ssh/terminal: replace with a golang.org/x/term wrapper

The package moved to x/term in CL 258001.

Fixes golang/go#31044

Change-Id: I9d39bfb6f54f09de60e2669fb0d939968af79b40
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/258003
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Katie Hockman <katie@golang.org>
Trust: Filippo Valsorda <filippo@golang.org>
diff --git a/go.mod b/go.mod
index 6a004e4..d46a8b4 100644
--- a/go.mod
+++ b/go.mod
@@ -4,5 +4,6 @@
 
 require (
 	golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3
-	golang.org/x/sys v0.0.0-20190412213103-97732733099d
+	golang.org/x/sys v0.0.0-20191026070338-33540a1f6037
+	golang.org/x/term v0.0.0-20201113234701-d7a72108b828
 )
diff --git a/go.sum b/go.sum
index 44da498..8332f28 100644
--- a/go.sum
+++ b/go.sum
@@ -2,7 +2,9 @@
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3 h1:0GoQqolDA55aaLxZyTzK/Y2ePZzZTUrRacwib7cNsYQ=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20190412213103-97732733099d h1:+R4KGOnez64A81RvjARKc4UT5/tI9ujCIVX+P5KiHuI=
-golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20191026070338-33540a1f6037 h1:YyJpGZS1sBuBCzLAR1VEpK193GlqGZbnPFnPV/5Rsb4=
+golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/term v0.0.0-20201113234701-d7a72108b828 h1:htWEtQEuEVJ4tU/Ngx7Cd/4Q7e3A5Up1owgyBtVsTwk=
+golang.org/x/term v0.0.0-20201113234701-d7a72108b828/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
diff --git a/ssh/terminal/terminal.go b/ssh/terminal/terminal.go
index 2ffb97b..a4d1919 100644
--- a/ssh/terminal/terminal.go
+++ b/ssh/terminal/terminal.go
@@ -2,986 +2,75 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Package terminal provides support functions for dealing with terminals, as
+// commonly found on UNIX systems.
+//
+// Deprecated: this package moved to golang.org/x/term.
 package terminal
 
 import (
-	"bytes"
 	"io"
-	"runtime"
-	"strconv"
-	"sync"
-	"unicode/utf8"
+
+	"golang.org/x/term"
 )
 
 // EscapeCodes contains escape sequences that can be written to the terminal in
 // order to achieve different styles of text.
-type EscapeCodes struct {
-	// Foreground colors
-	Black, Red, Green, Yellow, Blue, Magenta, Cyan, White []byte
-
-	// Reset all attributes
-	Reset []byte
-}
-
-var vt100EscapeCodes = EscapeCodes{
-	Black:   []byte{keyEscape, '[', '3', '0', 'm'},
-	Red:     []byte{keyEscape, '[', '3', '1', 'm'},
-	Green:   []byte{keyEscape, '[', '3', '2', 'm'},
-	Yellow:  []byte{keyEscape, '[', '3', '3', 'm'},
-	Blue:    []byte{keyEscape, '[', '3', '4', 'm'},
-	Magenta: []byte{keyEscape, '[', '3', '5', 'm'},
-	Cyan:    []byte{keyEscape, '[', '3', '6', 'm'},
-	White:   []byte{keyEscape, '[', '3', '7', 'm'},
-
-	Reset: []byte{keyEscape, '[', '0', 'm'},
-}
+type EscapeCodes = term.EscapeCodes
 
 // Terminal contains the state for running a VT100 terminal that is capable of
 // reading lines of input.
-type Terminal struct {
-	// AutoCompleteCallback, if non-null, is called for each keypress with
-	// the full input line and the current position of the cursor (in
-	// bytes, as an index into |line|). If it returns ok=false, the key
-	// press is processed normally. Otherwise it returns a replacement line
-	// and the new cursor position.
-	AutoCompleteCallback func(line string, pos int, key rune) (newLine string, newPos int, ok bool)
-
-	// Escape contains a pointer to the escape codes for this terminal.
-	// It's always a valid pointer, although the escape codes themselves
-	// may be empty if the terminal doesn't support them.
-	Escape *EscapeCodes
-
-	// lock protects the terminal and the state in this object from
-	// concurrent processing of a key press and a Write() call.
-	lock sync.Mutex
-
-	c      io.ReadWriter
-	prompt []rune
-
-	// line is the current line being entered.
-	line []rune
-	// pos is the logical position of the cursor in line
-	pos int
-	// echo is true if local echo is enabled
-	echo bool
-	// pasteActive is true iff there is a bracketed paste operation in
-	// progress.
-	pasteActive bool
-
-	// cursorX contains the current X value of the cursor where the left
-	// edge is 0. cursorY contains the row number where the first row of
-	// the current line is 0.
-	cursorX, cursorY int
-	// maxLine is the greatest value of cursorY so far.
-	maxLine int
-
-	termWidth, termHeight int
-
-	// outBuf contains the terminal data to be sent.
-	outBuf []byte
-	// remainder contains the remainder of any partial key sequences after
-	// a read. It aliases into inBuf.
-	remainder []byte
-	inBuf     [256]byte
-
-	// history contains previously entered commands so that they can be
-	// accessed with the up and down keys.
-	history stRingBuffer
-	// historyIndex stores the currently accessed history entry, where zero
-	// means the immediately previous entry.
-	historyIndex int
-	// When navigating up and down the history it's possible to return to
-	// the incomplete, initial line. That value is stored in
-	// historyPending.
-	historyPending string
-}
+type Terminal = term.Terminal
 
