backend/session: operate on wlr_device

Instead of operating on FDs in {open,close}_device, operate on
wlr_devices. This avoids the device lookup in wlr_session and allows
callers to have access to wlr_device fields.

For now, we use it to remove wlr_session_signal_add and replace it with
a more idiomatic wlr_session.events.change field. In the future, other
events will be added.

backend/backend.c

@@ -151,7 +151,7 @@ static struct wlr_backend *attempt_noop_backend(struct wl_display *display) {
 static struct wlr_backend *attempt_drm_backend(struct wl_display *display,
 		struct wlr_backend *backend, struct wlr_session *session,
 		wlr_renderer_create_func_t create_renderer_func) {
-	int gpus[8];
+	struct wlr_device *gpus[8];
 	size_t num_gpus = wlr_session_find_gpus(session, 8, gpus);
 	struct wlr_backend *primary_drm = NULL;
 	wlr_log(WLR_INFO, "Found %zu GPUs", num_gpus);
@@ -160,7 +160,7 @@ static struct wlr_backend *attempt_drm_backend(struct wl_display *display,
 		struct wlr_backend *drm = wlr_drm_backend_create(display, session,
 			gpus[i], primary_drm, create_renderer_func);
 		if (!drm) {
-			wlr_log(WLR_ERROR, "Failed to open DRM device %d", gpus[i]);
+			wlr_log(WLR_ERROR, "Failed to create DRM backend");
 			continue;
 		}
 

backend/drm/backend.c

@@ -50,7 +50,7 @@ static void backend_destroy(struct wlr_backend *backend) {
 
 	finish_drm_resources(drm);
 	finish_drm_renderer(&drm->renderer);
-	wlr_session_close_file(drm->session, drm->fd);
+	wlr_session_close_file(drm->session, drm->dev);
 	wl_event_source_remove(drm->drm_event);
 	free(drm);
 }
@@ -128,13 +128,14 @@ static void handle_display_destroy(struct wl_listener *listener, void *data) {
 }
 
 struct wlr_backend *wlr_drm_backend_create(struct wl_display *display,
-		struct wlr_session *session, int gpu_fd, struct wlr_backend *parent,
+		struct wlr_session *session, struct wlr_device *dev,
+		struct wlr_backend *parent,
 		wlr_renderer_create_func_t create_renderer_func) {
-	assert(display && session && gpu_fd >= 0);
+	assert(display && session && dev);
 	assert(!parent || wlr_backend_is_drm(parent));
 
-	char *name = drmGetDeviceNameFromFd2(gpu_fd);
-	drmVersion *version = drmGetVersion(gpu_fd);
+	char *name = drmGetDeviceNameFromFd2(dev->fd);
+	drmVersion *version = drmGetVersion(dev->fd);
 	wlr_log(WLR_INFO, "Initializing DRM backend for %s (%s)", name, version->name);
 	free(name);
 	drmFreeVersion(version);
@@ -149,13 +150,14 @@ struct wlr_backend *wlr_drm_backend_create(struct wl_display *display,
 	drm->session = session;
 	wl_list_init(&drm->outputs);
 
-	drm->fd = gpu_fd;
+	drm->dev = dev;
+	drm->fd = dev->fd;
 	if (parent != NULL) {
 		drm->parent = get_drm_backend_from_backend(parent);
 	}
 
 	drm->drm_invalidated.notify = drm_invalidated;
-	wlr_session_signal_add(session, gpu_fd, &drm->drm_invalidated);
+	wl_signal_add(&dev->events.change, &drm->drm_invalidated);
 
 	drm->display = display;
 	struct wl_event_loop *event_loop = wl_display_get_event_loop(display);
@@ -195,7 +197,7 @@ error_event:
 	wl_list_remove(&drm->session_signal.link);
 	wl_event_source_remove(drm->drm_event);
 error_fd:
-	wlr_session_close_file(drm->session, drm->fd);
+	wlr_session_close_file(drm->session, dev);
 	free(drm);
 	return NULL;
 }

backend/libinput/backend.c

@@ -17,12 +17,27 @@ static struct wlr_libinput_backend *get_libinput_backend_from_backend(
 static int libinput_open_restricted(const char *path,
 		int flags, void *_backend) {
 	struct wlr_libinput_backend *backend = _backend;
-	return wlr_session_open_file(backend->session, path);
+	struct wlr_device *dev = wlr_session_open_file(backend->session, path);
+	if (dev == NULL) {
+		return -1;
+	}
+	return dev->fd;
 }
 
