Add grace period feature

This includes:
* A --grace flag to specify how long to wait before requiring a password
* A --pointer-hysteresis flag to prevent minor mouse wiggles from unlocking
  the screen
* A helper process that ensures the screen locks before the system sleeps
  (which adds a dependency on logind, for sleep inhibition)
* A SIGINT2 handler to end the grace period

Author: mstoeckl

README.md

@@ -43,6 +43,45 @@ restart swaylock-plugin; or by switching to a different virtual terminal, runnin
 
 See the man page, [`swaylock-plugin(1)`](swaylock.1.scd), for instructions on using swaylock-plugin.
 
+## Grace period
+
+`swaylock-plugin` adds a grace period feature; unlike the original `swaylock`, it
+is not practical to emulate one using a separate program (like `chayang`) because
+any animated backgrounds would be interrupted. With the `--grace` flag, it is
+possible to unlock the screen without a password for the first few seconds after
+the screen locker starts with either a key press or significant mouse motion.
+
+This feature requires logind (systemd or elogind) support to automatically end the
+grace period just before the computer goes to sleep. The grace period also ends on
+receipt of the signal SIGUSR2.
+
+### Example
+
+Sway can be made to lock the screen with a grace period and the custom wallpaper
+program specified in the script `lock-bg-command.sh` with the following configuration:
+
+```
+exec swayidle \
+    timeout 300 'swaylock-plugin --grace 30sec --pointer-hysteresis 25.0 --command-each lock-bg-command.sh' \
+    timeout 600 'swaymsg "output * dpms off"' \
+       resume 'swaymsg "output * dpms on"' \
+       before-sleep 'swaylock-plugin --command-each lock-bg-command.sh'
+bindsym --locked Ctrl+Alt+L exec \
+    'killall -SIGUSR2 swaylock-plugin; \
+    swaylock-plugin --command-each lock-bg-command.sh'
+```
+
+This will, after 5 minutes of inactivity, start `swaylock-plugin`; for the next
+30 seconds, one can easily unlock the screen by pressing any key or moving the
+mouse more than 25 pixels in a one second period; afterwards, authentication
+will be required. When the computer goes to sleep, the screen will lock for
+certain. (If `swaylock-plugin` was running and in the grace period, the grace
+period will end; in case `swaylock-plugin` was not running, a new instance will
+be started without a grace period, that locks the screen if it was not already
+locked.) One can also immediately lock the screen with a keybinding (or use the
+keybinding to restart the lock screen, if it crashed.) Any screens will be turned
+off after 10 minutes of inactivity.
+
 ## Installation
 
 Install dependencies:
@@ -54,6 +93,7 @@ Install dependencies:
 * cairo
 * gdk-pixbuf2
 * pam (optional)
+* systemd or elogind (optional)
 * [scdoc](https://git.sr.ht/~sircmpwn/scdoc) (optional: man pages) \*
 * git \*
 * swaybg

include/seat.h

@@ -3,6 +3,8 @@
 #include <xkbcommon/xkbcommon.h>
 #include <stdint.h>
 #include <stdbool.h>
+#include <wayland-util.h>
+#include <time.h>
 
 struct loop;
 struct loop_timer;
@@ -24,6 +26,10 @@ struct swaylock_seat {
 	uint32_t repeat_sym;
 	uint32_t repeat_codepoint;
 	struct loop_timer *repeat_timer;
+	/* mouse tracking to check for deliberate mouse motion */
+	int64_t last_interval;
+	wl_fixed_t interval_start_x, interval_start_y;
+	wl_fixed_t last_mouse_x, last_mouse_y;
 };
 
 extern const struct wl_seat_listener seat_listener;

include/swaylock.h

@@ -76,6 +76,10 @@ struct swaylock_args {
 	bool indicator_idle_visible;
 	char *plugin_command;
 	bool plugin_per_output;
+	/* negative values = no grace; unit: seconds */
+	float grace_time;
+	/* max number of pixels/sec mouse motion which will be ignored */
+	float grace_pointer_hysteresis;
 };
 
 struct swaylock_password {
@@ -303,6 +307,8 @@ struct swaylock_state {
 	struct forward_state forward;
 	struct swaylock_bg_server server;
 	bool start_clientless_mode;
+	struct loop_timer *grace_timer; // timer for grace period to end
+	int sleep_comm_r, sleep_comm_w;
 
