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