Fix startup race condition

CHANGELOG.md

@@ -11,6 +11,7 @@ This project follows [semantic versioning](http://semver.org).
 - [changed] Updated dependencies
 - [changed] Rewrote argument parsing
 - [fixed] Fixed problem that could lead to 100% cpu consumption
+- [fixed] Fixed startup race condition
 
 
 ### v1.3.0 (2020-01-25)

assets/vpncloud@.service

@@ -5,16 +5,18 @@ Wants=network-online.target
 Documentation=man:vpncloud(1)
 
 [Service]
-Type=simple
-ExecStart=/usr/bin/vpncloud --config /etc/vpncloud/%i.net --log-file /var/log/vpncloud-%i.log --stats-file /var/log/vpncloud-%i.stats
+Type=forking
+ExecStart=/usr/bin/vpncloud --config /etc/vpncloud/%i.net --log-file /var/log/vpncloud-%i.log --stats-file /var/log/vpncloud-%i.stats --daemon --pid-file /run/vpncloud-%i.pid
+PIDFile=/run/vpncloud-%i.pid
 WorkingDirectory=/etc/vpncloud
 RestartSec=5s
 Restart=on-failure
-LimitNPROC=10
+TasksMax=10
+MemoryMax=50M
 PrivateTmp=yes
 ProtectHome=yes
 ProtectSystem=strict
-ReadWritePaths=/var/log
+ReadWritePaths=/var/log /run
 CapabilityBoundingSet=CAP_NET_ADMIN CAP_NET_BIND_SERVICE CAP_NET_RAW CAP_SETGID CAP_SETUID CAP_SYS_CHROOT
 DeviceAllow=/dev/null rw
 DeviceAllow=/dev/net/tun rw

src/main.rs

@@ -40,7 +40,8 @@ use std::{
     path::Path,
     process::Command,
     str::FromStr,
-    sync::Mutex
+    sync::Mutex,
+    thread
 };
 
 use crate::{
@@ -400,6 +401,8 @@ fn run<P: Protocol>(config: Config) {
         }
         if let Some(pid_file) = config.pid_file {
             daemonize = daemonize.pid_file(pid_file).chown_pid_file(true);
+            // Give child process some time to write PID file
+            daemonize = daemonize.exit_action(|| thread::sleep(std::time::Duration::from_millis(10)));
         }
         try_fail!(daemonize.start(), "Failed to daemonize: {}");
     } else if config.user.is_some() || config.group.is_some() {