index.js

/*!
 * convert-filename-ja
 * Copyright(c) 2018 ryoichi-obara
 * MIT Licensed
 */

const truncate = require('truncate-utf8-bytes');

const controlRe = /[\x00-\x1f\x80-\x9f]/g;
const reservedRe = /^\.+$/;
const windowsReservedRe = /^(con|prn|aux|nul|com[0-9]|lpt[0-9])(\..*)?$/i;
const windowsTrailingRe = /^[ ]+|[. ]+$/g;

/**
 * Converts/Replaces characters in strings that are illegal/unsafe for filenames.
 * Unsafe characters are either removed or replaced by a substitute set
 * in the optional `options` object.
 *
 * Unicode Control codes
 * C0 0x00-0x1f & C1 (0x80-0x9f)
 * http://en.wikipedia.org/wiki/C0_and_C1_control_codes
 *
 * Reserved filenames on Unix-based systems (".", "..")
 * Reserved filenames in Windows ("CON", "PRN", "AUX", "NUL", "COM1",
 * "COM2", "COM3", "COM4", "COM5", "COM6", "COM7", "COM8", "COM9",
 * "LPT1", "LPT2", "LPT3", "LPT4", "LPT5", "LPT6", "LPT7", "LPT8", and
 * "LPT9") case-insesitively and with or without filename extensions.
 *
 * Convert illegal characters on various Operating Systems to double byte characters.
 * / ? < > ¥ \ : * | "
 * https://kb.acronis.com/content/39790
 *
 * Capped at 255 characters in length.
 * http://unix.stackexchange.com/questions/32795/what-is-the-maximum-allowed-filename-and-folder-size-with-ecryptfs
 *
 * @param  {String} input Original filename
 * @return {String}       Converted filename
 */
module.exports.convert = (input) => {
  const converted = input
    .replace(controlRe, '')
    .replace(reservedRe, '')
    .replace(windowsReservedRe, '')
    .replace(windowsTrailingRe, '')
    .replace(/\//g, '／')
    .replace(/\?/g, '？')
    .replace(/</g, '＜')
    .replace(/>/g, '＞')
    .replace(/¥/g, '￥')
    .replace(/\\/g, '￥')
    .replace(/\*/g, '＊')
    .replace(/\|/g, '｜')
    .replace(/"/g, '”')
    .replace(/:/g, '：');

  return truncate(converted, 255);
};