1// Copyright 2011 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// +build darwin dragonfly freebsd linux,!appengine netbsd openbsd
6
7// Package terminal provides support functions for dealing with terminals, as
8// commonly found on UNIX systems.
9//
10// Putting a terminal into raw mode is the most common requirement:
11//
12// oldState, err := terminal.MakeRaw(0)
13// if err != nil {
14// panic(err)
15// }
16// defer terminal.Restore(0, oldState)
17package terminal // import "golang.org/x/crypto/ssh/terminal"
18
19import (
20 "golang.org/x/sys/unix"
21)
22
23// State contains the state of a terminal.
24type State struct {
25 termios unix.Termios
26}
27
28// IsTerminal returns true if the given file descriptor is a terminal.
29func IsTerminal(fd int) bool {
30 _, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
31 return err == nil
32}
33
34// MakeRaw put the terminal connected to the given file descriptor into raw
35// mode and returns the previous state of the terminal so that it can be
36// restored.
37func MakeRaw(fd int) (*State, error) {
38 termios, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
39 if err != nil {
40 return nil, err
41 }
42
43 oldState := State{termios: *termios}
44
45 // This attempts to replicate the behaviour documented for cfmakeraw in
46 // the termios(3) manpage.
47 termios.Iflag &^= unix.IGNBRK | unix.BRKINT | unix.PARMRK | unix.ISTRIP | unix.INLCR | unix.IGNCR | unix.ICRNL | unix.IXON
48 termios.Oflag &^= unix.OPOST
49 termios.Lflag &^= unix.ECHO | unix.ECHONL | unix.ICANON | unix.ISIG | unix.IEXTEN
50 termios.Cflag &^= unix.CSIZE | unix.PARENB
51 termios.Cflag |= unix.CS8
52 termios.Cc[unix.VMIN] = 1
53 termios.Cc[unix.VTIME] = 0
54 if err := unix.IoctlSetTermios(fd, ioctlWriteTermios, termios); err != nil {
55 return nil, err
56 }
57
58 return &oldState, nil
59}
60
61// GetState returns the current state of a terminal which may be useful to
62// restore the terminal after a signal.
63func GetState(fd int) (*State, error) {
64 termios, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
65 if err != nil {
66 return nil, err
67 }
68
69 return &State{termios: *termios}, nil
70}
71
72// Restore restores the terminal connected to the given file descriptor to a
73// previous state.
74func Restore(fd int, state *State) error {
75 return unix.IoctlSetTermios(fd, ioctlWriteTermios, &state.termios)
76}
77
78// GetSize returns the dimensions of the given terminal.
79func GetSize(fd int) (width, height int, err error) {
80 ws, err := unix.IoctlGetWinsize(fd, unix.TIOCGWINSZ)
81 if err != nil {
82 return -1, -1, err
83 }
84 return int(ws.Col), int(ws.Row), nil
85}
86
87// passwordReader is an io.Reader that reads from a specific file descriptor.
88type passwordReader int
89
90func (r passwordReader) Read(buf []byte) (int, error) {
91 return unix.Read(int(r), buf)
92}
93
94// ReadPassword reads a line of input from a terminal without local echo. This
95// is commonly used for inputting passwords and other sensitive data. The slice
96// returned does not include the \n.
97func ReadPassword(fd int) ([]byte, error) {
98 termios, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
99 if err != nil {
100 return nil, err
101 }
102
103 newState := *termios
104 newState.Lflag &^= unix.ECHO
105 newState.Lflag |= unix.ICANON | unix.ISIG
106 newState.Iflag |= unix.ICRNL
107 if err := unix.IoctlSetTermios(fd, ioctlWriteTermios, &newState); err != nil {
108 return nil, err
109 }
110
111 defer unix.IoctlSetTermios(fd, ioctlWriteTermios, termios)
112
113 return readPasswordLine(passwordReader(fd))
114}