Alternative safe_join

safe_join.py

def safe_join(directory, *pathnames):
    pathnames = tuple(posixpath.normpath(p) for p in pathnames)
    for filename in pathnames:
        for sep in _os_alt_seps:
            if sep in filename:
                raise NotFound()
        if os.path.isabs(filename) or \
           filename == '..' or \
           filename.startswith('../'):
            raise NotFound()
    return os.path.join(directory, *pathnames)