xC: fix crash with too many topic formatting items

Manually constructed formatters have no sentinel value.

This is a one-line change in relay_prepare_channel_buffer_update(),
however the whole block of "Relay output" code has been moved down,
resolving one TODO and rendering two function prototypes unnecessary.

1 files changed, 381 insertions, 384 deletions

diff --git a/xC.c b/xC.c
index fde1874..21dd846 100644
--- a/xC.c
+++ b/xC.c
@@ -2895,390 +2895,6 @@ serialize_configuration (struct config_item *root, struct str *output)
 	config_item_write (root, true, output);
 }
 
-// --- Relay output ------------------------------------------------------------
-
-static void
-client_kill (struct client *c)
-{
-	struct app_context *ctx = c->ctx;
-	poller_fd_reset (&c->socket_event);
-	xclose (c->socket_fd);
-	c->socket_fd = -1;
-
-	LIST_UNLINK (ctx->clients, c);
-	client_destroy (c);
-}
-
-static void
-client_update_poller (struct client *c, const struct pollfd *pfd)
-{
-	int new_events = POLLIN;
-	if (c->write_buffer.len)
-		new_events |= POLLOUT;
-
-	hard_assert (new_events != 0);
-	if (!pfd || pfd->events != new_events)
-		poller_fd_set (&c->socket_event, new_events);
-}
-
-// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-
-static void
-relay_send (struct client *c)
-{
-	struct relay_event_message *m = &c->ctx->relay_message;
-	m->event_seq = c->event_seq++;
-
-	// TODO: Also don't try sending anything if half-closed.
-	if (!c->initialized || c->socket_fd == -1)
-		return;
-
-	// liberty has msg_{reader,writer} already, but they use 8-byte lengths.
-	size_t frame_len_pos = c->write_buffer.len, frame_len = 0;
-	str_pack_u32 (&c->write_buffer, 0);
-	if (!relay_event_message_serialize (m, &c->write_buffer)
-	 || (frame_len = c->write_buffer.len - frame_len_pos - 4) > UINT32_MAX)
-	{
-		print_error ("serialization failed, killing client");
-		client_kill (c);
-		return;
-	}
-
-	uint32_t len = htonl (frame_len);
-	memcpy (c->write_buffer.str + frame_len_pos, &len, sizeof len);
-	client_update_poller (c, NULL);
-}
-
-static void
-relay_broadcast_except (struct app_context *ctx, struct client *exception)
-{
-	LIST_FOR_EACH (struct client, c, ctx->clients)
-		if (c != exception)
-			relay_send (c);
-}
-
-#define relay_broadcast(ctx) relay_broadcast_except ((ctx), NULL)
-
-static struct relay_event_message *
-relay_prepare (struct app_context *ctx)
-{
-	struct relay_event_message *m = &ctx->relay_message;
-	relay_event_message_free (m);
-	memset (m, 0, sizeof *m);
-	return m;
-}
-
-static void
-relay_prepare_ping (struct app_context *ctx)
-{
-	relay_prepare (ctx)->data.event = RELAY_EVENT_PING;
-}
-
-static union relay_item_data *
-relay_translate_formatter (struct app_context *ctx, union relay_item_data *p,
-	const struct formatter_item *i)
-{
-	// XXX: See attr_printer_decode_color(), this is a footgun.
