// SPDX-License-Identifier: MIT

package main

import (
	"errors"
	"os"
	"os/signal"
	"syscall"
)

var errNoTerminal = errors.New("there is no terminal to ask for the password on: " +
	"give it on standard input with --password-stdin")

// onInterrupt runs f if the program is interrupted before stop is called,
// and then exits. It is there for the moment the terminal is not echoing: a
// program ended while typing is hidden must not leave the terminal hiding it.
func onInterrupt(f func()) (stop func()) {
	sig := make(chan os.Signal, 1)
	signal.Notify(sig, os.Interrupt, syscall.SIGTERM)
	done := make(chan struct{})
	go func() {
		select {
		case <-sig:
			f()
			os.Exit(130)
		case <-done:
		}
	}()
	return func() {
		signal.Stop(sig)
		close(done)
	}
}