Get fixed DOS drives in Windows

drvs.go

package main

import (
	"errors"
	"fmt"
	"log"
	"syscall"
	"unsafe"
)

var (
	kernel32 = syscall.NewLazyDLL("kernel32.dll")

	getDriveTypeWProc = kernel32.NewProc("GetDriveTypeW")
)

func getDriveType(rootPathName []uint16) (int, error) {
	rc, _, _ := getDriveTypeWProc.Call(
		uintptr(unsafe.Pointer(&rootPathName[0])),
	)

	dt := int(rc)

	if dt == driveUnknown || dt == driveNoRootDir {
		return -1, driveTypeErrors[dt]
	}

	return dt, nil
}

var (
	errUnknownDriveType = errors.New("unknown drive type")
	errNoRootDir        = errors.New("invalid root drive path")

	driveTypeErrors = [...]error{
		0: errUnknownDriveType,
		1: errNoRootDir,
	}
)

const (
	driveUnknown = iota
	driveNoRootDir

	driveRemovable
	driveFixed
	driveRemote
	driveCDROM
	driveRamdisk
)

func getFixedDOSDrives() ([]string, error) {
	var drive = [4]uint16{
		1: ':',
		2: '\\',
	}

	var drives []string

	for c := 'A'; c <= 'Z'; c++ {
		drive[0] = uint16(c)
		dt, err := getDriveType(drive[:])

		if err != nil {
			if err == errNoRootDir {
				continue
			}
			return nil, fmt.Errorf("error getting type of: %s: %s",
				syscall.UTF16ToString(drive[:]), err)
		}

		if dt != driveFixed {
			continue
		}

		drives = append(drives, syscall.UTF16ToString(drive[:]))
	}

	return drives, nil
}

func main() {
	drives, err := getFixedDOSDrives()
	if err != nil {
		log.Fatal(err)
	}
	for _, drive := range drives {
		log.Println(drive)
	}
}

Running on by box (under Wine 4.0) I get:

tmp$ GOOS=windows go build drvs.go 
tmp$ wine64 ./drvs.exe
0009:fixme:process:SetProcessPriorityBoost (0xffffffffffffffff,1): stub
2020/07/06 21:06:02 C:\
2020/07/06 21:06:02 D:\
2020/07/06 21:06:02 X:\
2020/07/06 21:06:02 Z:\

(All drives are mapped using winecfg.)