//go:build unix

package ingest

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

// setProcessGroup puts the engine in a process group of its own so that stopping a run reaches
// everything it started, not only the process whose pid we happen to hold (PD-13).
//
// It does NOT survive a crash of the platform: a killed supervisor leaves the group running, and
// only the deploy unit's cgroup closes that hole — see deploy/tmplatformd.service.
func setProcessGroup(cmd *exec.Cmd) {
	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
}

// interruptGroup asks the whole group to stop. A negative pid is the POSIX spelling of "group";
// if the group is already gone, the single process is still worth the signal.
func interruptGroup(p *os.Process) error {
	if err := syscall.Kill(-p.Pid, syscall.SIGINT); err != nil {
		return p.Signal(os.Interrupt)
	}
	return nil
}

// stillRunning reports whether the process can still be signalled by us.
func stillRunning(p *os.Process) bool { return p.Signal(syscall.Signal(0)) == nil }