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// based on https://code.google.com/p/gopass
// Author: johnsiilver@gmail.com (John Doak)
//
// Original code is based on code by RogerV in the golang-nuts thread:
// https://groups.google.com/group/golang-nuts/browse_thread/thread/40cc41e9d9fc9247
// +build darwin dragonfly freebsd linux netbsd openbsd solaris
package speakeasy
import (
"fmt"
"os"
"os/signal"
"strings"
"syscall"
)
const sttyArg0 = "/bin/stty"
var (
sttyArgvEOff = []string{"stty", "-echo"}
sttyArgvEOn = []string{"stty", "echo"}
)
// getPassword gets input hidden from the terminal from a user. This is
// accomplished by turning off terminal echo, reading input from the user and
// finally turning on terminal echo.
func getPassword() (password string, err error) {
sig := make(chan os.Signal, 10)
brk := make(chan bool)
// File descriptors for stdin, stdout, and stderr.
fd := []uintptr{os.Stdin.Fd(), os.Stdout.Fd(), os.Stderr.Fd()}
// Setup notifications of termination signals to channel sig, create a process to
// watch for these signals so we can turn back on echo if need be.
signal.Notify(sig, syscall.SIGHUP, syscall.SIGINT, syscall.SIGKILL, syscall.SIGQUIT,
syscall.SIGTERM)
go catchSignal(fd, sig, brk)
// Turn off the terminal echo.
pid, err := echoOff(fd)
if err != nil {
return "", err
}
// Turn on the terminal echo and stop listening for signals.
defer signal.Stop(sig)
defer close(brk)
defer echoOn(fd)
syscall.Wait4(pid, nil, 0, nil)
line, err := readline()
if err == nil {
password = strings.TrimSpace(line)
} else {
err = fmt.Errorf("failed during password entry: %s", err)
}
return password, err
}
// echoOff turns off the terminal echo.
func echoOff(fd []uintptr) (int, error) {
pid, err := syscall.ForkExec(sttyArg0, sttyArgvEOff, &syscall.ProcAttr{Dir: "", Files: fd})
if err != nil {
return 0, fmt.Errorf("failed turning off console echo for password entry:\n\t%s", err)
}
return pid, nil
}
// echoOn turns back on the terminal echo.
func echoOn(fd []uintptr) {
// Turn on the terminal echo.
pid, e := syscall.ForkExec(sttyArg0, sttyArgvEOn, &syscall.ProcAttr{Dir: "", Files: fd})
if e == nil {
syscall.Wait4(pid, nil, 0, nil)
}
}
// catchSignal tries to catch SIGKILL, SIGQUIT and SIGINT so that we can turn
// terminal echo back on before the program ends. Otherwise the user is left
// with echo off on their terminal.
func catchSignal(fd []uintptr, sig chan os.Signal, brk chan bool) {
select {
case <-sig:
echoOn(fd)
os.Exit(-1)
case <-brk:
}
}
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