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//go:build linux || darwin || openbsd || freebsd || netbsd || solaris

package liner

import (

"bufio"

"errors"

"os"

"os/signal"

"strconv"

"strings"

"syscall"

"time"

)

type nexter struct {

r rune

err error

}

// State represents an open terminal

type State struct {

commonState

origMode termios

defaultMode termios

next <-chan nexter

winch chan os.Signal

pending []rune

useCHA bool

}

// NewLiner initializes a new *State, and sets the terminal into raw mode. To

// restore the terminal to its previous state, call State.Close().

func NewLiner() *State {

var s State

s.r = bufio.NewReader(os.Stdin)

s.terminalSupported = TerminalSupported()

if m, err := TerminalMode(); err == nil {

s.origMode = *m.(*termios)

} else {

s.inputRedirected = true

}

if _, err := getMode(syscall.Stdout); err != nil {

s.outputRedirected = true

}

if s.inputRedirected && s.outputRedirected {

s.terminalSupported = false

}

if s.terminalSupported && !s.inputRedirected && !s.outputRedirected {

mode := s.origMode

mode.Iflag &^= icrnl | inpck | istrip | ixon

mode.Cflag |= cs8

mode.Lflag &^= syscall.ECHO | icanon | iexten

mode.Cc[syscall.VMIN] = 1

mode.Cc[syscall.VTIME] = 0

mode.ApplyMode()

winch := make(chan os.Signal, 1)

signal.Notify(winch, syscall.SIGWINCH)

s.winch = winch

s.checkOutput()

}

if !s.outputRedirected {

s.outputRedirected = !s.getColumns()

}

return &s

}

var errTimedOut = errors.New("timeout")

func (s *State) startPrompt() {

if s.terminalSupported {

if m, err := TerminalMode(); err == nil {

s.defaultMode = *m.(*termios)

mode := s.defaultMode

mode.Lflag &^= isig

mode.ApplyMode()

}

}

s.restartPrompt()

}

func (s *State) inputWaiting() bool {

return len(s.next) > 0

}

func (s *State) restartPrompt() {

next := make(chan nexter, 200)

go func() {

for {

var n nexter

n.r, _, n.err = s.r.ReadRune()

next <- n

// Shut down nexter loop when an end condition has been reached

if n.err != nil || n.r == '\n' || n.r == '\r' || n.r == ctrlC || n.r == ctrlD {

close(next)

return

}

}

}()

s.next = next

}

func (s *State) stopPrompt() {

if s.terminalSupported {

s.defaultMode.ApplyMode()

}

}

func (s *State) nextPending(timeout <-chan time.Time) (rune, error) {

select {

case thing, ok := <-s.next:

if !ok {

return 0, ErrInternal

}

if thing.err != nil {

return 0, thing.err

}

s.pending = append(s.pending, thing.r)

return thing.r, nil

case <-timeout:

rv := s.pending[0]

s.pending = s.pending[1:]

return rv, errTimedOut

}

}

func (s *State) readNext() (any, error) {

if len(s.pending) > 0 {

rv := s.pending[0]

s.pending = s.pending[1:]

return rv, nil

}

var r rune

select {

case thing, ok := <-s.next:

if !ok {

return 0, ErrInternal

}

if thing.err != nil {

return nil, thing.err

}

r = thing.r

case <-s.winch:

s.getColumns()

return winch, nil

}

if r != esc {

return r, nil

}

s.pending = append(s.pending, r)

// Wait at most 50 ms for the rest of the escape sequence

// If nothing else arrives, it was an actual press of the esc key

timeout := time.After(50 * time.Millisecond)

flag, err := s.nextPending(timeout)

if err != nil {

if err == errTimedOut {

return flag, nil

}

return unknown, err

}

switch flag {

case '[':

code, err := s.nextPending(timeout)

if err != nil {

if err == errTimedOut {

return code, nil

}

return unknown, err

}

switch code {

case 'A':

s.pending = s.pending[:0] // escape code complete

return up, nil

case 'B':

s.pending = s.pending[:0] // escape code complete

return down, nil

case 'C':