 // NewTerminal runs a VT100 terminal on the given ReadWriter. If the ReadWriter is
 // a local terminal, that terminal must first have been put into raw mode.
 // prompt is a string that is written at the start of each input line (i.e.
 // "> ").
 func NewTerminal(c io.ReadWriter, prompt string) *Terminal {
-	return &Terminal{
-		Escape:       &vt100EscapeCodes,
-		c:            c,
-		prompt:       []rune(prompt),
-		termWidth:    80,
-		termHeight:   24,
-		echo:         true,
-		historyIndex: -1,
-	}
-}
-
-const (
-	keyCtrlC     = 3
-	keyCtrlD     = 4
-	keyCtrlU     = 21
-	keyEnter     = '\r'
-	keyEscape    = 27
-	keyBackspace = 127
-	keyUnknown   = 0xd800 /* UTF-16 surrogate area */ + iota
-	keyUp
-	keyDown
-	keyLeft
-	keyRight
-	keyAltLeft
-	keyAltRight
-	keyHome
-	keyEnd
-	keyDeleteWord
-	keyDeleteLine
-	keyClearScreen
-	keyPasteStart
-	keyPasteEnd
-)
-
-var (
-	crlf       = []byte{'\r', '\n'}
-	pasteStart = []byte{keyEscape, '[', '2', '0', '0', '~'}
-	pasteEnd   = []byte{keyEscape, '[', '2', '0', '1', '~'}
-)
-
-// bytesToKey tries to parse a key sequence from b. If successful, it returns
-// the key and the remainder of the input. Otherwise it returns utf8.RuneError.
-func bytesToKey(b []byte, pasteActive bool) (rune, []byte) {
-	if len(b) == 0 {
-		return utf8.RuneError, nil
-	}
-
-	if !pasteActive {
-		switch b[0] {
-		case 1: // ^A
-			return keyHome, b[1:]
-		case 2: // ^B
-			return keyLeft, b[1:]
-		case 5: // ^E
-			return keyEnd, b[1:]
-		case 6: // ^F
-			return keyRight, b[1:]
-		case 8: // ^H
-			return keyBackspace, b[1:]
-		case 11: // ^K
-			return keyDeleteLine, b[1:]
-		case 12: // ^L
-			return keyClearScreen, b[1:]
-		case 23: // ^W
-			return keyDeleteWord, b[1:]
-		case 14: // ^N
-			return keyDown, b[1:]
-		case 16: // ^P
-			return keyUp, b[1:]
-		}
-	}
-
-	if b[0] != keyEscape {
-		if !utf8.FullRune(b) {
-			return utf8.RuneError, b
-		}
-		r, l := utf8.DecodeRune(b)
-		return r, b[l:]
-	}
-
-	if !pasteActive && len(b) >= 3 && b[0] == keyEscape && b[1] == '[' {
-		switch b[2] {
-		case 'A':
-			return keyUp, b[3:]
-		case 'B':
-			return keyDown, b[3:]
-		case 'C':
-			return keyRight, b[3:]
-		case 'D':
-			return keyLeft, b[3:]
-		case 'H':
-			return keyHome, b[3:]
-		case 'F':
-			return keyEnd, b[3:]
-		}
-	}
-
-	if !pasteActive && len(b) >= 6 && b[0] == keyEscape && b[1] == '[' && b[2] == '1' && b[3] == ';' && b[4] == '3' {
-		switch b[5] {
-		case 'C':
-			return keyAltRight, b[6:]
-		case 'D':
-			return keyAltLeft, b[6:]
-		}
-	}
-
-	if !pasteActive && len(b) >= 6 && bytes.Equal(b[:6], pasteStart) {
-		return keyPasteStart, b[6:]
-	}
-
-	if pasteActive && len(b) >= 6 && bytes.Equal(b[:6], pasteEnd) {
-		return keyPasteEnd, b[6:]
-	}
-
-	// If we get here then we have a key that we don't recognise, or a
-	// partial sequence. It's not clear how one should find the end of a
-	// sequence without knowing them all, but it seems that [a-zA-Z~] only
-	// appears at the end of a sequence.
-	for i, c := range b[0:] {
-		if c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c == '~' {
-			return keyUnknown, b[i+1:]
-		}
-	}
-
-	return utf8.RuneError, b
-}
-
-// queue appends data to the end of t.outBuf
-func (t *Terminal) queue(data []rune) {
-	t.outBuf = append(t.outBuf, []byte(string(data))...)
-}
-
-var eraseUnderCursor = []rune{' ', keyEscape, '[', 'D'}
-var space = []rune{' '}
-
-func isPrintable(key rune) bool {
-	isInSurrogateArea := key >= 0xd800 && key <= 0xdbff
-	return key >= 32 && !isInSurrogateArea
-}
-
-// moveCursorToPos appends data to t.outBuf which will move the cursor to the
-// given, logical position in the text.
-func (t *Terminal) moveCursorToPos(pos int) {
-	if !t.echo {
-		return
-	}
-
-	x := visualLength(t.prompt) + pos
-	y := x / t.termWidth
-	x = x % t.termWidth
-
-	up := 0
-	if y < t.cursorY {
-		up = t.cursorY - y
-	}
-
-	down := 0
-	if y > t.cursorY {
-		down = y - t.cursorY
-	}
-
-	left := 0
-	if x < t.cursorX {
-		left = t.cursorX - x
-	}
-
-	right := 0
-	if x > t.cursorX {
-		right = x - t.cursorX
-	}
-
-	t.cursorX = x
-	t.cursorY = y
-	t.move(up, down, left, right)
-}
-
-func (t *Terminal) move(up, down, left, right int) {
-	m := []rune{}
-
-	// 1 unit up can be expressed as ^[[A or ^[A
-	// 5 units up can be expressed as ^[[5A
-
-	if up == 1 {
-		m = append(m, keyEscape, '[', 'A')
-	} else if up > 1 {
-		m = append(m, keyEscape, '[')
-		m = append(m, []rune(strconv.Itoa(up))...)
-		m = append(m, 'A')
-	}
-
-	if down == 1 {
-		m = append(m, keyEscape, '[', 'B')
-	} else if down > 1 {
-		m = append(m, keyEscape, '[')
-		m = append(m, []rune(strconv.Itoa(down))...)
-		m = append(m, 'B')
-	}
-
-	if right == 1 {
-		m = append(m, keyEscape, '[', 'C')
-	} else if right > 1 {
-		m = append(m, keyEscape, '[')
-		m = append(m, []rune(strconv.Itoa(right))...)
-		m = append(m, 'C')
-	}
-
-	if left == 1 {
-		m = append(m, keyEscape, '[', 'D')
-	} else if left > 1 {
-		m = append(m, keyEscape, '[')
-		m = append(m, []rune(strconv.Itoa(left))...)
-		m = append(m, 'D')
-	}
-
-	t.queue(m)
-}
-
-func (t *Terminal) clearLineToRight() {
-	op := []rune{keyEscape, '[', 'K'}
-	t.queue(op)
-}
-
-const maxLineLength = 4096
-
-func (t *Terminal) setLine(newLine []rune, newPos int) {
-	if t.echo {
-		t.moveCursorToPos(0)
-		t.writeLine(newLine)
-		for i := len(newLine); i < len(t.line); i++ {
-			t.writeLine(space)
-		}
-		t.moveCursorToPos(newPos)
-	}
-	t.line = newLine
-	t.pos = newPos
-}
-
-func (t *Terminal) advanceCursor(places int) {
-	t.cursorX += places
-	t.cursorY += t.cursorX / t.termWidth
-	if t.cursorY > t.maxLine {
-		t.maxLine = t.cursorY
-	}
-	t.cursorX = t.cursorX % t.termWidth
-
-	if places > 0 && t.cursorX == 0 {
-		// Normally terminals will advance the current position
-		// when writing a character. But that doesn't happen
-		// for the last character in a line. However, when
-		// writing a character (except a new line) that causes
-		// a line wrap, the position will be advanced two
-		// places.
-		//
-		// So, if we are stopping at the end of a line, we
-		// need to write a newline so that our cursor can be
-		// advanced to the next line.
-		t.outBuf = append(t.outBuf, '\r', '\n')
-	}
-}
-
-func (t *Terminal) eraseNPreviousChars(n int) {
-	if n == 0 {
-		return
-	}
-
-	if t.pos < n {
-		n = t.pos
-	}
-	t.pos -= n
-	t.moveCursorToPos(t.pos)
-
-	copy(t.line[t.pos:], t.line[n+t.pos:])
-	t.line = t.line[:len(t.line)-n]
-	if t.echo {
-		t.writeLine(t.line[t.pos:])
-		for i := 0; i < n; i++ {
-			t.queue(space)
-		}
-		t.advanceCursor(n)
-		t.moveCursorToPos(t.pos)
-	}
-}
-
-// countToLeftWord returns then number of characters from the cursor to the
-// start of the previous word.
-func (t *Terminal) countToLeftWord() int {
-	if t.pos == 0 {
-		return 0
-	}
-
-	pos := t.pos - 1
-	for pos > 0 {
-		if t.line[pos] != ' ' {
-			break
-		}
-		pos--
-	}
-	for pos > 0 {
-		if t.line[pos] == ' ' {
-			pos++
-			break
-		}
-		pos--
-	}
-
-	return t.pos - pos
-}
-
-// countToRightWord returns then number of characters from the cursor to the
-// start of the next word.
-func (t *Terminal) countToRightWord() int {
-	pos := t.pos
-	for pos < len(t.line) {
-		if t.line[pos] == ' ' {
-			break
-		}
-		pos++
-	}
-	for pos < len(t.line) {
-		if t.line[pos] != ' ' {
-			break
-		}
-		pos++
-	}
-	return pos - t.pos
-}
-
-// visualLength returns the number of visible glyphs in s.
-func visualLength(runes []rune) int {
-	inEscapeSeq := false
-	length := 0
-
-	for _, r := range runes {
-		switch {
-		case inEscapeSeq:
-			if (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') {
-				inEscapeSeq = false
-			}
-		case r == '\x1b':
-			inEscapeSeq = true
-		default:
-			length++
-		}
-	}
-
-	return length
-}
-
-// handleKey processes the given key and, optionally, returns a line of text
-// that the user has entered.
-func (t *Terminal) handleKey(key rune) (line string, ok bool) {
-	if t.pasteActive && key != keyEnter {
-		t.addKeyToLine(key)
-		return
-	}
-
-	switch key {
-	case keyBackspace:
-		if t.pos == 0 {
-			return
-		}
-		t.eraseNPreviousChars(1)
-	case keyAltLeft:
-		// move left by a word.
-		t.pos -= t.countToLeftWord()
-		t.moveCursorToPos(t.pos)
-	case keyAltRight:
-		// move right by a word.
-		t.pos += t.countToRightWord()
-		t.moveCursorToPos(t.pos)
-	case keyLeft:
-		if t.pos == 0 {
-			return
-		}
-		t.pos--
-		t.moveCursorToPos(t.pos)
-	case keyRight:
-		if t.pos == len(t.line) {
-			return
-		}
-		t.pos++
-		t.moveCursorToPos(t.pos)
-	case keyHome:
-		if t.pos == 0 {
-			return
-		}
-		t.pos = 0
-		t.moveCursorToPos(t.pos)
-	case keyEnd:
-		if t.pos == len(t.line) {
-			return
-		}
-		t.pos = len(t.line)
-		t.moveCursorToPos(t.pos)
-	case keyUp:
-		entry, ok := t.history.NthPreviousEntry(t.historyIndex + 1)
-		if !ok {
-			return "", false
-		}
-		if t.historyIndex == -1 {
-			t.historyPending = string(t.line)
-		}
-		t.historyIndex++
-		runes := []rune(entry)
-		t.setLine(runes, len(runes))
-	case keyDown:
-		switch t.historyIndex {
-		case -1:
-			return
