libweston/launcher: libseat backend

This adds support for libseat as a seat backend. libseat provides seatd,
(e)logind and direct seat backends as compile-time and runtime options.

The backend is currently disabled by default. It can be enabled through the
launcher-libseat option.

Signed-off-by: Kenny Levinsen <kl@kl.wtf>

libweston/launcher-impl.h

@@ -45,6 +45,7 @@ struct weston_launcher {
 	const struct launcher_interface *iface;
 };
 
+extern const struct launcher_interface launcher_libseat_iface;
 extern const struct launcher_interface launcher_logind_iface;
 extern const struct launcher_interface launcher_weston_launch_iface;
 extern const struct launcher_interface launcher_direct_iface;

libweston/launcher-libseat.c

+/*
+ * Copyright © 2020 Kenny Levinsen
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "config.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <libseat.h>
+
+#include <libweston/libweston.h>
+#include "backend.h"
+#include "dbus.h"
+#include "launcher-impl.h"
+
+struct launcher_libseat_device {
+	struct wl_list link;
+	int fd;
+	int device_id;
+	dev_t fsdev;
+};
+
+struct launcher_libseat {
+	struct weston_launcher base;
+	struct weston_compositor *compositor;
+	struct libseat *seat;
+
+	struct wl_event_source *seat_ctx;
+	struct wl_list devices;
+};
+
+static struct launcher_libseat_device *
+find_device_by_fd(struct launcher_libseat *wl, int fd)
+{
+	struct launcher_libseat_device *dev;
+	wl_list_for_each(dev, &wl->devices, link) {
+		if (dev->fd == fd) {
+			return dev;
+		}
+	}
+	return NULL;
+}
+
+static void
+handle_enable_seat(struct libseat *seat, void *data)
+{
+	struct launcher_libseat *wl = data;
+	if (wl->compositor->session_active)
+		return;
+
+	wl->compositor->session_active = true;
+
+	wl_signal_emit(&wl->compositor->session_signal,
+		       wl->compositor);
+}
+
+static void
+handle_disable_seat(struct libseat *seat, void *data)
+{
+	struct launcher_libseat *wl = data;
+	if (!wl->compositor->session_active)
+		return;
+
+	wl->compositor->session_active = false;
+
+	wl_signal_emit(&wl->compositor->session_signal,
+		       wl->compositor);
+	libseat_disable_seat(wl->seat);
+}
+
+static struct libseat_seat_listener seat_listener = {
+	.enable_seat = handle_enable_seat,
+	.disable_seat = handle_disable_seat,
+};
+
+static int
+seat_open_device(struct weston_launcher *launcher, const char *path, int flags)
+{
+	struct launcher_libseat *wl = wl_container_of(launcher, wl, base);
+	struct launcher_libseat_device *dev;
+	struct stat st;
+
+	dev = zalloc(sizeof(struct launcher_libseat_device));
+	if (dev == NULL) {
+		goto err_alloc;
+	}
+
+	dev->device_id = libseat_open_device(wl->seat, path, &dev->fd);
+	if (dev->device_id == -1) {
+		goto err_open;
+	}
+
+	if (fstat(dev->fd, &st) == -1) {
+		goto err_fd;
+	}
+	dev->fsdev = st.st_rdev;
+
+	wl_list_insert(&wl->devices, &dev->link);
+	return dev->fd;
+
+err_fd:
+	libseat_close_device(wl->seat, dev->device_id);
+	close(dev->fd);
+err_open:
+	free(dev);
+err_alloc:
+	return -1;
+}
+
+static void
+seat_close_device(struct weston_launcher *launcher, int fd)
+{
+	struct launcher_libseat *wl = wl_container_of(launcher, wl, base);
+	struct launcher_libseat_device *dev;
+
+	dev = find_device_by_fd(wl, fd);
+	if (dev == NULL) {
+		weston_log("libseat: No device with fd %d found\n", fd);
+		close(fd);