s.pending = s.pending[:0] // escape code complete

return right, nil

case 'D':

s.pending = s.pending[:0] // escape code complete

return left, nil

case 'F':

s.pending = s.pending[:0] // escape code complete

return end, nil

case 'H':

s.pending = s.pending[:0] // escape code complete

return home, nil

case 'Z':

s.pending = s.pending[:0] // escape code complete

return shiftTab, nil

case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':

num := []rune{code}

for {

code, err := s.nextPending(timeout)

if err != nil {

if err == errTimedOut {

return code, nil

}

return nil, err

}

switch code {

case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':

num = append(num, code)

case ';':

// Modifier code to follow

// This only supports Ctrl-left and Ctrl-right for now

x, _ := strconv.ParseInt(string(num), 10, 32)

if x != 1 {

// Can't be left or right

rv := s.pending[0]

s.pending = s.pending[1:]

return rv, nil

}

num = num[:0]

for {

code, err = s.nextPending(timeout)

if err != nil {

if err == errTimedOut {

rv := s.pending[0]

s.pending = s.pending[1:]

return rv, nil

}

return nil, err

}

switch code {

case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':

num = append(num, code)

case 'C', 'D':

// right, left

mod, _ := strconv.ParseInt(string(num), 10, 32)

if mod != 5 {

// Not bare Ctrl

rv := s.pending[0]

s.pending = s.pending[1:]

return rv, nil

}

s.pending = s.pending[:0] // escape code complete

if code == 'C' {

return wordRight, nil

}

return wordLeft, nil

default:

// Not left or right

rv := s.pending[0]

s.pending = s.pending[1:]

return rv, nil

}

}

case '~':

s.pending = s.pending[:0] // escape code complete

x, _ := strconv.ParseInt(string(num), 10, 32)

switch x {

case 2:

return insert, nil

case 3:

return del, nil

case 5:

return pageUp, nil

case 6:

return pageDown, nil

case 1, 7:

return home, nil

case 4, 8:

return end, nil

case 15:

return f5, nil

case 17:

return f6, nil

case 18:

return f7, nil

case 19:

return f8, nil

case 20:

return f9, nil

case 21:

return f10, nil

case 23:

return f11, nil

case 24:

return f12, nil

default:

return unknown, nil

}

default:

// unrecognized escape code

rv := s.pending[0]

s.pending = s.pending[1:]

return rv, nil

}

}

}

case 'O':

code, err := s.nextPending(timeout)

if err != nil {

if err == errTimedOut {

return code, nil

}

return nil, err

}

s.pending = s.pending[:0] // escape code complete

switch code {

case 'c':

return wordRight, nil

case 'd':

return wordLeft, nil

case 'H':

return home, nil

case 'F':

return end, nil

case 'P':

return f1, nil

case 'Q':

return f2, nil

case 'R':

return f3, nil

case 'S':

return f4, nil

default:

return unknown, nil

}

case 'b':

s.pending = s.pending[:0] // escape code complete

return altB, nil

case 'd':

s.pending = s.pending[:0] // escape code complete

return altD, nil

case bs:

s.pending = s.pending[:0] // escape code complete

return altBs, nil

case 'f':

s.pending = s.pending[:0] // escape code complete

return altF, nil

case 'y':

s.pending = s.pending[:0] // escape code complete

return altY, nil

default:

rv := s.pending[0]

s.pending = s.pending[1:]

return rv, nil

}

// not reached

return r, nil

}

// Close returns the terminal to its previous mode

func (s *State) Close() error {

signal.Stop(s.winch)

if !s.inputRedirected {

s.origMode.ApplyMode()

}

return nil

}

// TerminalSupported returns true if the current terminal supports

// line editing features, and false if liner will use the 'dumb'

// fallback for input.

// Note that TerminalSupported does not check all factors that may

// cause liner to not fully support the terminal (such as stdin redirection)

func TerminalSupported() bool {

bad := map[string]bool{"": true, "dumb": true, "cons25": true}

return !bad[strings.ToLower(os.Getenv("TERM"))]

}