Remove dependency express-fileupload

server/libs/expressFileupload/LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2015 Richard Girges
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

server/libs/expressFileupload/fileFactory.js

@@ -0,0 +1,65 @@
+'use strict';
+
+const {
+  isFunc,
+  debugLog,
+  moveFile,
+  promiseCallback,
+  checkAndMakeDir,
+  saveBufferToFile
+} = require('./utilities');
+
+/**
+ * Returns Local function that moves the file to a different location on the filesystem
+ * which takes two function arguments to make it compatible w/ Promise or Callback APIs
+ * @param {String} filePath - destination file path.
+ * @param {Object} options - file factory options.
+ * @param {Object} fileUploadOptions - middleware options.
+ * @returns {Function}
+ */
+const moveFromTemp = (filePath, options, fileUploadOptions) => (resolve, reject) => {
+  debugLog(fileUploadOptions, `Moving temporary file ${options.tempFilePath} to ${filePath}`);
+  moveFile(options.tempFilePath, filePath, promiseCallback(resolve, reject));
+};
+
+/**
+ * Returns Local function that moves the file from buffer to a different location on the filesystem
+ * which takes two function arguments to make it compatible w/ Promise or Callback APIs
+ * @param {String} filePath - destination file path.
+ * @param {Object} options - file factory options.
+ * @param {Object} fileUploadOptions - middleware options.
+ * @returns {Function}
+ */
+const moveFromBuffer = (filePath, options, fileUploadOptions) => (resolve, reject) => {
+  debugLog(fileUploadOptions, `Moving uploaded buffer to ${filePath}`);
+  saveBufferToFile(options.buffer, filePath, promiseCallback(resolve, reject));
+};
+
+module.exports = (options, fileUploadOptions = {}) => {
+  // see: https://github.com/richardgirges/express-fileupload/issues/14
+  // firefox uploads empty file in case of cache miss when f5ing page.
+  // resulting in unexpected behavior. if there is no file data, the file is invalid.
+  // if (!fileUploadOptions.useTempFiles && !options.buffer.length) return;
+  
+  // Create and return file object.
+  return {
+    name: options.name,
+    data: options.buffer,
+    size: options.size,
+    encoding: options.encoding,
+    tempFilePath: options.tempFilePath,
+    truncated: options.truncated,
+    mimetype: options.mimetype,
+    md5: options.hash,
+    mv: (filePath, callback) => {
+      // Define a propper move function.
+      const moveFunc = fileUploadOptions.useTempFiles
+        ? moveFromTemp(filePath, options, fileUploadOptions)
+        : moveFromBuffer(filePath, options, fileUploadOptions);
+      // Create a folder for a file.
+      checkAndMakeDir(fileUploadOptions, filePath);
+      // If callback is passed in, use the callback API, otherwise return a promise.
+      return isFunc(callback) ? moveFunc(callback) : new Promise(moveFunc);
+    }
+  };
+};

server/libs/expressFileupload/index.js

@@ -0,0 +1,39 @@
+'use strict';
+
+const path = require('path');
+const processMultipart = require('./processMultipart');
+const isEligibleRequest = require('./isEligibleRequest');
+const { buildOptions, debugLog } = require('./utilities');
+const busboy = require('../busboy'); // eslint-disable-line no-unused-vars
+
+const DEFAULT_OPTIONS = {
+  debug: false,
+  uploadTimeout: 60000,
+  fileHandler: false,
+  uriDecodeFileNames: false,
+  safeFileNames: false,
+  preserveExtension: false,
+  abortOnLimit: false,
+  responseOnLimit: 'File size limit has been reached',
+  limitHandler: false,
+  createParentPath: false,
+  parseNested: false,
+  useTempFiles: false,
+  tempFileDir: path.join(process.cwd(), 'tmp')
+};
+
+/**
+ * Expose the file upload middleware
+ * @param {DEFAULT_OPTIONS & busboy.BusboyConfig} options - Middleware options.
+ * @returns {Function} - express-fileupload middleware.
+ */
+module.exports = (options) => {
+  const uploadOptions = buildOptions(DEFAULT_OPTIONS, options);
+  return (req, res, next) => {
+    if (!isEligibleRequest(req)) {
+      debugLog(uploadOptions, 'Request is not eligible for file upload!');
+      return next();
+    }
+    processMultipart(uploadOptions, req, res, next);
+  };
+};