 static void libinput_close_restricted(int fd, void *_backend) {
 	struct wlr_libinput_backend *backend = _backend;
-	wlr_session_close_file(backend->session, fd);
+
+	struct wlr_device *dev;
+	bool found = false;
+	wl_list_for_each(dev, &backend->session->devices, link) {
+		if (dev->fd == fd) {
+			found = true;
+			break;
+		}
+	}
+	if (found) {
+		wlr_session_close_file(backend->session, dev);
+	}
 }
 
 static const struct libinput_interface libinput_impl = {

backend/session/session.c

@@ -55,7 +55,7 @@ static int udev_event(int fd, uint32_t mask, void *data) {
 
 	wl_list_for_each(dev, &session->devices, link) {
 		if (dev->dev == devnum) {
-			wlr_signal_emit_safe(&dev->signal, session);
+			wlr_signal_emit_safe(&dev->events.change, NULL);
 			break;
 		}
 	}
@@ -169,10 +169,11 @@ void wlr_session_destroy(struct wlr_session *session) {
 	session->impl->destroy(session);
 }
 
-int wlr_session_open_file(struct wlr_session *session, const char *path) {
+struct wlr_device *wlr_session_open_file(struct wlr_session *session,
+		const char *path) {
 	int fd = session->impl->open(session, path);
 	if (fd < 0) {
-		return fd;
+		return NULL;
 	}
 
 	struct wlr_device *dev = malloc(sizeof(*dev));
@@ -189,46 +190,24 @@ int wlr_session_open_file(struct wlr_session *session, const char *path) {
 
 	dev->fd = fd;
 	dev->dev = st.st_rdev;
-	wl_signal_init(&dev->signal);
+	wl_signal_init(&dev->events.change);
 	wl_list_insert(&session->devices, &dev->link);
 
-	return fd;
+	return dev;
 
 error:
 	free(dev);
 	close(fd);
-	return -1;
-}
-
-static struct wlr_device *find_device(struct wlr_session *session, int fd) {
-	struct wlr_device *dev;
-
-	wl_list_for_each(dev, &session->devices, link) {
-		if (dev->fd == fd) {
-			return dev;
-		}
-	}
-
-	wlr_log(WLR_ERROR, "Tried to use fd %d not opened by session", fd);
-	assert(0);
 	return NULL;
 }
 
-void wlr_session_close_file(struct wlr_session *session, int fd) {
-	struct wlr_device *dev = find_device(session, fd);
-
-	session->impl->close(session, fd);
+void wlr_session_close_file(struct wlr_session *session,
+		struct wlr_device *dev) {
+	session->impl->close(session, dev->fd);
 	wl_list_remove(&dev->link);
 	free(dev);
 }
 
-void wlr_session_signal_add(struct wlr_session *session, int fd,
-		struct wl_listener *listener) {
-	struct wlr_device *dev = find_device(session, fd);
-
-	wl_signal_add(&dev->signal, listener);
-}
-
 bool wlr_session_change_vt(struct wlr_session *session, unsigned vt) {
 	if (!session) {
 		return false;
@@ -240,32 +219,32 @@ bool wlr_session_change_vt(struct wlr_session *session, unsigned vt) {
 /* Tests if 'path' is KMS compatible by trying to open it.
  * It leaves the open device in *fd_out it it succeeds.
  */
-static int open_if_kms(struct wlr_session *restrict session,
+static struct wlr_device *open_if_kms(struct wlr_session *restrict session,
 		const char *restrict path) {
 	if (!path) {
-		return -1;
+		return NULL;
 	}
 
-	int fd = wlr_session_open_file(session, path);
-	if (fd < 0) {
-		return -1;
+	struct wlr_device *dev = wlr_session_open_file(session, path);
+	if (!dev) {
+		return NULL;
 	}
 
-	drmVersion *ver = drmGetVersion(fd);
+	drmVersion *ver = drmGetVersion(dev->fd);
 	if (!ver) {
-		goto out_fd;
+		goto out_dev;
 	}
 
 	drmFreeVersion(ver);
-	return fd;
+	return dev;
 
