From 412c11ea91647c30abce3c4a0ec6f6b97b408bf0 Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Wed, 28 Aug 2024 15:05:03 +0200
Subject: [PATCH] cage: fix abort on shutdown

Workaround for [1]: register a listener for wl_display destroy and
avoid calling wl_display_terminate() after.

[1]: https://gitlab.freedesktop.org/wayland/wayland/-/merge_requests/421
---
 cage.c   | 33 ++++++++++++++++++++++++++-------
 output.c |  2 +-
 seat.c   |  2 +-
 server.h |  4 ++++
 4 files changed, 32 insertions(+), 9 deletions(-)

diff --git a/cage.c b/cage.c
index b5ba6c5..26ab9ef 100644
--- a/cage.c
+++ b/cage.c
@@ -61,6 +61,24 @@
 #include "xwayland.h"
 #endif
 
+void
+server_terminate(struct cg_server *server)
+{
+	// Workaround for https://gitlab.freedesktop.org/wayland/wayland/-/merge_requests/421
+	if (server->terminated) {
+		return;
+	}
+
+	wl_display_terminate(server->wl_display);
+}
+
+static void
+handle_display_destroy(struct wl_listener *listener, void *data)
+{
+	struct cg_server *server = wl_container_of(listener, server, display_destroy);
+	server->terminated = true;
+}
+
 static int
 sigchld_handler(int fd, uint32_t mask, void *data)
 {
@@ -76,7 +94,7 @@ sigchld_handler(int fd, uint32_t mask, void *data)
 	}
 
 	server->return_app_code = true;
-	wl_display_terminate(server->wl_display);
+	server_terminate(server);
 	return 0;
 }
 
@@ -189,13 +207,13 @@ drop_permissions(void)
 static int
 handle_signal(int signal, void *data)
 {
-	struct wl_display *display = data;
+	struct cg_server *server = data;
 
 	switch (signal) {
 	case SIGINT:
 		/* Fallthrough */
 	case SIGTERM:
-		wl_display_terminate(display);
+		server_terminate(server);
 		return 0;
 	default:
 		return 0;
@@ -288,11 +306,12 @@ main(int argc, char *argv[])
 		return 1;
 	}
 
+	server.display_destroy.notify = handle_display_destroy;
+	wl_display_add_destroy_listener(server.wl_display, &server.display_destroy);
+
 	struct wl_event_loop *event_loop = wl_display_get_event_loop(server.wl_display);
-	struct wl_event_source *sigint_source =
-		wl_event_loop_add_signal(event_loop, SIGINT, handle_signal, server.wl_display);
-	struct wl_event_source *sigterm_source =
-		wl_event_loop_add_signal(event_loop, SIGTERM, handle_signal, server.wl_display);
+	struct wl_event_source *sigint_source = wl_event_loop_add_signal(event_loop, SIGINT, handle_signal, &server);
+	struct wl_event_source *sigterm_source = wl_event_loop_add_signal(event_loop, SIGTERM, handle_signal, &server);
 
 	server.backend = wlr_backend_autocreate(event_loop, &server.session);
 	if (!server.backend) {
diff --git a/output.c b/output.c
index 6eb2472..f1c0419 100644
--- a/output.c
+++ b/output.c
@@ -240,7 +240,7 @@ output_destroy(struct cg_output *output)
 	free(output);
 
 	if (wl_list_empty(&server->outputs) && was_nested_output) {
-		wl_display_terminate(server->wl_display);
+		server_terminate(server);
 	} else if (server->output_mode == CAGE_MULTI_OUTPUT_MODE_LAST && !wl_list_empty(&server->outputs)) {
 		struct cg_output *prev = wl_container_of(server->outputs.next, prev, link);
 		output_enable(prev);
diff --git a/seat.c b/seat.c
index 4e287d9..cdf8798 100644
--- a/seat.c
+++ b/seat.c
@@ -258,7 +258,7 @@ handle_keybinding(struct cg_server *server, xkb_keysym_t sym)
 {
 #ifdef DEBUG
 	if (sym == XKB_KEY_Escape) {
-		wl_display_terminate(server->wl_display);
+		server_terminate(server);
 		return true;
 	}
 #endif
diff --git a/server.h b/server.h
index 8759ed5..f7d70d7 100644
--- a/server.h
+++ b/server.h
@@ -25,6 +25,7 @@ struct cg_server {
 	struct wlr_renderer *renderer;
 	struct wlr_allocator *allocator;
 	struct wlr_session *session;
+	struct wl_listener display_destroy;
 
 	struct cg_seat *seat;
 	struct wlr_idle_notifier_v1 *idle;
@@ -61,6 +62,9 @@ struct cg_server {
 	bool xdg_decoration;
 	bool allow_vt_switch;
 	bool return_app_code;
+	bool terminated;
 };
 
+void server_terminate(struct cg_server *server);
+
 #endif