receipt rework and discovery rework

veilid-server/src/unix.rs

@@ -6,6 +6,7 @@ use async_std::task;
 use clap::ArgMatches;
 use signal_hook::consts::signal::*;
 use signal_hook_async_std::Signals;
+use std::io::Read;
 
 async fn handle_signals(mut signals: Signals) {
     while let Some(signal) = signals.next().await {
@@ -26,8 +27,25 @@ pub fn run_daemon(settings: Settings, _matches: ArgMatches) -> Result<(), String
     let daemon = {
         let mut daemon = daemonize::Daemonize::new();
         let s = settings.read();
-        if let Some(pid_file) = &s.daemon.pid_file {
-            daemon = daemon.pid_file(pid_file); //.chown_pid_file(true);
+        if let Some(pid_file) = s.daemon.pid_file.clone() {
+            daemon = daemon.pid_file(pid_file.clone()); //.chown_pid_file(true);
+            daemon = daemon.exit_action(move || {
+                // wait for pid file to exist before exiting parent
+                let pid_path = std::path::Path::new(&pid_file);
+                loop {
+                    if let Ok(mut f) = std::fs::File::open(pid_path) {
+                        let mut s = String::new();
+                        if f.read_to_string(&mut s).is_ok()
+                            && !s.is_empty()
+                            && s.parse::<u32>().is_ok()
+                        {
+                            println!("pidfile found");
+                            break;
+                        }
+                    }
+                    std::thread::sleep(std::time::Duration::from_millis(100));
+                }
+            })
         }
         if let Some(chroot) = &s.daemon.chroot {
             daemon = daemon.chroot(chroot);