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syscall: Kill pid argument cannot be a pgid because it is forced to be an unsigned int #53199

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singuliere opened this issue Jun 2, 2022 · 2 comments
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NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. WaitingForInfo Issue is not actionable because of missing required information, which needs to be provided.
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@singuliere
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singuliere commented Jun 2, 2022

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

$ go version
go version go1.18 linux/amd64

Does this issue reproduce with the latest release?

Yes.

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

go env Output
$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/singuliere/.cache/go-build"
GOENV="/home/singuliere/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/singuliere/.go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/singuliere/.go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.18"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
GOWORK=""
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 -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build2335311840=/tmp/go-build -gno-record-gcc-switches"

What did you do?

package main

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

func main() {
	c := exec.Command(ctx, "/bin/bash", "-c", `echo "sleep 100000" | bash`)
	c.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
	c.Start()
	fmt.Println("running err = ", c.Process.Pid)
	time.Sleep(5 * time.Second)
	syscall.Kill(-c.Process.Pid, syscall.SIGKILL)
	fmt.Println("run err = ", c.Wait())
}

What did you expect to see?

Because of the negative argument to syscall.Kill I was expecting all children of the processgroup to be killed, as per https://man7.org/linux/man-pages/man2/kill.2.html

What did you see instead?

The argument of syscall.Kill is converted into an unsigned integer instead of being passed as a negative number and only the immediate child is killed, not the entire process group. Which pretty much defeats the purpose of creating a process group in this particular case.

@singuliere singuliere changed the title affected/package: https://pkg.go.dev/syscall affected/package: https://pkg.go.dev/syscall Kill pid argument cannot be a pgid because it is forced to be an unsigned int Jun 2, 2022
@mengzhuo mengzhuo changed the title affected/package: https://pkg.go.dev/syscall Kill pid argument cannot be a pgid because it is forced to be an unsigned int syscall: Kill pid argument cannot be a pgid because it is forced to be an unsigned int Jun 2, 2022
@ianlancetaylor
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Your program does not compile because ctx is not defined. When I remove that, the programs works as expected on my Debian linux/amd64 system. It's true that the PID value is converted from int to uintptr, but this doesn't matter; the kernel will convert it back again.

Can you show us exactly what is wrong after you run your program?

@ianlancetaylor ianlancetaylor added WaitingForInfo Issue is not actionable because of missing required information, which needs to be provided. NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. labels Jun 2, 2022
@ianlancetaylor ianlancetaylor added this to the Backlog milestone Jun 2, 2022
@singuliere
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@ianlancetaylor I was a little too quick when making my tests it seems... sorry for the noise. It works as advertised.

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