Function svn_auth_next_credentials 

pub unsafe extern "C" fn svn_auth_next_credentials(
    credentials: *mut *mut c_void,
    state: *mut svn_auth_iterstate_t,
    pool: *mut apr_pool_t,
) -> *mut svn_error_t

Get another set of credentials, assuming previous ones failed to authenticate.

Use @a state to fetch a different set of @a *credentials, as a follow-up to svn_auth_first_credentials() or svn_auth_next_credentials(). If no more credentials are available, set @a *credentials to NULL.

Note that @a *credentials will be allocated in @c auth_baton’s pool.