server: don't create headless backend twice

This may happen when running with WLR_BACKENDS=headless.

Fixes: #1618

diff --git a/src/server.c b/src/server.c
index ceac9cec1a59d8245d8e559dbb8ed0e47224115f..4210f069d69a82baefd6f952f4eb00b8edaa1239 100644 (file)
--- a/src/server.c
+++ b/src/server.c
@@ -278,6 +278,15 @@ static const char helpful_seat_error_message[] =
 "If the above does not work, try running with `WLR_RENDERER=pixman labwc` in\n"
 "order to use the software rendering fallback\n";
 
+static void
+get_headless_backend(struct wlr_backend *backend, void *data)
+{
+       if (wlr_backend_is_headless(backend)) {
+               struct wlr_backend **headless = data;
+               *headless = backend;
+       }
+}
+
 void
 server_init(struct server *server)
 {
@@ -327,7 +336,16 @@ server_init(struct server *server)
        }
 
        /* Create headless backend to enable adding virtual outputs later on */
-       server->headless.backend = wlr_headless_backend_create(server->wl_display);
+       wlr_multi_for_each_backend(server->backend,
+               get_headless_backend, &server->headless.backend);
+
+       if (!server->headless.backend) {
+               wlr_log(WLR_DEBUG, "manually creating headless backend");
+               server->headless.backend = wlr_headless_backend_create(server->wl_display);
+       } else {
+               wlr_log(WLR_DEBUG, "headless backend already exists");
+       }
+
        if (!server->headless.backend) {
                wlr_log(WLR_ERROR, "unable to create headless backend");
                exit(EXIT_FAILURE);