-	int16_t c16  = i->color;
-	int16_t c256 = i->color >> 16;
-
-	unsigned attrs = i->attribute;
-	switch (i->type)
-	{
-	case FORMATTER_ITEM_TEXT:
-		p->text.text = str_from_cstr (i->text);
-		(p++)->kind = RELAY_ITEM_TEXT;
-		break;
-	case FORMATTER_ITEM_FG_COLOR:
-		p->fg_color.color = c256 <= 0 ? c16 : c256;
-		(p++)->kind = RELAY_ITEM_FG_COLOR;
-		break;
-	case FORMATTER_ITEM_BG_COLOR:
-		p->bg_color.color = c256 <= 0 ? c16 : c256;
-		(p++)->kind = RELAY_ITEM_BG_COLOR;
-		break;
-	case FORMATTER_ITEM_ATTR:
-		(p++)->kind = RELAY_ITEM_RESET;
-		if ((c256 = ctx->theme[i->attribute].fg) >= 0)
-		{
-			p->fg_color.color = c256;
-			(p++)->kind = RELAY_ITEM_FG_COLOR;
-		}
-		if ((c256 = ctx->theme[i->attribute].bg) >= 0)
-		{
-			p->bg_color.color = c256;
-			(p++)->kind = RELAY_ITEM_BG_COLOR;
-		}
-
-		attrs = ctx->theme[i->attribute].attrs;
-		// Fall-through
-	case FORMATTER_ITEM_SIMPLE:
-		if (attrs & TEXT_BOLD)
-			(p++)->kind = RELAY_ITEM_FLIP_BOLD;
-		if (attrs & TEXT_ITALIC)
-			(p++)->kind = RELAY_ITEM_FLIP_ITALIC;
-		if (attrs & TEXT_UNDERLINE)
-			(p++)->kind = RELAY_ITEM_FLIP_UNDERLINE;
-		if (attrs & TEXT_INVERSE)
-			(p++)->kind = RELAY_ITEM_FLIP_INVERSE;
-		if (attrs & TEXT_CROSSED_OUT)
-			(p++)->kind = RELAY_ITEM_FLIP_CROSSED_OUT;
-		if (attrs & TEXT_MONOSPACE)
-			(p++)->kind = RELAY_ITEM_FLIP_MONOSPACE;
-		break;
-	default:
-		break;
-	}
-	return p;
-}
-
-static union relay_item_data *
-relay_items (struct app_context *ctx, const struct formatter_item *items,
-	uint32_t *len)
-{
-	size_t items_len = 0;
-	for (size_t i = 0; items[i].type; i++)
-		items_len++;
-
-	// Beware of the upper bound, currently dominated by FORMATTER_ITEM_ATTR.
-	union relay_item_data *a = xcalloc (items_len * 9, sizeof *a), *p = a;
-	for (const struct formatter_item *i = items; items_len--; i++)
-		p = relay_translate_formatter (ctx, p, i);
-
-	*len = p - a;
-	return a;
-}
-
-static void
-relay_prepare_buffer_line (struct app_context *ctx, struct buffer *buffer,
-	struct buffer_line *line, bool leak_to_active)
-{
-	struct relay_event_message *m = relay_prepare (ctx);
-	struct relay_event_data_buffer_line *e = &m->data.buffer_line;
-	e->event = RELAY_EVENT_BUFFER_LINE;
-	e->buffer_name = str_from_cstr (buffer->name);
-	e->is_unimportant = !!(line->flags & BUFFER_LINE_UNIMPORTANT);
-	e->is_highlight = !!(line->flags & BUFFER_LINE_HIGHLIGHT);
-	e->rendition = 1 + line->r;
-	e->when = line->when * 1000;
-	e->leak_to_active = leak_to_active;
-	e->items = relay_items (ctx, line->items, &e->items_len);
-}
-
-// TODO: Consider pushing this whole block of code much further down.
-static void formatter_add (struct formatter *self, const char *format, ...);
-static char *irc_to_utf8 (const char *text);
-
-static void
-relay_prepare_channel_buffer_update (struct app_context *ctx,
-	struct buffer *buffer, struct relay_buffer_context_channel *e)
-{
-	struct channel *channel = buffer->channel;
-	struct formatter f = formatter_make (ctx, buffer->server);
-	if (channel->topic)
-		formatter_add (&f, "#m", channel->topic);
-	e->topic = relay_items (ctx, f.items, &e->topic_len);
-	formatter_free (&f);
-
-	// As in make_prompt(), conceal the last known channel modes.
-	// XXX: This should use irc_channel_is_joined().
