Enumerating Registry Values in Go (Golang)

Question

I'm trying to enumerate over a list of values in the Windows registry using Go, but I'm running into some trouble. I've tried two approaches: using both the Go-provided syscall library to call into RegEnumValue, as well as using a Windows API wrapper by lxn. In both cases, I'm having the same issue. This is the code I'm using (which is currently using the win library from lxn):

var root win.HKEY
rootpath, _ := syscall.UTF16PtrFromString("HARDWARE\\DEVICEMAP\\SERIALCOMM")
fmt.Println(win.RegOpenKeyEx(win.HKEY_LOCAL_MACHINE, rootpath, 0, win.KEY_READ, &root))

var name_length uint32 = 72
var name *uint16
var key_type uint32
var lpData *byte
var lpDataLength uint32 = 72
var zero_uint uint32 = 0
fmt.Println(win.RegEnumValue(root, zero_uint, name, &name_length, nil, &key_type, lpData, &lpDataLength))

win.RegCloseKey(root)

In this case, RegEnumValue always returns code 87, which MSDN's only explanation is "The parameter is incorrect."

Does anyone have any ideas that can point me in the right direction for this?

Answer 1

A member of the Golang sub-reddit pointed out that I was not actually allocating any memory to the buffers passed in to RegEnumValue. As such, I've corrected the above example to the following:

var name_length uint32 = 72
var key_type uint32
var lpDataLength uint32 = 72
var zero_uint uint32 = 0
name := make([]uint16, 72)
lpData := make([]byte, 72)

win.RegEnumValue(root, zero_uint, &name[0], &name_length, nil, &key_type, &lpData[0], &lpDataLength)

Obviously, the "magic number" of 72 should probably be replaced with something else. There is another method called RegQueryInfoKey that can retrieve information about the registry key to allocate the correct number of bytes for the largest name and value in the key.

Answer 2

Maybe someone found this useful:

const regKey = `SOFTWARE\Microsoft\Windows NT\CurrentVersion`

func getSettingsFromRegistry() (settings map[string]string, error) {
    settings = make(map[string]string)

    k, err := registry.OpenKey(registry.LOCAL_MACHINE, regKey, registry.QUERY_VALUE)
    if err != nil {
        
        return fmt.Errorf("open registry key %q: %w", regKey, err)
    }
    defer k.Close()

    params, err := k.ReadValueNames(0)
    if err != nil {
        return fmt.Errorf("read value names %q: %w", psaConfRegistry32, err)
    }

    for _, param := range params {
        val, err := getRegistryValueAsString(k, param)
        if err != nil {
            return fmt.Errorf("get value as string %q: %w", k, err)
        }
        settings[param] = val
    }

    self.Log.Printf("%#v\n", settings)
    return
}

func getRegistryValueAsString(key registry.Key, subKey string) (string, error) {
    valString, _, err := key.GetStringValue(subKey)
    if err == nil {
        return valString, nil
    }
    valStrings, _, err := key.GetStringsValue(subKey)
    if err == nil {
        return strings.Join(valStrings, "\n"), nil
    }
    valBinary, _, err := key.GetBinaryValue(subKey)
    if err == nil {
        return string(valBinary), nil
    }
    valInteger, _, err := key.GetIntegerValue(subKey)
    if err == nil {
        return strconv.FormatUint(valInteger, 10), nil
    }

    return "", fmt.Errorf("failed to get type for sub key %q", subKey)
}

REG_BINARY values will looks like "\x01\x00\x00..."