registry.go

package main

import (
	"bytes"
	"io/ioutil"
	"strings"
)

func isLetterWorks(entry []byte) bool {
	return strings.Contains(strings.ToLower(compact(entry)), "letterworks")
}

func compact(data []byte) string {
	var compacted bytes.Buffer

	for _, char := range data {
		if char != null {
			compacted.WriteByte(char)
		}
	}

	return compacted.String()
}

func explode(s string) []byte {
	var exploded bytes.Buffer

	for _, char := range s {
		exploded.WriteByte(null)
		exploded.WriteRune(char)
	}

	return exploded.Bytes()
}

func filterEntry(entry []byte) []byte {
	compacted := compact(entry)

	return explode(strings.Replace(compacted, "HKEY_USERS\\S-1-5-21-1941644472-1406884306-2145277243-500", "HKEY_CURRENT_USER", 1))
}

const openingBracket = 91
const null = 0

func main() {
	contents, err := ioutil.ReadFile("./registry.reg")
	if err != nil {
		panic(err)
	}

	var output []byte
	var entry []byte
	first := true

	for _, char := range contents {
		if char == openingBracket {
			if first {
				first = false
				output = append(output, entry[0:len(entry)-1]...)
			} else if isLetterWorks(entry) {
				output = append(output, filterEntry(entry)...)
			}
			entry = []byte{null}
		}
		entry = append(entry, char)
	}

	err = ioutil.WriteFile("./out.reg", output, 0666)
	if err != nil {
		panic(err)
	}
}