server/libs/expressFileupload/isEligibleRequest.js

@@ -0,0 +1,34 @@
+const ACCEPTABLE_CONTENT_TYPE = /^(multipart\/.+);(.*)$/i;
+const UNACCEPTABLE_METHODS = ['GET', 'HEAD'];
+
+/**
+ * Ensures the request contains a content body
+ * @param  {Object}  req Express req object
+ * @returns {Boolean}
+ */
+const hasBody = (req) => {
+  return ('transfer-encoding' in req.headers) ||
+    ('content-length' in req.headers && req.headers['content-length'] !== '0');
+};
+
+/**
+ * Ensures the request is not using a non-compliant multipart method
+ * such as GET or HEAD
+ * @param  {Object}  req Express req object
+ * @returns {Boolean}
+ */
+const hasAcceptableMethod = req => !UNACCEPTABLE_METHODS.includes(req.method);
+
+/**
+ * Ensures that only multipart requests are processed by express-fileupload
+ * @param  {Object}  req Express req object
+ * @returns {Boolean}
+ */
+const hasAcceptableContentType = req => ACCEPTABLE_CONTENT_TYPE.test(req.headers['content-type']);
+
+/**
+ * Ensures that the request in question is eligible for file uploads
+ * @param {Object} req Express req object
+ * @returns {Boolean}
+ */
+module.exports = req => hasBody(req) && hasAcceptableMethod(req) && hasAcceptableContentType(req);

server/libs/expressFileupload/memHandler.js

@@ -0,0 +1,42 @@
+const crypto = require('crypto');
+const { debugLog } = require('./utilities');
+
+/**
+ * memHandler - In memory upload handler
+ * @param {Object} options
+ * @param {String} fieldname
+ * @param {String} filename
+ * @returns {Object}
+ */
+module.exports = (options, fieldname, filename) => {
+  const buffers = [];
+  const hash = crypto.createHash('md5');
+  let fileSize = 0;
+  let completed = false;
+
+  const getBuffer = () => Buffer.concat(buffers, fileSize);
+
+  return {
+    dataHandler: (data) => {
+      if (completed === true) {
+        debugLog(options, `Error: got ${fieldname}->${filename} data chunk for completed upload!`);
+        return;
+      }
+      buffers.push(data);
+      hash.update(data);
+      fileSize += data.length;
+      debugLog(options, `Uploading ${fieldname}->${filename}, bytes:${fileSize}...`);
+    },
+    getBuffer: getBuffer,
+    getFilePath: () => '',
+    getFileSize: () => fileSize,
+    getHash: () => hash.digest('hex'),
+    complete: () => {
+      debugLog(options, `Upload ${fieldname}->${filename} completed, bytes:${fileSize}.`);
+      completed = true;
+      return getBuffer();
+    },
+    cleanup: () => { completed = true; },
+    getWritePromise: () => Promise.resolve()
+  };
+};

