@deftypefun {void} {gnutls_pkcs11_set_pin_function} (gnutls_pin_callback_t @var{fn}, void * @var{userdata})
@var{fn}: The PIN callback, a @code{gnutls_pin_callback_t()}  function.

@var{userdata}: data to be supplied to callback

This function will set a callback function to be used when a PIN is
required for PKCS 11 operations.  See
@code{gnutls_pin_callback_t()}  on how the callback should behave.

@strong{Since:} 2.12.0
@end deftypefun