From 998fd807373ee7e28cc88717f5f20dd3f4a0c342 Mon Sep 17 00:00:00 2001
From: Jos Dehaes <jos.dehaes@gmail.com>
Date: Wed, 29 Apr 2026 11:14:21 +0200
Subject: [PATCH] session: run activation env update synchronously

dbus-update-activation-environment and systemctl --user import-environment
were fired asynchronously via spawn_async_no_shell, racing with the autostart
script. Any systemd user service started from autostart (e.g. via
labwc-session.target) could start before the import completed, leaving
WAYLAND_DISPLAY and related variables absent from its environment and those
of any apps it launches.

Run both commands synchronously via a new spawn_sync_no_shell helper so
the import is guaranteed to complete before the autostart script executes.
---
 include/common/spawn.h |  6 ++++++
 src/common/spawn.c     | 32 ++++++++++++++++++++++++++++++++
 src/config/session.c   |  4 ++--
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/include/common/spawn.h b/include/common/spawn.h
index 43123269..4df5ed0b 100644
--- a/include/common/spawn.h
+++ b/include/common/spawn.h
@@ -16,6 +16,12 @@ pid_t spawn_primary_client(const char *command);
  */
 void spawn_async_no_shell(char const *command);
 
+/**
+ * spawn_sync_no_shell - execute synchronously
+ * @command: command to be executed
+ */
+void spawn_sync_no_shell(char const *command);
+
 /**
  * spawn_piped - execute asynchronously
  * @command: command to be executed
diff --git a/src/common/spawn.c b/src/common/spawn.c
index 898c4800..a703bee5 100644
--- a/src/common/spawn.c
+++ b/src/common/spawn.c
@@ -89,6 +89,38 @@ out:
 	g_strfreev(argv);
 }
 
+void
+spawn_sync_no_shell(char const *command)
+{
+	GError *err = NULL;
+	gchar **argv = NULL;
+
+	assert(command);
+
+	g_shell_parse_argv((gchar *)command, NULL, &argv, &err);
+	if (err) {
+		g_message("%s", err->message);
+		g_error_free(err);
+		return;
+	}
+
+	pid_t child = fork();
+	switch (child) {
+	case -1:
+		wlr_log(WLR_ERROR, "unable to fork()");
+		goto out;
+	case 0:
+		reset_signals_and_limits();
+		execvp(argv[0], argv);
+		_exit(1);
+	default:
+		waitpid(child, NULL, 0);
+		break;
+	}
+out:
+	g_strfreev(argv);
+}
+
 pid_t
 spawn_primary_client(const char *command)
 {
diff --git a/src/config/session.c b/src/config/session.c
index 7df6236c..61ce156f 100644
--- a/src/config/session.c
+++ b/src/config/session.c
@@ -219,12 +219,12 @@ execute_update(const char *env_keys, const char *env_unset_keys, bool initialize
 	char *cmd =
 		strdup_printf("dbus-update-activation-environment %s",
 			initialize ? env_keys : env_unset_keys);
-	spawn_async_no_shell(cmd);
+	spawn_sync_no_shell(cmd);
 	free(cmd);
 
 	cmd = strdup_printf("systemctl --user %s %s",
 		initialize ? "import-environment" : "unset-environment", env_keys);
-	spawn_async_no_shell(cmd);
+	spawn_sync_no_shell(cmd);
 	free(cmd);
 }