Add exit_river keybinding

Recently, river removed the hardcoded Ctrl+Alt Delete keybinding that
exits river and replaces it with a new `exit_session` request. This adds
support for that request via the new `exit_session` bind. We also added
3 hardcoded default keybinds to: exit river, reload the config, and
open foot. This way, if the config fails to load or is missing, you
should still be able to try reload. I guess you're still SOL if you have
at least one keybind and it's not reload_config, but you do what you can
do.

src/Config.zig

@@ -127,9 +127,27 @@ pub fn create() !*Config {
         };
     }
 
+    if (config.keybinds.count() == 0) {
+        config.addFallbackKeybinds();
+    }
+
     return config;
 }
 
+fn addFallbackKeybinds(config: *Config) void {
+    const Entry = struct { keybind.Key, XkbBindings.Command };
+    const fallbacks = [_]Entry{
+        .{ .{ .modifiers = .{ .ctrl = true, .mod1 = true }, .keysym = .Delete }, @unionInit(XkbBindings.Command, "exit_river", {}) },
+        .{ .{ .modifiers = .{ .mod4 = true, .shift = true }, .keysym = .R }, @unionInit(XkbBindings.Command, "reload_config", {}) },
+        .{ .{ .modifiers = .{ .mod4 = true }, .keysym = .T }, .{ .spawn = utils.gpa.dupe([]const u8, &.{
+            utils.gpa.dupe(u8, "foot") catch @panic("Out of memory"),
+        }) catch @panic("Out of memory") } },
+    };
+    for (&fallbacks) |*entry| {
+        config.keybinds.put(utils.gpa, entry[0], entry[1]) catch @panic("Out of memory");
+    }
+}
+
 pub fn destroy(config: *Config) void {
     for (config.keybinds.values()) |cmd| {
         cmd.deinit();

src/XkbBindings.zig

@@ -22,6 +22,7 @@ pub const Command = union(enum) {
     reload_config,
     toggle_fullscreen,
     close_window,
+    exit_river,
     // Tag management
     set_output_tags: u32,
     set_window_tags: u32,
@@ -70,6 +71,7 @@ pub const Command = union(enum) {
             .reload_config,
             .toggle_fullscreen,
             .close_window,
+            .exit_river,
             .set_output_tags,
             .set_window_tags,
             .toggle_output_tags,
@@ -246,6 +248,7 @@ const XkbBinding = struct {
                     window.river_window_v1.close();
                 }
             },
+            .exit_river => context.wm.river_window_manager_v1.exitSession(),
             .set_output_tags => |tags| {
                 const seat = first_seat orelse return;
                 const output = seat.focused_output orelse return;

src/config/keybind.zig

@@ -140,6 +140,7 @@ pub fn load(config: *Config, parser: *kdl.Parser, hostname: ?[]const u8) !void {
                         .reload_config,
                         .toggle_fullscreen,
                         .close_window,
+                        .exit_river,
                         .increment_primary_count,
                         .decrement_primary_count,
                         .swap_next,

src/main.zig

@@ -262,7 +262,8 @@ fn registryListener(registry: *wl.Registry, event: wl.Registry.Event, globals: *
                     fatal("Failed to bind to river_layer_shell_v1: {any}", .{@errorName(e)});
                 };
             } else if (mem.orderZ(u8, ev.interface, river.WindowManagerV1.interface.name) == .eq) {
-                globals.river_window_manager_v1 = registry.bind(ev.name, river.WindowManagerV1, 3) catch |e| {
+                if (ev.version < 4) utils.versionNotSupported(river.WindowManagerV1, ev.version, 4);
+                globals.river_window_manager_v1 = registry.bind(ev.name, river.WindowManagerV1, 4) catch |e| {
                     fatal("Failed to bind to river_window_manager_v1: {any}", .{@errorName(e)});
                 };
             } else if (mem.orderZ(u8, ev.interface, river.XkbBindingsV1.interface.name) == .eq) {