1// Copyright 2011 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 5// +build darwin dragonfly freebsd linux,!appengine netbsd openbsd 6 7// Package terminal provides support functions for dealing with terminals, as 8// commonly found on UNIX systems. 9// 10// Putting a terminal into raw mode is the most common requirement: 11// 12// oldState, err := terminal.MakeRaw(0) 13// if err != nil { 14// panic(err) 15// } 16// defer terminal.Restore(0, oldState) 17package terminal // import "golang.org/x/crypto/ssh/terminal" 18 19import ( 20 "syscall" 21 "unsafe" 22 23 "golang.org/x/sys/unix" 24) 25 26// State contains the state of a terminal. 27type State struct { 28 termios syscall.Termios 29} 30 31// IsTerminal returns true if the given file descriptor is a terminal. 32func IsTerminal(fd int) bool { 33 var termios syscall.Termios 34 _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlReadTermios, uintptr(unsafe.Pointer(&termios)), 0, 0, 0) 35 return err == 0 36} 37 38// MakeRaw put the terminal connected to the given file descriptor into raw 39// mode and returns the previous state of the terminal so that it can be 40// restored. 41func MakeRaw(fd int) (*State, error) { 42 var oldState State 43 if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlReadTermios, uintptr(unsafe.Pointer(&oldState.termios)), 0, 0, 0); err != 0 { 44 return nil, err 45 } 46 47 newState := oldState.termios 48 // This attempts to replicate the behaviour documented for cfmakeraw in 49 // the termios(3) manpage. 50 newState.Iflag &^= syscall.IGNBRK | syscall.BRKINT | syscall.PARMRK | syscall.ISTRIP | syscall.INLCR | syscall.IGNCR | syscall.ICRNL | syscall.IXON 51 newState.Oflag &^= syscall.OPOST 52 newState.Lflag &^= syscall.ECHO | syscall.ECHONL | syscall.ICANON | syscall.ISIG | syscall.IEXTEN 53 newState.Cflag &^= syscall.CSIZE | syscall.PARENB 54 newState.Cflag |= syscall.CS8 55 newState.Cc[unix.VMIN] = 1 56 newState.Cc[unix.VTIME] = 0 57 if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlWriteTermios, uintptr(unsafe.Pointer(&newState)), 0, 0, 0); err != 0 { 58 return nil, err 59 } 60 61 return &oldState, nil 62} 63 64// GetState returns the current state of a terminal which may be useful to 65// restore the terminal after a signal. 66func GetState(fd int) (*State, error) { 67 var oldState State 68 if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlReadTermios, uintptr(unsafe.Pointer(&oldState.termios)), 0, 0, 0); err != 0 { 69 return nil, err 70 } 71 72 return &oldState, nil 73} 74 75// Restore restores the terminal connected to the given file descriptor to a 76// previous state. 77func Restore(fd int, state *State) error { 78 if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlWriteTermios, uintptr(unsafe.Pointer(&state.termios)), 0, 0, 0); err != 0 { 79 return err 80 } 81 return nil 82} 83 84// GetSize returns the dimensions of the given terminal. 85func GetSize(fd int) (width, height int, err error) { 86 var dimensions [4]uint16 87 88 if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), uintptr(syscall.TIOCGWINSZ), uintptr(unsafe.Pointer(&dimensions)), 0, 0, 0); err != 0 { 89 return -1, -1, err 90 } 91 return int(dimensions[1]), int(dimensions[0]), nil 92} 93 94// passwordReader is an io.Reader that reads from a specific file descriptor. 95type passwordReader int 96 97func (r passwordReader) Read(buf []byte) (int, error) { 98 return syscall.Read(int(r), buf) 99} 100 101// ReadPassword reads a line of input from a terminal without local echo. This 102// is commonly used for inputting passwords and other sensitive data. The slice 103// returned does not include the \n. 104func ReadPassword(fd int) ([]byte, error) { 105 var oldState syscall.Termios 106 if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlReadTermios, uintptr(unsafe.Pointer(&oldState)), 0, 0, 0); err != 0 { 107 return nil, err 108 } 109 110 newState := oldState 111 newState.Lflag &^= syscall.ECHO 112 newState.Lflag |= syscall.ICANON | syscall.ISIG 113 newState.Iflag |= syscall.ICRNL 114 if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlWriteTermios, uintptr(unsafe.Pointer(&newState)), 0, 0, 0); err != 0 { 115 return nil, err 116 } 117 118 defer func() { 119 syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlWriteTermios, uintptr(unsafe.Pointer(&oldState)), 0, 0, 0) 120 }() 121 122 return readPasswordLine(passwordReader(fd)) 123} 124