Function truncate

lib/fs.js:1261–1286

* Truncates the file. * @param {string | Buffer | URL} path * @param {number} [len] * @param {(err?: Error) => any} callback * @returns {void}

(path, len, callback)

 * @returns {void}
 */
function truncate(path, len, callback) {
  if (typeof len === 'function') {
    callback = len;
    len = 0;
  } else if (len === undefined) {
    len = 0;
  }

  validateInteger(len, 'len');
  len = MathMax(0, len);
  validateFunction(callback, 'cb');

  const h = vfsState.handlers;
  if (h !== null && vfsVoid(h.truncate(path, len), callback)) return;

  fs.open(path, 'r+', (er, fd) => {
    if (er) return callback(er);
    const req = new FSReqCallback();
    req.oncomplete = function oncomplete(er) {
      fs.close(fd, (er2) => {
        callback(aggregateTwoErrors(er2, er));
      });
    };
    binding.ftruncate(fd, len, req);
  });
}

/**
 * Synchronously truncates the file.