From 2823ffb5405ea116b984b7429b2a4ca6f3c36a7c Mon Sep 17 00:00:00 2001
From: Qi Xiao <xiaqqaix@gmail.com>
Date: Wed, 3 Feb 2016 02:19:09 +0100
Subject: [PATCH] more elaborate signal handling

---
 edit/editor.go | 21 +++++++++++++++++++--
 main.go        |  8 ++------
 sys/trace.go   | 11 +++++++++++
 3 files changed, 32 insertions(+), 8 deletions(-)
 create mode 100644 sys/trace.go

diff --git a/edit/editor.go b/edit/editor.go
index bcd74ddd..a1861df0 100644
--- a/edit/editor.go
+++ b/edit/editor.go
@@ -4,6 +4,7 @@ package edit
 import (
 	"fmt"
 	"os"
+	"os/signal"
 	"strings"
 	"syscall"
 
@@ -57,7 +58,7 @@ type Editor struct {
 	file      *os.File
 	writer    *writer
 	reader    *Reader
-	sigs      <-chan os.Signal
+	sigs      chan os.Signal
 	histories []string
 	store     *store.Store
 	evaler    *eval.Evaler
@@ -151,7 +152,7 @@ func (ed *Editor) nextHistory() bool {
 }
 
 // NewEditor creates an Editor.
-func NewEditor(file *os.File, sigs <-chan os.Signal, ev *eval.Evaler, st *store.Store) *Editor {
+func NewEditor(file *os.File, sigs chan os.Signal, ev *eval.Evaler, st *store.Store) *Editor {
 	seq := -1
 	if st != nil {
 		var err error
@@ -350,6 +351,22 @@ MainLoop:
 				goto MainLoop
 			case syscall.SIGWINCH:
 				continue MainLoop
+			case syscall.SIGQUIT:
+				// Emulate default behavior
+				sys.DumpStack()
+				os.Exit(1)
+			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)
 			}
 		case or := <-ones:
 			// Alert about error
diff --git a/main.go b/main.go
index 286fb3f4..b36f7ca1 100644
--- a/main.go
+++ b/main.go
@@ -7,7 +7,6 @@ import (
 	"os"
 	"os/signal"
 	"os/user"
-	"runtime"
 	"syscall"
 
 	"github.com/elves/elvish/edit"
@@ -16,6 +15,7 @@ import (
 	"github.com/elves/elvish/osutil"
 	"github.com/elves/elvish/parse"
 	"github.com/elves/elvish/store"
+	"github.com/elves/elvish/sys"
 )
 
 const (
@@ -132,11 +132,7 @@ var usage = `Usage:
 func rescue() {
 	r := recover()
 	if r != nil {
-		buf := make([]byte, 1024)
-		for runtime.Stack(buf, true) == cap(buf) {
-			buf = make([]byte, cap(buf)*2)
-		}
-		print(string(buf))
+		sys.DumpStack()
 		println("execing recovery shell /bin/sh")
 		syscall.Exec("/bin/sh", []string{}, os.Environ())
 	}
diff --git a/sys/trace.go b/sys/trace.go
new file mode 100644
index 00000000..7a6930be
--- /dev/null
+++ b/sys/trace.go
@@ -0,0 +1,11 @@
+package sys
+
+import "runtime"
+
+func DumpStack() {
+	buf := make([]byte, 1024)
+	for runtime.Stack(buf, true) == cap(buf) {
+		buf = make([]byte, cap(buf)*2)
+	}
+	print(string(buf))
+}