Vendor dependencies

Let's see how I like this workflow.

vendor/signal-hook-registry/tests/unregister_signal.rs

@@ -0,0 +1,59 @@
+//! Tests for the [unregister_signal] function.
+//!
+//! As a separate integration level test, so it doesn't clash with other tests on the signals.
+
+// The unregister_signal itself is deprecated. But we still want to test it, so it's not deprecated
+// and broken at the same time.
+#![allow(deprecated)]
+
+extern crate libc;
+extern crate signal_hook_registry;
+
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
+
+use libc::{SIGINT, SIGTERM}; // We'll use these here because SIGUSR1 is not available on Windows.
+use signal_hook_registry::{register, unregister_signal};
+
+#[test]
+fn register_unregister() {
+    let called = Arc::new(AtomicUsize::new(0));
+
+    let hook = {
+        let called = Arc::clone(&called);
+        move || {
+            called.fetch_add(1, Ordering::Relaxed);
+        }
+    };
+
+    unsafe {
+        register(SIGTERM, hook.clone()).unwrap();
+        register(SIGTERM, hook.clone()).unwrap();
+        register(SIGINT, hook.clone()).unwrap();
+
+        libc::raise(SIGTERM);
+    }
+
+    // The closure is run twice.
+    assert_eq!(2, called.load(Ordering::Relaxed));
+
+    assert!(unregister_signal(SIGTERM));
+
+    unsafe { libc::raise(SIGTERM) };
+    // Second one unregisters nothing.
+    assert!(!unregister_signal(SIGTERM));
+
+    // After unregistering (both), it is no longer run at all.
+    assert_eq!(2, called.load(Ordering::Relaxed));
+
+    // The SIGINT one is not disturbed.
+    unsafe { libc::raise(SIGINT) };
+    assert_eq!(3, called.load(Ordering::Relaxed));
+
+    // But it's possible to register it again just fine.
+    unsafe {
+        register(SIGTERM, hook).unwrap();
+        libc::raise(SIGTERM);
+    }
+    assert_eq!(4, called.load(Ordering::Relaxed));
+}