config: allow waylandsessions and xsessions to be set to null

Makes both fields optional (?[]const u8), consistent with other nullable
config fields such as xinitrc. Setting either to null in config.ini cleanly
skips crawling for that session type with no side effects.

res/config.ini

@@ -363,6 +363,7 @@ vi_mode = false
 # Wayland desktop environments
 # You can specify multiple directories,
 # e.g. $PREFIX_DIRECTORY/share/wayland-sessions:$PREFIX_DIRECTORY/local/share/wayland-sessions
+# If null, Wayland sessions will not be shown
 waylandsessions = $PREFIX_DIRECTORY/share/wayland-sessions
 
 # Xorg server command
@@ -384,6 +385,7 @@ xinitrc = ~/.xinitrc
 # Xorg desktop environments
 # You can specify multiple directories,
 # e.g. $PREFIX_DIRECTORY/share/xsessions:$PREFIX_DIRECTORY/local/share/xsessions
+# If null, X11 sessions will not be shown
 xsessions = $PREFIX_DIRECTORY/share/xsessions
 
 # Custom Commands and Labels:

src/config/Config.zig

@@ -92,9 +92,9 @@ start_cmd: ?[]const u8 = null,
 text_in_center: bool = false,
 vi_default_mode: ViMode = .normal,
 vi_mode: bool = false,
-waylandsessions: []const u8 = build_options.prefix_directory ++ "/share/wayland-sessions",
+waylandsessions: ?[]const u8 = build_options.prefix_directory ++ "/share/wayland-sessions",
 x_cmd: []const u8 = build_options.prefix_directory ++ "/bin/X",
 x_vt: ?u8 = null,
 xauth_cmd: []const u8 = build_options.prefix_directory ++ "/bin/xauth",
 xinitrc: ?[]const u8 = "~/.xinitrc",
-xsessions: []const u8 = build_options.prefix_directory ++ "/share/xsessions",
+xsessions: ?[]const u8 = build_options.prefix_directory ++ "/share/xsessions",

src/main.zig

@@ -769,32 +769,36 @@ pub fn main() !void {
     var has_crawl_error = false;
 
     // Crawl session directories (Wayland, X11 and custom respectively)
-    var wayland_session_dirs = std.mem.splitScalar(u8, state.config.waylandsessions, ':');
+    if (state.config.waylandsessions) |waylandsessions| {
-    while (wayland_session_dirs.next()) |dir| {
+        var wayland_session_dirs = std.mem.splitScalar(u8, waylandsessions, ':');
-        crawl(&state.session, state.lang, dir, .wayland) catch |err| {
+        while (wayland_session_dirs.next()) |dir| {
-            has_crawl_error = true;
+            crawl(&state.session, state.lang, dir, .wayland) catch |err| {
-            try state.log_file.err(
-                "sys",
-                "failed to crawl wayland session directory '{s}': {s}",
-                .{ dir, @errorName(err) },
-            );
-        };
-    }
-
-    if (build_options.enable_x11_support) {
-        var x_session_dirs = std.mem.splitScalar(u8, state.config.xsessions, ':');
-        while (x_session_dirs.next()) |dir| {
-            crawl(&state.session, state.lang, dir, .x11) catch |err| {
                 has_crawl_error = true;
                 try state.log_file.err(
                     "sys",
-                    "failed to crawl x11 session directory '{s}': {s}",
+                    "failed to crawl wayland session directory '{s}': {s}",
                     .{ dir, @errorName(err) },
                 );
             };
         }
     }
 
+    if (build_options.enable_x11_support) {
+        if (state.config.xsessions) |xsessions| {
+            var x_session_dirs = std.mem.splitScalar(u8, xsessions, ':');
+            while (x_session_dirs.next()) |dir| {
+                crawl(&state.session, state.lang, dir, .x11) catch |err| {
+                    has_crawl_error = true;
+                    try state.log_file.err(
+                        "sys",
+                        "failed to crawl x11 session directory '{s}': {s}",
+                        .{ dir, @errorName(err) },
+                    );
+                };
+            }
+        }
+    }
+
     var custom_session_dirs = std.mem.splitScalar(u8, state.config.custom_sessions, ':');
     while (custom_session_dirs.next()) |dir| {
         crawl(&state.session, state.lang, dir, .custom) catch |err| {