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 aix darwin dragonfly freebsd linux,!appengine netbsd openbsd os400 solaris
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)
17
package readline
18

19
import (
20
	"io"
21
	"syscall"
22
)
23

24
// State contains the state of a terminal.
25
type State struct {
26
	termios Termios
27
}
28

29
// IsTerminal returns true if the given file descriptor is a terminal.
30
func IsTerminal(fd int) bool {
31
	_, err := getTermios(fd)
32
	return err == nil
33
}
34

35
// MakeRaw put the terminal connected to the given file descriptor into raw
36
// mode and returns the previous state of the terminal so that it can be
37
// restored.
38
func MakeRaw(fd int) (*State, error) {
39
	var oldState State
40

41
	if termios, err := getTermios(fd); err != nil {
42
		return nil, err
43
	} else {
44
		oldState.termios = *termios
45
	}
46

47
	newState := oldState.termios
48
	// This attempts to replicate the behaviour documented for cfmakeraw in
49
	// the termios(3) manpage.
50
	newState.Iflag &^= syscall.IGNBRK | syscall.BRKINT | syscall.PARMRK | syscall.ISTRIP | syscall.INLCR | syscall.IGNCR | syscall.ICRNL | syscall.IXON
51
	// newState.Oflag &^= syscall.OPOST
52
	newState.Lflag &^= syscall.ECHO | syscall.ECHONL | syscall.ICANON | syscall.ISIG | syscall.IEXTEN
53
	newState.Cflag &^= syscall.CSIZE | syscall.PARENB
54
	newState.Cflag |= syscall.CS8
55

56
	newState.Cc[syscall.VMIN] = 1
57
	newState.Cc[syscall.VTIME] = 0
58

59
	return &oldState, setTermios(fd, &newState)
60
}
61

62
// GetState returns the current state of a terminal which may be useful to
63
// restore the terminal after a signal.
64
func GetState(fd int) (*State, error) {
65
	termios, err := getTermios(fd)
66
	if err != nil {
67
		return nil, err
68
	}
69

70
	return &State{termios: *termios}, nil
71
}
72

73
// Restore restores the terminal connected to the given file descriptor to a
74
// previous state.
75
func restoreTerm(fd int, state *State) error {
76
	return setTermios(fd, &state.termios)
77
}
78

79
// ReadPassword reads a line of input from a terminal without local echo.  This
80
// is commonly used for inputting passwords and other sensitive data. The slice
81
// returned does not include the \n.
82
func ReadPassword(fd int) ([]byte, error) {
83
	oldState, err := getTermios(fd)
84
	if err != nil {
85
		return nil, err
86
	}
87

88
	newState := oldState
89
	newState.Lflag &^= syscall.ECHO
90
	newState.Lflag |= syscall.ICANON | syscall.ISIG
91
	newState.Iflag |= syscall.ICRNL
92
	if err := setTermios(fd, newState); err != nil {
93
		return nil, err
94
	}
95

96
	defer func() {
97
		setTermios(fd, oldState)
98
	}()
99

100
	var buf [16]byte
101
	var ret []byte
102
	for {
103
		n, err := syscall.Read(fd, buf[:])
104
		if err != nil {
105
			return nil, err
106
		}
107
		if n == 0 {
108
			if len(ret) == 0 {
109
				return nil, io.EOF
110
			}
111
			break
112
		}
113
		if buf[n-1] == '\n' {
114
			n--
115
		}
116
		ret = append(ret, buf[:n]...)
117
		if n < len(buf) {
118
			break
119
		}
120
	}
121

122
	return ret, nil
123
}
124

125