-	if (!channel->users_len)
-		return;
-
-	struct str modes = str_make ();
-	str_append_str (&modes, &channel->no_param_modes);
-
-	struct str params = str_make ();
-	struct str_map_iter iter = str_map_iter_make (&channel->param_modes);
-	const char *param;
-	while ((param = str_map_iter_next (&iter)))
-	{
-		str_append_c (&modes, iter.link->key[0]);
-		str_append_c (&params, ' ');
-		str_append (&params, param);
-	}
-
-	str_append_str (&modes, &params);
-	str_free (&params);
-
-	char *modes_utf8 = irc_to_utf8 (modes.str);
-	str_free (&modes);
-	e->modes = str_from_cstr (modes_utf8);
-	free (modes_utf8);
-}
-
-static void
-relay_prepare_buffer_update (struct app_context *ctx, struct buffer *buffer)
-{
-	struct relay_event_message *m = relay_prepare (ctx);
-	struct relay_event_data_buffer_update *e = &m->data.buffer_update;
-	e->event = RELAY_EVENT_BUFFER_UPDATE;
-	e->buffer_name = str_from_cstr (buffer->name);
-	e->hide_unimportant = buffer->hide_unimportant;
-
-	struct str *server_name = NULL;
-	switch (buffer->type)
-	{
-	case BUFFER_GLOBAL:
-		e->context.kind = RELAY_BUFFER_KIND_GLOBAL;
-		break;
-	case BUFFER_SERVER:
-		e->context.kind = RELAY_BUFFER_KIND_SERVER;
-		server_name = &e->context.server.server_name;
-		break;
-	case BUFFER_CHANNEL:
-		e->context.kind = RELAY_BUFFER_KIND_CHANNEL;
-		server_name = &e->context.channel.server_name;
-		relay_prepare_channel_buffer_update (ctx, buffer, &e->context.channel);
-		break;
-	case BUFFER_PM:
-		e->context.kind = RELAY_BUFFER_KIND_PRIVATE_MESSAGE;
-		server_name = &e->context.private_message.server_name;
-		break;
-	}
-	if (server_name)
-		*server_name = str_from_cstr (buffer->server->name);
-}
-
-static void
-relay_prepare_buffer_stats (struct app_context *ctx, struct buffer *buffer)
-{
-	struct relay_event_message *m = relay_prepare (ctx);
-	struct relay_event_data_buffer_stats *e = &m->data.buffer_stats;
-	e->event = RELAY_EVENT_BUFFER_STATS;
-	e->buffer_name = str_from_cstr (buffer->name);
-	e->new_messages = MIN (UINT32_MAX,
-		buffer->new_messages_count - buffer->new_unimportant_count);
-	e->new_unimportant_messages = MIN (UINT32_MAX,
-		buffer->new_unimportant_count);
-	e->highlighted = buffer->highlighted;
-}
-
-static void
-relay_prepare_buffer_rename (struct app_context *ctx, struct buffer *buffer,
-	const char *new_name)
-{
-	struct relay_event_message *m = relay_prepare (ctx);
-	struct relay_event_data_buffer_rename *e = &m->data.buffer_rename;
-	e->event = RELAY_EVENT_BUFFER_RENAME;
-	e->buffer_name = str_from_cstr (buffer->name);
-	e->new = str_from_cstr (new_name);
-}
-
-static void
-relay_prepare_buffer_remove (struct app_context *ctx, struct buffer *buffer)
-{
-	struct relay_event_message *m = relay_prepare (ctx);
-	struct relay_event_data_buffer_remove *e = &m->data.buffer_remove;
-	e->event = RELAY_EVENT_BUFFER_REMOVE;
-	e->buffer_name = str_from_cstr (buffer->name);
-}
-
-static void
