demo: add an option to --wait for VM

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

qemu-display/src/display.rs

@@ -19,6 +19,32 @@ pub struct Display {
 }
 
 impl Display {
+    pub async fn lookup(
+        conn: &Connection,
+        wait: bool,
+        name: Option<&str>,
+    ) -> Result<Option<OwnedUniqueName>> {
+        let mut changed = fdo::DBusProxy::new(conn)
+            .await?
+            .receive_name_owner_changed()
+            .await?;
+        loop {
+            let list = Display::by_name(&conn).await?;
+            if let Some(name) = name {
+                let res = list.get(name);
+                if res.is_some() {
+                    return Ok(res.cloned());
+                }
+            } else if !list.is_empty() {
+                return Ok(None);
+            }
+            if !wait {
+                return Err(Error::Failed("Can't find VM".into()));
+            };
+            let _ = changed.next().await;
+        }
+    }
+
     pub async fn by_name(conn: &Connection) -> Result<HashMap<String, OwnedUniqueName>> {
         let mut hm = HashMap::new();
         let list = match fdo::DBusProxy::new(conn)

qemu-rdw/src/main.rs

@@ -27,6 +27,7 @@ struct AppOptions {
     vm_name: Option<String>,
     address: Option<String>,
     list: bool,
+    wait: bool,
 }
 
 impl App {
@@ -56,6 +57,14 @@ impl App {
             "List available VM names",
             None,
         );
+        app.add_main_option(
+            "wait",
+            glib::Char(0),
+            glib::OptionFlags::NONE,
+            glib::OptionArg::None,
+            "Wait for display to be available",
+            None,
+        );
         app.add_main_option(
             "version",
             glib::Char(0),
@@ -79,6 +88,9 @@ impl App {
             if opt.lookup_value("list", None).is_some() {
                 app_opt.list = true;
             }
+            if opt.lookup_value("wait", None).is_some() {
+                app_opt.wait = true;
+            }
             app_opt.vm_name = opt
                 .lookup_value(&glib::OPTION_REMAINING, None)
                 .and_then(|args| args.child_value(0).get::<String>());
@@ -135,15 +147,11 @@ impl App {
                     app_clone.inner.app.quit();
                     return;
                 }
-                let dest = if let Some(name) = opt_clone.borrow().vm_name.as_ref() {
+                let dest = {
-                    let list = Display::by_name(&conn).await.unwrap();
+                    let name = opt_clone.borrow().vm_name.clone();
-                    Some(
+                    let wait = opt_clone.borrow().wait;
-                        list.get(name)
+
-                            .unwrap_or_else(|| panic!("Can't find VM name: {}", name))
+                    Display::lookup(&conn, wait, name.as_deref()).await.unwrap()
-                            .clone(),
-                    )
-                } else {
-                    None
                 };
                 let display = Display::new(&conn, dest.as_ref()).await.unwrap();