server/libs/expressFileupload/processMultipart.js

@@ -0,0 +1,168 @@
+const Busboy = require('../busboy');
+const UploadTimer = require('./uploadtimer');
+const fileFactory = require('./fileFactory');
+const memHandler = require('./memHandler');
+const tempFileHandler = require('./tempFileHandler');
+const processNested = require('./processNested');
+const {
+  isFunc,
+  debugLog,
+  buildFields,
+  buildOptions,
+  parseFileName
+} = require('./utilities');
+
+const waitFlushProperty = Symbol('wait flush property symbol');
+
+/**
+ * Processes multipart request
+ * Builds a req.body object for fields
+ * Builds a req.files object for files
+ * @param  {Object}   options expressFileupload and Busboy options
+ * @param  {Object}   req     Express request object
+ * @param  {Object}   res     Express response object
+ * @param  {Function} next    Express next method
+ * @return {void}
+ */
+module.exports = (options, req, res, next) => {
+  req.files = null;
+
+  // Build busboy options and init busboy instance.
+  const busboyOptions = buildOptions(options, { headers: req.headers });
+  const busboy = Busboy(busboyOptions);
+
+  // Close connection with specified reason and http code, default: 400 Bad Request.
+  const closeConnection = (code, reason) => {
+    req.unpipe(busboy);
+    res.writeHead(code || 400, { Connection: 'close' });
+    res.end(reason || 'Bad Request');
+  };
+
+  // Express proxies sometimes attach multipart data to a buffer
+  if (req.body instanceof Buffer) {
+    req.body = Object.create(null);
+  }
+  // Build multipart req.body fields
+  busboy.on('field', (field, val) => req.body = buildFields(req.body, field, val));
+
+  // Build req.files fields
+  busboy.on('file', (field, file, info) => {
+    // Parse file name(cutting huge names, decoding, etc..).
+    const { filename: name, encoding, mimeType: mime } = info;
+    const filename = parseFileName(options, name);
+    // Define methods and handlers for upload process.
+    const {
+      dataHandler,
+      getFilePath,
+      getFileSize,
+      getHash,
+      complete,
+      cleanup,
+      getWritePromise
+    } = options.useTempFiles
+        ? tempFileHandler(options, field, filename) // Upload into temporary file.
+        : memHandler(options, field, filename);     // Upload into RAM.
+
+    const writePromise = options.useTempFiles
+      ? getWritePromise().catch(err => {
+        req.unpipe(busboy);
+        req.resume();
+        cleanup();
+        next(err);
+      }) : getWritePromise();
+
+    // Define upload timer.
+    const uploadTimer = new UploadTimer(options.uploadTimeout, () => {
+      file.removeAllListeners('data');
+      file.resume();
+      // After destroy an error event will be emitted and file clean up will be done.
+      file.destroy(new Error(`Upload timeout ${field}->${filename}, bytes:${getFileSize()}`));
+    });
+
+    file.on('limit', () => {
+      debugLog(options, `Size limit reached for ${field}->${filename}, bytes:${getFileSize()}`);
+      // Reset upload timer in case of file limit reached.
+      uploadTimer.clear();
+      // Run a user defined limit handler if it has been set.
+      if (isFunc(options.limitHandler)) return options.limitHandler(req, res, next);
+      // Close connection with 413 code and do cleanup if abortOnLimit set(default: false).
+      if (options.abortOnLimit) {
+        debugLog(options, `Aborting upload because of size limit ${field}->${filename}.`);
+        !isFunc(options.limitHandler) ? closeConnection(413, options.responseOnLimit) : '';
+        cleanup();
+      }
+    });
+
+    file.on('data', (data) => {
+      uploadTimer.set(); // Refresh upload timer each time new data chunk came.
+      dataHandler(data); // Handle new piece of data.
+    });
+
+    file.on('end', () => {
+      const size = getFileSize();
+      // Debug logging for file upload ending.
+      debugLog(options, `Upload finished ${field}->${filename}, bytes:${size}`);
+      // Reset upload timer in case of end event.
+      uploadTimer.clear();
+      // See https://github.com/richardgirges/express-fileupload/issues/191
+      // Do not add file instance to the req.files if original name and size are empty.
+      // Empty name and zero size indicates empty file field in the posted form.
+      if (!name && size === 0) {
+        if (options.useTempFiles) {
+          cleanup();
+          debugLog(options, `Removing the empty file ${field}->${filename}`);
+        }
+        return debugLog(options, `Don't add file instance if original name and size are empty`);
+      }
+      req.files = buildFields(req.files, field, fileFactory({
+        buffer: complete(),
+        name: filename,
+        tempFilePath: getFilePath(),
+        hash: getHash(),
+        size,
+        encoding,
+        truncated: file.truncated,
+        mimetype: mime
+      }, options));
+
+      if (!req[waitFlushProperty]) {
+        req[waitFlushProperty] = [];
+      }
+      req[waitFlushProperty].push(writePromise);
+    });
+
+    file.on('error', (err) => {
+      uploadTimer.clear(); // Reset upload timer in case of errors.
+      debugLog(options, err);
+      cleanup();
+      next();
+    });
+
+    // Debug logging for a new file upload.
+    debugLog(options, `New upload started ${field}->${filename}, bytes:${getFileSize()}`);
+    // Set new upload timeout for a new file.
+    uploadTimer.set();
+  });
+
+  busboy.on('finish', () => {
+    debugLog(options, `Busboy finished parsing request.`);
+    if (options.parseNested) {
+      req.body = processNested(req.body);
+      req.files = processNested(req.files);
+    }
+
+    if (!req[waitFlushProperty]) return next();
+    Promise.all(req[waitFlushProperty])
+      .then(() => {
+        delete req[waitFlushProperty];
+        next();
+      });
+  });
+
+  busboy.on('error', (err) => {
+    debugLog(options, `Busboy error`);
+    next(err);
+  });
+
+  req.pipe(busboy);
+};

