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os/signal: SIGTSTP can't be handled #41996

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kke opened this issue Oct 15, 2020 · 3 comments
Closed

os/signal: SIGTSTP can't be handled #41996

kke opened this issue Oct 15, 2020 · 3 comments
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@kke
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kke commented Oct 15, 2020

What version of Go are you using (go version)?

$ go version
go version go1.15.2 darwin/amd64

Does this issue reproduce with the latest release?

It is the latest release

What operating system and processor architecture are you using (go env)?

go env Output
$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/kimmo/Library/Caches/go-build"
GOENV="/Users/kimmo/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/kimmo/Projects/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/kimmo/Projects/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/Cellar/go/1.15.2/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.15.2/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/kimmo/Projects/go/src/github.com/Mirantis/mcc/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/t5/k06n6kss3qz1z5sf0y8pqsw40000gn/T/go-build559599993=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

I'm trying to write a remote terminal client that needs to relay Ctrl-Z to the remote host. Intercepting Ctrl-C works fine by using signal.Notify(c, os.Interrupt), but signal.Notify(c, syscall.SIGTSTP) works only half way.

package main

import (
	"os"
	"os/signal"
	"syscall"
	"time"
)

func main() {
	c := make(chan os.Signal)
	signal.Notify(c, syscall.SIGTSTP)

	go func() {
		for {
			<-c
			println("received ctrl-z")
		}
	}()

	for {
		println("Sleeping...")
		time.Sleep(time.Second * 10)
	}
}

What did you expect to see?

Pressing Ctrl-Z should be intercepted and the go process should not suspend.

$ go run main.go
Sleeping...
received ctrl-z
Sleeping...
Sleeping...

What did you see instead?

received ctrl-z is printed but the go process itself is also suspended.

$ go run main.go
Sleeping...
received ctrl-z
[1]+  Stopped                 go run main.go
$ _
@seankhliao
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use go build and run the executable instead of using go run

@toothrot toothrot changed the title SIGTSTP can't be handled os/signal: SIGTSTP can't be handled Oct 15, 2020
@toothrot
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@kke I am closing this, as I believe @seankhliao's answer is correct. Please comment if I am mistaken.

@kke
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kke commented Oct 16, 2020 •
edited

@seankhliao is correct. Setting the local terminal to raw mode (for example via "golang.org/x/crypto/ssh/terminal"s MakeRaw()) makes it work even in go run mode (which also makes ctrl-d work)

@golang golang locked and limited conversation to collaborators Oct 16, 2021
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@toothrot @kke @gopherbot @seankhliao