 	// for nested server, output was destroyed
 	struct wl_list stale_wl_output_resources;

main.c

@@ -674,11 +674,16 @@ static const struct wl_registry_listener registry_listener = {
 };
 
 static int sigusr_fds[2] = {-1, -1};
+static int sigusr2_fds[2] = {-1, -1};
 
 void do_sigusr(int sig) {
 	(void)write(sigusr_fds[1], "1", 1);
 }
 
+void do_sigusr2(int sig) {
+	(void)write(sigusr2_fds[1], "1", 1);
+}
+
 static cairo_surface_t *select_image(struct swaylock_state *state,
 		struct swaylock_surface *surface) {
 	struct swaylock_image *image;
@@ -854,6 +859,8 @@ static int parse_options(int argc, char **argv, struct swaylock_state *state,
 		LO_TEXT_CAPS_LOCK_COLOR,
 		LO_TEXT_VER_COLOR,
 		LO_TEXT_WRONG_COLOR,
+		LO_PLUGIN_GRACE,
+		LO_PLUGIN_POINTER_HYSTERESIS,
 		LO_PLUGIN_COMMAND,
 		LO_PLUGIN_COMMAND_EACH,
 	};
@@ -913,6 +920,8 @@ static int parse_options(int argc, char **argv, struct swaylock_state *state,
 		{"text-caps-lock-color", required_argument, NULL, LO_TEXT_CAPS_LOCK_COLOR},
 		{"text-ver-color", required_argument, NULL, LO_TEXT_VER_COLOR},
 		{"text-wrong-color", required_argument, NULL, LO_TEXT_WRONG_COLOR},
+		{"grace", required_argument, NULL, LO_PLUGIN_GRACE},
+		{"pointer-hysteresis", required_argument, NULL, LO_PLUGIN_POINTER_HYSTERESIS},
 		{"command", required_argument, NULL, LO_PLUGIN_COMMAND},
 		{"command-each", required_argument, NULL, LO_PLUGIN_COMMAND_EACH},
 		{0, 0, 0, 0}
@@ -1037,6 +1046,10 @@ static int parse_options(int argc, char **argv, struct swaylock_state *state,
 			"Sets the color of the text when verifying.\n"
 		"  --text-wrong-color <color>       "
 			"Sets the color of the text when invalid.\n"
+		"  --grace <seconds>                "
+			"Allow unlocking without a password before <seconds> elapse\n"
+		"  --pointer-hysteresis <distance>  "
+			"If --grace used, minimum mouse motion needed to auto-unlock\n"
 		"  --command <cmd>                  "
 			"Indicates which program to run to draw backgrounds.\n"
 		"  --command-each <cmd>             "
@@ -1322,6 +1335,38 @@ static int parse_options(int argc, char **argv, struct swaylock_state *state,
 				state->args.colors.text.wrong = parse_color(optarg);
 			}
 			break;
+		case LO_PLUGIN_GRACE:
+			if (state) {
+				char *end = NULL;
+				float value = strtof(optarg, &end);
+				float unit = 1.0;
+				if (*end == 0 || strcmp(end, "s") == 0 || strcmp(end, "sec") == 0) {
+					unit = 1.0;
+				} else if (strcmp(end, "m") == 0 || strcmp(end, "min") == 0) {
+					unit = 60.0;
+				} else if (strcmp(end, "h") == 0 || strcmp(end, "hr") == 0) {
+					unit = 3600.0;
+				} else {
+					swaylock_log(LOG_ERROR,
+						"'%s' is not a valid grace time specification. Valid examples: 11.5, 100s, 30min, 2hr",
+						optarg);
+					break;
+				}
+				state->args.grace_time = value * unit;
+			}
+			break;
+		case LO_PLUGIN_POINTER_HYSTERESIS:
+			if (state) {
+				char *end = NULL;
+				float value = strtof(optarg, &end);
+				if (*end == '\0') {
+					state->args.grace_pointer_hysteresis = value;
+				} else {
+					swaylock_log(LOG_ERROR,
+						"Invalid value for pointer hysteresis: '%s' is not a real number", optarg);
+				}
+			}
+			break;
 		case LO_PLUGIN_COMMAND:
 			if (state) {
 				free(state->args.plugin_command);
@@ -1852,6 +1897,19 @@ static void output_redraw_timeout(void *data) {
 	client_timeout(surface->client ? surface->client : surface->state->server.main_client);
 }
 
+static void grace_timeout(void *data) {
+	struct swaylock_state *state = data;
+	// The event loop frees the timer object; setting grace_timer to null marks
+	// the grace period as over
+	swaylock_log(LOG_DEBUG, "Grace period ended");
+	state->grace_timer = NULL;
+	loop_remove_fd(state->eventloop, state->sleep_comm_r);
+	close(state->sleep_comm_r);
+	close(state->sleep_comm_w);
+	state->sleep_comm_r = -1;
+	state->sleep_comm_w = -1;
+}
+
 uint32_t posix_spawn_setsid_flag(void);
 static bool spawn_command(struct swaylock_state *state, int sock_child,
 		int sock_local, const char *output_name, const char *output_desc) {
@@ -2103,6 +2161,71 @@ static void term_in(int fd, short mask, void *data) {
 	state.run_display = false;
 }
 
