cmd/tracker-announce: Rework for better utility in shell scripts

cmd/tracker-announce/main.go

@@ -3,8 +3,10 @@ package main
 import (
 	"log"
 	"net/url"
+	"os"
 	"strings"
 	"sync"
+	"sync/atomic"
 
 	"github.com/davecgh/go-spew/spew"
 
@@ -36,39 +38,47 @@ func main() {
 		Port: 50007,
 	}
 	tagflag.Parse(&flags)
-	ar := tracker.AnnounceRequest{
-		NumWant: -1,
-		Left:    -1,
-		Port:    flags.Port,
-	}
+	var exitCode int32
 	var wg sync.WaitGroup
 	for _, arg := range flags.Torrents {
 		ts, err := argSpec(arg)
 		if err != nil {
 			log.Fatal(err)
 		}
-		ar.InfoHash = ts.InfoHash
 		for _, tier := range ts.Trackers {
 			for _, tURI := range tier {
+				ar := tracker.AnnounceRequest{
+					NumWant:  -1,
+					Left:     -1,
+					Port:     flags.Port,
+					InfoHash: ts.InfoHash,
+				}
 				wg.Add(1)
-				go doTracker(tURI, wg.Done, ar)
+				go func(tURI string) {
+					defer wg.Done()
+					if doTracker(tURI, ar) {
+						atomic.StoreInt32(&exitCode, 1)
+					}
+				}(tURI)
 			}
 		}
 	}
 	wg.Wait()
+	os.Exit(int(exitCode))
 }
 
-func doTracker(tURI string, done func(), ar tracker.AnnounceRequest) {
-	defer done()
+func doTracker(tURI string, ar tracker.AnnounceRequest) (hadError bool) {
 	for _, res := range announces(tURI, ar) {
 		err := res.error
 		resp := res.AnnounceResponse
 		if err != nil {
+			hadError = true
 			log.Printf("error announcing to %q: %s", tURI, err)
 			continue
 		}
-		log.Printf("tracker response from %q: %s", tURI, spew.Sdump(resp))
+		spew.Dump(resp)
 	}
+	return
 }
 
 type announceResult struct {