xwayland: Expose DISPLAY variable to clients

src/input/mod.rs

@@ -900,6 +900,15 @@ impl State {
                     .arg("-c")
                     .arg(command)
                     .env("WAYLAND_DISPLAY", &self.common.socket)
+                    .env(
+                        "DISPLAY",
+                        &self
+                            .common
+                            .xwayland_state
+                            .values()
+                            .find_map(|s| s.display.map(|v| format!(":{}", v)))
+                            .unwrap_or(String::new()),
+                    )
                     .env_remove("COSMIC_SESSION_SOCK")
                     .spawn()
                 {

src/session.rs

@@ -77,6 +77,9 @@ pub fn setup_socket(handle: LoopHandle<Data>, state: &State) -> Result<()> {
                     .into_string()
                     .map_err(|_| anyhow!("wayland socket is no valid utf-8 string?"))?,
             );
+            if let Some(display) = state.common.xwayland_state.values().find_map(|s| s.display) {
+                env.insert(String::from("DISPLAY"), format!(":{}", display));
+            }
             let message = serde_json::to_string(&Message::SetEnv { variables: env })
                 .with_context(|| "Failed to encode environment variables into json")?;
             let bytes = message.into_bytes();

src/systemd.rs

@@ -7,13 +7,22 @@ use std::process::Command;
 pub fn ready(state: &State) {
     if booted() {
         match Command::new("systemctl")
-            .args(["--user", "import-environment", "WAYLAND_DISPLAY"])
+            .args(["--user", "import-environment", "WAYLAND_DISPLAY", "DISPLAY"])
             .env("WAYLAND_DISPLAY", &state.common.socket)
+            .env(
+                "DISPLAY",
+                &state
+                    .common
+                    .xwayland_state
+                    .values()
+                    .find_map(|s| s.display.map(|v| format!(":{}", v)))
+                    .unwrap_or(String::new()),
+            )
             .status()
         {
             Ok(x) if x.success() => {}
             Ok(x) => slog_scope::warn!(
-                "Failed to import WAYLAND_DISPLAY into systemd (exit code {:?})",
+                "Failed to import WAYLAND_DISPLAY/DISPLAY into systemd (exit code {:?})",
                 x.code()
             ),
             Err(err) => slog_scope::error!(