readdir method
Returns a pointer to a dirent representing the next directory entry
in the directory stream pointed to by dirp. Returns null on reaching
the end of the directory stream or if an error occurred.
Implementation
dirent? readdir(DIR? dirp) {
if (dirp == null || !dirp._isOpen || dirp._iterator == null) return null;
if (dirp._iterator!.moveNext()) {
return dirent(ioGetDirentName(dirp._iterator!.current));
}
return null;
}