-		case 0:
-			runes := []rune(t.historyPending)
-			t.setLine(runes, len(runes))
-			t.historyIndex--
-		default:
-			entry, ok := t.history.NthPreviousEntry(t.historyIndex - 1)
-			if ok {
-				t.historyIndex--
-				runes := []rune(entry)
-				t.setLine(runes, len(runes))
-			}
-		}
-	case keyEnter:
-		t.moveCursorToPos(len(t.line))
-		t.queue([]rune("\r\n"))
-		line = string(t.line)
-		ok = true
-		t.line = t.line[:0]
-		t.pos = 0
-		t.cursorX = 0
-		t.cursorY = 0
-		t.maxLine = 0
-	case keyDeleteWord:
-		// Delete zero or more spaces and then one or more characters.
-		t.eraseNPreviousChars(t.countToLeftWord())
-	case keyDeleteLine:
-		// Delete everything from the current cursor position to the
-		// end of line.
-		for i := t.pos; i < len(t.line); i++ {
-			t.queue(space)
-			t.advanceCursor(1)
-		}
-		t.line = t.line[:t.pos]
-		t.moveCursorToPos(t.pos)
-	case keyCtrlD:
-		// Erase the character under the current position.
-		// The EOF case when the line is empty is handled in
-		// readLine().
-		if t.pos < len(t.line) {
-			t.pos++
-			t.eraseNPreviousChars(1)
-		}
-	case keyCtrlU:
-		t.eraseNPreviousChars(t.pos)
-	case keyClearScreen:
-		// Erases the screen and moves the cursor to the home position.
-		t.queue([]rune("\x1b[2J\x1b[H"))
-		t.queue(t.prompt)
-		t.cursorX, t.cursorY = 0, 0
-		t.advanceCursor(visualLength(t.prompt))
-		t.setLine(t.line, t.pos)
-	default:
-		if t.AutoCompleteCallback != nil {
-			prefix := string(t.line[:t.pos])
-			suffix := string(t.line[t.pos:])
-
-			t.lock.Unlock()
-			newLine, newPos, completeOk := t.AutoCompleteCallback(prefix+suffix, len(prefix), key)
-			t.lock.Lock()
-
-			if completeOk {
-				t.setLine([]rune(newLine), utf8.RuneCount([]byte(newLine)[:newPos]))
-				return
-			}
-		}
-		if !isPrintable(key) {
-			return
-		}
-		if len(t.line) == maxLineLength {
-			return
-		}
-		t.addKeyToLine(key)
-	}
-	return
-}
-
-// addKeyToLine inserts the given key at the current position in the current
-// line.
-func (t *Terminal) addKeyToLine(key rune) {
-	if len(t.line) == cap(t.line) {
-		newLine := make([]rune, len(t.line), 2*(1+len(t.line)))
-		copy(newLine, t.line)
-		t.line = newLine
-	}
-	t.line = t.line[:len(t.line)+1]
-	copy(t.line[t.pos+1:], t.line[t.pos:])
-	t.line[t.pos] = key
-	if t.echo {
-		t.writeLine(t.line[t.pos:])
-	}
-	t.pos++
-	t.moveCursorToPos(t.pos)
-}
-
-func (t *Terminal) writeLine(line []rune) {
-	for len(line) != 0 {
-		remainingOnLine := t.termWidth - t.cursorX
-		todo := len(line)
-		if todo > remainingOnLine {
-			todo = remainingOnLine
-		}
-		t.queue(line[:todo])
-		t.advanceCursor(visualLength(line[:todo]))
-		line = line[todo:]
-	}
-}
-
-// writeWithCRLF writes buf to w but replaces all occurrences of \n with \r\n.
-func writeWithCRLF(w io.Writer, buf []byte) (n int, err error) {
-	for len(buf) > 0 {
-		i := bytes.IndexByte(buf, '\n')
-		todo := len(buf)
-		if i >= 0 {
-			todo = i
-		}
-
-		var nn int
-		nn, err = w.Write(buf[:todo])
-		n += nn
-		if err != nil {
-			return n, err
-		}
-		buf = buf[todo:]
-
-		if i >= 0 {
-			if _, err = w.Write(crlf); err != nil {
-				return n, err
-			}
-			n++
-			buf = buf[1:]
-		}
-	}
-
-	return n, nil
-}
-
-func (t *Terminal) Write(buf []byte) (n int, err error) {
-	t.lock.Lock()
-	defer t.lock.Unlock()
-
-	if t.cursorX == 0 && t.cursorY == 0 {
-		// This is the easy case: there's nothing on the screen that we
-		// have to move out of the way.
-		return writeWithCRLF(t.c, buf)
-	}
-
-	// We have a prompt and possibly user input on the screen. We
-	// have to clear it first.
-	t.move(0 /* up */, 0 /* down */, t.cursorX /* left */, 0 /* right */)
-	t.cursorX = 0
-	t.clearLineToRight()
-
-	for t.cursorY > 0 {
-		t.move(1 /* up */, 0, 0, 0)
-		t.cursorY--
-		t.clearLineToRight()
-	}
-
-	if _, err = t.c.Write(t.outBuf); err != nil {
-		return
-	}
-	t.outBuf = t.outBuf[:0]
-
-	if n, err = writeWithCRLF(t.c, buf); err != nil {
-		return
-	}
-
-	t.writeLine(t.prompt)
-	if t.echo {
-		t.writeLine(t.line)
-	}
-
-	t.moveCursorToPos(t.pos)
-
-	if _, err = t.c.Write(t.outBuf); err != nil {
-		return
-	}
-	t.outBuf = t.outBuf[:0]
-	return
-}
-
-// ReadPassword temporarily changes the prompt and reads a password, without
-// echo, from the terminal.
-func (t *Terminal) ReadPassword(prompt string) (line string, err error) {
-	t.lock.Lock()
-	defer t.lock.Unlock()
-
-	oldPrompt := t.prompt
-	t.prompt = []rune(prompt)
-	t.echo = false
-
-	line, err = t.readLine()
-
-	t.prompt = oldPrompt
-	t.echo = true
-
-	return
-}
-
-// ReadLine returns a line of input from the terminal.
-func (t *Terminal) ReadLine() (line string, err error) {
-	t.lock.Lock()
-	defer t.lock.Unlock()
-
-	return t.readLine()
-}
-
-func (t *Terminal) readLine() (line string, err error) {
-	// t.lock must be held at this point
-
-	if t.cursorX == 0 && t.cursorY == 0 {
-		t.writeLine(t.prompt)
-		t.c.Write(t.outBuf)
-		t.outBuf = t.outBuf[:0]
-	}
-
-	lineIsPasted := t.pasteActive
-
-	for {
-		rest := t.remainder
-		lineOk := false
-		for !lineOk {
-			var key rune
-			key, rest = bytesToKey(rest, t.pasteActive)
-			if key == utf8.RuneError {
-				break
-			}
-			if !t.pasteActive {
-				if key == keyCtrlD {
-					if len(t.line) == 0 {
-						return "", io.EOF
-					}
-				}
-				if key == keyCtrlC {
-					return "", io.EOF
-				}
-				if key == keyPasteStart {
-					t.pasteActive = true
-					if len(t.line) == 0 {
-						lineIsPasted = true
-					}
-					continue
-				}
-			} else if key == keyPasteEnd {
-				t.pasteActive = false
-				continue
-			}
-			if !t.pasteActive {
-				lineIsPasted = false
-			}
-			line, lineOk = t.handleKey(key)
-		}
-		if len(rest) > 0 {
-			n := copy(t.inBuf[:], rest)
-			t.remainder = t.inBuf[:n]
-		} else {
-			t.remainder = nil
-		}
-		t.c.Write(t.outBuf)
-		t.outBuf = t.outBuf[:0]
-		if lineOk {
-			if t.echo {
-				t.historyIndex = -1
-				t.history.Add(line)
-			}
-			if lineIsPasted {
-				err = ErrPasteIndicator
-			}
-			return
-		}
-
-		// t.remainder is a slice at the beginning of t.inBuf
-		// containing a partial key sequence
-		readBuf := t.inBuf[len(t.remainder):]
-		var n int
-
-		t.lock.Unlock()
-		n, err = t.c.Read(readBuf)
-		t.lock.Lock()
-
-		if err != nil {
-			return
-		}
-
-		t.remainder = t.inBuf[:n+len(t.remainder)]
-	}
-}
-
-// SetPrompt sets the prompt to be used when reading subsequent lines.
-func (t *Terminal) SetPrompt(prompt string) {
-	t.lock.Lock()
-	defer t.lock.Unlock()
-
-	t.prompt = []rune(prompt)
-}
-
-func (t *Terminal) clearAndRepaintLinePlusNPrevious(numPrevLines int) {
-	// Move cursor to column zero at the start of the line.
-	t.move(t.cursorY, 0, t.cursorX, 0)
-	t.cursorX, t.cursorY = 0, 0
-	t.clearLineToRight()
-	for t.cursorY < numPrevLines {
-		// Move down a line
-		t.move(0, 1, 0, 0)
-		t.cursorY++
-		t.clearLineToRight()
-	}
-	// Move back to beginning.
-	t.move(t.cursorY, 0, 0, 0)
-	t.cursorX, t.cursorY = 0, 0
-
-	t.queue(t.prompt)
-	t.advanceCursor(visualLength(t.prompt))
-	t.writeLine(t.line)
-	t.moveCursorToPos(t.pos)
-}
-
-func (t *Terminal) SetSize(width, height int) error {
-	t.lock.Lock()
-	defer t.lock.Unlock()
-
-	if width == 0 {
-		width = 1
-	}
-
-	oldWidth := t.termWidth
-	t.termWidth, t.termHeight = width, height
-
-	switch {
-	case width == oldWidth:
-		// If the width didn't change then nothing else needs to be
-		// done.
-		return nil
-	case len(t.line) == 0 && t.cursorX == 0 && t.cursorY == 0:
-		// If there is nothing on current line and no prompt printed,
-		// just do nothing
-		return nil
-	case width < oldWidth:
-		// Some terminals (e.g. xterm) will truncate lines that were
-		// too long when shinking. Others, (e.g. gnome-terminal) will
-		// attempt to wrap them. For the former, repainting t.maxLine
-		// works great, but that behaviour goes badly wrong in the case
-		// of the latter because they have doubled every full line.
-
-		// We assume that we are working on a terminal that wraps lines
-		// and adjust the cursor position based on every previous line
-		// wrapping and turning into two. This causes the prompt on
-		// xterms to move upwards, which isn't great, but it avoids a
-		// huge mess with gnome-terminal.
-		if t.cursorX >= t.termWidth {
-			t.cursorX = t.termWidth - 1
-		}
-		t.cursorY *= 2
-		t.clearAndRepaintLinePlusNPrevious(t.maxLine * 2)
-	case width > oldWidth:
-		// If the terminal expands then our position calculations will
-		// be wrong in the future because we think the cursor is
-		// |t.pos| chars into the string, but there will be a gap at
-		// the end of any wrapped line.
-		//
-		// But the position will actually be correct until we move, so
-		// we can move back to the beginning and repaint everything.
-		t.clearAndRepaintLinePlusNPrevious(t.maxLine)
-	}
-
-	_, err := t.c.Write(t.outBuf)
-	t.outBuf = t.outBuf[:0]
-	return err
-}
-
-type pasteIndicatorError struct{}
-
-func (pasteIndicatorError) Error() string {
-	return "terminal: ErrPasteIndicator not correctly handled"
+	return term.NewTerminal(c, prompt)
 }
 