+static void lock_in(int fd, short mask, void *data) {
+	/* On receipt of SIGUSR2, end the grace period */
+	if (state.grace_timer) {
+		/* Timer will automatically be freed later */
+		swaylock_log(LOG_DEBUG, "Received SIGUSR2, ending unlock grace period");
+		loop_remove_timer(state.eventloop, state.grace_timer);
+		state.grace_timer = NULL;
+		loop_remove_fd(state.eventloop, state.sleep_comm_r);
+		close(state.sleep_comm_r);
+		close(state.sleep_comm_w);
+		state.sleep_comm_r = -1;
+		state.sleep_comm_w = -1;
+	}
+}
+
+static void sleep_in(int fd, short mask, void *data) {
+	struct swaylock_state *state = data;
+	if (state->grace_timer) {
+		swaylock_log(LOG_DEBUG, "Received sleep notification, ending unlock grace period");
+		loop_remove_timer(state->eventloop, state->grace_timer);
+		state->grace_timer = NULL;
+		close(state->sleep_comm_r);
+		close(state->sleep_comm_w);
+		state->sleep_comm_r = -1;
+		state->sleep_comm_w = -1;
+	}
+	loop_remove_fd(state->eventloop, state->sleep_comm_r);
+}
+
+static int start_sleep_watcher(int *sleep_comm_r, int* sleep_comm_w) {
+	int comm_r[2], comm_w[2];
+	if (pipe(comm_r) != 0 || pipe(comm_w) != 0) {
+		swaylock_log(LOG_ERROR, "Failed to create communication pipes");
+		return -1;
+	}
+
+	if (!set_cloexec(comm_r[0]) || !set_cloexec(comm_w[1])) {
+		swaylock_log(LOG_ERROR, "Failed to make pipes close-on-exec");
+		close(comm_r[0]);
+		close(comm_r[1]);
+		close(comm_w[0]);
+		close(comm_w[1]);
+		return -1;
+	}
+
+	pid_t pid;
+	char proc_r_str[20], proc_w_str[20];
+	snprintf(proc_r_str, sizeof(proc_r_str), "%d", comm_w[0]);
+	snprintf(proc_w_str, sizeof(proc_w_str), "%d", comm_r[1]);
+	char *args[] = {"swaylock-sleep-watcher", proc_w_str, proc_r_str, NULL};
+	if (posix_spawnp(&pid, "swaylock-sleep-watcher", NULL, NULL, args, environ) == -1) {
+		close(comm_r[0]);
+		close(comm_r[1]);
+		close(comm_w[0]);
+		close(comm_w[1]);
+		swaylock_log(LOG_ERROR, "Failed to run sleep detection helper");
+		return -1;
+	}
+	close(comm_r[1]);
+	close(comm_w[0]);
+	*sleep_comm_r = comm_r[0];
+	*sleep_comm_w = comm_w[1];
+	return 0;
+}
+
 // Check for --debug 'early' we also apply the correct loglevel
 // to the forked child, without having to first proces all of the
 // configuration (including from file) before forking and (in the
@@ -2130,6 +2253,15 @@ void log_init(int argc, char **argv) {
 }
 
 int main(int argc, char **argv) {
+	/* Initially ignore SIGUSR1 + SIGUSR2 to prevent stray signals (like
+	 * `killall -SIGUSR2`) from affecting the pw backend subprocess */
+	struct sigaction sa;
+	sa.sa_handler = SIG_IGN;
+	sigemptyset(&sa.sa_mask);
+	sa.sa_flags = 0;
+	sigaction(SIGUSR1, &sa, NULL);
+	sigaction(SIGUSR2, &sa, NULL);
+
 	log_init(argc, argv);
 	initialize_pw_backend(argc, argv);
 	srand(time(NULL));
@@ -2156,6 +2288,8 @@ int main(int argc, char **argv) {
 		.indicator_idle_visible = false,
 		.ready_fd = -1,
 		.plugin_command = NULL,
+		.grace_time = 0.0f,
+		.grace_pointer_hysteresis = 10.0f,
 	};
 	wl_list_init(&state.images);
 	set_default_colors(&state.args.colors);
@@ -2214,6 +2348,18 @@ int main(int argc, char **argv) {
 		swaylock_log(LOG_ERROR, "Failed to make pipe end nonblocking");
 		return EXIT_FAILURE;
 	}
+	if (pipe(sigusr2_fds) != 0) {
+		swaylock_log(LOG_ERROR, "Failed to pipe");
+		return EXIT_FAILURE;
+	}
+	if (!set_cloexec(sigusr2_fds[0]) || !set_cloexec(sigusr2_fds[1])) {
+		swaylock_log(LOG_ERROR, "Failed to make pipes close-on-exec");
+		return EXIT_FAILURE;
+	}
+	if (fcntl(sigusr2_fds[1], F_SETFL, O_NONBLOCK) == -1) {
+		swaylock_log(LOG_ERROR, "Failed to make pipe end nonblocking");
+		return EXIT_FAILURE;
+	}
 
