File: cancelreader_windows.go

package info (click to toggle)
golang-github-charmbracelet-x 0.0~git20251028.0cf22f8%2Bds-3
  • links: PTS, VCS
  • area: main
  • in suites: forky, sid
  • size: 2,940 kB
  • sloc: sh: 124; makefile: 5
file content (143 lines) | stat: -rw-r--r-- 3,403 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
//go:build windows
// +build windows

package input

import (
	"fmt"
	"io"
	"os"
	"sync"

	xwindows "github.com/charmbracelet/x/windows"
	"github.com/muesli/cancelreader"
	"golang.org/x/sys/windows"
)

type conInputReader struct {
	cancelMixin
	conin        windows.Handle
	originalMode uint32
}

var _ cancelreader.CancelReader = &conInputReader{}

func newCancelreader(r io.Reader, flags int) (cancelreader.CancelReader, error) {
	fallback := func(io.Reader) (cancelreader.CancelReader, error) {
		return cancelreader.NewReader(r)
	}

	var dummy uint32
	if f, ok := r.(cancelreader.File); !ok || f.Fd() != os.Stdin.Fd() ||
		// If data was piped to the standard input, it does not emit events
		// anymore. We can detect this if the console mode cannot be set anymore,
		// in this case, we fallback to the default cancelreader implementation.
		windows.GetConsoleMode(windows.Handle(f.Fd()), &dummy) != nil {
		return fallback(r)
	}

	conin, err := windows.GetStdHandle(windows.STD_INPUT_HANDLE)
	if err != nil {
		return fallback(r)
	}

	// Discard any pending input events.
	if err := xwindows.FlushConsoleInputBuffer(conin); err != nil {
		return fallback(r)
	}

	modes := []uint32{
		windows.ENABLE_WINDOW_INPUT,
		windows.ENABLE_EXTENDED_FLAGS,
	}

	// Enabling mouse mode implicitly blocks console text selection. Thus, we
	// need to enable it only if the mouse mode is requested.
	// In order to toggle mouse mode, the caller must recreate the reader with
	// the appropriate flag toggled.
	if flags&FlagMouseMode != 0 {
		modes = append(modes, windows.ENABLE_MOUSE_INPUT)
	}

	originalMode, err := prepareConsole(conin, modes...)
	if err != nil {
		return nil, fmt.Errorf("failed to prepare console input: %w", err)
	}

	return &conInputReader{
		conin:        conin,
		originalMode: originalMode,
	}, nil
}

// Cancel implements cancelreader.CancelReader.
func (r *conInputReader) Cancel() bool {
	r.setCanceled()

	return windows.CancelIoEx(r.conin, nil) == nil || windows.CancelIo(r.conin) == nil
}

// Close implements cancelreader.CancelReader.
func (r *conInputReader) Close() error {
	if r.originalMode != 0 {
		err := windows.SetConsoleMode(r.conin, r.originalMode)
		if err != nil {
			return fmt.Errorf("reset console mode: %w", err)
		}
	}

	return nil
}

// Read implements cancelreader.CancelReader.
func (r *conInputReader) Read(data []byte) (int, error) {
	if r.isCanceled() {
		return 0, cancelreader.ErrCanceled
	}

	var n uint32
	if err := windows.ReadFile(r.conin, data, &n, nil); err != nil {
		return int(n), fmt.Errorf("read console input: %w", err)
	}

	return int(n), nil
}

func prepareConsole(input windows.Handle, modes ...uint32) (originalMode uint32, err error) {
	err = windows.GetConsoleMode(input, &originalMode)
	if err != nil {
		return 0, fmt.Errorf("get console mode: %w", err)
	}

	var newMode uint32
	for _, mode := range modes {
		newMode |= mode
	}

	err = windows.SetConsoleMode(input, newMode)
	if err != nil {
		return 0, fmt.Errorf("set console mode: %w", err)
	}

	return originalMode, nil
}

// cancelMixin represents a goroutine-safe cancelation status.
type cancelMixin struct {
	unsafeCanceled bool
	lock           sync.Mutex
}

func (c *cancelMixin) setCanceled() {
	c.lock.Lock()
	defer c.lock.Unlock()

	c.unsafeCanceled = true
}

func (c *cancelMixin) isCanceled() bool {
	c.lock.Lock()
	defer c.lock.Unlock()

	return c.unsafeCanceled
}