sanitize_filenames.go

package main

import (
	"strconv"
	"strings"
)

var windowsSubst = map[rune]string{
	'<':  "&lt;",
	'>':  "&gt;",
	':':  "-",
	'"':  "&quot;",
	'/':  "",
	'\\': "",
	'|':  "",
	'?':  "",
	'*':  "",
}

var minimalSubst = map[rune]string{
	'/':  "",
	'\\': "",
}

var winBan = map[string]bool{
	"CON": true, "PRN": true, "AUX": true, "NUL": true,
	"COM1": true, "COM2": true, "COM3": true, "COM4": true,
	"COM5": true, "COM6": true, "COM7": true, "COM8": true, "COM9": true,
	"LPT1": true, "LPT2": true, "LPT3": true, "LPT4": true,
	"LPT5": true, "LPT6": true, "LPT7": true, "LPT8": true, "LPT9": true,
}

func sanitizeWindowsFilename(name string) string {
	name = strings.Trim(name, " .")
	sansExt := strings.SplitN(name, ".", 2)[0]
	if winBan[sansExt] {
		return "__" + name
	}
	if name == "" {
		return "__Blank__"
	}
	return name
}

func sanitizeFileName(filename string, allowSpecialChars bool) string {
	var b strings.Builder
	var banned map[rune]string
	if allowSpecialChars {
		banned = minimalSubst
	} else {
		banned = windowsSubst
	}
	for _, r := range filename {
		repl, spec := banned[r]
		if spec {
			b.WriteString(repl)
		} else if !strconv.IsPrint(r) {
			b.WriteRune('-')
		} else {
			b.WriteRune(r)
		}
	}
	if allowSpecialChars {
		return b.String()
	}
	return sanitizeWindowsFilename(b.String())
}