-relay_prepare_buffer_activate (struct app_context *ctx, struct buffer *buffer)
-{
-	struct relay_event_message *m = relay_prepare (ctx);
-	struct relay_event_data_buffer_activate *e = &m->data.buffer_activate;
-	e->event = RELAY_EVENT_BUFFER_ACTIVATE;
-	e->buffer_name = str_from_cstr (buffer->name);
-}
-
-static void
-relay_prepare_buffer_input (struct app_context *ctx, struct buffer *buffer,
-	const char *input)
-{
-	struct relay_event_message *m = relay_prepare (ctx);
-	struct relay_event_data_buffer_input *e = &m->data.buffer_input;
-	e->event = RELAY_EVENT_BUFFER_INPUT;
-	e->buffer_name = str_from_cstr (buffer->name);
-	e->text = str_from_cstr (input);
-}
-
-static void
-relay_prepare_buffer_clear (struct app_context *ctx,
-	struct buffer *buffer)
-{
-	struct relay_event_message *m = relay_prepare (ctx);
-	struct relay_event_data_buffer_clear *e = &m->data.buffer_clear;
-	e->event = RELAY_EVENT_BUFFER_CLEAR;
-	e->buffer_name = str_from_cstr (buffer->name);
-}
-
-enum relay_server_state
-relay_server_state_for_server (struct server *s)
-{
-	switch (s->state)
-	{
-	case IRC_DISCONNECTED: return RELAY_SERVER_STATE_DISCONNECTED;
-	case IRC_CONNECTING:   return RELAY_SERVER_STATE_CONNECTING;
-	case IRC_CONNECTED:    return RELAY_SERVER_STATE_CONNECTED;
-	case IRC_REGISTERED:   return RELAY_SERVER_STATE_REGISTERED;
-	case IRC_CLOSING:
-	case IRC_HALF_CLOSED:  return RELAY_SERVER_STATE_DISCONNECTING;
-	}
-	return 0;
-}
-
-static void
-relay_prepare_server_update (struct app_context *ctx, struct server *s)
-{
-	struct relay_event_message *m = relay_prepare (ctx);
-	struct relay_event_data_server_update *e = &m->data.server_update;
-	e->event = RELAY_EVENT_SERVER_UPDATE;
-	e->server_name = str_from_cstr (s->name);
-	e->data.state = relay_server_state_for_server (s);
-	if (s->state == IRC_REGISTERED)
-	{
-		char *user_utf8 = irc_to_utf8 (s->irc_user->nickname);
-		e->data.registered.user = str_from_cstr (user_utf8);
-		free (user_utf8);
-
-		char *user_modes_utf8 = irc_to_utf8 (s->irc_user_modes.str);
-		e->data.registered.user_modes = str_from_cstr (user_modes_utf8);
-		free (user_modes_utf8);
-	}
-}
-
-static void
-relay_prepare_server_rename (struct app_context *ctx, struct server *s,
-	const char *new_name)
-{
-	struct relay_event_message *m = relay_prepare (ctx);
-	struct relay_event_data_server_rename *e = &m->data.server_rename;
-	e->event = RELAY_EVENT_SERVER_RENAME;
-	e->server_name = str_from_cstr (s->name);
-	e->new = str_from_cstr (new_name);
-}
-
-static void
-relay_prepare_server_remove (struct app_context *ctx, struct server *s)
-{
-	struct relay_event_message *m = relay_prepare (ctx);
-	struct relay_event_data_server_remove *e = &m->data.server_remove;
-	e->event = RELAY_EVENT_SERVER_REMOVE;
-	e->server_name = str_from_cstr (s->name);
-}
-
-static void
-relay_prepare_error (struct app_context *ctx, uint32_t seq, const char *message)
-{
-	struct relay_event_message *m = relay_prepare (ctx);
