From b9854af690195b3eeadeba11272304be4623c4f8 Mon Sep 17 00:00:00 2001
From: Manolo van Ee <manolo.vanee@gmail.com>
Date: Wed, 4 Sep 2024 15:05:23 +0200
Subject: [PATCH] Get watchdog configuration from systemd

---
 Sources/Systemd/SystemdHelpers.swift          | 23 +++++++++++++++++++
 Sources/SystemdLifecycle/SystemdService.swift | 16 +++++--------
 2 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/Sources/Systemd/SystemdHelpers.swift b/Sources/Systemd/SystemdHelpers.swift
index ec60a84..6b7724c 100644
--- a/Sources/Systemd/SystemdHelpers.swift
+++ b/Sources/Systemd/SystemdHelpers.swift
@@ -1,12 +1,17 @@
 
 #if os(Linux)
 import Glibc
+import CSystemd
 #endif
 
 import Foundation
 
 public struct SystemdHelpers {
     public static let isSystemdService: Bool = getIsSystemdService()
+    public static let watchdogTimeout: Duration? = getWatchdogTimeout()
+
+    public static var watchdogEnabled: Bool { watchdogTimeout != nil }
+    public static var watchdogRecommendedNotifyInterval: Duration? { watchdogTimeout.map { $0 / 2 } }
 
     private static func getIsSystemdService() -> Bool {
         #if os(Linux)
@@ -22,4 +27,22 @@ public struct SystemdHelpers {
 
         return false
     }
+
+    private static func getWatchdogTimeout() -> Duration? {
+        #if os(Linux)
+        var usec: UInt64 = 0
+        let ret = sd_watchdog_enabled(0, &usec)
+        if ret > 0 {
+            return .microseconds(usec)
+        } else if ret == 0 {
+            return nil // Watchdog disabled
+        } else {
+            let error = String(cString: strerror(-ret))
+            print("Unable to get watchdog configuration: \(error)")
+            return nil
+        }
+        #else
+        return nil
+        #endif
+   }
 }
diff --git a/Sources/SystemdLifecycle/SystemdService.swift b/Sources/SystemdLifecycle/SystemdService.swift
index 91b8174..41a5b2e 100644
--- a/Sources/SystemdLifecycle/SystemdService.swift
+++ b/Sources/SystemdLifecycle/SystemdService.swift
@@ -4,14 +4,7 @@ import ServiceLifecycle
 import Systemd
 
 public struct SystemdService: Service {
-    private let _watchdogEnabled: Bool
-    private let _watchdogInterval: Duration
-
-    public init(watchdogEnabled: Bool = false,
-                watchdogInterval: Duration = .seconds(5)) {
-        _watchdogEnabled = watchdogEnabled
-        _watchdogInterval = watchdogInterval
-    }
+    public init() {}
 
     public func run() async throws {
         let notifier = SystemdNotifier()
@@ -19,9 +12,12 @@ public struct SystemdService: Service {
         // Send ready signal at startup
         notifier.notify(ServiceState.Ready)
 
+
         // Run the task until cancelled
-        for await _ in AsyncTimerSequence(interval: _watchdogInterval, clock: .continuous).cancelOnGracefulShutdown() {
-            if _watchdogEnabled {
+        let watchdogEnabled = SystemdHelpers.watchdogEnabled
+        let interval = SystemdHelpers.watchdogRecommendedNotifyInterval ?? .seconds(3600)
+        for await _ in AsyncTimerSequence(interval: interval, clock: .continuous).cancelOnGracefulShutdown() {
+            if watchdogEnabled {
                 notifier.notify(ServiceState.Watchdog)
             }
         }