@deftypefun {void} {gnutls_transport_set_errno_function} (gnutls_session_t @var{session}, gnutls_errno_func @var{errno_func})
@var{session}: is a @code{gnutls_session_t}  type.

@var{errno_func}: a callback function similar to @code{write()} 

This is the function where you set a function to retrieve errno
after a failed push or pull operation.

 @code{errno_func} is of the form,
int (*gnutls_errno_func)(gnutls_transport_ptr_t);
and should return the errno.

@strong{Since:} 2.12.0
@end deftypefun