-	struct relay_event_data_error *e = &m->data.error;
-	e->event = RELAY_EVENT_ERROR;
-	e->command_seq = seq;
-	e->error = str_from_cstr (message);
-}
-
-static struct relay_event_data_response *
-relay_prepare_response (struct app_context *ctx, uint32_t seq)
-{
-	struct relay_event_message *m = relay_prepare (ctx);
-	struct relay_event_data_response *e = &m->data.response;
-	e->event = RELAY_EVENT_RESPONSE;
-	e->command_seq = seq;
-	return e;
-}
-
 // --- Terminal output ---------------------------------------------------------
 
 /// Default colour pair
@@ -4519,6 +4135,387 @@ formatter_flush (struct formatter *self, FILE *stream, int flush_opts)
 	attr_printer_reset (&state);
 }
 
+// --- Relay output ------------------------------------------------------------
+
+static void
+client_kill (struct client *c)
+{
+	struct app_context *ctx = c->ctx;
+	poller_fd_reset (&c->socket_event);
+	xclose (c->socket_fd);
+	c->socket_fd = -1;
+
+	LIST_UNLINK (ctx->clients, c);
+	client_destroy (c);
+}
+
+static void
+client_update_poller (struct client *c, const struct pollfd *pfd)
+{
+	int new_events = POLLIN;
+	if (c->write_buffer.len)
+		new_events |= POLLOUT;
+
+	hard_assert (new_events != 0);
+	if (!pfd || pfd->events != new_events)
+		poller_fd_set (&c->socket_event, new_events);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static void
+relay_send (struct client *c)
+{
+	struct relay_event_message *m = &c->ctx->relay_message;
+	m->event_seq = c->event_seq++;
+
+	// TODO: Also don't try sending anything if half-closed.
+	if (!c->initialized || c->socket_fd == -1)
+		return;
+
+	// liberty has msg_{reader,writer} already, but they use 8-byte lengths.
+	size_t frame_len_pos = c->write_buffer.len, frame_len = 0;
+	str_pack_u32 (&c->write_buffer, 0);
+	if (!relay_event_message_serialize (m, &c->write_buffer)
+	 || (frame_len = c->write_buffer.len - frame_len_pos - 4) > UINT32_MAX)
+	{
+		print_error ("serialization failed, killing client");
+		client_kill (c);
+		return;
+	}
+
+	uint32_t len = htonl (frame_len);
+	memcpy (c->write_buffer.str + frame_len_pos, &len, sizeof len);
+	client_update_poller (c, NULL);
+}
+
+static void
+relay_broadcast_except (struct app_context *ctx, struct client *exception)
+{
+	LIST_FOR_EACH (struct client, c, ctx->clients)
+		if (c != exception)
+			relay_send (c);
+}
+
+#define relay_broadcast(ctx) relay_broadcast_except ((ctx), NULL)
+
+static struct relay_event_message *
+relay_prepare (struct app_context *ctx)
+{
+	struct relay_event_message *m = &ctx->relay_message;
+	relay_event_message_free (m);
+	memset (m, 0, sizeof *m);
+	return m;
+}
+
+static void
+relay_prepare_ping (struct app_context *ctx)
+{
+	relay_prepare (ctx)->data.event = RELAY_EVENT_PING;
+}
+
+static union relay_item_data *
+relay_translate_formatter (struct app_context *ctx, union relay_item_data *p,
+	const struct formatter_item *i)
+{
+	// XXX: See attr_printer_decode_color(), this is a footgun.
