Windows でジャンクション作れない・リベンジ編

• 前回 → Windows でジャンクション作れない - 標準愚痴出力
• 完成品→ https://github.com/nyaosorg/go-windows-junction

「DeviceIoControl用の構造体」を作るのに、Microsoft ご本家の Go 言語パッケージ Microsoft/go-winio: Win32 IO-related utilities for Goを使ったら、うまく動作するようになった！やったね、たえちゃん、nyagosの機能が増えるよ

junction_run.go

package main

import (
    "errors"
    "os"

    "golang.org/x/sys/windows"
    "golang.org/x/xerrors"

    "github.com/Microsoft/go-winio"
)

const (
    _FSCTL_SET_REPARSE_POINT          = 589988
    _INVALID_HANDLE_VALUE = ^windows.Handle(0)
)


func MountPointCreate(mountPointPath, target string) error {
    _mountPointPath, err := windows.UTF16FromString(mountPointPath)
    if err != nil {
        return xerrors.Errorf("UTF16FromString(%s): %v", mountPointPath, err)
    }

    err = windows.CreateDirectory(&_mountPointPath[0], nil)
    if err != nil {
        return xerrors.Errorf("windows.CreateDirectory(%s): %v", mountPointPath, err)
    }
    ok := false
    defer func() {
        if !ok {
            os.Remove(mountPointPath)
        }
    }()

    handle, err := windows.CreateFile(&_mountPointPath[0],
        windows.GENERIC_WRITE,
        0,
        nil,
        windows.OPEN_EXISTING,
        windows.FILE_FLAG_BACKUP_SEMANTICS,
        0)
    if err != nil {
        return xerrors.Errorf("windows.CreateFile(%s): %v", mountPointPath, err)
    }
    if handle == _INVALID_HANDLE_VALUE {
        return errors.New("windows.CreateFile: invalid handle value")
    }
    defer windows.CloseHandle(handle)

    rp := winio.ReparsePoint{
        Target:       target,
        IsMountPoint: true,
    }

    data := winio.EncodeReparsePoint(&rp)

    var size uint32

    err = windows.DeviceIoControl(
        handle,
        _FSCTL_SET_REPARSE_POINT,
        &data[0],
        uint32(len(data)),
        nil,
        0,
        &size,
        nil)

    if err != nil {
        return xerrors.Errorf("windows.DeviceIoControl: %v", err)
    }
    ok = true
    return nil
}

func main() {
    if len(os.Args) < 3 {
        println("go run junction.go DST SRC")
        return
    }
    if err := MountPointCreate(os.Args[1], os.Args[2]); err != nil {
        println(err.Error())
        os.Exit(1)
    }
}

$ go run junction_run.go Hoge c:\tmp
$ ls -ld Hoge\
-rw---- 0 Mar 24 20:06:42 Hoge@ -> c:\tmp
$ cd Hoge\
$