add: OsSignal for scala-native

kyo-core/native/src/main/scala/kyo/internal/OSSignalPlatformSpecific.scala

@@ -0,0 +1,34 @@
+package kyo.internal
+
+import OsSignal.Handler
+import scala.scalanative.posix.signal as posix
+import scala.scalanative.unsafe.*
+
+/** Internal global dispatcher to avoid capturing local state in C callbacks. */
+private object NativeSignalDispatch:
+    private val registry = scala.collection.mutable.HashMap.empty[Int, () => Unit]
+
+    val cHandler: CFuncPtr1[CInt, Unit] = CFuncPtr1.fromScalaFunction { (sig: CInt) =>
+        val cb = registry.synchronized { registry.get(sig) }
+        cb.foreach(_.apply())
+    }
+
+    def install(signum: CInt, cb: () => Unit): Unit =
+        registry.synchronized { registry.update(signum, cb) }
+end NativeSignalDispatch
+
+/** Native-specific implementation using POSIX signals via Scala Native. */
+private[internal] class OsSignalPlatformSpecific:
+    val handle: Handler = new Handler:
+        private def signum(signal: String): CInt =
+            signal match
+                case "INT"  => posix.SIGINT
+                case "TERM" => posix.SIGTERM
+                case "HUP"  => posix.SIGHUP
+
+        override def apply(signalName: String, handler: () => Unit): Unit =
+            val num = signum(signalName)
+            NativeSignalDispatch.install(num, handler)
+            val _ = posix.signal(num, NativeSignalDispatch.cHandler)
+        end apply
+end OsSignalPlatformSpecific