+	int16_t c16  = i->color;
+	int16_t c256 = i->color >> 16;
+
+	unsigned attrs = i->attribute;
+	switch (i->type)
+	{
+	case FORMATTER_ITEM_TEXT:
+		p->text.text = str_from_cstr (i->text);
+		(p++)->kind = RELAY_ITEM_TEXT;
+		break;
+	case FORMATTER_ITEM_FG_COLOR:
+		p->fg_color.color = c256 <= 0 ? c16 : c256;
+		(p++)->kind = RELAY_ITEM_FG_COLOR;
+		break;
+	case FORMATTER_ITEM_BG_COLOR:
+		p->bg_color.color = c256 <= 0 ? c16 : c256;
+		(p++)->kind = RELAY_ITEM_BG_COLOR;
+		break;
+	case FORMATTER_ITEM_ATTR:
+		(p++)->kind = RELAY_ITEM_RESET;
+		if ((c256 = ctx->theme[i->attribute].fg) >= 0)
+		{
+			p->fg_color.color = c256;
+			(p++)->kind = RELAY_ITEM_FG_COLOR;
+		}
+		if ((c256 = ctx->theme[i->attribute].bg) >= 0)
+		{
+			p->bg_color.color = c256;
+			(p++)->kind = RELAY_ITEM_BG_COLOR;
+		}
+
+		attrs = ctx->theme[i->attribute].attrs;
+		// Fall-through
+	case FORMATTER_ITEM_SIMPLE:
+		if (attrs & TEXT_BOLD)
+			(p++)->kind = RELAY_ITEM_FLIP_BOLD;
+		if (attrs & TEXT_ITALIC)
+			(p++)->kind = RELAY_ITEM_FLIP_ITALIC;
+		if (attrs & TEXT_UNDERLINE)
+			(p++)->kind = RELAY_ITEM_FLIP_UNDERLINE;
+		if (attrs & TEXT_INVERSE)
+			(p++)->kind = RELAY_ITEM_FLIP_INVERSE;
+		if (attrs & TEXT_CROSSED_OUT)
+			(p++)->kind = RELAY_ITEM_FLIP_CROSSED_OUT;
+		if (attrs & TEXT_MONOSPACE)
+			(p++)->kind = RELAY_ITEM_FLIP_MONOSPACE;
+		break;
+	default:
+		break;
+	}
+	return p;
+}
+
+static union relay_item_data *
+relay_items (struct app_context *ctx, const struct formatter_item *items,
+	uint32_t *len)
+{
+	size_t items_len = 0;
+	for (size_t i = 0; items[i].type; i++)
+		items_len++;
+
+	// Beware of the upper bound, currently dominated by FORMATTER_ITEM_ATTR.
+	union relay_item_data *a = xcalloc (items_len * 9, sizeof *a), *p = a;
+	for (const struct formatter_item *i = items; items_len--; i++)
+		p = relay_translate_formatter (ctx, p, i);
+
+	*len = p - a;
+	return a;
+}
+
+static void
+relay_prepare_buffer_line (struct app_context *ctx, struct buffer *buffer,
+	struct buffer_line *line, bool leak_to_active)
+{
+	struct relay_event_message *m = relay_prepare (ctx);
+	struct relay_event_data_buffer_line *e = &m->data.buffer_line;
+	e->event = RELAY_EVENT_BUFFER_LINE;
+	e->buffer_name = str_from_cstr (buffer->name);
+	e->is_unimportant = !!(line->flags & BUFFER_LINE_UNIMPORTANT);
+	e->is_highlight = !!(line->flags & BUFFER_LINE_HIGHLIGHT);
+	e->rendition = 1 + line->r;
+	e->when = line->when * 1000;
+	e->leak_to_active = leak_to_active;
+	e->items = relay_items (ctx, line->items, &e->items_len);
+}
+
+static void
+relay_prepare_channel_buffer_update (struct app_context *ctx,
+	struct buffer *buffer, struct relay_buffer_context_channel *e)
+{
+	struct channel *channel = buffer->channel;
+	struct formatter f = formatter_make (ctx, buffer->server);
+	if (channel->topic)
+		formatter_add (&f, "#m", channel->topic);
+	FORMATTER_ADD_ITEM (&f, END);
+	e->topic = relay_items (ctx, f.items, &e->topic_len);
+	formatter_free (&f);
+
+	// As in make_prompt(), conceal the last known channel modes.
+	// XXX: This should use irc_channel_is_joined().
