From 9bb9afb251f24f2d1ba94cbf4100e4cc198beed6 Mon Sep 17 00:00:00 2001
From: Qi Xiao <xiaqqaix@gmail.com>
Date: Tue, 9 Feb 2016 18:38:26 +0100
Subject: [PATCH] Improve signal handling.

---
 edit/editor.go | 19 +++----------------
 main.go        | 24 ++++++++++++++++++++++++
 2 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/edit/editor.go b/edit/editor.go
index 7e75be1d..373b5f23 100644
--- a/edit/editor.go
+++ b/edit/editor.go
@@ -4,7 +4,6 @@ package edit
 import (
 	"fmt"
 	"os"
-	"os/signal"
 	"strings"
 	"syscall"
 
@@ -376,22 +375,10 @@ MainLoop:
 				goto MainLoop
 			case syscall.SIGWINCH:
 				continue MainLoop
-			case syscall.SIGQUIT:
-				// Emulate default behavior
-				print(sys.DumpStack())
-				os.Exit(1)
+			case syscall.SIGCHLD:
+				// ignore
 			default:
-				// Other signals: turn off signal catching, and resend
-				signal.Stop(ed.sigs)
-				p, err := os.FindProcess(os.Getpid())
-				if err != nil {
-					panic(err)
-				}
-				err = p.Signal(sig)
-				if err != nil {
-					panic(err)
-				}
-				signal.Notify(ed.sigs)
+				ed.pushTip(fmt.Sprintf("ignored signal %s", sig))
 			}
 		case or := <-ones:
 			// Alert about error
diff --git a/main.go b/main.go
index dbc3300d..cab7262d 100644
--- a/main.go
+++ b/main.go
@@ -14,6 +14,7 @@ import (
 	"github.com/elves/elvish/edit"
 	"github.com/elves/elvish/errutil"
 	"github.com/elves/elvish/eval"
+	"github.com/elves/elvish/logutil"
 	"github.com/elves/elvish/osutil"
 	"github.com/elves/elvish/parse"
 	"github.com/elves/elvish/store"
@@ -26,6 +27,8 @@ const (
 	outChanLeader = "▶ "
 )
 
+var Logger = logutil.Discard
+
 func usage() {
 	fmt.Println("usage: elvish [flags] [script]")
 	fmt.Println("flags:")
@@ -55,10 +58,13 @@ func main() {
 		}
 		defer f.Close()
 
+		Logger = log.New(f, "[main]", log.LstdFlags)
 		eval.Logger = log.New(f, "[eval] ", log.LstdFlags)
 		edit.Logger = log.New(f, "[edit] ", log.LstdFlags)
 	}
 
+	go logSignals()
+
 	args := flag.Args()
 	switch len(args) {
 	case 0:
@@ -106,6 +112,8 @@ func interact() {
 	}
 	rpromptStr := username + "@" + hostname
 
+	go dumpstackOnQuit()
+
 	sigch := make(chan os.Signal, sigchSize)
 	signal.Notify(sigch)
 
@@ -142,6 +150,22 @@ func interact() {
 	}
 }
 
+func logSignals() {
+	sigs := make(chan os.Signal)
+	signal.Notify(sigs)
+	for sig := range sigs {
+		Logger.Println("signal", sig)
+	}
+}
+
+func dumpstackOnQuit() {
+	quitSigs := make(chan os.Signal)
+	signal.Notify(quitSigs, syscall.SIGQUIT)
+	for range quitSigs {
+		fmt.Print(sys.DumpStack())
+	}
+}
+
 func script(fname string) {
 	ev, _ := newEvalerAndStore()
 	err := ev.Source(fname)