@deftypefun {gnutls_hmac_hd_t} {gnutls_hmac_copy} (gnutls_hmac_hd_t @var{handle})
@var{handle}: is a @code{gnutls_hmac_hd_t}  type

This function will create a copy of MAC context, containing all its current
state. Copying contexts for MACs registered using
@code{gnutls_crypto_register_mac()}  is not supported and will always result in an
error. In addition to that, some of the MAC implementations do not support
this operation. Applications should check the return value and provide a
proper fallback.

@strong{Returns:} new MAC context or NULL in case of an error.

@strong{Since:} 3.6.9
@end deftypefun