Implement custom session support (fixes #757)

Signed-off-by: AnErrupTion <anerruption@disroot.org>

src/Environment.zig

@@ -8,6 +8,7 @@ pub const DesktopEntry = struct {
     Exec: []const u8 = "",
     Name: [:0]const u8 = "",
     DesktopNames: ?[:0]u8 = null,
+    Terminal: ?bool = null,
 };
 
 pub const Entry = struct { @"Desktop Entry": DesktopEntry = .{} };
@@ -19,3 +20,4 @@ xdg_desktop_names: ?[:0]const u8 = null,
 cmd: []const u8 = "",
 specifier: []const u8 = "",
 display_server: DisplayServer = .wayland,
+is_terminal: bool = false,

src/auth.zig

@@ -180,6 +180,7 @@ fn startSession(
             const vt = try std.fmt.bufPrint(&vt_buf, "vt{d}", .{options.tty});
             try executeX11Cmd(pwd.pw_shell.?, pwd.pw_dir.?, options, current_environment.cmd, vt);
         },
+        .custom => try executeCustomCmd(pwd.pw_shell.?, options, current_environment.is_terminal, current_environment.cmd),
     }
 }
 
@@ -201,6 +202,7 @@ fn setXdgEnv(tty_str: [:0]u8, environment: Environment) !void {
         .wayland => "wayland",
         .shell => "tty",
         .xinitrc, .x11 => "x11",
+        .custom => "unspecified",
     }, 0);
 
     // The "/run/user/%d" directory is not available on FreeBSD. It is much
@@ -462,6 +464,22 @@ fn executeX11Cmd(shell: [*:0]const u8, pw_dir: [*:0]const u8, options: AuthOptio
     _ = std.c.waitpid(x_pid, &status, 0);
 }
 
+fn executeCustomCmd(shell: [*:0]const u8, options: AuthOptions, is_terminal: bool, exec_cmd: []const u8) !void {
+    var maybe_log_file: ?std.fs.File = null;
+    if (!is_terminal) {
+        // For custom desktop entries, the "Terminal" value here determines if
+        // we redirect standard output & error or not. That is, we redirect only
+        // if it's equal to false (so if it's not running in a TTY).
+        maybe_log_file = try redirectStandardStreams(options.session_log, true);
+    }
+    defer if (maybe_log_file) |log_file| log_file.close();
+
+    var cmd_buffer: [1024]u8 = undefined;
+    const cmd_str = try std.fmt.bufPrintZ(&cmd_buffer, "{s} {s} {s}", .{ options.setup_cmd, options.login_cmd orelse "", exec_cmd });
+    const args = [_:null]?[*:0]const u8{ shell, "-c", cmd_str };
+    return std.posix.execveZ(shell, &args, std.c.environ);
+}
+
 fn redirectStandardStreams(session_log: []const u8, create: bool) !std.fs.File {
     const log_file = if (create) (try std.fs.cwd().createFile(session_log, .{ .mode = 0o666 })) else (try std.fs.cwd().openFile(session_log, .{ .mode = .read_write }));
 

src/config/Config.zig

@@ -28,6 +28,7 @@ cmatrix_max_codepoint: u16 = 0x7B,
 colormix_col1: u32 = 0x00FF0000,
 colormix_col2: u32 = 0x000000FF,
 colormix_col3: u32 = 0x20000000,
+custom_sessions: []const u8 = build_options.config_directory ++ "/ly/custom-sessions",
 default_input: Input = .login,
 doom_fire_height: u8 = 6,
 doom_fire_spread: u8 = 2,

src/config/Lang.zig

@@ -7,6 +7,7 @@ authenticating: []const u8 = "authenticating...",
 brightness_down: []const u8 = "decrease brightness",
 brightness_up: []const u8 = "increase brightness",
 capslock: []const u8 = "capslock",
+custom: []const u8 = "custom",
 err_alloc: []const u8 = "failed memory allocation",
 err_bounds: []const u8 = "out-of-bounds index",
 err_brightness_change: []const u8 = "failed to change brightness",

src/enums.zig

@@ -11,6 +11,7 @@ pub const DisplayServer = enum {
     shell,
     xinitrc,
     x11,
+    custom,
 };
 
 pub const Input = enum {

src/main.zig

@@ -290,10 +290,12 @@ pub fn main() !void {
         try info_line.addMessage(hostname, config.bg, config.fg);
     }
 
