example lockscreen protocol implementation

config.in

@@ -20,6 +20,8 @@ set $term foot
 # on the original workspace that the command was run on.
 set $menu dmenu_path | dmenu | xargs swaymsg exec --
 
+set $lock swaylock -f -c 000000
+
 ### Output configuration
 #
 # Default wallpaper (more resolutions are available in @datadir@/backgrounds/sway/)
@@ -36,9 +38,9 @@ output * bg @datadir@/backgrounds/sway/Sway_Wallpaper_Blue_1920x1080.png fill
 # Example configuration:
 #
 # exec swayidle -w \
-#          timeout 300 'swaylock -f -c 000000' \
+#          timeout 300 'swaymsg -- lock_screen $lock' \
 #          timeout 600 'swaymsg "output * dpms off"' resume 'swaymsg "output * dpms on"' \
-#          before-sleep 'swaylock -f -c 000000'
+#          before-sleep 'swaymsg -- lock_screen $lock'
 #
 # This will lock your screen after 300 seconds of inactivity, then turn off
 # your displays after another 300 seconds, and turn your screens back on when
@@ -214,4 +216,16 @@ bar {
     }
 }
 
+#
+# Lock screen. 
+#
+bindsym $mod+Shift+L lock_screen --fail-unlocked $lock
+
+# For additional security, you can configure sway to deny access if
+# the lock screen crashes. You may (depending on what caused the crash)
+# be able to recover from this by running the lock screen again.
+#
+# bindsym --locked $mod+Shift+L lock_screen --fail-locked $lock
+
+
 include @sysconfdir@/sway/config.d/*

include/sway/commands.h

@@ -143,6 +143,7 @@ sway_cmd cmd_hide_edge_borders;
 sway_cmd cmd_include;
 sway_cmd cmd_inhibit_idle;
 sway_cmd cmd_input;
+sway_cmd cmd_lock_screen;
 sway_cmd cmd_seat;
 sway_cmd cmd_ipc;
 sway_cmd cmd_kill;

include/sway/lock.h

@@ -0,0 +1,29 @@
+#ifndef _SWAY_LOCK_H
+#define _SWAY_LOCK_H
+
+#include <wlr/types/wlr_buffer.h>
+
+#define PERMALOCK_CLIENT (struct wl_client *)(-1)
+
+struct sway_lock_state {
+	// true -> if lock screen crashes, unrecoverable
+	bool fail_locked;
+	// if this is not NULL, screen is locked. If the lock screen crashed,
+	// this may be set to PERMALOCK_CLIENT .
+	struct wl_client *client;
+	struct wl_listener client_destroy;
+
+	struct wlr_texture *permalock_message;
+	struct wl_global *ext_unlocker_v1_global;
+};
+
+// todo: need destroy
+void sway_lock_state_create(struct sway_lock_state *state,
+		struct wl_display *display);
+struct cmd_results *run_lockscreen_cmd(const char *cmd, bool fail_locked);
+
+struct sway_output;
+/** Create a texture which briefly explains the permalock state. */
+struct wlr_texture *draw_permalock_message(struct sway_output *output);
+
+#endif /* _SWAY_LOCK_H */

include/sway/output.h

@@ -56,6 +56,8 @@ struct sway_output {
 	uint32_t refresh_nsec;
 	int max_render_time; // In milliseconds
 	struct wl_event_source *repaint_timer;
+
+	struct wlr_texture *permalock_message;
 };
 
 struct sway_output *output_create(struct wlr_output *wlr_output);

include/sway/security.h

@@ -0,0 +1,10 @@
+#ifndef _SWAY_SECURITY_H
+#define _SWAY_SECURITY_H
+
+#include <stdbool.h>
+#include <wayland-server-core.h>
+
+bool security_global_filter(const struct wl_client *client,
+	const struct wl_global *global, void *data);
+
+#endif /* _SWAY_SECURITY_H */

include/sway/server.h

@@ -2,6 +2,7 @@
 #define _SWAY_SERVER_H
 #include <stdbool.h>
 #include <wayland-server-core.h>
+#include <sway/lock.h>
 #include <wlr/backend.h>
 #include <wlr/backend/session.h>
 #include <wlr/render/wlr_renderer.h>
@@ -90,6 +91,8 @@ struct sway_server {
 	struct wlr_xdg_activation_v1 *xdg_activation_v1;
 	struct wl_listener xdg_activation_v1_request_activate;
 
+	struct sway_lock_state lock_screen;
+
 	// The timeout for transactions, after which a transaction is applied
 	// regardless of readiness.
 	size_t txn_timeout_ms;

protocols/ext-unlocker-v1.xml

@@ -0,0 +1,47 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="ext_unlocker_v1">
+  <copyright>
+    Copyright 2021 Manuel Stoeckl
+
+    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 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.
+  </copyright>
+
+  <interface name="ext_unlocker_v1" version="1">
+    <description summary="protocol for a session (un)locker">
+      This protocol provides an interface for letting a special lock screen
+      client, which was created when the session was locked, communicate to
+      the compositor that the session should be unlocked.
+    </description>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy ext_unlocker_v1 object">
+        Announce that this object will no longer be used.
+      </description>
+    </request>
+
+    <request name="unlock">
+      <description summary="unlock screen">
+        Let the compositor know that it should unlock the screen.
+
+        After this request has been sent by the client, sending it again shall
+        have no effect.
+      </description>
+    </request>
+  </interface>
+</protocol>

protocols/meson.build

@@ -19,6 +19,7 @@ protocols = [
 	['idle.xml'],
 	['wlr-input-inhibitor-unstable-v1.xml'],
 	['wlr-output-power-management-unstable-v1.xml'],
+	['ext-unlocker-v1.xml'],
 ]
 
