overleaf/libraries/overleaf-editor-core/lib/safe_pathname.js

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/** @module */
'use strict'
const path = require('path')
/**
* Regular expressions for Overleaf v2 taken from
* https://github.com/overleaf/internal/blob/f7b287b6a07354000a6b463ca3a5828104e4a811/services/web/app/src/Features/Project/SafePath.js
*/
//
// Regex of characters that are invalid in filenames
//
// eslint-disable-next-line no-control-regex
const BAD_CHAR_RX = /[/*\u0000-\u001F\u007F\u0080-\u009F\uD800-\uDFFF]/g
//
// Regex of filename patterns that are invalid ("." ".." and leading/trailing
// whitespace)
//
const BAD_FILE_RX = /(^\.$)|(^\.\.$)|(^\s+)|(\s+$)/g
//
// Put a block on filenames which match javascript property names, as they
// can cause exceptions where the code puts filenames into a hash. This is a
// temporary workaround until the code in other places is made safe against
// property names.
//
// See https://github.com/overleaf/write_latex/wiki/Using-javascript-Objects-as-Maps
//
const BLOCKED_FILE_RX =
/^(prototype|constructor|toString|toLocaleString|valueOf|hasOwnProperty|isPrototypeOf|propertyIsEnumerable|__defineGetter__|__lookupGetter__|__defineSetter__|__lookupSetter__|__proto__)$/
//
// Maximum path length, in characters. This is fairly arbitrary.
//
const MAX_PATH = 1024
/**
* Replace invalid characters and filename patterns in a filename with
* underscores.
*/
function cleanPart(filename) {
filename = filename.replace(BAD_CHAR_RX, '_')
filename = filename.replace(BAD_FILE_RX, function (match) {
return new Array(match.length + 1).join('_')
})
return filename
}
/**
* All pathnames in a Snapshot must be clean. We want pathnames that:
*
* 1. are unambiguous (e.g. no `.`s or redundant path separators)
* 2. do not allow directory traversal attacks (e.g. no `..`s or absolute paths)
* 3. do not contain leading/trailing space
* 4. do not contain the character '*' in filenames
*
* We normalise the pathname, split it by the separator and then clean each part
* as a filename
*
* @param {string} pathname
* @return {String}
*/
exports.clean = function (pathname) {
pathname = path.normalize(pathname)
pathname = pathname.replace(/\\/g, '/') // workaround for IE
pathname = pathname.replace(/\/+/g, '/') // no multiple slashes
pathname = pathname.replace(/^(\/.*)$/, '_$1') // no leading /
pathname = pathname.replace(/^(.+)\/$/, '$1') // no trailing /
pathname = pathname.replace(/^ *(.*)$/, '$1') // no leading spaces
pathname = pathname.replace(/^(.*[^ ]) *$/, '$1') // no trailing spaces
if (pathname.length === 0) pathname = '_'
pathname = pathname.split('/').map(cleanPart).join('/')
pathname = pathname.replace(BLOCKED_FILE_RX, '@$1')
return pathname
}
/**
* A pathname is clean (see clean) and not too long.
*
* @param {string} pathname
* @return {Boolean}
*/
exports.isClean = function pathnameIsClean(pathname) {
return (
exports.clean(pathname) === pathname &&
pathname.length <= MAX_PATH &&
pathname.length > 0
)
}