Function processAlive

cli/connhelper/commandconn/commandconn_unix_test.go:213–234

processAlive returns true if a process with a given pid is running. It only considers positive PIDs; 0 (all processes in the current process group), -1 (all processes with a PID larger than 1), and negative (-n, all processes in process group "n") values for pid are never considered to be alive. It

(pid int)

//
// It was forked from https://github.com/moby/moby/blob/v28.3.3/pkg/process/process_unix.go#L17-L42
func processAlive(pid int) bool {
	if pid < 1 {
		return false
	}
	switch runtime.GOOS {
	case "darwin":
		// OS X does not have a proc filesystem. Use kill -0 pid to judge if the
		// process exists. From KILL(2): https://www.freebsd.org/cgi/man.cgi?query=kill&sektion=2&manpath=OpenDarwin+7.2.1
		//
		// Sig may be one of the signals specified in sigaction(2) or it may
		// be 0, in which case error checking is performed but no signal is
		// actually sent. This can be used to check the validity of pid.
		err := syscall.Kill(pid, 0)

		// Either the PID was found (no error), or we get an EPERM, which means
		// the PID exists, but we don't have permissions to signal it.
		return err == nil || errors.Is(err, syscall.EPERM)
	default:
		_, err := os.Stat(filepath.Join("/proc", strconv.Itoa(pid)))
		return err == nil
	}
}