Fix startup command and holder fallback

src/bin/dosh-client.rs

@@ -1048,7 +1048,7 @@ fn startup_command(args: &[String]) -> Option<Vec<u8>> {
         return None;
     }
     let mut command = args.join(" ");
-    command.push('\n');
+    command.push('\r');
     Some(command.into_bytes())
 }
 
@@ -1121,7 +1121,7 @@ fn expand_command_extension(template: &str, args: &[String]) -> String {
 
 fn startup_command_from_string(command: &str) -> Vec<u8> {
     let mut command = command.to_string();
-    command.push('\n');
+    command.push('\r');
     command.into_bytes()
 }
 
@@ -5540,6 +5540,7 @@ mod tests {
         assert!(Predictor::predictable(b"hello world"));
         assert!(!Predictor::predictable(b""));
         assert!(!Predictor::predictable(b"\n"));
+        assert!(!Predictor::predictable(b"\r"));
         assert!(!Predictor::predictable(b"\x1b[A"));
         assert!(!Predictor::predictable("snowman: \u{2603}".as_bytes()));
         assert!(!Predictor::predictable("wide: 你".as_bytes()));
@@ -5760,10 +5761,10 @@ mod tests {
     #[test]
     fn startup_command_joins_args_for_remote_shell() {
         assert_eq!(startup_command(&[]), None);
-        assert_eq!(startup_command(&["tm".to_string()]), Some(b"tm\n".to_vec()));
+        assert_eq!(startup_command(&["tm".to_string()]), Some(b"tm\r".to_vec()));
         assert_eq!(
             startup_command(&["tm".to_string(), "work".to_string()]),
-            Some(b"tm work\n".to_vec())
+            Some(b"tm work\r".to_vec())
         );
     }
 
@@ -5845,7 +5846,7 @@ mod tests {
 
         assert_eq!(
             resolved_startup_command(&["tm".into(), "work space".into()], &config, &host),
-            Some(b"tm 'work space'\n".to_vec())
+            Some(b"tm 'work space'\r".to_vec())
         );
     }
 
@@ -5872,7 +5873,7 @@ mod tests {
 
         assert_eq!(
             resolved_startup_command(&["tm".into(), "dosh".into()], &config, &host),
-            Some(b"/opt/tm/bin/tm --remote 'dosh'\n".to_vec())
+            Some(b"/opt/tm/bin/tm --remote 'dosh'\r".to_vec())
         );
     }
 
@@ -5913,11 +5914,11 @@ mod tests {
 
         assert_eq!(
             resolved_startup_command(&["echo".into(), "ok".into()], &config, &host),
-            Some(b"echo ok\n".to_vec())
+            Some(b"echo ok\r".to_vec())
         );
         assert_eq!(
             resolved_startup_command(&[], &config, &host),
-            Some(b"tm\n".to_vec())
+            Some(b"tm\r".to_vec())
         );
 
         host.default_command = None;

src/persist.rs

@@ -28,6 +28,7 @@ use std::time::Duration;
 /// One-byte commands a server sends to a holder over its control socket after
 /// the holder has handed back the master fd.
 const HOLDER_CMD_SHUTDOWN: u8 = b'X';
+const HOLDER_STARTUP_TIMEOUT: Duration = Duration::from_millis(750);
 
 /// Magic written into a holder's `meta` file, bumped if the on-disk layout
 /// changes so a stale holder from an incompatible build is ignored.
@@ -236,11 +237,14 @@ pub fn spawn_holder(
     // Wait (briefly) for the holder to come up. The holder forks/setsids before
     // creating the socket; once the socket exists we can connect. We also reap
     // the short-lived launcher child so it never becomes a zombie.
-    let deadline = std::time::Instant::now() + Duration::from_secs(5);
+    let deadline = std::time::Instant::now() + HOLDER_STARTUP_TIMEOUT;
     loop {
         if sock.exists() {
             break;
         }
+        if let Some(status) = child.try_wait().context("wait holder launcher")? {
+            bail!("holder launcher for session {session} exited before socket was ready: {status}");
+        }
         if std::time::Instant::now() >= deadline {
             let _ = child.kill();
             let _ = child.wait();