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 windows
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
18
19import (
20	"os"
21
22	"golang.org/x/sys/windows"
23)
24
25type State struct {
26	mode uint32
27}
28
29// IsTerminal returns whether the given file descriptor is a terminal.
30func IsTerminal(fd int) bool {
31	var st uint32
32	err := windows.GetConsoleMode(windows.Handle(fd), &st)
33	return err == nil
34}
35
36// MakeRaw put the terminal connected to the given file descriptor into raw
37// mode and returns the previous state of the terminal so that it can be
38// restored.
39func MakeRaw(fd int) (*State, error) {
40	var st uint32
41	if err := windows.GetConsoleMode(windows.Handle(fd), &st); err != nil {
42		return nil, err
43	}
44	raw := st &^ (windows.ENABLE_ECHO_INPUT | windows.ENABLE_PROCESSED_INPUT | windows.ENABLE_LINE_INPUT | windows.ENABLE_PROCESSED_OUTPUT)
45	if err := windows.SetConsoleMode(windows.Handle(fd), raw); err != nil {
46		return nil, err
47	}
48	return &State{st}, nil
49}
50
51// GetState returns the current state of a terminal which may be useful to
52// restore the terminal after a signal.
53func GetState(fd int) (*State, error) {
54	var st uint32
55	if err := windows.GetConsoleMode(windows.Handle(fd), &st); err != nil {
56		return nil, err
57	}
58	return &State{st}, nil
59}
60
61// Restore restores the terminal connected to the given file descriptor to a
62// previous state.
63func Restore(fd int, state *State) error {
64	return windows.SetConsoleMode(windows.Handle(fd), state.mode)
65}
66
67// GetSize returns the visible dimensions of the given terminal.
68//
69// These dimensions don't include any scrollback buffer height.
70func GetSize(fd int) (width, height int, err error) {
71	var info windows.ConsoleScreenBufferInfo
72	if err := windows.GetConsoleScreenBufferInfo(windows.Handle(fd), &info); err != nil {
73		return 0, 0, err
74	}
75	return int(info.Window.Right - info.Window.Left + 1), int(info.Window.Bottom - info.Window.Top + 1), nil
76}
77
78// ReadPassword reads a line of input from a terminal without local echo.  This
79// is commonly used for inputting passwords and other sensitive data. The slice
80// returned does not include the \n.
81func ReadPassword(fd int) ([]byte, error) {
82	var st uint32
83	if err := windows.GetConsoleMode(windows.Handle(fd), &st); err != nil {
84		return nil, err
85	}
86	old := st
87
88	st &^= (windows.ENABLE_ECHO_INPUT)
89	st |= (windows.ENABLE_PROCESSED_INPUT | windows.ENABLE_LINE_INPUT | windows.ENABLE_PROCESSED_OUTPUT)
90	if err := windows.SetConsoleMode(windows.Handle(fd), st); err != nil {
91		return nil, err
92	}
93
94	defer windows.SetConsoleMode(windows.Handle(fd), old)
95
96	var h windows.Handle
97	p, _ := windows.GetCurrentProcess()
98	if err := windows.DuplicateHandle(p, windows.Handle(fd), p, &h, 0, false, windows.DUPLICATE_SAME_ACCESS); err != nil {
99		return nil, err
100	}
101
102	f := os.NewFile(uintptr(h), "stdin")
103	defer f.Close()
104	return readPasswordLine(f)
105}
106