From 97641dde0b55b588bfd27817a6a9deac3b337513 Mon Sep 17 00:00:00 2001
From: Simon Ruderich <simon@ruderich.org>
Date: Tue, 20 Apr 2021 16:17:53 +0200
Subject: [PATCH] safcm: print unfinished hosts on Ctrl-C

---
 cmd/safcm/sync.go | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/cmd/safcm/sync.go b/cmd/safcm/sync.go
index 7fa2c93..238ed62 100644
--- a/cmd/safcm/sync.go
+++ b/cmd/safcm/sync.go
@@ -22,6 +22,7 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"os/signal"
 	"sort"
 	"strings"
 	"sync"
@@ -135,6 +136,38 @@ func MainSync(args []string) error {
 		done <- failed
 	}()
 
+	hostsLeft := make(map[string]bool)
+	for _, x := range toSync {
+		hostsLeft[x.Name] = true
+	}
+	var hostsLeftMutex sync.Mutex // protects hostsLeft
+
+	// Show unfinished hosts on Ctrl-C
+	sigint := make(chan os.Signal, 1)   // buffered for Notify()
+	signal.Notify(sigint, os.Interrupt) // = SIGINT = Ctrl-C
+	go func() {
+		// Running `ssh` processes get killed by SIGINT which is sent
+		// to all processes
+
+		<-sigint
+		log.Print("Received SIGINT, aborting ...")
+
+		// Print all queued events
+		events <- Event{} // poison pill
+		<-done
+		// "races" with <-done in the main function and will hang here
+		// if the other is faster. This is fine because then all hosts
+		// were synced successfully.
+
+		hostsLeftMutex.Lock()
+		var hosts []string
+		for x := range hostsLeft {
+			hosts = append(hosts, x)
+		}
+		sort.Strings(hosts)
+		log.Fatalf("Failed to sync %s", strings.Join(hosts, ", "))
+	}()
+
 	// Sync all hosts concurrently
 	var wg sync.WaitGroup
 	for _, x := range toSync {
@@ -160,6 +193,10 @@ func MainSync(args []string) error {
 				}
 			}
 			wg.Done()
+
+			hostsLeftMutex.Lock()
+			defer hostsLeftMutex.Unlock()
+			delete(hostsLeft, x.Name)
 		}()
 	}
 
-- 
2.43.2