1// Copyright 2019 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
5package term
6
7import (
8	"io"
9	"syscall"
10
11	"golang.org/x/sys/unix"
12)
13
14// State contains the state of a terminal.
15type state struct {
16	termios unix.Termios
17}
18
19func isTerminal(fd int) bool {
20	_, err := unix.IoctlGetTermio(fd, unix.TCGETA)
21	return err == nil
22}
23
24func readPassword(fd int) ([]byte, error) {
25	// see also: http://src.illumos.org/source/xref/illumos-gate/usr/src/lib/libast/common/uwin/getpass.c
26	val, err := unix.IoctlGetTermios(fd, unix.TCGETS)
27	if err != nil {
28		return nil, err
29	}
30	oldState := *val
31
32	newState := oldState
33	newState.Lflag &^= syscall.ECHO
34	newState.Lflag |= syscall.ICANON | syscall.ISIG
35	newState.Iflag |= syscall.ICRNL
36	err = unix.IoctlSetTermios(fd, unix.TCSETS, &newState)
37	if err != nil {
38		return nil, err
39	}
40
41	defer unix.IoctlSetTermios(fd, unix.TCSETS, &oldState)
42
43	var buf [16]byte
44	var ret []byte
45	for {
46		n, err := syscall.Read(fd, buf[:])
47		if err != nil {
48			return nil, err
49		}
50		if n == 0 {
51			if len(ret) == 0 {
52				return nil, io.EOF
53			}
54			break
55		}
56		if buf[n-1] == '\n' {
57			n--
58		}
59		ret = append(ret, buf[:n]...)
60		if n < len(buf) {
61			break
62		}
63	}
64
65	return ret, nil
66}
67
68func makeRaw(fd int) (*State, error) {
69	// see http://cr.illumos.org/~webrev/andy_js/1060/
70	termios, err := unix.IoctlGetTermios(fd, unix.TCGETS)
71	if err != nil {
72		return nil, err
73	}
74
75	oldState := State{state{termios: *termios}}
76
77	termios.Iflag &^= unix.IGNBRK | unix.BRKINT | unix.PARMRK | unix.ISTRIP | unix.INLCR | unix.IGNCR | unix.ICRNL | unix.IXON
78	termios.Oflag &^= unix.OPOST
79	termios.Lflag &^= unix.ECHO | unix.ECHONL | unix.ICANON | unix.ISIG | unix.IEXTEN
80	termios.Cflag &^= unix.CSIZE | unix.PARENB
81	termios.Cflag |= unix.CS8
82	termios.Cc[unix.VMIN] = 1
83	termios.Cc[unix.VTIME] = 0
84
85	if err := unix.IoctlSetTermios(fd, unix.TCSETS, termios); err != nil {
86		return nil, err
87	}
88
89	return &oldState, nil
90}
91
92func restore(fd int, oldState *State) error {
93	return unix.IoctlSetTermios(fd, unix.TCSETS, &oldState.termios)
94}
95
96func getState(fd int) (*State, error) {
97	termios, err := unix.IoctlGetTermios(fd, unix.TCGETS)
98	if err != nil {
99		return nil, err
100	}
101
102	return &State{state{termios: *termios}}, nil
103}
104
105func getSize(fd int) (width, height int, err error) {
106	ws, err := unix.IoctlGetWinsize(fd, unix.TIOCGWINSZ)
107	if err != nil {
108		return 0, 0, err
109	}
110	return int(ws.Col), int(ws.Row), nil
111}
112