David K. Bainbridge | 215e024 | 2017-09-05 23:18:24 -0700 | [diff] [blame] | 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) |
| 17 | package terminal // import "golang.org/x/crypto/ssh/terminal" |
| 18 | |
| 19 | import ( |
| 20 | "syscall" |
| 21 | "unsafe" |
| 22 | |
| 23 | "golang.org/x/sys/unix" |
| 24 | ) |
| 25 | |
| 26 | // State contains the state of a terminal. |
| 27 | type State struct { |
| 28 | termios syscall.Termios |
| 29 | } |
| 30 | |
| 31 | // IsTerminal returns true if the given file descriptor is a terminal. |
| 32 | func 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. |
| 41 | func 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. |
| 66 | func 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. |
| 77 | func 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. |
| 85 | func 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. |
| 95 | type passwordReader int |
| 96 | |
| 97 | func (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. |
| 104 | func 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 | } |