From 92ce4be9e56dd87e99ceeb9094cfdfb0ed6e29c4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Anders=20F=20Bj=C3=B6rklund?= <anders.f.bjorklund@gmail.com>
Date: Fri, 25 Oct 2024 09:32:33 +0200
Subject: [PATCH] Avoid warning message when /dev/rtc does not exist
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For instance the Raspberry Pi does not have any real-time clock,
so rely on network time synchronization instead (systemd-timesyncd).

Signed-off-by: Anders F Björklund <anders.f.bjorklund@gmail.com>
---
 pkg/guestagent/guestagent_linux.go        | 5 +++++
 pkg/guestagent/timesync/timesync_linux.go | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/pkg/guestagent/guestagent_linux.go b/pkg/guestagent/guestagent_linux.go
index 141d8d9f0f2..8fe3857a68c 100644
--- a/pkg/guestagent/guestagent_linux.go
+++ b/pkg/guestagent/guestagent_linux.go
@@ -324,6 +324,11 @@ const deltaLimit = 2 * time.Second
 
 func (a *agent) fixSystemTimeSkew() {
 	for {
+		ok, err := timesync.HasRTC()
+		if !ok {
+			logrus.Warnf("fixSystemTimeSkew: error: %s", err.Error())
+			break
+		}
 		ticker := time.NewTicker(10 * time.Second)
 		for now := range ticker.C {
 			rtc, err := timesync.GetRTCTime()
diff --git a/pkg/guestagent/timesync/timesync_linux.go b/pkg/guestagent/timesync/timesync_linux.go
index 3ad02fb5f52..38f88fc8f5e 100644
--- a/pkg/guestagent/timesync/timesync_linux.go
+++ b/pkg/guestagent/timesync/timesync_linux.go
@@ -1,6 +1,7 @@
 package timesync
 
 import (
+	"errors"
 	"os"
 	"time"
 
@@ -9,6 +10,11 @@ import (
 
 const rtc = "/dev/rtc"
 
+func HasRTC() (bool, error) {
+	_, err := os.Stat(rtc)
+	return !errors.Is(err, os.ErrNotExist), err
+}
+
 func GetRTCTime() (t time.Time, err error) {
 	f, err := os.Open(rtc)
 	if err != nil {