+    // Crawl session directories (Wayland, X11 and custom respectively)
     var wayland_session_dirs = std.mem.splitScalar(u8, config.waylandsessions, ':');
     while (wayland_session_dirs.next()) |dir| {
         try crawl(&session, lang, dir, .wayland);
     }
+
     if (build_options.enable_x11_support) {
         var x_session_dirs = std.mem.splitScalar(u8, config.xsessions, ':');
         while (x_session_dirs.next()) |dir| {
@@ -301,6 +303,11 @@ pub fn main() !void {
         }
     }
 
+    var custom_session_dirs = std.mem.splitScalar(u8, config.custom_sessions, ':');
+    while (custom_session_dirs.next()) |dir| {
+        try crawl(&session, lang, dir, .custom);
+    }
+
     var login = Text.init(allocator, &buffer, false, null);
     defer login.deinit();
 
@@ -864,11 +871,7 @@ fn addOtherEnvironment(session: *Session, lang: Lang, display_server: DisplaySer
         .xdg_session_desktop = null,
         .xdg_desktop_names = null,
         .cmd = exec orelse "",
-        .specifier = switch (display_server) {
-            .wayland => lang.wayland,
-            .x11 => lang.x11,
-            else => lang.other,
-        },
+        .specifier = lang.other,
         .display_server = display_server,
     });
 }
@@ -890,40 +893,43 @@ fn crawl(session: *Session, lang: Lang, path: []const u8, display_server: Displa
         });
         errdefer entry_ini.deinit();
 
-        var xdg_session_desktop: []const u8 = undefined;
+        var maybe_xdg_session_desktop: ?[]const u8 = null;
         const maybe_desktop_names = entry_ini.data.@"Desktop Entry".DesktopNames;
         if (maybe_desktop_names) |desktop_names| {
-            xdg_session_desktop = std.mem.sliceTo(desktop_names, ';');
-        } else {
-            // if DesktopNames is empty, we'll take the name of the session file
-            xdg_session_desktop = std.fs.path.stem(item.name);
+            maybe_xdg_session_desktop = std.mem.sliceTo(desktop_names, ';');
+        } else if (display_server != .custom) {
+            // If DesktopNames is empty, and this isn't a custom session entry,
+            // we'll take the name of the session file
+            maybe_xdg_session_desktop = std.fs.path.stem(item.name);
         }
 
         // Prepare the XDG_CURRENT_DESKTOP environment variable here
         const entry = entry_ini.data.@"Desktop Entry";
-        var xdg_desktop_names: ?[:0]const u8 = null;
+        var maybe_xdg_desktop_names: ?[:0]const u8 = null;
         if (entry.DesktopNames) |desktop_names| {
             for (desktop_names) |*c| {
                 if (c.* == ';') c.* = ':';
             }
-            xdg_desktop_names = desktop_names;
+            maybe_xdg_desktop_names = desktop_names;
         }
 
-        const session_desktop = try session.label.allocator.dupeZ(u8, xdg_session_desktop);
-        errdefer session.label.allocator.free(session_desktop);
+        const maybe_session_desktop = if (maybe_xdg_session_desktop) |xdg_session_desktop| try session.label.allocator.dupeZ(u8, xdg_session_desktop) else null;
+        errdefer if (maybe_session_desktop) |session_desktop| session.label.allocator.free(session_desktop);
 
         try session.addEnvironment(.{
             .entry_ini = entry_ini,
             .name = entry.Name,
-            .xdg_session_desktop = session_desktop,
-            .xdg_desktop_names = xdg_desktop_names,
+            .xdg_session_desktop = maybe_session_desktop,
+            .xdg_desktop_names = maybe_xdg_desktop_names,
             .cmd = entry.Exec,
             .specifier = switch (display_server) {
                 .wayland => lang.wayland,
                 .x11 => lang.x11,
+                .custom => lang.custom,
                 else => lang.other,
             },
             .display_server = display_server,
+            .is_terminal = entry.Terminal orelse false,
         });
     }
 }