server/libs/expressFileupload/processNested.js

@@ -0,0 +1,35 @@
+const { isSafeFromPollution } = require("./utilities");
+
+module.exports = function(data){
+  if (!data || data.length < 1) return Object.create(null);
+
+  let d = Object.create(null),
+    keys = Object.keys(data);
+
+  for (let i = 0; i < keys.length; i++) {
+    let key = keys[i],
+      value = data[key],
+      current = d,
+      keyParts = key
+        .replace(new RegExp(/\[/g), '.')
+        .replace(new RegExp(/\]/g), '')
+        .split('.');
+
+    for (let index = 0; index < keyParts.length; index++){
+      let k = keyParts[index];
+
+      // Ensure we don't allow prototype pollution
+      if (!isSafeFromPollution(current, k)) {
+        continue;
+      }
+
+      if (index >= keyParts.length - 1){
+        current[k] = value;
+      } else {
+        if (!current[k]) current[k] = !isNaN(keyParts[index + 1]) ? [] : Object.create(null);
+        current = current[k];
+      }
+    }
+  }
+  return d;
+};

server/libs/expressFileupload/tempFileHandler.js

@@ -0,0 +1,64 @@
+const fs = require('fs');
+const path = require('path');
+const crypto = require('crypto');
+const {
+  debugLog,
+  checkAndMakeDir,
+  getTempFilename,
+  deleteFile
+} = require('./utilities');
+
+module.exports = (options, fieldname, filename) => {
+  const dir = path.normalize(options.tempFileDir);
+  const tempFilePath = path.join(dir, getTempFilename());
+  checkAndMakeDir({ createParentPath: true }, tempFilePath);
+
+  debugLog(options, `Temporary file path is ${tempFilePath}`);
+ 
+  const hash = crypto.createHash('md5');
+  let fileSize = 0;
+  let completed = false;
+
+  debugLog(options, `Opening write stream for ${fieldname}->${filename}...`);
+  const writeStream = fs.createWriteStream(tempFilePath);
+  const writePromise = new Promise((resolve, reject) => {
+    writeStream.on('finish', () => resolve());
+    writeStream.on('error', (err) => {
+      debugLog(options, `Error write temp file: ${err}`);
+      reject(err);
+    });
+  });
+
+  return {
+    dataHandler: (data) => {
+      if (completed === true) {
+        debugLog(options, `Error: got ${fieldname}->${filename} data chunk for completed upload!`);
+        return;
+      }
+      writeStream.write(data);
+      hash.update(data);
+      fileSize += data.length;
+      debugLog(options, `Uploading ${fieldname}->${filename}, bytes:${fileSize}...`);
+    },
+    getFilePath: () => tempFilePath,
+    getFileSize: () => fileSize,
+    getHash: () => hash.digest('hex'),
+    complete: () => {
+      completed = true;
+      debugLog(options, `Upload ${fieldname}->${filename} completed, bytes:${fileSize}.`);
+      if (writeStream !== false) writeStream.end();
+      // Return empty buff since data was uploaded into a temp file.
+      return Buffer.concat([]);
+    },
+    cleanup: () => {
+      completed = true;
+      debugLog(options, `Cleaning up temporary file ${tempFilePath}...`);
+      writeStream.end();
+      deleteFile(tempFilePath, err => (err 
+        ? debugLog(options, `Cleaning up temporary file ${tempFilePath} failed: ${err}`)
+        : debugLog(options, `Cleaning up temporary file ${tempFilePath} done.`)
+      ));
+    },
+    getWritePromise: () => writePromise
+  };
+};

