multibackend skeleton

include/sway/server.h

@@ -11,12 +11,29 @@
 // TODO WLR: make Xwayland optional
 #include <wlr/xwayland.h>
 
+enum sway_subbackend_type {
+	SWAY_SUBBACKEND_WAYLAND,
+	SWAY_SUBBACKEND_X11,
+	SWAY_SUBBACKEND_DRM,
+	SWAY_SUBBACKEND_HEADLESS,
+};
+
+struct sway_subbackend {
+	char *name;
+	enum sway_subbackend_type type;
+	struct wlr_backend *backend;
+	struct wl_list link; // sway_server::subbackends
+
+	struct wl_listener backend_destroy;
+};
+
 struct sway_server {
 	struct wl_display *wl_display;
 	struct wl_event_loop *wl_event_loop;
 	const char *socket;
 
 	struct wlr_backend *backend;
+	struct wl_list subbackends; // sway_server_subbackend::link
 	struct wlr_renderer *renderer;
 
 	struct wlr_compositor *compositor;
@@ -51,4 +68,10 @@ void handle_xdg_shell_v6_surface(struct wl_listener *listener, void *data);
 void handle_xwayland_surface(struct wl_listener *listener, void *data);
 void handle_wl_shell_surface(struct wl_listener *listener, void *data);
 
+struct sway_subbackend *sway_subbackend_create(enum sway_subbackend_type type,
+		char *name);
+void sway_server_add_subbackend(struct sway_server *server,
+		struct sway_subbackend *subbackend);
+void sway_server_remove_subbackend(struct sway_server *server, char *name);
+
 #endif

sway/server.c

@@ -1,9 +1,11 @@
 #define _POSIX_C_SOURCE 200112L
+#include <strings.h>
 #include <stdlib.h>
 #include <stdbool.h>
 #include <wayland-server.h>
 #include <wlr/backend.h>
 #include <wlr/backend/session.h>
+#include <wlr/backend/multi.h>
 #include <wlr/render.h>
 #include <wlr/render/gles2.h>
 #include <wlr/types/wlr_compositor.h>
@@ -20,6 +22,7 @@ bool server_init(struct sway_server *server) {
 	server->wl_display = wl_display_create();
 	server->wl_event_loop = wl_display_get_event_loop(server->wl_display);
 	server->backend = wlr_backend_autocreate(server->wl_display);
+	wl_list_init(&server->subbackends);
 
 	server->renderer = wlr_gles2_renderer_create(server->backend);
 	wl_display_init_shm(server->wl_display);
@@ -82,3 +85,110 @@ void server_run(struct sway_server *server) {
 	setenv("WAYLAND_DISPLAY", server->socket, true);
 	wl_display_run(server->wl_display);
 }
+
+static void sway_subbackend_destroy(struct sway_subbackend *subbackend) {
+	wl_list_remove(&subbackend->backend_destroy.link);
+	wl_list_remove(&subbackend->link);
+	// free(name)?
+	free(subbackend);
+}
+
+struct sway_subbackend *sway_subbackend_create(enum sway_subbackend_type type,
+		char *name) {
+	struct sway_subbackend *subbackend =
+		calloc(1, sizeof(struct sway_subbackend));
+	if (subbackend == NULL) {
+		sway_log(L_ERROR, "could not allocate subbackend");
+		return NULL;
+	}
+
+	if (name == NULL) {
+		// TODO: figure out what to call the backend based on what the backend
+		// type is and how many other backends are configured of that type
+		// (<type>-<num>).
+	} else {
+		subbackend->name = name;
+	}
+
+	subbackend->type = type;
+	wl_list_init(&subbackend->link);
+
+	return subbackend;
+}
+
+static void handle_subbackend_backend_destroy(struct wl_listener *listener,
+		void *data) {
+	struct sway_subbackend *subbackend =
+		wl_container_of(listener, subbackend, backend_destroy);
+	sway_subbackend_destroy(subbackend);
+}
+
+static struct wlr_backend *wayland_backend_create() {
+	sway_log(L_DEBUG, "TODO: create wayland backend");
+	return NULL;
+}
+
+static struct wlr_backend *x11_backend_create() {
+	sway_log(L_DEBUG, "TODO: create x11 backend");
+	return NULL;
+}
+
+static struct wlr_backend *headless_backend_create() {
+	sway_log(L_DEBUG, "TODO: create headless backend");
+	return NULL;
+}
+
+static struct wlr_backend *drm_backend_create() {
+	sway_log(L_DEBUG, "TODO: create drm backend");
+	return NULL;
+}
+
+void sway_server_add_subbackend(struct sway_server *server,
+		struct sway_subbackend *subbackend) {
+	struct wlr_backend *backend = NULL;
+
+	switch (subbackend->type) {
+	case SWAY_SUBBACKEND_WAYLAND:
+		backend = wayland_backend_create();
+		break;
+	case SWAY_SUBBACKEND_X11:
+		backend = x11_backend_create();
+		break;
+	case SWAY_SUBBACKEND_DRM:
+		backend = drm_backend_create();
+		break;
+	case SWAY_SUBBACKEND_HEADLESS:
+		backend = headless_backend_create();
+		break;
+	}
+
+	if (backend == NULL) {
+		sway_log(L_ERROR, "could not create subbackend '%s'", subbackend->name);
+		sway_subbackend_destroy(subbackend);
+		return;
+	}
+
+	wl_list_remove(&subbackend->link);
+	wl_list_insert(&server->subbackends, &subbackend->link);
+
+	wl_signal_add(&backend->events.destroy, &subbackend->backend_destroy);
+	subbackend->backend_destroy.notify = handle_subbackend_backend_destroy;
+
+	wlr_multi_backend_add(server->backend, backend);
+}
+
+void sway_server_remove_subbackend(struct sway_server *server, char *name) {
+	struct sway_subbackend *subbackend = NULL;
+	wl_list_for_each(subbackend, &server->subbackends, link) {
+		if (strcasecmp(subbackend->name, name) == 0) {
+			break;
+		}
+	}
+
+	if (!subbackend) {
+		sway_log(L_DEBUG, "could not find subbackend named '%s'", name);
+		return;
+	}
+
+	wlr_backend_destroy(subbackend->backend);
+}