 // ErrPasteIndicator may be returned from ReadLine as the error, in addition
 // to valid line data. It indicates that bracketed paste mode is enabled and
 // that the returned line consists only of pasted data. Programs may wish to
 // interpret pasted data more literally than typed data.
-var ErrPasteIndicator = pasteIndicatorError{}
+var ErrPasteIndicator = term.ErrPasteIndicator
 
-// SetBracketedPasteMode requests that the terminal bracket paste operations
-// with markers. Not all terminals support this but, if it is supported, then
-// enabling this mode will stop any autocomplete callback from running due to
-// pastes. Additionally, any lines that are completely pasted will be returned
-// from ReadLine with the error set to ErrPasteIndicator.
-func (t *Terminal) SetBracketedPasteMode(on bool) {
-	if on {
-		io.WriteString(t.c, "\x1b[?2004h")
-	} else {
-		io.WriteString(t.c, "\x1b[?2004l")
-	}
+// State contains the state of a terminal.
+type State = term.State
+
+// IsTerminal returns whether the given file descriptor is a terminal.
+func IsTerminal(fd int) bool {
+	return term.IsTerminal(fd)
 }
 
-// stRingBuffer is a ring buffer of strings.
-type stRingBuffer struct {
-	// entries contains max elements.
-	entries []string
-	max     int
-	// head contains the index of the element most recently added to the ring.
-	head int
-	// size contains the number of elements in the ring.
-	size int
+// ReadPassword reads a line of input from a terminal without local echo.  This
+// is commonly used for inputting passwords and other sensitive data. The slice
+// returned does not include the \n.
+func ReadPassword(fd int) ([]byte, error) {
+	return term.ReadPassword(fd)
 }
 
-func (s *stRingBuffer) Add(a string) {
-	if s.entries == nil {
-		const defaultNumEntries = 100
-		s.entries = make([]string, defaultNumEntries)
-		s.max = defaultNumEntries
-	}
-
-	s.head = (s.head + 1) % s.max
-	s.entries[s.head] = a
-	if s.size < s.max {
-		s.size++
-	}
+// MakeRaw puts the terminal connected to the given file descriptor into raw
+// mode and returns the previous state of the terminal so that it can be
+// restored.
+func MakeRaw(fd int) (*State, error) {
+	return term.MakeRaw(fd)
 }
 
