From 1a3c1315d2c2c594714736b6d36554482a2de469 Mon Sep 17 00:00:00 2001
From: Simon Ruderich <simon@ruderich.org>
Date: Fri, 1 Nov 2024 09:35:33 +0100
Subject: [PATCH] Terminate programs in namespaces before deleting them

---
 main.go | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/main.go b/main.go
index 6e3f1e1..85ddd3b 100644
--- a/main.go
+++ b/main.go
@@ -15,6 +15,9 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strconv"
+	"strings"
+	"syscall"
 )
 
 func main() {
@@ -42,6 +45,16 @@ func main() {
 		// One namespace per node, named as the node's name
 		ns := node.Name
 		if netnsExists(ns) {
+			// Terminate processes in old namespaces
+			for _, x := range netnsPids(ns) {
+				log.Printf("  Killing old PID %d", x)
+				err := syscall.Kill(x, syscall.SIGTERM)
+				if err != nil {
+					log.Fatalf("failed to kill %d: %v", x, err)
+				}
+				// Also try SIGHUP to terminate shells which ignore SIGTERM
+				_ = syscall.Kill(x, syscall.SIGHUP)
+			}
 			// Prevent any conflicts with existing data
 			ip("netns", "del", ns)
 			// Don't remove anything in /etc/netns/ as the user might store
@@ -135,6 +148,30 @@ func netnsExists(name string) bool {
 	return true
 }
 
+func netnsPids(netns string) []int {
+	args := []string{"netns", "pids", netns}
+	xargs := append([]string{"ip"}, args...)
+
+	cmd := exec.Command("ip", args...)
+	out, err := cmd.Output()
+	if err != nil {
+		log.Fatalf("failed to run %q: %v", xargs, err)
+	}
+
+	var res []int
+	xs := strings.FieldsFunc(string(out), func(c rune) bool {
+		return c == '\n'
+	})
+	for _, x := range xs {
+		y, err := strconv.Atoi(x)
+		if err != nil {
+			log.Fatal(err)
+		}
+		res = append(res, y)
+	}
+	return res
+}
+
 func ifaceExists(netns, name string) bool {
 	args := []string{"-n", netns, "-json", "link"}
 	xargs := append([]string{"ip"}, args...)
-- 
2.45.2