client/local_notwindows.go

// Copyright 2021 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// +build !windows

package main

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

func newCmd(args []string) *exec.Cmd {
	cmd := exec.Command(args[0], args[1:]...)

	// Set a process group ID so that later we can kill child processes too. As an
	// example, if the command is `go run main.go`, Go will build a binary in a
	// temp dir and then execute it. If we simply cmd.Process.Kill() the exec.Command
	// then the running binary will not be killed. Only if we make a group and then
	// kill the group will child processes be killed.
	cmd.SysProcAttr = &syscall.SysProcAttr{
		Setpgid: true,
	}

	return cmd
}

func stopCmd(cmd *exec.Cmd) error {
	pgid, err := syscall.Getpgid(cmd.Process.Pid)
	if err != nil {
		// Kill just the parent process since we failed to get the process group ID.
		if err := cmd.Process.Kill(); err != nil {
			return fmt.Errorf("failed to kill process: %v", err)
		}
	} else {
		// Kill the whole process group.
		if err := syscall.Kill(-pgid, syscall.SIGKILL); err != nil {
			return fmt.Errorf("failed to kill process group: %v", err)
		}
	}

	return nil
}