-// NthPreviousEntry returns the value passed to the nth previous call to Add.
-// If n is zero then the immediately prior value is returned, if one, then the
-// next most recent, and so on. If such an element doesn't exist then ok is
-// false.
-func (s *stRingBuffer) NthPreviousEntry(n int) (value string, ok bool) {
-	if n >= s.size {
-		return "", false
-	}
-	index := s.head - n
-	if index < 0 {
-		index += s.max
-	}
-	return s.entries[index], true
+// Restore restores the terminal connected to the given file descriptor to a
+// previous state.
+func Restore(fd int, oldState *State) error {
+	return term.Restore(fd, oldState)
 }
 
-// readPasswordLine reads from reader until it finds \n or io.EOF.
-// The slice returned does not include the \n.
-// readPasswordLine also ignores any \r it finds.
-// Windows uses \r as end of line. So, on Windows, readPasswordLine
-// reads until it finds \r and ignores any \n it finds during processing.
-func readPasswordLine(reader io.Reader) ([]byte, error) {
-	var buf [1]byte
-	var ret []byte
+// GetState returns the current state of a terminal which may be useful to
+// restore the terminal after a signal.
+func GetState(fd int) (*State, error) {
+	return term.GetState(fd)
+}
 
-	for {
-		n, err := reader.Read(buf[:])
-		if n > 0 {
-			switch buf[0] {
-			case '\b':
-				if len(ret) > 0 {
-					ret = ret[:len(ret)-1]
-				}
-			case '\n':
-				if runtime.GOOS != "windows" {
-					return ret, nil
-				}
-				// otherwise ignore \n
-			case '\r':
-				if runtime.GOOS == "windows" {
-					return ret, nil
-				}
-				// otherwise ignore \r
-			default:
-				ret = append(ret, buf[0])
-			}
-			continue
-		}
-		if err != nil {
-			if err == io.EOF && len(ret) > 0 {
-				return ret, nil
-			}
-			return ret, err
-		}
-	}
+// GetSize returns the dimensions of the given terminal.
+func GetSize(fd int) (width, height int, err error) {
+	return term.GetSize(fd)
 }
diff --git a/ssh/terminal/terminal_test.go b/ssh/terminal/terminal_test.go
deleted file mode 100644
index c99638d..0000000
--- a/ssh/terminal/terminal_test.go
+++ /dev/null
@@ -1,439 +0,0 @@
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build aix darwin dragonfly freebsd linux,!appengine netbsd openbsd windows plan9 solaris
-
-package terminal
-
-import (
-	"bytes"
-	"io"
-	"os"
-	"runtime"
-	"testing"
-)
-
-type MockTerminal struct {
-	toSend       []byte
-	bytesPerRead int
-	received     []byte
-}
-
-func (c *MockTerminal) Read(data []byte) (n int, err error) {
-	n = len(data)
-	if n == 0 {
-		return
-	}
-	if n > len(c.toSend) {
-		n = len(c.toSend)
-	}
-	if n == 0 {
-		return 0, io.EOF
-	}
-	if c.bytesPerRead > 0 && n > c.bytesPerRead {
-		n = c.bytesPerRead
-	}
-	copy(data, c.toSend[:n])
-	c.toSend = c.toSend[n:]
-	return
-}
-
-func (c *MockTerminal) Write(data []byte) (n int, err error) {
-	c.received = append(c.received, data...)
-	return len(data), nil
-}
-
-func TestClose(t *testing.T) {
-	c := &MockTerminal{}
-	ss := NewTerminal(c, "> ")
-	line, err := ss.ReadLine()
-	if line != "" {
-		t.Errorf("Expected empty line but got: %s", line)
-	}
-	if err != io.EOF {
-		t.Errorf("Error should have been EOF but got: %s", err)
-	}
-}
-
-var keyPressTests = []struct {
-	in             string
-	line           string
-	err            error
-	throwAwayLines int
-}{
-	{
-		err: io.EOF,
-	},
-	{
-		in:   "\r",
-		line: "",
-	},
-	{
-		in:   "foo\r",
-		line: "foo",
-	},
-	{
-		in:   "a\x1b[Cb\r", // right
-		line: "ab",
-	},
-	{
-		in:   "a\x1b[Db\r", // left
-		line: "ba",
-	},
-	{
-		in:   "a\006b\r", // ^F
-		line: "ab",
-	},
-	{
-		in:   "a\002b\r", // ^B
-		line: "ba",
-	},
-	{
-		in:   "a\177b\r", // backspace
-		line: "b",
-	},
-	{
-		in: "\x1b[A\r", // up
-	},
-	{
-		in: "\x1b[B\r", // down
-	},
-	{
-		in: "\016\r", // ^P
-	},
-	{
-		in: "\014\r", // ^N
-	},
-	{
-		in:   "line\x1b[A\x1b[B\r", // up then down
-		line: "line",
-	},
-	{
-		in:             "line1\rline2\x1b[A\r", // recall previous line.
-		line:           "line1",
-		throwAwayLines: 1,
-	},
-	{
-		// recall two previous lines and append.
-		in:             "line1\rline2\rline3\x1b[A\x1b[Axxx\r",
-		line:           "line1xxx",
-		throwAwayLines: 2,
-	},
-	{
-		// Ctrl-A to move to beginning of line followed by ^K to kill
-		// line.
-		in:   "a b \001\013\r",
-		line: "",
-	},
-	{
-		// Ctrl-A to move to beginning of line, Ctrl-E to move to end,
-		// finally ^K to kill nothing.
-		in:   "a b \001\005\013\r",
-		line: "a b ",
-	},
-	{
-		in:   "\027\r",
-		line: "",
-	},
-	{
-		in:   "a\027\r",
-		line: "",
-	},
-	{
-		in:   "a \027\r",
-		line: "",
-	},
-	{
-		in:   "a b\027\r",
-		line: "a ",
-	},
-	{
-		in:   "a b \027\r",
-		line: "a ",
-	},
-	{
-		in:   "one two thr\x1b[D\027\r",
-		line: "one two r",
-	},
-	{
-		in:   "\013\r",
-		line: "",
-	},
-	{
-		in:   "a\013\r",
-		line: "a",
-	},
-	{
-		in:   "ab\x1b[D\013\r",
-		line: "a",
-	},
-	{
-		in:   "Ξεσκεπάζω\r",
-		line: "Ξεσκεπάζω",
-	},
-	{
-		in:             "£\r\x1b[A\177\r", // non-ASCII char, enter, up, backspace.
-		line:           "",
-		throwAwayLines: 1,
-	},
-	{
-		in:             "£\r££\x1b[A\x1b[B\177\r", // non-ASCII char, enter, 2x non-ASCII, up, down, backspace, enter.
-		line:           "£",
-		throwAwayLines: 1,
-	},
-	{
-		// Ctrl-D at the end of the line should be ignored.
-		in:   "a\004\r",
-		line: "a",
-	},
-	{
-		// a, b, left, Ctrl-D should erase the b.
-		in:   "ab\x1b[D\004\r",
-		line: "a",
-	},
-	{
-		// a, b, c, d, left, left, ^U should erase to the beginning of
-		// the line.
-		in:   "abcd\x1b[D\x1b[D\025\r",
-		line: "cd",
-	},
-	{
-		// Bracketed paste mode: control sequences should be returned
-		// verbatim in paste mode.
-		in:   "abc\x1b[200~de\177f\x1b[201~\177\r",
-		line: "abcde\177",
-	},
-	{
-		// Enter in bracketed paste mode should still work.
-		in:             "abc\x1b[200~d\refg\x1b[201~h\r",
-		line:           "efgh",
-		throwAwayLines: 1,
-	},
-	{
-		// Lines consisting entirely of pasted data should be indicated as such.
-		in:   "\x1b[200~a\r",
-		line: "a",
-		err:  ErrPasteIndicator,
-	},
-	{
-		// Ctrl-C terminates readline
-		in:  "\003",
-		err: io.EOF,
-	},
-	{
-		// Ctrl-C at the end of line also terminates readline
-		in:  "a\003\r",
-		err: io.EOF,
-	},
-}
-
-func TestKeyPresses(t *testing.T) {
-	for i, test := range keyPressTests {
-		for j := 1; j < len(test.in); j++ {
-			c := &MockTerminal{
-				toSend:       []byte(test.in),
-				bytesPerRead: j,
-			}
-			ss := NewTerminal(c, "> ")
-			for k := 0; k < test.throwAwayLines; k++ {