 client_protocols = [

sway/commands.c

@@ -73,6 +73,7 @@ static const struct cmd_handler handlers[] = {
 	{ "gaps", cmd_gaps },
 	{ "hide_edge_borders", cmd_hide_edge_borders },
 	{ "input", cmd_input },
+	{ "lock_screen", cmd_lock_screen},
 	{ "mode", cmd_mode },
 	{ "mouse_warping", cmd_mouse_warping },
 	{ "new_float", cmd_new_float },

sway/commands/lock_screen.c

@@ -0,0 +1,49 @@
+#define _POSIX_C_SOURCE 200809L
+#include <string.h>
+
+#include "log.h"
+#include "util.h"
+#include "stringop.h"
+#include "sway/commands.h"
+#include "sway/config.h"
+#include "sway/server.h"
+#include "sway/input/seat.h"
+#include "sway/output.h"
+
+struct cmd_results *cmd_lock_screen(int argc, char **argv) {
+	struct cmd_results *error = NULL;
+	if ((error = cmd_exec_validate(argc, argv))) {
+		return error;
+	}
+	bool fail_locked;
+	if (strcmp(argv[0], "--fail-locked") == 0) {
+		fail_locked = true;
+		argv++;
+		argc--;
+	} else if (strcmp(argv[0], "--fail-unlocked") == 0) {
+		fail_locked = false;
+		argv++;
+		argc--;
+	} else {
+		return cmd_results_new(CMD_FAILURE, "must set either --fail-locked or --fail-unlocked");
+	}
+
+	char *cmd;
+	if (argc == 1 && (argv[0][0] == '\'' || argv[0][0] == '"')) {
+		cmd = strdup(argv[0]);
+		strip_quotes(cmd);
+	} else {
+		cmd = join_args(argv, argc);
+	}
+
+	if (config->reloading) {
+		char *args = join_args(argv, argc);
+		sway_log(SWAY_DEBUG, "Ignoring 'cmd_lock_screen %s' due to reload", args);
+		free(args);
+		return cmd_results_new(CMD_SUCCESS, NULL);
+	}
+
+	struct cmd_results *res = run_lockscreen_cmd(cmd, fail_locked);
+	free(cmd);
+	return res;
+}

sway/desktop/render.c

@@ -21,6 +21,7 @@
 #include "sway/input/input-manager.h"
 #include "sway/input/seat.h"
 #include "sway/layers.h"
+#include "sway/lock.h"
 #include "sway/output.h"
 #include "sway/server.h"
 #include "sway/tree/arrange.h"
@@ -144,6 +145,11 @@ static void render_surface_iterator(struct sway_output *output,
 		return;
 	}
 
+	struct wl_client* client = wl_resource_get_client(surface->resource);
+	if (server.lock_screen.client && server.lock_screen.client != client) {
+		return;
+	}
+
 	struct wlr_fbox src_box;
 	wlr_surface_get_buffer_source_box(surface, &src_box);
 
@@ -1048,6 +1054,47 @@ void output_render(struct sway_output *output, struct timespec *when,
 		pixman_region32_union_rect(damage, damage, 0, 0, width, height);
 	}
 
+	if (server.lock_screen.client) {
+		/* assume lock screen client is overlay surface, etc */
+
+		// repaint the background, to hide old data
+		float clear_color[] = {0.0f, 0.0f, 0.0f, 1.0f};
+		if (server.lock_screen.client == PERMALOCK_CLIENT) {
+			clear_color[0] = 1.f;
+		}
+		int nrects;
+		pixman_box32_t *rects = pixman_region32_rectangles(damage, &nrects);
+		for (int i = 0; i < nrects; ++i) {
+			scissor_output(wlr_output, &rects[i]);
+			wlr_renderer_clear(renderer, clear_color);
+		}
+
+		if (server.lock_screen.client == PERMALOCK_CLIENT) {
+			if (!output->permalock_message) {
+				output->permalock_message = draw_permalock_message(output);
+			}
+
+			wlr_renderer_scissor(renderer, NULL);
+
+			if (output->permalock_message) {
+				float matrix[9];
+				/* todo: rescale message to fit into screen */
+				wlr_matrix_identity(matrix);
+				float x_expand = output->width / (float)output->permalock_message->width;
+				float y_expand = output->height / (float)output->permalock_message->height;
+				float expand = x_expand > y_expand ? y_expand : x_expand;
+
+				wlr_matrix_scale(matrix, expand, expand);
+				int x = output->width / 2 / expand - output->permalock_message->width / 2;
+				int y = output->height / 2 / expand - output->permalock_message->height / 2;
+
+				wlr_render_texture(renderer, output->permalock_message, matrix, x, y, 1.0);
+			}
+		}
+
+		// then go to clear lock screen
+		goto render_overlay;
+	}
 	if (output_has_opaque_overlay_layer_surface(output)) {
 		goto render_overlay;
 	}

sway/input/input-manager.c

@@ -290,6 +290,11 @@ static void handle_inhibit_deactivate(struct wl_listener *listener, void *data)
 			listener, input_manager, inhibit_deactivate);
 	struct sway_seat *seat;
 	wl_list_for_each(seat, &input_manager->seats, link) {
+		if (seat->exclusive_client != input_manager->inhibit->active_client)  {
+			// the permalock screen can also set exclusive clients,
+			// so don't undo its work.
+			continue;
+		}
 		seat_set_exclusive_client(seat, NULL);
 		struct sway_node *previous = seat_get_focus(seat);
 		if (previous) {