+	if (!channel->users_len)
+		return;
+
+	struct str modes = str_make ();
+	str_append_str (&modes, &channel->no_param_modes);
+
+	struct str params = str_make ();
+	struct str_map_iter iter = str_map_iter_make (&channel->param_modes);
+	const char *param;
+	while ((param = str_map_iter_next (&iter)))
+	{
+		str_append_c (&modes, iter.link->key[0]);
+		str_append_c (&params, ' ');
+		str_append (&params, param);
+	}
+
+	str_append_str (&modes, &params);
+	str_free (&params);
+
+	char *modes_utf8 = irc_to_utf8 (modes.str);
+	str_free (&modes);
+	e->modes = str_from_cstr (modes_utf8);
+	free (modes_utf8);
+}
+
+static void
+relay_prepare_buffer_update (struct app_context *ctx, struct buffer *buffer)
+{
+	struct relay_event_message *m = relay_prepare (ctx);
+	struct relay_event_data_buffer_update *e = &m->data.buffer_update;
+	e->event = RELAY_EVENT_BUFFER_UPDATE;
+	e->buffer_name = str_from_cstr (buffer->name);
+	e->hide_unimportant = buffer->hide_unimportant;
+
+	struct str *server_name = NULL;
+	switch (buffer->type)
+	{
+	case BUFFER_GLOBAL:
+		e->context.kind = RELAY_BUFFER_KIND_GLOBAL;
+		break;
+	case BUFFER_SERVER:
+		e->context.kind = RELAY_BUFFER_KIND_SERVER;
+		server_name = &e->context.server.server_name;
+		break;
+	case BUFFER_CHANNEL:
+		e->context.kind = RELAY_BUFFER_KIND_CHANNEL;
+		server_name = &e->context.channel.server_name;
+		relay_prepare_channel_buffer_update (ctx, buffer, &e->context.channel);
+		break;
+	case BUFFER_PM:
+		e->context.kind = RELAY_BUFFER_KIND_PRIVATE_MESSAGE;
+		server_name = &e->context.private_message.server_name;
+		break;
+	}
+	if (server_name)
+		*server_name = str_from_cstr (buffer->server->name);
+}
+
+static void
+relay_prepare_buffer_stats (struct app_context *ctx, struct buffer *buffer)
+{
+	struct relay_event_message *m = relay_prepare (ctx);
+	struct relay_event_data_buffer_stats *e = &m->data.buffer_stats;
+	e->event = RELAY_EVENT_BUFFER_STATS;
+	e->buffer_name = str_from_cstr (buffer->name);
+	e->new_messages = MIN (UINT32_MAX,
+		buffer->new_messages_count - buffer->new_unimportant_count);
+	e->new_unimportant_messages = MIN (UINT32_MAX,
+		buffer->new_unimportant_count);
+	e->highlighted = buffer->highlighted;
+}
+
+static void
+relay_prepare_buffer_rename (struct app_context *ctx, struct buffer *buffer,
+	const char *new_name)
+{
+	struct relay_event_message *m = relay_prepare (ctx);
+	struct relay_event_data_buffer_rename *e = &m->data.buffer_rename;
+	e->event = RELAY_EVENT_BUFFER_RENAME;
+	e->buffer_name = str_from_cstr (buffer->name);
+	e->new = str_from_cstr (new_name);
+}
+
+static void
+relay_prepare_buffer_remove (struct app_context *ctx, struct buffer *buffer)
+{
+	struct relay_event_message *m = relay_prepare (ctx);
+	struct relay_event_data_buffer_remove *e = &m->data.buffer_remove;
+	e->event = RELAY_EVENT_BUFFER_REMOVE;
+	e->buffer_name = str_from_cstr (buffer->name);
+}
+
+static void
+relay_prepare_buffer_activate (struct app_context *ctx, struct buffer *buffer)
+{
+	struct relay_event_message *m = relay_prepare (ctx);
+	struct relay_event_data_buffer_activate *e = &m->data.buffer_activate;
+	e->event = RELAY_EVENT_BUFFER_ACTIVATE;
+	e->buffer_name = str_from_cstr (buffer->name);
