1 files changed, 50 insertions, 0 deletions
diff --git a/src/bin/rbw-agent/daemon.rs b/src/bin/rbw-agent/daemon.rs
new file mode 100644
index 0000000..64cf298
--- /dev/null
+++ b/src/bin/rbw-agent/daemon.rs
@@ -0,0 +1,50 @@
+pub struct StartupAck {
+    writer: std::os::unix::io::RawFd,
+}
+
+impl StartupAck {
+    pub fn ack(&self) {
+        nix::unistd::write(self.writer, &[0]).unwrap();
+        nix::unistd::close(self.writer).unwrap();
+    }
+}
+
+impl Drop for StartupAck {
+    fn drop(&mut self) {
+        nix::unistd::close(self.writer).unwrap();
+    }
+}
+
+pub fn daemonize() -> StartupAck {
+    let runtime_dir = rbw::dirs::runtime_dir();
+    std::fs::create_dir_all(&runtime_dir).unwrap();
+
+    let (r, w) = nix::unistd::pipe().unwrap();
+    let res = daemonize::Daemonize::new()
+        .pid_file(runtime_dir.join("pidfile"))
+        .exit_action(move || {
+            nix::unistd::close(w).unwrap();
+            let mut buf = [0; 1];
+            nix::unistd::read(r, &mut buf).unwrap();
+            nix::unistd::close(r).unwrap();
+        })
+        .start();
+    nix::unistd::close(r).unwrap();
+
+    match res {
+        Ok(_) => (),
+        Err(e) => {
+            match e {
+                daemonize::DaemonizeError::LockPidfile(_) => {
+                    // this means that there is already an agent running, so
+                    // return a special exit code to allow the cli to detect
+                    // this case and not error out
+                    std::process::exit(23);
+                }
+                _ => panic!("failed to daemonize: {}", e),
+            }
+        }
+    }
+
+    StartupAck { writer: w }
+}