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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 darwin dragonfly freebsd linux,!appengine netbsd openbsd
// 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 (
"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.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlReadTermios, uintptr(unsafe.Pointer(&termios)), 0, 0, 0)
return err == 0
}
// 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.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlReadTermios, uintptr(unsafe.Pointer(&oldState.termios)), 0, 0, 0); err != 0 {
return nil, err
}
newState := oldState.termios
// This attempts to replicate the behaviour documented for cfmakeraw in
// the termios(3) manpage.
newState.Iflag &^= syscall.IGNBRK | syscall.BRKINT | syscall.PARMRK | syscall.ISTRIP | syscall.INLCR | syscall.IGNCR | syscall.ICRNL | syscall.IXON
newState.Oflag &^= syscall.OPOST
newState.Lflag &^= syscall.ECHO | syscall.ECHONL | syscall.ICANON | syscall.ISIG | syscall.IEXTEN
newState.Cflag &^= syscall.CSIZE | syscall.PARENB
newState.Cflag |= syscall.CS8
if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlWriteTermios, uintptr(unsafe.Pointer(&newState)), 0, 0, 0); err != 0 {
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) {
var oldState State
if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlReadTermios, uintptr(unsafe.Pointer(&oldState.termios)), 0, 0, 0); err != 0 {
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 {
if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlWriteTermios, uintptr(unsafe.Pointer(&state.termios)), 0, 0, 0); err != 0 {
return err
}
return nil
}
// GetSize returns the dimensions of the given terminal.
func GetSize(fd int) (width, height int, err error) {
var dimensions [4]uint16
if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), uintptr(syscall.TIOCGWINSZ), uintptr(unsafe.Pointer(&dimensions)), 0, 0, 0); err != 0 {
return -1, -1, err
}
return int(dimensions[1]), int(dimensions[0]), 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 syscall.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) {
var oldState syscall.Termios
if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlReadTermios, uintptr(unsafe.Pointer(&oldState)), 0, 0, 0); err != 0 {
return nil, err
}
newState := oldState
newState.Lflag &^= syscall.ECHO
newState.Lflag |= syscall.ICANON | syscall.ISIG
newState.Iflag |= syscall.ICRNL
if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlWriteTermios, uintptr(unsafe.Pointer(&newState)), 0, 0, 0); err != 0 {
return nil, err
}
defer func() {
syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlWriteTermios, uintptr(unsafe.Pointer(&oldState)), 0, 0, 0)
}()
return readPasswordLine(passwordReader(fd))
}
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