windows input without echoing typed chars

noecho.go

package main

import (
  "bufio"
	"fmt"
	"os"
	"syscall"
	"unsafe"
)

// input modes
const (
	ENABLE_PROCESSED_INPUT = 1 << iota
	ENABLE_LINE_INPUT
	ENABLE_ECHO_INPUT
	ENABLE_WINDOW_INPUT
	ENABLE_MOUSE_INPUT
	ENABLE_INSERT_MODE
	ENABLE_QUICK_EDIT_MODE
	ENABLE_EXTENDED_FLAGS
)

// output modes
const (
	ENABLE_PROCESSED_OUTPUT = 1 << iota
	ENABLE_WRAP_AT_EOL_OUTPUT
)

func abort(funcname string, err error) {
	panic(funcname + " failed: " + err.Error())
}

var kernel32 = mustLoadLibrary("kernel32.dll")

var (
	addrGetConsoleMode = mustGetProcAddress(kernel32, "GetConsoleMode")
	addrSetConsoleMode = mustGetProcAddress(kernel32, "SetConsoleMode")
)

func main() {
	mode, err := getConsoleMode(os.Stdin)
	if err != nil {
		panic(err)
	}
	mode &= ^ENABLE_ECHO_INPUT
	err = setConsoleMode(os.Stdin, mode)
	if err != nil {
		panic(err)
	}
	os.Stdout.Write([]byte("noecho: "))
	b := bufio.NewReader(os.Stdin)
	line, err := b.ReadBytes('\n')
	os.Stdout.Write([]byte{'\n'})
	if err != nil {
		panic(err)
	}
	fmt.Printf("got %q\n", string(line))
}

func getConsoleMode(f *os.File) (mode int32, err error) {
	p := uintptr(unsafe.Pointer(&mode))
	_, _, e := syscall.Syscall(addrGetConsoleMode, 2, f.Fd(), p, 0)
	if e != 0 {
		err = e
	}
	return
}

func setConsoleMode(f *os.File, mode int32) error {
	_, _, e := syscall.Syscall(addrSetConsoleMode, 2, f.Fd(), uintptr(mode), 0)
	if e != 0 {
		return e
	}
	return nil
}

func mustLoadLibrary(name string) syscall.Handle {
	h, err := syscall.LoadLibrary("kernel32.dll")
	if err != nil {
		abort("LoadLibrary", err)
	}
	return h
}

func mustGetProcAddress(h syscall.Handle, name string) uintptr {
	addr, err := syscall.GetProcAddress(h, name)
	if err != nil {
		abort("GetProcAddress", err)
	}
	return addr
}