From dcc08eb928995cff8e64261d0c2b20f28514c8c8 Mon Sep 17 00:00:00 2001
From: "T. R. Bernstein" <developer@tabshift.dev>
Date: Sun, 13 Sep 2026 22:59:15 +0200
Subject: [PATCH] Cancel the event reader before closing the descriptor

`deinit` closed the inotify descriptor while its dispatch source was
still active. The kernel drops the epoll registration on close, but
libdispatch keeps its own; an instance created afterwards that reuses
the descriptor number could inherit that stale state and never
receive events. Roughly one test run in three lost a single event
this way.

The reader is now cancelled in `deinit` and the descriptor closed in
its cancel handler, as libdispatch requires.
---
 Sources/Inotify/Inotify.swift                 |  9 +++++--
 .../LifecycleTests.swift                      | 24 +++++++++++++++++++
 2 files changed, 31 insertions(+), 2 deletions(-)
 create mode 100644 Tests/InotifyIntegrationTests/LifecycleTests.swift

diff --git a/Sources/Inotify/Inotify.swift b/Sources/Inotify/Inotify.swift
index 582ad05..3d5d856 100644
--- a/Sources/Inotify/Inotify.swift
+++ b/Sources/Inotify/Inotify.swift
@@ -5,7 +5,7 @@ public actor Inotify {
 	private let fd: CInt
 	private var excludedItemNames: Set<String> = []
 	private var watches = InotifyWatchManager()
-	private var eventReader: any DispatchSourceRead
+	private nonisolated(unsafe) let eventReader: any DispatchSourceRead
 	private nonisolated let eventStream: AsyncStream<RawInotifyEvent>
 	public nonisolated var events: AsyncCompactMapSequence<AsyncStream<RawInotifyEvent>, InotifyEvent> {
 		self.eventStream.compactMap(self.transform(_:))
@@ -73,7 +73,11 @@ public actor Inotify {
 	}
 
 	deinit {
-		cinotify_deinit(self.fd)
+		// The file descriptor is closed by the reader's cancel handler once
+		// libdispatch has unregistered it. Closing it here would leave a
+		// registration behind that a later instance reusing the descriptor
+		// number could inherit, silently losing its events.
+		self.eventReader.cancel()
 	}
 
 	private func transform(_ rawEvent: RawInotifyEvent) async -> InotifyEvent? {
@@ -112,6 +116,7 @@ public actor Inotify {
 			}
 		}
 		reader.setCancelHandler {
+			cinotify_deinit(fd)
 			continuation.finish()
 		}
 		reader.activate()
diff --git a/Tests/InotifyIntegrationTests/LifecycleTests.swift b/Tests/InotifyIntegrationTests/LifecycleTests.swift
new file mode 100644
index 0000000..f3d1bb4
--- /dev/null
+++ b/Tests/InotifyIntegrationTests/LifecycleTests.swift
@@ -0,0 +1,24 @@
+import Foundation
+import Testing
+@testable import Inotify
+
+@Suite("Instance Lifecycle")
+struct LifecycleTests {
+	@Test func aDeallocatedInstanceDoesNotStealEventsOfItsSuccessor() async throws {
+		try await withTempDir { dir in
+			let filename = "after-reuse.txt"
+			do {
+				let predecessor = try Inotify()
+				try await predecessor.addWatch(path: dir, mask: .create)
+			}
+
+			let events = try await getEventsForTrigger(
+				in: dir,
+				mask: .create,
+			) { try createFile(at: "\($0)/\(filename)") }
+
+			let createEvent = events.first { $0.mask.contains(.create) && $0.path.lastComponent?.string == filename }
+			#expect(createEvent != nil, "Expected CREATE for '\(filename)', got: \(events)")
+		}
+	}
+}