-				_, err := ss.ReadLine()
-				if err != nil {
-					t.Errorf("Throwaway line %d from test %d resulted in error: %s", k, i, err)
-				}
-			}
-			line, err := ss.ReadLine()
-			if line != test.line {
-				t.Errorf("Line resulting from test %d (%d bytes per read) was '%s', expected '%s'", i, j, line, test.line)
-				break
-			}
-			if err != test.err {
-				t.Errorf("Error resulting from test %d (%d bytes per read) was '%v', expected '%v'", i, j, err, test.err)
-				break
-			}
-		}
-	}
-}
-
-var renderTests = []struct {
-	in       string
-	received string
-	err      error
-}{
-	{
-		// Cursor move after keyHome (left 4) then enter (right 4, newline)
-		in:       "abcd\x1b[H\r",
-		received: "> abcd\x1b[4D\x1b[4C\r\n",
-	},
-	{
-		// Write, home, prepend, enter. Prepends rewrites the line.
-		in: "cdef\x1b[Hab\r",
-		received: "> cdef" + // Initial input
-			"\x1b[4Da" + // Move cursor back, insert first char
-			"cdef" + // Copy over original string
-			"\x1b[4Dbcdef" + // Repeat for second char with copy
-			"\x1b[4D" + // Put cursor back in position to insert again
-			"\x1b[4C\r\n", // Put cursor at the end of the line and newline.
-	},
-}
-
-func TestRender(t *testing.T) {
-	for i, test := range renderTests {
-		for j := 1; j < len(test.in); j++ {
-			c := &MockTerminal{
-				toSend:       []byte(test.in),
-				bytesPerRead: j,
-			}
-			ss := NewTerminal(c, "> ")
-			_, err := ss.ReadLine()
-			if err != test.err {
-				t.Errorf("Error resulting from test %d (%d bytes per read) was '%v', expected '%v'", i, j, err, test.err)
-				break
-			}
-			if test.received != string(c.received) {
-				t.Errorf("Results rendered from test %d (%d bytes per read) was '%s', expected '%s'", i, j, c.received, test.received)
-				break
-			}
-		}
-	}
-}
-
-func TestPasswordNotSaved(t *testing.T) {
-	c := &MockTerminal{
-		toSend:       []byte("password\r\x1b[A\r"),
-		bytesPerRead: 1,
-	}
-	ss := NewTerminal(c, "> ")
-	pw, _ := ss.ReadPassword("> ")
-	if pw != "password" {
-		t.Fatalf("failed to read password, got %s", pw)
-	}
-	line, _ := ss.ReadLine()
-	if len(line) > 0 {
-		t.Fatalf("password was saved in history")
-	}
-}
-
-var setSizeTests = []struct {
-	width, height int
-}{
-	{40, 13},
-	{80, 24},
-	{132, 43},
-}
-
-func TestTerminalSetSize(t *testing.T) {
-	for _, setSize := range setSizeTests {
-		c := &MockTerminal{
-			toSend:       []byte("password\r\x1b[A\r"),
-			bytesPerRead: 1,
-		}
-		ss := NewTerminal(c, "> ")
-		ss.SetSize(setSize.width, setSize.height)
-		pw, _ := ss.ReadPassword("Password: ")
-		if pw != "password" {
-			t.Fatalf("failed to read password, got %s", pw)
-		}
-		if string(c.received) != "Password: \r\n" {
-			t.Errorf("failed to set the temporary prompt expected %q, got %q", "Password: ", c.received)
-		}
-	}
-}
-
-func TestReadPasswordLineEnd(t *testing.T) {
-	type testType struct {
-		input string
-		want  string
-	}
-	var tests = []testType{
-		{"\r\n", ""},
-		{"test\r\n", "test"},
-		{"test\r", "test"},
-		{"test\n", "test"},
-		{"testtesttesttes\n", "testtesttesttes"},
-		{"testtesttesttes\r\n", "testtesttesttes"},
-		{"testtesttesttesttest\n", "testtesttesttesttest"},
-		{"testtesttesttesttest\r\n", "testtesttesttesttest"},
-		{"\btest", "test"},
-		{"t\best", "est"},
-		{"te\bst", "tst"},
-		{"test\b", "tes"},
-		{"test\b\r\n", "tes"},
-		{"test\b\n", "tes"},
-		{"test\b\r", "tes"},
-	}
-	eol := "\n"
-	if runtime.GOOS == "windows" {
-		eol = "\r"
-	}
-	tests = append(tests, testType{eol, ""})
-	for _, test := range tests {
-		buf := new(bytes.Buffer)
-		if _, err := buf.WriteString(test.input); err != nil {
-			t.Fatal(err)
-		}
-
-		have, err := readPasswordLine(buf)
-		if err != nil {
-			t.Errorf("readPasswordLine(%q) failed: %v", test.input, err)
-			continue
-		}
-		if string(have) != test.want {
-			t.Errorf("readPasswordLine(%q) returns %q, but %q is expected", test.input, string(have), test.want)
-			continue
-		}
-
-		if _, err = buf.WriteString(test.input); err != nil {
-			t.Fatal(err)
-		}
-		have, err = readPasswordLine(buf)
-		if err != nil {
-			t.Errorf("readPasswordLine(%q) failed: %v", test.input, err)
-			continue
-		}
-		if string(have) != test.want {
-			t.Errorf("readPasswordLine(%q) returns %q, but %q is expected", test.input, string(have), test.want)
-			continue
-		}
-	}
-}
-
-func TestMakeRawState(t *testing.T) {
-	fd := int(os.Stdout.Fd())
-	if !IsTerminal(fd) {
-		t.Skip("stdout is not a terminal; skipping test")
-	}
-
-	st, err := GetState(fd)
-	if err != nil {
-		t.Fatalf("failed to get terminal state from GetState: %s", err)
-	}
-
-	if runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64") {
-		t.Skip("MakeRaw not allowed on iOS; skipping test")
-	}
-
-	defer Restore(fd, st)
-	raw, err := MakeRaw(fd)
-	if err != nil {
-		t.Fatalf("failed to get terminal state from MakeRaw: %s", err)
-	}
-
-	if *st != *raw {
-		t.Errorf("states do not match; was %v, expected %v", raw, st)
-	}
-}
-
-func TestOutputNewlines(t *testing.T) {
-	// \n should be changed to \r\n in terminal output.
-	buf := new(bytes.Buffer)
-	term := NewTerminal(buf, ">")
-
-	term.Write([]byte("1\n2\n"))
-	output := string(buf.Bytes())
-	const expected = "1\r\n2\r\n"
-
-	if output != expected {
-		t.Errorf("incorrect output: was %q, expected %q", output, expected)
-	}
-}
diff --git a/ssh/terminal/util.go b/ssh/terminal/util.go
deleted file mode 100644
index 73b370a..0000000
--- a/ssh/terminal/util.go
+++ /dev/null
@@ -1,114 +0,0 @@
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build aix darwin dragonfly freebsd linux,!appengine netbsd openbsd zos
-
-// Package terminal provides support functions for dealing with terminals, as
-// commonly found on UNIX systems.
-//
-// Putting a terminal into raw mode is the most common requirement:
-//
-// 	oldState, err := terminal.MakeRaw(0)
-// 	if err != nil {
-// 	        panic(err)
-// 	}
-// 	defer terminal.Restore(0, oldState)
-package terminal // import "golang.org/x/crypto/ssh/terminal"
-
-import (
-	"golang.org/x/sys/unix"
-)
-
-// State contains the state of a terminal.
-type State struct {
-	termios unix.Termios
-}
-
-// IsTerminal returns whether the given file descriptor is a terminal.
-func IsTerminal(fd int) bool {
-	_, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
-	return err == nil
-}
-
-// MakeRaw put the terminal connected to the given file descriptor into raw
-// mode and returns the previous state of the terminal so that it can be
-// restored.
-func MakeRaw(fd int) (*State, error) {
