Exit gracefully on SIGTERM

* Exit gracefully on `SIGTERM`

Save current state and close ncspot on `SIGTERM`

Fixes #948

* Disable signal handling on non-UNIX platforms

Cargo.lock

@@ -1589,6 +1589,7 @@ dependencies = [
  "serde",
  "serde_cbor",
  "serde_json",
+ "signal-hook",
  "strum 0.24.1",
  "strum_macros 0.24.3",
  "tokio",

Cargo.toml

@@ -46,9 +46,13 @@ toml = "0.5"
 unicode-width = "0.1.9"
 url = "2.2"
 cursive_buffered_backend = "0.6.1"
+
 [target.'cfg(target_os = "linux")'.dependencies]
 wl-clipboard-rs = {version = "0.7", optional = true}
 
+[target.'cfg(unix)'.dependencies]
+signal-hook = "0.3.0"
+
 [dependencies.rspotify]
 default-features = false
 features = ["client-ureq", "ureq-rustls-tls"]

src/main.rs

@@ -18,6 +18,9 @@ use librespot_core::cache::Cache;
 use librespot_playback::audio_backend;
 use log::{error, info, trace};
 
+#[cfg(unix)]
+use signal_hook::{consts::SIGTERM, iterator::Signals};
+
 mod authentication;
 mod command;
 mod commands;
@@ -313,9 +316,22 @@ async fn main() -> Result<(), String> {
 
     cursive.add_fullscreen_layer(layout.with_name("main"));
 
+    // catch SIGTERM to save current state
+    #[cfg(unix)]
+    let mut signals = Signals::new(&[SIGTERM]).expect("could not register SIGTERM handler");
+
     // cursive event loop
     while cursive.is_running() {
         cursive.step();
+        #[cfg(unix)]
+        for signal in signals.pending() {
+            if signal == SIGTERM {
+                info!("Caught SIGTERM, cleaning up and closing");
+                if let Some(data) = cursive.user_data::<UserData>().cloned() {
+                    data.cmd.handle(&mut cursive, Command::Quit);
+                }
+            }
+        }
         for event in event_manager.msg_iter() {
             match event {
                 Event::Player(state) => {