From cdfa0beafb3942ef8a9c2c295b6de1ed4678c039 Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Wed, 22 Mar 2023 10:44:47 +0000
Subject: [PATCH] lib/atexit: ensure OnError only calls cancel function once

Before this change the cancelFunc could be called twice, once while
handling the interrupt (CTRL-C) and once while unwinding the stack if
the function happened to finish.

This change ensure the cancelFunc is only called once by wrapping it
in a sync.Once
---
 lib/atexit/atexit.go | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/lib/atexit/atexit.go b/lib/atexit/atexit.go
index 363d3267b..fa1dcc8b7 100644
--- a/lib/atexit/atexit.go
+++ b/lib/atexit/atexit.go
@@ -115,12 +115,18 @@ func Run() {
 //
 // So cancelFunc will be run if the function exits with an error or
 // at exit.
+//
+// cancelFunc will only be run once.
 func OnError(perr *error, fn func()) func() {
-	handle := Register(fn)
+	var once sync.Once
+	onceFn := func() {
+		once.Do(fn)
+	}
+	handle := Register(onceFn)
 	return func() {
 		defer Unregister(handle)
 		if *perr != nil {
-			fn()
+			onceFn()
 		}
 	}