server/libs/expressFileupload/uploadtimer.js

@@ -0,0 +1,26 @@
+class UploadTimer {
+  /**
+   * @constructor
+   * @param {number} timeout - timer timeout in msecs. 
+   * @param {Function} callback - callback to run when timeout reached.
+   */
+  constructor(timeout = 0, callback = () => {}) {
+    this.timeout = timeout;
+    this.callback = callback;
+    this.timer = null;
+  }
+
+  clear() {
+    clearTimeout(this.timer);
+  }
+
+  set() {
+    // Do not start a timer if zero timeout or it hasn't been set. 
+    if (!this.timeout) return false;
+    this.clear();
+    this.timer = setTimeout(this.callback, this.timeout);
+    return true;
+  }
+}
+
+module.exports = UploadTimer;

server/libs/expressFileupload/utilities.js

@@ -0,0 +1,311 @@
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+const { Readable } = require('stream');
+
+// Parameters for safe file name parsing.
+const SAFE_FILE_NAME_REGEX = /[^\w-]/g;
+const MAX_EXTENSION_LENGTH = 3;
+
+// Parameters to generate unique temporary file names:
+const TEMP_COUNTER_MAX = 65536;
+const TEMP_PREFIX = 'tmp';
+let tempCounter = 0;
+
+/**
+ * Logs message to console if debug option set to true.
+ * @param {Object} options - options object.
+ * @param {string} msg - message to log.
+ * @returns {boolean} - false if debug is off.
+ */
+const debugLog = (options, msg) => {
+  const opts = options || {};
+  if (!opts.debug) return false;
+  console.log(`Express-file-upload: ${msg}`); // eslint-disable-line
+  return true;
+};
+
+/**
+ * Generates unique temporary file name. e.g. tmp-5000-156788789789.
+ * @param {string} prefix - a prefix for generated unique file name.
+ * @returns {string}
+ */
+const getTempFilename = (prefix = TEMP_PREFIX) => {
+  tempCounter = tempCounter >= TEMP_COUNTER_MAX ? 1 : tempCounter + 1;
+  return `${prefix}-${tempCounter}-${Date.now()}`;
+};
+
+/**
+ * isFunc: Checks if argument is a function.
+ * @returns {boolean} - Returns true if argument is a function.
+ */
+const isFunc = func => func && func.constructor && func.call && func.apply ? true: false;
+
+/**
+ * Set errorFunc to the same value as successFunc for callback mode.
+ * @returns {Function}
+ */
+const errorFunc = (resolve, reject) => isFunc(reject) ? reject : resolve;
+
+/**
+ * Return a callback function for promise resole/reject args.
+ * Ensures that callback is called only once.
+ * @returns {Function}
+ */
+const promiseCallback = (resolve, reject) => {
+  let hasFired = false;
+  return (err) => {
+    if (hasFired) {
+      return;
+    }
+
+    hasFired = true;
+    return err ? errorFunc(resolve, reject)(err) : resolve();
+  };
+};
+
+/**
+ * Builds instance options from arguments objects(can't be arrow function).
+ * @returns {Object} - result options.
+ */
+const buildOptions = function() {
+  const result = {};
+  [...arguments].forEach(options => {
+    if (!options || typeof options !== 'object') return;
+    Object.keys(options).forEach(i => result[i] = options[i]);
+  });
+  return result;
+};
+
+// The default prototypes for both objects and arrays.
+// Used by isSafeFromPollution
+const OBJECT_PROTOTYPE_KEYS = Object.getOwnPropertyNames(Object.prototype);
+const ARRAY_PROTOTYPE_KEYS = Object.getOwnPropertyNames(Array.prototype);
+
+/**
+ * Determines whether a key insertion into an object could result in a prototype pollution
+ * @param {Object} base - The object whose insertion we are checking
+ * @param {string} key - The key that will be inserted
+ */
+const isSafeFromPollution = (base, key) => {
