@deftypefun {int} {gnutls_certificate_set_x509_system_trust} (gnutls_certificate_credentials_t       @var{cred})
@var{cred}: is a @code{gnutls_certificate_credentials_t}  type.

This function adds the system's default trusted CAs in order to
verify client or server certificates.

In the case the system is currently unsupported @code{GNUTLS_E_UNIMPLEMENTED_FEATURE} 
is returned.

@strong{Returns:} the number of certificates processed or a negative error code
on error.

@strong{Since:} 3.0.20
@end deftypefun