PHP_HTTP_API size_t php_http_etag_update(php_http_etag_t *e, const char *data_ptr, size_t data_len);
PHP_HTTP_API char *php_http_etag_finish(php_http_etag_t *e);
PHP_HTTP_API size_t php_http_etag_update(php_http_etag_t *e, const char *data_ptr, size_t data_len);
PHP_HTTP_API char *php_http_etag_finish(php_http_etag_t *e);