-out_fd:
-	wlr_session_close_file(session, fd);
-	return -1;
+out_dev:
+	wlr_session_close_file(session, dev);
+	return NULL;
 }
 
 static size_t explicit_find_gpus(struct wlr_session *session,
-		size_t ret_len, int ret[static ret_len], const char *str) {
+		size_t ret_len, struct wlr_device *ret[static ret_len], const char *str) {
 	char *gpus = strdup(str);
 	if (!gpus) {
 		wlr_log_errno(WLR_ERROR, "Allocation failed");
@@ -281,7 +260,7 @@ static size_t explicit_find_gpus(struct wlr_session *session,
 		}
 
 		ret[i] = open_if_kms(session, ptr);
-		if (ret[i] < 0) {
+		if (!ret[i]) {
 			wlr_log(WLR_ERROR, "Unable to open %s as DRM device", ptr);
 		} else {
 			++i;
@@ -296,7 +275,7 @@ static size_t explicit_find_gpus(struct wlr_session *session,
  * If it's not found, it returns the first valid GPU it finds.
  */
 size_t wlr_session_find_gpus(struct wlr_session *session,
-		size_t ret_len, int *ret) {
+		size_t ret_len, struct wlr_device **ret) {
 	const char *explicit = getenv("WLR_DRM_DEVICES");
 	if (explicit) {
 		return explicit_find_gpus(session, ret_len, ret, explicit);
@@ -348,17 +327,18 @@ size_t wlr_session_find_gpus(struct wlr_session *session,
 			}
 		}
 
-		int fd = open_if_kms(session, udev_device_get_devnode(dev));
-		if (fd < 0) {
+		struct wlr_device *wlr_dev =
+			open_if_kms(session, udev_device_get_devnode(dev));
+		if (!wlr_dev) {
 			udev_device_unref(dev);
 			continue;
 		}
 
 		udev_device_unref(dev);
 
-		ret[i] = fd;
+		ret[i] = wlr_dev;
 		if (is_boot_vga) {
-			int tmp = ret[0];
+			struct wlr_device *tmp = ret[0];
 			ret[0] = ret[i];
 			ret[i] = tmp;
 		}

include/backend/drm/drm.h

@@ -82,6 +82,7 @@ struct wlr_drm_backend {
 	bool addfb2_modifiers;
 
 	int fd;
+	struct wlr_device *dev;
 
 	size_t num_crtcs;
 	struct wlr_drm_crtc *crtcs;

include/wlr/backend/drm.h

@@ -22,7 +22,8 @@
  * a DRM backend, other kinds of backends raise SIGABRT).
  */
 struct wlr_backend *wlr_drm_backend_create(struct wl_display *display,
-	struct wlr_session *session, int gpu_fd, struct wlr_backend *parent,
+	struct wlr_session *session, struct wlr_device *dev,
+	struct wlr_backend *parent,
 	wlr_renderer_create_func_t create_renderer_func);
 
 bool wlr_backend_is_drm(struct wlr_backend *backend);

include/wlr/backend/session.h

@@ -11,9 +11,11 @@ struct session_impl;
 struct wlr_device {
 	int fd;
 	dev_t dev;
-	struct wl_signal signal;
-
 	struct wl_list link;
+
+	struct {
+		struct wl_signal change;
+	} events;
 };
 
 struct wlr_session {
@@ -74,21 +76,21 @@ void wlr_session_destroy(struct wlr_session *session);
  *
  * Returns -errno on error.
  */
-int wlr_session_open_file(struct wlr_session *session, const char *path);
+struct wlr_device *wlr_session_open_file(struct wlr_session *session,
+	const char *path);
 
 /*
  * Closes a file previously opened with wlr_session_open_file.
  */
-void wlr_session_close_file(struct wlr_session *session, int fd);
+void wlr_session_close_file(struct wlr_session *session,
+	struct wlr_device *device);
 
-void wlr_session_signal_add(struct wlr_session *session, int fd,
-	struct wl_listener *listener);
 /*
  * Changes the virtual terminal.
  */
 bool wlr_session_change_vt(struct wlr_session *session, unsigned vt);
 
 size_t wlr_session_find_gpus(struct wlr_session *session,
-	size_t ret_len, int *ret);
+	size_t ret_len, struct wlr_device **ret);
 
 #endif