+		return;
+	}
+
+	if (libseat_close_device(wl->seat, dev->device_id) == -1) {
+		weston_log("libseat: Could not close device %d",
+				dev->device_id);
+	}
+
+	wl_list_remove(&dev->link);
+	free(dev);
+	close(fd);
+}
+
+static int
+seat_switch_session(struct weston_launcher *launcher, int vt)
+{
+	struct launcher_libseat *wl = wl_container_of(launcher, wl, base);
+	return libseat_switch_session(wl->seat, vt);
+}
+
+static int
+libseat_event(int fd, uint32_t mask, void *data)
+{
+	struct libseat *seat = data;
+	if (libseat_dispatch(seat, 0) == -1) {
+		weston_log("libseat: dispatch failed: %s\n", strerror(errno));
+		exit(-1);
+	}
+	return 1;
+}
+
+static int
+seat_open(struct weston_launcher **out, struct weston_compositor *compositor,
+	  int tty, const char *seat_id, bool sync_drm)
+{
+	struct launcher_libseat *wl;
+	struct wl_event_loop *event_loop;
+
+	wl = zalloc(sizeof(*wl));
+	if (wl == NULL) {
+		goto err_out;
+	}
+
+	wl->base.iface = &launcher_libseat_iface;
+	wl->compositor = compositor;
+	wl_list_init(&wl->devices);
+
+	wl->seat = libseat_open_seat(&seat_listener, wl);
+	if (wl->seat == NULL) {
+		weston_log("libseat: could not open seat\n");
+		goto err_seat;
+	}
+
+	event_loop = wl_display_get_event_loop(compositor->wl_display);
+	wl->seat_ctx = wl_event_loop_add_fd(event_loop,
+			libseat_get_fd(wl->seat), WL_EVENT_READABLE,
+			libseat_event, wl->seat);
+	if (wl->seat_ctx == NULL) {
+		weston_log("libseat: could not register connection to event loop\n");
+		goto err_session;
+	}
+	if (libseat_dispatch(wl->seat, 0) == -1) {
+		weston_log("libseat: dispatch failed\n");
+		goto err_session;
+	}
+
+	weston_log("libseat: session control granted\n");
+	*out = &wl->base;
+	return 0;
+
+err_session:
+	libseat_close_seat(wl->seat);
+err_seat:
+	free(wl);
+err_out:
+	return -1;
+}
+
+static void
+seat_close(struct weston_launcher *launcher)
+{
+	struct launcher_libseat *wl = wl_container_of(launcher, wl, base);
+
+	if (wl->seat != NULL) {
+		libseat_close_seat(wl->seat);
+	}
+	wl_event_source_remove(wl->seat_ctx);
+	free(wl);
+}
+
+static int
+seat_get_vt(struct weston_launcher *launcher)
+{
+	return -ENOSYS;
+}
+
+const struct launcher_interface launcher_libseat_iface = {
+	.name = "libseat",
+	.connect = seat_open,
+	.destroy = seat_close,
+	.open = seat_open_device,
+	.close = seat_close_device,
+	.activate_vt = seat_switch_session,
+	.get_vt = seat_get_vt,
+};

libweston/launcher-util.c

@@ -36,6 +36,9 @@
 #include <linux/input.h>
 
 static const struct launcher_interface *ifaces[] = {
+#ifdef HAVE_LIBSEAT
+	&launcher_libseat_iface,
+#endif
 #ifdef HAVE_SYSTEMD_LOGIN
 	&launcher_logind_iface,
 #endif

libweston/meson.build

@@ -180,6 +180,16 @@ if get_option('launcher-logind')
 		systemd_dep,
 	]
 endif
+if get_option('launcher-libseat')
+	libseat_dep = dependency('libseat', version: '>= 0.4')
+	config_h.set('HAVE_LIBSEAT', '1')
+	srcs_session_helper += [
+		'launcher-libseat.c',
+	]
+	deps_session_helper += [
+		libseat_dep,
+	]
+endif
 
 lib_session_helper = static_library(
 	'session-helper',

meson_options.txt

@@ -158,6 +158,13 @@ option(
 	description: 'Compositor: support systemd-logind D-Bus protocol'
 )
 
+option(
+	'launcher-libseat',
+	type: 'boolean',
+	value: false,
+	description: 'Compositor: support libseat'
+)
+
 option(
 	'image-jpeg',
 	type: 'boolean',