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6 commits 1 branch 0 tags 0 releases158.8 KiB

Commit `61c6e94355d9`

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atagen <boss@atagen.co>2026-09-27 03:59 UTC

2 files changed+49-9

daemon: take a socket from systemd and never outlive a wiped runtime dir

Socket activation lets systemd hold the socket across daemon restarts, so a client knocking while the daemon idles out just waits instead of racing a respawn. The idle exit also needs the spawn lock, and it opened that without create, so deleting the runtime dir left a daemon idling forever with no way out. Config falls back to /etc/rabt/config.toml so a system can set defaults for every user.

Modified file: src/daemon.rs+39 additions−5 deletions@@ -1,10 +1,16 @@
 use std::{
     collections::BTreeMap,
     fs, io,
-    os::unix::net::{UnixListener, UnixStream},
+    os::{
+        fd::FromRawFd,
+        unix::net::{UnixListener, UnixStream},
+    },
     path::PathBuf,
     process,
-    sync::{Arc, Mutex, MutexGuard},
+    sync::{
+        Arc, Mutex, MutexGuard,
+        atomic::{AtomicBool, Ordering},
+    },
     thread,
     time::{Duration, Instant},
 };
@@ -489,6 +495,11 @@ fn tick(shared: &Shared) {
         st.fire_overdue();
         if st.conns == 0 && st.leases.is_empty() && st.idle_since.elapsed() >= st.cfg.queue.linger.0
         {
+            // systemd owns the socket and queues whoever knocks while we're
+            // leaving, so there's nothing to tidy
+            if ACTIVATED.load(Ordering::Relaxed) {
+                process::exit(0);
+            }
             // a spawner holds this while it clears a stale socket, so taking it
             // here stops us unlinking our successor's socket on the way out
             if let Some(_guard) = try_spawn_lock() {
@@ -558,15 +569,30 @@ fn watch_config(shared: &Shared) {
     }
 }
 
+/// creates the file if it's gone, else a wiped runtime dir leaves us idling
+/// forever unable to take the lock we need to exit
 fn try_spawn_lock() -> Option<client::Flock> {
     let file = fs::OpenOptions::new()
+        .create(true)
+        .truncate(false)
         .write(true)
         .open(paths::spawn_lock())
         .ok()?;
     client::Flock::try_exclusive(file)
 }
 
-pub fn main(cfg: Config) -> ! {
+static ACTIVATED: AtomicBool = AtomicBool::new(false);
+
+fn inherited() -> Option<UnixListener> {
+    let ours = std::env::var("LISTEN_PID").ok()?.parse::<u32>().ok()? == process::id();
+    if !ours || std::env::var("LISTEN_FDS").ok()? != "1" {
+        return None;
+    }
+    // SAFETY: sd_listen_fds protocol, fd 3 is the listening socket
+    Some(unsafe { UnixListener::from_raw_fd(3) })
+}
+
+fn bind() -> UnixListener {
     // fork once more so the client that spawned us can reap its child now
     // instead of carrying a zombie for the length of its build
     match unsafe { libc::fork() } {
@@ -577,8 +603,7 @@ pub fn main(cfg: Config) -> ! {
         0 => {}
         _ => process::exit(0),
     }
-
-    let listener = match UnixListener::bind(paths::socket()) {
+    match UnixListener::bind(paths::socket()) {
         Ok(l) => l,
         Err(e) if e.kind() == io::ErrorKind::AddrInUse && client::connect().is_some() => {
             process::exit(0)
@@ -587,6 +612,15 @@ pub fn main(cfg: Config) -> ! {
             eprintln!("roundabout: bind: {e}");
             process::exit(1);
         }
+    }
+}
+
+pub fn main(cfg: Config) -> ! {
+    let listener = if let Some(l) = inherited() {
+        ACTIVATED.store(true, Ordering::Relaxed);
+        l
+    } else {
+        bind()
     };
 
     let shared: Shared = Arc::new(Mutex::new(State::new(cfg)));

Modified file: src/paths.rs+10 additions−4 deletions@@ -16,10 +16,16 @@ fn xdg(var: &str, fallback: &str) -> PathBuf {
 }
 
 pub fn config_file() -> PathBuf {
-    env::var_os("ROUNDABOUT_CONFIG").map_or_else(
-        || xdg("XDG_CONFIG_HOME", ".config").join("roundabout/config.toml"),
-        PathBuf::from,
-    )
+    if let Some(p) = env::var_os("ROUNDABOUT_CONFIG") {
+        return p.into();
+    }
+    let user = xdg("XDG_CONFIG_HOME", ".config").join("roundabout/config.toml");
+    let system = PathBuf::from("/etc/roundabout/config.toml");
+    if !user.exists() && system.exists() {
+        system
+    } else {
+        user
+    }
 }
 
 pub fn state_dir() -> PathBuf {

roundabout

Commit 61c6e94355d9

Commit `61c6e94355d9`