-	termios, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
-	if err != nil {
-		return nil, err
-	}
-
-	oldState := State{termios: *termios}
-
-	// This attempts to replicate the behaviour documented for cfmakeraw in
-	// the termios(3) manpage.
-	termios.Iflag &^= unix.IGNBRK | unix.BRKINT | unix.PARMRK | unix.ISTRIP | unix.INLCR | unix.IGNCR | unix.ICRNL | unix.IXON
-	termios.Oflag &^= unix.OPOST
-	termios.Lflag &^= unix.ECHO | unix.ECHONL | unix.ICANON | unix.ISIG | unix.IEXTEN
-	termios.Cflag &^= unix.CSIZE | unix.PARENB
-	termios.Cflag |= unix.CS8
-	termios.Cc[unix.VMIN] = 1
-	termios.Cc[unix.VTIME] = 0
-	if err := unix.IoctlSetTermios(fd, ioctlWriteTermios, termios); err != nil {
-		return nil, err
-	}
-
-	return &oldState, nil
-}
-
-// GetState returns the current state of a terminal which may be useful to
-// restore the terminal after a signal.
-func GetState(fd int) (*State, error) {
-	termios, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
-	if err != nil {
-		return nil, err
-	}
-
-	return &State{termios: *termios}, nil
-}
-
-// Restore restores the terminal connected to the given file descriptor to a
-// previous state.
-func Restore(fd int, state *State) error {
-	return unix.IoctlSetTermios(fd, ioctlWriteTermios, &state.termios)
-}
-
-// GetSize returns the dimensions of the given terminal.
-func GetSize(fd int) (width, height int, err error) {
-	ws, err := unix.IoctlGetWinsize(fd, unix.TIOCGWINSZ)
-	if err != nil {
-		return -1, -1, err
-	}
-	return int(ws.Col), int(ws.Row), nil
-}
-
-// passwordReader is an io.Reader that reads from a specific file descriptor.
-type passwordReader int
-
-func (r passwordReader) Read(buf []byte) (int, error) {
-	return unix.Read(int(r), buf)
-}
-
-// ReadPassword reads a line of input from a terminal without local echo.  This
-// is commonly used for inputting passwords and other sensitive data. The slice
-// returned does not include the \n.
-func ReadPassword(fd int) ([]byte, error) {
-	termios, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
-	if err != nil {
-		return nil, err
-	}
-
-	newState := *termios
-	newState.Lflag &^= unix.ECHO
-	newState.Lflag |= unix.ICANON | unix.ISIG
-	newState.Iflag |= unix.ICRNL
-	if err := unix.IoctlSetTermios(fd, ioctlWriteTermios, &newState); err != nil {
-		return nil, err
-	}
-
-	defer unix.IoctlSetTermios(fd, ioctlWriteTermios, termios)
-
-	return readPasswordLine(passwordReader(fd))
-}
diff --git a/ssh/terminal/util_aix.go b/ssh/terminal/util_aix.go
deleted file mode 100644
index dfcd627..0000000
--- a/ssh/terminal/util_aix.go
+++ /dev/null
@@ -1,12 +0,0 @@
-// Copyright 2018 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build aix
-
-package terminal
-
-import "golang.org/x/sys/unix"
-
-const ioctlReadTermios = unix.TCGETS
-const ioctlWriteTermios = unix.TCSETS
diff --git a/ssh/terminal/util_bsd.go b/ssh/terminal/util_bsd.go
deleted file mode 100644
index cb23a59..0000000
--- a/ssh/terminal/util_bsd.go
+++ /dev/null
@@ -1,12 +0,0 @@
-// Copyright 2013 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build darwin dragonfly freebsd netbsd openbsd
-
-package terminal
-
-import "golang.org/x/sys/unix"
-
-const ioctlReadTermios = unix.TIOCGETA
-const ioctlWriteTermios = unix.TIOCSETA
diff --git a/ssh/terminal/util_linux.go b/ssh/terminal/util_linux.go
deleted file mode 100644
index 5fadfe8..0000000
--- a/ssh/terminal/util_linux.go
+++ /dev/null
@@ -1,10 +0,0 @@
-// Copyright 2013 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package terminal
-
-import "golang.org/x/sys/unix"
-
-const ioctlReadTermios = unix.TCGETS
-const ioctlWriteTermios = unix.TCSETS
diff --git a/ssh/terminal/util_plan9.go b/ssh/terminal/util_plan9.go
deleted file mode 100644
index 9317ac7..0000000
--- a/ssh/terminal/util_plan9.go
+++ /dev/null
@@ -1,58 +0,0 @@
-// Copyright 2016 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Package terminal provides support functions for dealing with terminals, as
-// commonly found on UNIX systems.
-//
-// Putting a terminal into raw mode is the most common requirement:
-//
-// 	oldState, err := terminal.MakeRaw(0)
-// 	if err != nil {
-// 	        panic(err)
-// 	}
-// 	defer terminal.Restore(0, oldState)
-package terminal
-
-import (
-	"fmt"
-	"runtime"
-)
-
-type State struct{}
-
-// IsTerminal returns whether the given file descriptor is a terminal.
-func IsTerminal(fd int) bool {
-	return false
-}
-
-// MakeRaw put the terminal connected to the given file descriptor into raw
-// mode and returns the previous state of the terminal so that it can be
-// restored.
-func MakeRaw(fd int) (*State, error) {
-	return nil, fmt.Errorf("terminal: MakeRaw not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
-}
-
-// GetState returns the current state of a terminal which may be useful to
-// restore the terminal after a signal.
-func GetState(fd int) (*State, error) {
-	return nil, fmt.Errorf("terminal: GetState not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
-}
-
-// Restore restores the terminal connected to the given file descriptor to a
-// previous state.
-func Restore(fd int, state *State) error {
-	return fmt.Errorf("terminal: Restore not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
-}
-
-// GetSize returns the dimensions of the given terminal.
-func GetSize(fd int) (width, height int, err error) {
-	return 0, 0, fmt.Errorf("terminal: GetSize not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
-}
-
-// ReadPassword reads a line of input from a terminal without local echo.  This
-// is commonly used for inputting passwords and other sensitive data. The slice
-// returned does not include the \n.
-func ReadPassword(fd int) ([]byte, error) {
-	return nil, fmt.Errorf("terminal: ReadPassword not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
-}
diff --git a/ssh/terminal/util_solaris.go b/ssh/terminal/util_solaris.go
deleted file mode 100644
index 3d5f06a..0000000
--- a/ssh/terminal/util_solaris.go
+++ /dev/null
@@ -1,124 +0,0 @@
-// Copyright 2015 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build solaris
-
-package terminal // import "golang.org/x/crypto/ssh/terminal"
-
-import (
-	"golang.org/x/sys/unix"
-	"io"
-	"syscall"
-)
-
-// State contains the state of a terminal.
-type State struct {
-	termios unix.Termios
-}
-
-// IsTerminal returns whether the given file descriptor is a terminal.
-func IsTerminal(fd int) bool {
-	_, err := unix.IoctlGetTermio(fd, unix.TCGETA)
-	return err == nil
-}
-
-// ReadPassword reads a line of input from a terminal without local echo.  This