+  // We perform an instanceof check instead of Array.isArray as the former is more
+  // permissive for cases in which the object as an Array prototype but was not constructed
+  // via an Array constructor or literal.
+  const TOUCHES_ARRAY_PROTOTYPE = (base instanceof Array) && ARRAY_PROTOTYPE_KEYS.includes(key);
+  const TOUCHES_OBJECT_PROTOTYPE = OBJECT_PROTOTYPE_KEYS.includes(key);
+
+  return !TOUCHES_ARRAY_PROTOTYPE && !TOUCHES_OBJECT_PROTOTYPE;
+};
+
+/**
+ * Builds request fields (using to build req.body and req.files)
+ * @param {Object} instance - request object.
+ * @param {string} field - field name.
+ * @param {any} value - field value.
+ * @returns {Object}
+ */
+const buildFields = (instance, field, value) => {
+  // Do nothing if value is not set.
+  if (value === null || value === undefined) return instance;
+  instance = instance || Object.create(null);
+
+  if (!isSafeFromPollution(instance, field)) {
+    return instance;
+  }
+  // Non-array fields
+  if (!instance[field]) {
+    instance[field] = value;
+    return instance;
+  }
+  // Array fields
+  if (instance[field] instanceof Array) {
+    instance[field].push(value);
+  } else {
+    instance[field] = [instance[field], value];
+  }
+  return instance;
+};
+
+/**
+ * Creates a folder for file specified in the path variable
+ * @param {Object} fileUploadOptions
+ * @param {string} filePath
+ * @returns {boolean}
+ */
+const checkAndMakeDir = (fileUploadOptions, filePath) => {
+  // Check upload options were set.
+  if (!fileUploadOptions) return false;
+  if (!fileUploadOptions.createParentPath) return false;
+  // Check whether folder for the file exists.
+  if (!filePath) return false;
+  const parentPath = path.dirname(filePath);
+  // Create folder if it doesn't exist.
+  if (!fs.existsSync(parentPath)) fs.mkdirSync(parentPath, { recursive: true });
+  // Checks folder again and return a results.
+  return fs.existsSync(parentPath);
+};
+
+/**
+ * Deletes a file.
+ * @param {string} file - Path to the file to delete.
+ * @param {Function} callback
+ */
+const deleteFile = (file, callback) => fs.unlink(file, callback);
+
+/**
+ * Copy file via streams
+ * @param {string} src - Path to the source file
+ * @param {string} dst - Path to the destination file.
+ */
+const copyFile = (src, dst, callback) => {
+  // cbCalled flag and runCb helps to run cb only once.
+  let cbCalled = false;
+  let runCb = (err) => {
+    if (cbCalled) return;
+    cbCalled = true;
+    callback(err);
+  };
+  // Create read stream
+  let readable = fs.createReadStream(src);
+  readable.on('error', runCb);
+  // Create write stream
+  let writable = fs.createWriteStream(dst);
+  writable.on('error', (err)=>{
+    readable.destroy();
+    runCb(err);
+  });
+  writable.on('close', () => runCb());
+  // Copy file via piping streams.
+  readable.pipe(writable);
+};
+
+/**
+ * moveFile: moves the file from src to dst.
+ * Firstly trying to rename the file if no luck copying it to dst and then deleteing src.
+ * @param {string} src - Path to the source file
+ * @param {string} dst - Path to the destination file.
+ * @param {Function} callback - A callback function.
+ */
+const moveFile = (src, dst, callback) => fs.rename(src, dst, err => (err
+  ? copyFile(src, dst, err => err ? callback(err) : deleteFile(src, callback))
+  : callback()
+));
+
+/**
+ * Save buffer data to a file.
+ * @param {Buffer} buffer - buffer to save to a file.
+ * @param {string} filePath - path to a file.
+ */
+const saveBufferToFile = (buffer, filePath, callback) => {
+  if (!Buffer.isBuffer(buffer)) {
