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// 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 linux
// 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 (
"io"
"syscall"
"unsafe"
)
// State contains the state of a terminal.
type State struct {
termios syscall.Termios
}
// IsTerminal returns true if the given file descriptor is a terminal.
func IsTerminal(fd int) bool {
var termios syscall.Termios
err := syscall.Tcgetattr(fd, &termios)
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 oldState State
if err := syscall.Tcgetattr(fd, &oldState.termios); err != nil {
return nil, err
}
newState := oldState.termios
newState.Iflag &^= syscall.ISTRIP | syscall.INLCR | syscall.ICRNL | syscall.IGNCR | syscall.IXON | syscall.IXOFF
newState.Lflag &^= syscall.ECHO | syscall.ICANON | syscall.ISIG
if err := syscall.Tcsetattr(fd, syscall.TCSANOW, &newState); 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, state *State) error {
err := syscall.Tcsetattr(fd, syscall.TCSANOW, &state.termios)
return err
}
//extern ioctl
func ioctl(int, int, unsafe.Pointer) int
// GetSize returns the dimensions of the given terminal.
func GetSize(fd int) (width, height int, err error) {
var dimensions [4]uint16
if ioctl(fd, syscall.TIOCGWINSZ, unsafe.Pointer(&dimensions)) < 0 {
return -1, -1, syscall.GetErrno()
}
return int(dimensions[1]), int(dimensions[0]), 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 oldState syscall.Termios
if err := syscall.Tcgetattr(fd, &oldState); err != nil {
return nil, err
}
newState := oldState
newState.Lflag &^= syscall.ECHO
if err := syscall.Tcsetattr(fd, syscall.TCSANOW, &newState); err != nil {
return nil, err
}
defer func() {
syscall.Tcsetattr(fd, syscall.TCSANOW, &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
}
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