Add --xsession-wrapper argument for X11 session setup

README.md

@@ -14,6 +14,9 @@ Options:
     -s, --sessions DIRS colon-separated list of Wayland session paths
     -x, --xsessions DIRS
                         colon-separated list of X11 session paths
+        --xsession-wrapper 'CMD [ARGS]...'
+                        wrapper command to initialize X server and launch X11
+                        sessions (default: startx /usr/bin/env)
     -w, --width WIDTH   width of the main prompt (default: 80)
     -i, --issue         show the host's issue file
     -g, --greeting GREETING

contrib/man/tuigreet-1.scd

@@ -28,6 +28,11 @@ tuigreet - A graphical console greeter for greetd
 	Location of desktop-files to be used as X11 session definitions. By
 	default, X11 sessions are fetched from */usr/share/xsessions*.
 
+*--xsession-wrapper 'CMD [ARGS]...'*
+	Specify a wrapper command to initialize X server and launch X11 sessions.
+	By default, *startx /usr/bin/env* will be prepended to all X11 session
+	commands.
+
 *-w, --width COLS*
 	Number of columns the main prompt area should take on the screen.
 

src/greeter.rs

@@ -29,6 +29,9 @@ use crate::{
 
 const DEFAULT_LOCALE: Locale = Locale::en_US;
 const DEFAULT_ASTERISKS_CHAR: char = '*';
+// `startx` wants an absolute path to the executable as a first argument.
+// We don't want to resolve the session command in the greeter though, so it should be additionally wrapped with a known noop command (like `/usr/bin/env`).
+const DEFAULT_XSESSION_WRAPPER: &str = "startx /usr/bin/env";
 
 #[derive(Debug, Copy, Clone)]
 pub enum AuthStatus {
@@ -103,6 +106,7 @@ pub struct Greeter {
   pub session_paths: Vec<(PathBuf, SessionType)>,
   pub sessions: Vec<Session>,
   pub selected_session: usize,
+  pub xsession_wrapper: Option<String>,
 
   pub selected_power_option: usize,
 
@@ -285,11 +289,14 @@ impl Greeter {
   async fn parse_options(&mut self) {
     let mut opts = Options::new();
 
+    let xsession_wrapper_desc = format!("wrapper command to initialize X server and launch X11 sessions (default: {DEFAULT_XSESSION_WRAPPER})");
+
     opts.optflag("h", "help", "show this usage information");
     opts.optflag("v", "version", "print version information");
     opts.optopt("c", "cmd", "command to run", "COMMAND");
     opts.optopt("s", "sessions", "colon-separated list of Wayland session paths", "DIRS");
     opts.optopt("x", "xsessions", "colon-separated list of X11 session paths", "DIRS");
+    opts.optopt("", "xsession-wrapper", xsession_wrapper_desc.as_str(), "'CMD [ARGS]...'");
     opts.optopt("w", "width", "width of the main prompt (default: 80)", "WIDTH");
     opts.optflag("i", "issue", "show the host's issue file");
     opts.optopt("g", "greeting", "show custom text above login prompt", "GREETING");
@@ -402,6 +409,8 @@ impl Greeter {
       self.session_paths.extend(env::split_paths(&dirs).map(|dir| (dir, SessionType::X11)));
     }
 
+    self.xsession_wrapper = self.option("xsession-wrapper").or_else(|| Some(DEFAULT_XSESSION_WRAPPER.to_string()));
+
     if self.config().opt_present("issue") {
       self.greeting = get_issue();
     }

src/ipc.rs

@@ -118,16 +118,23 @@ impl Ipc {
           greeter.mode = Mode::Processing;
 
           let session = greeter.sessions.get(greeter.selected_session).filter(|s| &s.command == command);
+          let mut command = command.clone();
           let mut env = vec![];
 
           if let Some(Session { session_type, .. }) = session {
             if *session_type != SessionType::None {
               env.push(format!("XDG_SESSION_TYPE={}", session_type.to_xdg_session_type()));
             }
+
+            if *session_type == SessionType::X11 {
+              if let Some(ref wrap) = greeter.xsession_wrapper {
+                command = format!("{} {}", wrap, command);
+              }
+            }
           }
 
           #[cfg(not(debug_assertions))]
-          self.send(Request::StartSession { cmd: vec![command.clone()], env }).await;
+          self.send(Request::StartSession { cmd: vec![command], env }).await;
 
           #[cfg(debug_assertions)]
           {