-// is commonly used for inputting passwords and other sensitive data. The slice
-// returned does not include the \n.
-func ReadPassword(fd int) ([]byte, error) {
-	// see also: http://src.illumos.org/source/xref/illumos-gate/usr/src/lib/libast/common/uwin/getpass.c
-	val, err := unix.IoctlGetTermios(fd, unix.TCGETS)
-	if err != nil {
-		return nil, err
-	}
-	oldState := *val
-
-	newState := oldState
-	newState.Lflag &^= syscall.ECHO
-	newState.Lflag |= syscall.ICANON | syscall.ISIG
-	newState.Iflag |= syscall.ICRNL
-	err = unix.IoctlSetTermios(fd, unix.TCSETS, &newState)
-	if err != nil {
-		return nil, err
-	}
-
-	defer unix.IoctlSetTermios(fd, unix.TCSETS, &oldState)
-
-	var buf [16]byte
-	var ret []byte
-	for {
-		n, err := syscall.Read(fd, buf[:])
-		if err != nil {
-			return nil, err
-		}
-		if n == 0 {
-			if len(ret) == 0 {
-				return nil, io.EOF
-			}
-			break
-		}
-		if buf[n-1] == '\n' {
-			n--
-		}
-		ret = append(ret, buf[:n]...)
-		if n < len(buf) {
-			break
-		}
-	}
-
-	return ret, nil
-}
-
-// MakeRaw puts the terminal connected to the given file descriptor into raw
-// mode and returns the previous state of the terminal so that it can be
-// restored.
-// see http://cr.illumos.org/~webrev/andy_js/1060/
-func MakeRaw(fd int) (*State, error) {
-	termios, err := unix.IoctlGetTermios(fd, unix.TCGETS)
-	if err != nil {
-		return nil, err
-	}
-
-	oldState := State{termios: *termios}
-
-	termios.Iflag &^= unix.IGNBRK | unix.BRKINT | unix.PARMRK | unix.ISTRIP | unix.INLCR | unix.IGNCR | unix.ICRNL | unix.IXON
-	termios.Oflag &^= unix.OPOST
-	termios.Lflag &^= unix.ECHO | unix.ECHONL | unix.ICANON | unix.ISIG | unix.IEXTEN
-	termios.Cflag &^= unix.CSIZE | unix.PARENB
-	termios.Cflag |= unix.CS8
-	termios.Cc[unix.VMIN] = 1
-	termios.Cc[unix.VTIME] = 0
-
-	if err := unix.IoctlSetTermios(fd, unix.TCSETS, termios); err != nil {
-		return nil, err
-	}
-
-	return &oldState, nil
-}
-
-// Restore restores the terminal connected to the given file descriptor to a
-// previous state.
-func Restore(fd int, oldState *State) error {
-	return unix.IoctlSetTermios(fd, unix.TCSETS, &oldState.termios)
-}
-
-// GetState returns the current state of a terminal which may be useful to
-// restore the terminal after a signal.
-func GetState(fd int) (*State, error) {
-	termios, err := unix.IoctlGetTermios(fd, unix.TCGETS)
-	if err != nil {
-		return nil, err
-	}
-
-	return &State{termios: *termios}, nil
-}
-
-// GetSize returns the dimensions of the given terminal.
-func GetSize(fd int) (width, height int, err error) {
-	ws, err := unix.IoctlGetWinsize(fd, unix.TIOCGWINSZ)
-	if err != nil {
-		return 0, 0, err
-	}
-	return int(ws.Col), int(ws.Row), nil
-}
diff --git a/ssh/terminal/util_windows.go b/ssh/terminal/util_windows.go
deleted file mode 100644
index f614e9c..0000000
--- a/ssh/terminal/util_windows.go
+++ /dev/null
@@ -1,105 +0,0 @@
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build windows
-
-// Package terminal provides support functions for dealing with terminals, as
-// commonly found on UNIX systems.
-//
-// Putting a terminal into raw mode is the most common requirement:
-//
-// 	oldState, err := terminal.MakeRaw(0)
-// 	if err != nil {
-// 	        panic(err)
-// 	}
-// 	defer terminal.Restore(0, oldState)
-package terminal
-
-import (
-	"os"
-
-	"golang.org/x/sys/windows"
-)
-
-type State struct {
-	mode uint32
-}
-
-// IsTerminal returns whether the given file descriptor is a terminal.
-func IsTerminal(fd int) bool {
-	var st uint32
-	err := windows.GetConsoleMode(windows.Handle(fd), &st)
-	return err == nil
-}
-
-// MakeRaw put the terminal connected to the given file descriptor into raw
-// mode and returns the previous state of the terminal so that it can be
-// restored.
-func MakeRaw(fd int) (*State, error) {
-	var st uint32
-	if err := windows.GetConsoleMode(windows.Handle(fd), &st); err != nil {
-		return nil, err
-	}
-	raw := st &^ (windows.ENABLE_ECHO_INPUT | windows.ENABLE_PROCESSED_INPUT | windows.ENABLE_LINE_INPUT | windows.ENABLE_PROCESSED_OUTPUT)
-	if err := windows.SetConsoleMode(windows.Handle(fd), raw); err != nil {
-		return nil, err
-	}
-	return &State{st}, nil
-}
-
-// GetState returns the current state of a terminal which may be useful to
-// restore the terminal after a signal.
-func GetState(fd int) (*State, error) {
-	var st uint32
-	if err := windows.GetConsoleMode(windows.Handle(fd), &st); err != nil {
-		return nil, err
-	}
-	return &State{st}, nil
-}
-
-// Restore restores the terminal connected to the given file descriptor to a
-// previous state.
-func Restore(fd int, state *State) error {
-	return windows.SetConsoleMode(windows.Handle(fd), state.mode)
-}
-
-// GetSize returns the visible dimensions of the given terminal.
-//
-// These dimensions don't include any scrollback buffer height.
-func GetSize(fd int) (width, height int, err error) {
-	var info windows.ConsoleScreenBufferInfo
-	if err := windows.GetConsoleScreenBufferInfo(windows.Handle(fd), &info); err != nil {
-		return 0, 0, err
-	}
-	return int(info.Window.Right - info.Window.Left + 1), int(info.Window.Bottom - info.Window.Top + 1), nil
-}
-
-// ReadPassword reads a line of input from a terminal without local echo.  This
-// is commonly used for inputting passwords and other sensitive data. The slice
-// returned does not include the \n.
-func ReadPassword(fd int) ([]byte, error) {
-	var st uint32
-	if err := windows.GetConsoleMode(windows.Handle(fd), &st); err != nil {
-		return nil, err
-	}
-	old := st
-
-	st &^= (windows.ENABLE_ECHO_INPUT | windows.ENABLE_LINE_INPUT)
-	st |= (windows.ENABLE_PROCESSED_OUTPUT | windows.ENABLE_PROCESSED_INPUT)
-	if err := windows.SetConsoleMode(windows.Handle(fd), st); err != nil {
-		return nil, err
-	}
-
-	defer windows.SetConsoleMode(windows.Handle(fd), old)
-
-	var h windows.Handle
-	p, _ := windows.GetCurrentProcess()
-	if err := windows.DuplicateHandle(p, windows.Handle(fd), p, &h, 0, false, windows.DUPLICATE_SAME_ACCESS); err != nil {
-		return nil, err
-	}
-
-	f := os.NewFile(uintptr(h), "stdin")
-	defer f.Close()
-	return readPasswordLine(f)
-}
diff --git a/ssh/terminal/util_zos.go b/ssh/terminal/util_zos.go
deleted file mode 100644
index 8314a2d..0000000
--- a/ssh/terminal/util_zos.go
+++ /dev/null
@@ -1,10 +0,0 @@
-// Copyright 2020 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package terminal
-
-import "golang.org/x/sys/unix"
-
-const ioctlReadTermios = unix.TCGETS
-const ioctlWriteTermios = unix.TCSETS