Function readFileSync

lib/fs.js:524–607

* Synchronously reads the entire contents of a file. * @param {string | Buffer | URL | number} path * @param {{ * encoding?: string | null; * flag?: string; * }} [options] * @returns {string | Buffer}

(path, options)

 * @returns {string | Buffer}
 */
function readFileSync(path, options) {
  const h = vfsState.handlers;
  if (h !== null) {
    const result = h.readFileSync(path, options);
    if (result !== undefined) return result;
  }
  options = getOptions(options, { flag: 'r' });
  validateReadFileBufferOptions(options);
  const hasUserBuffer = options.buffer !== undefined;

  if ((options.encoding === 'utf8' || options.encoding === 'utf-8') &&
      !hasUserBuffer) {
    if (!isInt32(path)) {
      path = getValidatedPath(path);
    }
    return binding.readFileUtf8(path, stringToFlags(options.flag));
  }

  const isUserFd = isFd(path); // File descriptor ownership
  const fd = isUserFd ? path : fs.openSync(path, options.flag, 0o666);

  const stats = tryStatSync(fd, isUserFd);
  const size = isFileType(stats, S_IFREG) ? stats[8] : 0;
  let pos = 0;
  let buffer; // Single buffer with file data
  let buffers; // List for when size is unknown

  if (hasUserBuffer) {
    buffer = tryGetReadFileBuffer(options, size, fd, isUserFd);
  } else if (size === 0) {
    buffers = [];
  } else {
    buffer = tryCreateBuffer(size, fd, isUserFd);
  }

  let bytesRead;

  if (hasUserBuffer) {
    if (size !== 0) {
      do {
        bytesRead = tryReadSync(fd, isUserFd, buffer, pos, size - pos);
        pos += bytesRead;
      } while (bytesRead !== 0 && pos < size);
    } else {
      pos = tryReadSyncWithUserBuffer(
        fd,
        isUserFd,
        buffer,
        getReadFileBufferByteLengthName(options),
      );
    }
  } else if (size !== 0) {
    do {
      bytesRead = tryReadSync(fd, isUserFd, buffer, pos, size - pos);
      pos += bytesRead;
    } while (bytesRead !== 0 && pos < size);
  } else {
    do {