+}
+
+static void
+relay_prepare_buffer_input (struct app_context *ctx, struct buffer *buffer,
+	const char *input)
+{
+	struct relay_event_message *m = relay_prepare (ctx);
+	struct relay_event_data_buffer_input *e = &m->data.buffer_input;
+	e->event = RELAY_EVENT_BUFFER_INPUT;
+	e->buffer_name = str_from_cstr (buffer->name);
+	e->text = str_from_cstr (input);
+}
+
+static void
+relay_prepare_buffer_clear (struct app_context *ctx,
+	struct buffer *buffer)
+{
+	struct relay_event_message *m = relay_prepare (ctx);
+	struct relay_event_data_buffer_clear *e = &m->data.buffer_clear;
+	e->event = RELAY_EVENT_BUFFER_CLEAR;
+	e->buffer_name = str_from_cstr (buffer->name);
+}
+
+enum relay_server_state
+relay_server_state_for_server (struct server *s)
+{
+	switch (s->state)
+	{
+	case IRC_DISCONNECTED: return RELAY_SERVER_STATE_DISCONNECTED;
+	case IRC_CONNECTING:   return RELAY_SERVER_STATE_CONNECTING;
+	case IRC_CONNECTED:    return RELAY_SERVER_STATE_CONNECTED;
+	case IRC_REGISTERED:   return RELAY_SERVER_STATE_REGISTERED;
+	case IRC_CLOSING:
+	case IRC_HALF_CLOSED:  return RELAY_SERVER_STATE_DISCONNECTING;
+	}
+	return 0;
+}
+
+static void
+relay_prepare_server_update (struct app_context *ctx, struct server *s)
+{
+	struct relay_event_message *m = relay_prepare (ctx);
+	struct relay_event_data_server_update *e = &m->data.server_update;
+	e->event = RELAY_EVENT_SERVER_UPDATE;
+	e->server_name = str_from_cstr (s->name);
+	e->data.state = relay_server_state_for_server (s);
+	if (s->state == IRC_REGISTERED)
+	{
+		char *user_utf8 = irc_to_utf8 (s->irc_user->nickname);
+		e->data.registered.user = str_from_cstr (user_utf8);
+		free (user_utf8);
+
+		char *user_modes_utf8 = irc_to_utf8 (s->irc_user_modes.str);
+		e->data.registered.user_modes = str_from_cstr (user_modes_utf8);
+		free (user_modes_utf8);
+	}
+}
+
+static void
+relay_prepare_server_rename (struct app_context *ctx, struct server *s,
+	const char *new_name)
+{
+	struct relay_event_message *m = relay_prepare (ctx);
+	struct relay_event_data_server_rename *e = &m->data.server_rename;
+	e->event = RELAY_EVENT_SERVER_RENAME;
+	e->server_name = str_from_cstr (s->name);
+	e->new = str_from_cstr (new_name);
+}
+
+static void
+relay_prepare_server_remove (struct app_context *ctx, struct server *s)
+{
+	struct relay_event_message *m = relay_prepare (ctx);
+	struct relay_event_data_server_remove *e = &m->data.server_remove;
+	e->event = RELAY_EVENT_SERVER_REMOVE;
+	e->server_name = str_from_cstr (s->name);
+}
+
+static void
+relay_prepare_error (struct app_context *ctx, uint32_t seq, const char *message)
+{
+	struct relay_event_message *m = relay_prepare (ctx);
+	struct relay_event_data_error *e = &m->data.error;
+	e->event = RELAY_EVENT_ERROR;
+	e->command_seq = seq;
+	e->error = str_from_cstr (message);
+}
+
+static struct relay_event_data_response *
+relay_prepare_response (struct app_context *ctx, uint32_t seq)
+{
+	struct relay_event_message *m = relay_prepare (ctx);
+	struct relay_event_data_response *e = &m->data.response;
+	e->event = RELAY_EVENT_RESPONSE;
+	e->command_seq = seq;
+	return e;
+}
+
 // --- Buffers -----------------------------------------------------------------
 
 static void