? desc : "Unknown");
 			first = false;
 		}
-		fputc(']', r);
+		fputc(']', response);
-
-		return fclose(r) ? -errno : 0;
 	} else if (spa_streq(message, "get-codec")) {
 		if (active == SPA_ID_INVALID)
-			*response = strdup("null");
+			fputs("null", response);
 		else
-			*response = spa_aprintf("\"%d\"", (int)codecs[active].id);
+			fprintf(response, "\"%d\"", (int) codecs[active].id);
-		return *response ? 0 : -ENOMEM;
+	} else {
+		return -ENOSYS;
 	}
 
-	return -ENOSYS;
+	return 0;
 }
 
-static int core_object_message_handler(struct pw_manager *m, struct pw_manager_object *o, const char *message, const char *params, char **response)
+static int core_object_message_handler(struct pw_manager *m, struct pw_manager_object *o, const char *message, const char *params, FILE *response)
 {
 	pw_log_debug(": core %p object message:'%s' params:'%s'", o, message, params);
 
 	if (spa_streq(message, "list-handlers")) {
-		FILE *r;
-		size_t size;
 		bool first = true;
 
-		r = open_memstream(response, &size);
+		fputc('[', response);
-		if (r == NULL)
-			return -errno;
-
-		fputc('[', r);
 		spa_list_for_each(o, &m->object_list, link) {
 			if (o->message_object_path) {
-				fprintf(r, "%s{\"name\":\"%s\",\"description\":\"%s\"}",
+				fprintf(response, "%s{\"name\":\"%s\",\"description\":\"%s\"}",
 						first ? "" : ",",
 						o->message_object_path, o->type);
 				first = false;
 			}
 		}
-		fputc(']', r);
+		fputc(']', response);
-		return fclose(r) ? -errno : 0;
+	} else {
+		return -ENOSYS;
 	}
 
-	return -ENOSYS;
+	return 0;
 }
 
 void register_object_message_handlers(struct pw_manager_object *o)

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

@@ -5099,12 +5099,12 @@ static int do_send_object_message(struct client *client, uint32_t command, uint3
 {
 	struct impl *impl = client->impl;
 	struct pw_manager *manager = client->manager;
-	const char *object_path = NULL;
+	const char *object_path = NULL, *message = NULL, *params = NULL;
-	const char *message = NULL;
-	const char *params = NULL;
-	struct message *reply;
 	struct pw_manager_object *o;
-	int len = 0;
+	char *response_str = NULL;
+	size_t path_len = 0, response_len = 0;
+	FILE *response;
+	int res = -ENOENT;
 
 	if (message_get(m,
 			TAG_STRING, &object_path,
@@ -5120,36 +5120,44 @@ static int do_send_object_message(struct client *client, uint32_t command, uint3
 	if (object_path == NULL || message == NULL)
 		return -EINVAL;
 
-	len = strlen(object_path);
+	path_len = strlen(object_path);
-	if (len > 0 && object_path[len - 1] == '/')
+	if (path_len > 0 && object_path[path_len - 1] == '/')
-		--len;
+		--path_len;
-
+	spa_autofree char *path = strndup(object_path, path_len);
-	spa_autofree char *path = strndup(object_path, len);
 	if (path == NULL)
 		return -ENOMEM;
 
-	spa_autofree char *response = NULL;
-	int res = -ENOENT;
-
 	spa_list_for_each(o, &manager->object_list, link) {
-		if (spa_streq(o->message_object_path, path)) {
+		if (spa_streq(o->message_object_path, path))
-			if (o->message_handler)
-				res = o->message_handler(manager, o, message, params, &response);
-			else
-				res = -ENOSYS;
 			break;
-		}
+	}
+	if (spa_list_is_end(o, &manager->object_list, link))
+		return -ENOENT;
+
+	if (o->message_handler == NULL)
+		return -ENOSYS;
+
+	response = open_memstream(&response_str, &response_len);
+	if (response == NULL)
+		return -errno;
+
+	res = o->message_handler(manager, o, message, params, response);
+
+	if (fclose(response))
+		return -errno;
+
+	pw_log_debug("%p: object message response: (%d) '%s'", impl, res, response_str ? response_str : "<null>");
+
+	if (res >= 0) {
+		struct message *reply = reply_new(client, tag);
+
+		message_put(reply, TAG_STRING, response_str, TAG_INVALID);
+		res = client_queue_message(client, reply);
 	}
 
-	if (res < 0)
+	free(response_str);
-		return res;
 
-	pw_log_debug("%p: object message response:'%s'", impl, response ? response : "<null>");
+	return res;
-
-	reply = reply_new(client, tag);
-	message_put(reply, TAG_STRING, response, TAG_INVALID);
-
-	return client_queue_message(client, reply);
 }
 
 static int do_error_access(struct client *client, uint32_t command, uint32_t tag, struct message *m)