os: Process.Exited returns false after exiting on signal

[bombela]

Please answer these questions before submitting your issue. Thanks!

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

go version go1.7.5 linux/amd64

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

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/bombela/u/go"
GORACE=""
GOROOT="/home/bombela/u/go/go1.7.5"
GOTOOLDIR="/home/bombela/u/go/go1.7.5/pkg/tool/linux_amd64"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build016673509=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"

What did you do?

package main

import (
	"fmt"
	"os"
	"os/exec"
	"syscall"
	"time"
)

func main() {
	cmd := exec.Command("sleep", "10")
	if err := cmd.Start(); err != nil {
		panic(err)
	}
	time.Sleep(time.Second * 2)
	cmd.Process.Signal(os.Interrupt)
	err := cmd.Wait()
	fmt.Println(err) // prints signal interrupt error
	fmt.Printf("ProcessState: Exited=%v, Success=%v\n", cmd.ProcessState.Exited(),
		cmd.ProcessState.Success()) // Exited should be true.
	waitstatus := cmd.ProcessState.Sys().(syscall.WaitStatus)
	fmt.Printf("WaitStatus:   Exited=%v, Signaled=%v\n",
		waitstatus.Exited(), waitstatus.Signaled())
}

What did you expect to see?

$ go run main.go 
signal: interrupt
ProcessState: Exited=true, Success=false
WaitStatus:   Exited=false, Signaled=true

What did you see instead?

$ go run main.go 
signal: interrupt
ProcessState: Exited=false, Success=false # I expect exited == true here,
WaitStatus:   Exited=false, Signaled=true    # and here

It looks like Exited() returns true only if the process exited via exit(), not when it exited via signal. It could be that Exited() should return true on signal.

Casting to syscall.WaitStatus allows to check for both Exited() and Signaled(), making it possible to know if the process is running or not. It seems to be impossible to know if the process is still running via the Command abstraction.

Naive suggestion: maybe a IsRunning() should be provided on Command.

[ianlancetaylor]

I'm not sure we can change Exited now.

Perhaps we should simply add Signaled.

[gopherbot]

Change https://golang.org/cl/135515 mentions this issue: os/exec: add method Signaled to ProcessState

[andybons]

This needs to be a formal proposal (https://golang.org/s/proposal) before we can move forward.

[gopherbot]

Timed out in state WaitingForInfo. Closing.

(I am just a bot, though. Please speak up if this is a mistake or you have the requested information.)