Function ftruncate

lib/internal/vfs/setup.js:434–438

(fd, len)

      return vfd.entry.stat(options);
    },
    ftruncate(fd, len) {
      const vfd = getVirtualFd(fd);
      if (!vfd) return undefined;
      return vfd.entry.truncate(len).then(() => true);
    },
    fchmod: noopFd,
    fchown: noopFd,
    futimes: noopFd,