+    return callback(new Error('buffer variable should be type of Buffer!'));
+  }
+  // Setup readable stream from buffer.
+  let streamData = buffer;
+  let readStream = Readable();
+  readStream._read = () => {
+    readStream.push(streamData);
+    streamData = null;
+  };
+  // Setup file system writable stream.
+  let fstream = fs.createWriteStream(filePath);
+  // console.log("Calling saveBuffer");
+  fstream.on('error', err => {
+    // console.log("err cb")
+    callback(err);
+  });
+  fstream.on('close', () => {
+    // console.log("close cb");
+    callback();
+  });
+  // Copy file via piping streams.
+  readStream.pipe(fstream);
+};
+
+/**
+ * Decodes uriEncoded file names.
+ * @param fileName {String} - file name to decode.
+ * @returns {String}
+ */
+const uriDecodeFileName = (opts, fileName) => {
+  return opts.uriDecodeFileNames ? decodeURIComponent(fileName) : fileName;
+};
+
+/**
+ * Parses filename and extension and returns object {name, extension}.
+ * @param {boolean|integer} preserveExtension - true/false or number of characters for extension.
+ * @param {string} fileName - file name to parse.
+ * @returns {Object} - { name, extension }.
+ */
+const parseFileNameExtension = (preserveExtension, fileName) => {
+  const preserveExtensionLength = parseInt(preserveExtension);
+  const result = {name: fileName, extension: ''};
+  if (!preserveExtension && preserveExtensionLength !== 0) return result;
+  // Define maximum extension length
+  const maxExtLength = isNaN(preserveExtensionLength)
+    ? MAX_EXTENSION_LENGTH
+    : Math.abs(preserveExtensionLength);
+
+  const nameParts = fileName.split('.');
+  if (nameParts.length < 2) return result;
+
+  let extension = nameParts.pop();
+  if (
+    extension.length > maxExtLength &&
+    maxExtLength > 0
+  ) {
+    nameParts[nameParts.length - 1] +=
+      '.' +
+      extension.substr(0, extension.length - maxExtLength);
+    extension = extension.substr(-maxExtLength);
+  }
+
+  result.extension = maxExtLength ? extension : '';
+  result.name = nameParts.join('.');
+  return result;
+};
+
+/**
+ * Parse file name and extension.
+ * @param {Object} opts - middleware options.
+ * @param {string} fileName - Uploaded file name.
+ * @returns {string}
+ */
+const parseFileName = (opts, fileName) => {
+  // Check fileName argument
+  if (!fileName || typeof fileName !== 'string') return getTempFilename();
+  // Cut off file name if it's lenght more then 255.
+  let parsedName = fileName.length <= 255 ? fileName : fileName.substr(0, 255);
+  // Decode file name if uriDecodeFileNames option set true.
+  parsedName = uriDecodeFileName(opts, parsedName);
+  // Stop parsing file name if safeFileNames options hasn't been set.
+  if (!opts.safeFileNames) return parsedName;
+  // Set regular expression for the file name.
+  const nameRegex = typeof opts.safeFileNames === 'object' && opts.safeFileNames instanceof RegExp
+    ? opts.safeFileNames
+    : SAFE_FILE_NAME_REGEX;
+  // Parse file name extension.
+  let {name, extension} = parseFileNameExtension(opts.preserveExtension, parsedName);
+  if (extension.length) extension = '.' + extension.replace(nameRegex, '');
+
+  return name.replace(nameRegex, '').concat(extension);
+};
+
+module.exports = {
+  isFunc,
+  debugLog,
+  copyFile, // For testing purpose.
+  moveFile,
+  errorFunc,
+  deleteFile, // For testing purpose.
+  buildFields,
+  buildOptions,
+  parseFileName,
+  getTempFilename,
+  promiseCallback,
+  checkAndMakeDir,
+  saveBufferToFile,
+  uriDecodeFileName,
+  isSafeFromPollution
+};