def local_open(url):
    """Read a local path, with special support for directories"""
    scheme, server, path, param, query, frag = urllib.parse.urlparse(url)
    filename = urllib.request.url2pathname(path)
    if os.path.isfile(filename):
        return urllib.request.urlopen(url)
    elif path.endswith('/') and os.path.isdir(filename):
        files = []
        for f in os.listdir(filename):
            filepath = os.path.join(filename, f)
            if f == 'index.html':
                with open(filepath, 'r') as fp:
                    body = fp.read()
                break
            elif os.path.isdir(filepath):
                f += '/'
            files.append('<a href="{name}">{name}</a>'.format(name=f))
        else:
            tmpl = (
                "<html><head><title>{url}</title>" "</head><body>{files}</body></html>"
            )
            body = tmpl.format(url=url, files='\n'.join(files))
        status, message = 200, "OK"
    else:
        status, message, body = 404, "Path not found", "Not found"

    headers = {'content-type': 'text/html'}
    body_stream = io.StringIO(body)
    return urllib.error.HTTPError(url, status, message, headers, body_stream)
Read a local path, with special support for directories
product/gradle-plugin/src/main/python/setuptools/package_index.py