Implement init/deinit of inotify system

Use RAII to handle inotify resource lifetime, i.e. initialize with actor
creation and deinitialize with actor deletion.

Package.swift

@@ -22,9 +22,11 @@ let package = Package(
 		.package(url: "https://github.com/tuist/Noora", from: "0.55.1")
 	],
 	targets: [
+		.systemLibrary(name: "CInotify"),
 		.target(
 			name: "Inotify",
 			dependencies: [
+				"CInotify",
 				.product(name: "Logging", package: "swift-log"),
 			]
 		),

Sources/CInotify/cinotify.h

@@ -0,0 +1,24 @@
+#ifndef CINOTIFY_H
+#define CINOTIFY_H
+
+#include <stdlib.h>
+#include <sys/inotify.h>
+#include <errno.h>
+
+static inline int cinotify_deinit(int fd) {
+	return close(fd);
+}
+
+static inline int cinotify_get_errno(void) {
+	return errno;
+}
+
+static inline char* get_error_message() {
+	int error_number = errno;
+	errno = 0;
+	char* error_message = strerror(error_number);
+	if (errno > 0) return NULL;
+	return error_message;
+}
+
+#endif

Sources/CInotify/module.modulemap

@@ -0,0 +1,4 @@
+module CInotify [system] {
+	header "cinotify.h"
+	export *
+}

Sources/Inotify/Inotify.swift

@@ -1,2 +1,16 @@
-actor Inotify {
+import CInotify
+
+public actor Inotify {
+	private let fd: Int32
+
+	public init() throws {
+		self.fd = inotify_init1(Int32(IN_NONBLOCK | IN_CLOEXEC))
+		guard self.fd >= 0 else {
+			throw InotifyError.initFailed(errno: cinotify_get_errno())
+		}
+	}
+
+	deinit {
+		cinotify_deinit(self.fd)
+	}
 }

Sources/Inotify/InotifyError.swift

@@ -0,0 +1,19 @@
+import CInotify
+
+public enum InotifyError: Error, Sendable, CustomStringConvertible {
+	case initFailed(errno: Int32)
+
+	public var description: String {
+		switch self {
+		case .initFailed(let code):
+			"inotify_init1 failed: \(readableErrno(code))"
+		}
+	}
+
+	private func readableErrno(_ code: Int32) -> String {
+		if let cStr = get_error_message() {
+			return String(cString: cStr) + " (errno \(code))"
+		}
+		return "errno \(code)"
+	}
+}

Tests/InotifyIntegrationTests/InitialisationTests.swift

@@ -4,6 +4,6 @@ import Testing
 @Suite("Initialisation")
 struct InitTests {
 	@Test func createsCleanly() async throws {
-		let _ = Inotify()
+		let _ = try Inotify()
 	}
 }