prototype safe screen locking interface

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>

include/swaylock.h

@@ -79,6 +79,7 @@ struct swaylock_state {
 	struct wl_subcompositor *subcompositor;
 	struct zwlr_layer_shell_v1 *layer_shell;
 	struct zwlr_input_inhibit_manager_v1 *input_inhibit_manager;
+	struct ext_unlocker_v1 *unlocker;
 	struct wl_shm *shm;
 	struct wl_list surfaces;
 	struct wl_list images;

main.c

@@ -23,6 +23,7 @@
 #include "pool-buffer.h"
 #include "seat.h"
 #include "swaylock.h"
+#include "ext-unlocker-v1-client-protocol.h"
 #include "wlr-input-inhibitor-unstable-v1-client-protocol.h"
 #include "wlr-layer-shell-unstable-v1-client-protocol.h"
 #include "xdg-output-unstable-v1-client-protocol.h"
@@ -344,6 +345,9 @@ static void handle_global(void *data, struct wl_registry *registry,
 			create_layer_surface(surface);
 			wl_display_roundtrip(state->display);
 		}
+	} else if (strcmp(interface, ext_unlocker_v1_interface.name) == 0) {
+		state->unlocker = wl_registry_bind(
+			registry, name, &ext_unlocker_v1_interface, 1);
 	}
 }
 
@@ -1086,6 +1090,11 @@ static void display_in(int fd, short mask, void *data) {
 
 static void comm_in(int fd, short mask, void *data) {
 	if (read_comm_reply()) {
+		if (state.unlocker) {
+			ext_unlocker_v1_unlock(state.unlocker);
+			// ensure compositor sees this immediately
+			wl_display_roundtrip(state.display);
+		}
 		// Authentication succeeded
 		state.run_display = false;
 	} else {

meson.build

@@ -88,6 +88,7 @@ client_protocols = [
 	[wl_protocol_dir, 'unstable/xdg-output/xdg-output-unstable-v1.xml'],
 	['wlr-layer-shell-unstable-v1.xml'],
 	['wlr-input-inhibitor-unstable-v1.xml'],
+	['ext-unlocker-v1.xml'],
 ]
 
 foreach p : client_protocols