if e != nil {
		return e
	}
	defer f.Close()
	_, e = f.Write([]byte(data))
	return e
}

func (p *Process) signal(sig Signal) error {
	switch p.pidStatus() {
	case statusDone:
		return ErrProcessDone
	case statusReleased:
		return syscall.ENOENT
	}

	if e := p.writeProcFile("note", sig.String()); e != nil {
		return NewSyscallError("signal", e)
	}

	// completes its wait.
	//
	// Checking for statusDone here would not be a complete fix, as the PID
	// could still be waited on and reused prior to blockUntilWaitable.
	switch p.pidStatus() {
	case statusReleased:
		return nil, syscall.EINVAL
	}

	// If we can block until Wait4 will succeed immediately, do so.
	ready, err := p.blockUntilWaitable()
	if err != nil {
		return nil, err
	}