 	// temp: make all backgrounds use some sort of plugin command
 	if (!state.args.plugin_command) {
@@ -2340,6 +2486,19 @@ int main(int argc, char **argv) {
 		daemonize();
 	}
 
+	state.sleep_comm_r = -1;
+	state.sleep_comm_w = -1;
+	if (state.args.grace_time > 0.) {
+		float delay_ms = ceilf(state.args.grace_time * 1000.f);
+		int delay = delay_ms >= (float)INT_MAX ? INT_MAX : (int)delay_ms;
+
+		/* Failure of this process just cancels the grace period */
+		if (start_sleep_watcher(&state.sleep_comm_r, &state.sleep_comm_w) == 0) {
+			state.grace_timer = loop_add_timer(state.eventloop, delay, grace_timeout, &state);
+			loop_add_fd(state.eventloop, state.sleep_comm_r, POLLIN, sleep_in, &state);
+		}
+	}
+
 	/* fill in dmabuf modifier list if empty and upstream provided dmabuf-feedback */
 	if (state.forward.linux_dmabuf && zwp_linux_dmabuf_v1_get_version(state.forward.linux_dmabuf) >= 4) {
 		size_t npairs = 0;
@@ -2420,13 +2579,18 @@ int main(int argc, char **argv) {
 		POLLIN, dispatch_nested, NULL);
 
 	loop_add_fd(state.eventloop, sigusr_fds[0], POLLIN, term_in, NULL);
+	loop_add_fd(state.eventloop, sigusr2_fds[0], POLLIN, lock_in, NULL);
 
-	struct sigaction sa;
 	sa.sa_handler = do_sigusr;
 	sigemptyset(&sa.sa_mask);
 	sa.sa_flags = SA_RESTART;
 	sigaction(SIGUSR1, &sa, NULL);
 
+	sa.sa_handler = do_sigusr2;
+	sigemptyset(&sa.sa_mask);
+	sa.sa_flags = SA_RESTART;
+	sigaction(SIGUSR2, &sa, NULL);
+
 	// Ignore SIGCHLD, to make child processes be automatically reaped.
 	// (This setting is not inherited to child processes.)
 	struct sigaction sa2;

meson.build

@@ -40,6 +40,7 @@ libpam = cc.find_library('pam', required: get_option('pam'))
 crypt = cc.find_library('crypt', required: not libpam.found())
 math = cc.find_library('m')
 rt = cc.find_library('rt')
+logind = dependency('lib' + get_option('logind-provider'), required: get_option('logind'))
 
 git = find_program('git', required: false)
 scdoc = find_program('scdoc', required: get_option('man-pages'))
@@ -110,6 +111,11 @@ conf_data = configuration_data()
 conf_data.set_quoted('SYSCONFDIR', get_option('prefix') / get_option('sysconfdir'))
 conf_data.set_quoted('SWAYLOCK_VERSION', version)
 conf_data.set10('HAVE_GDK_PIXBUF', gdk_pixbuf.found())
+conf_data.set10('HAVE_SYSTEMD', false)
+conf_data.set10('HAVE_ELOGIND', false)
+if logind.found()
+	conf_data.set10('HAVE_' + get_option('logind-provider').to_upper(), true)
+endif
 
 subdir('include')
 
@@ -159,6 +165,13 @@ executable('swaylock-plugin',
 	install: true
 )
 
+executable('swaylock-sleep-watcher',
+	['sleep-watcher.c', 'log.c'],
+	include_directories: [swaylock_inc],
+	dependencies: [logind],
+	install: true
+)
+
 if libpam.found()
 	install_data(
 		'pam/swaylock-plugin',

meson_options.txt

@@ -4,3 +4,5 @@ option('man-pages', type: 'feature', value: 'auto', description: 'Generate and i
 option('zsh-completions', type: 'boolean', value: true, description: 'Install zsh shell completions')
 option('bash-completions', type: 'boolean', value: true, description: 'Install bash shell completions')
 option('fish-completions', type: 'boolean', value: true, description: 'Install fish shell completions')
+option('logind', type: 'feature', value: 'auto', description: 'Enable support for logind (to automatically end grace period on sleep)')
+option('logind-provider', type: 'combo', choices: ['systemd', 'elogind'], value: 'systemd', description: 'Provider of logind support library')