Postgres C API: How can we copy a Datum?

As far as I understand, SPI_getbinval returns a pointer into the passed row. That is, the following would be unsafe:

dat = SPI_getbinval(SPI_tuptable->vals, SPI_tuptable->tupdesc, 1, &isnull);
SPI_finished();
if (isnull)
    PG_RETURN_NULL();
// Unsafe since SPI_finished() deallocates SPI_tuptable
return dat;

The SPI interface provides the utility SPI_copytuple. Is the following safe? Is there any problem with using SPI_tuptable->tupdesc? Moreover, is there a more efficient way to do this directly with the returned Datum instead of copying the entire HeapTuple?

// We copy the whole tuple into the outer context.  Better way to copy an individual Datum?
dat = SPI_getbinval(SPI_copytuple(SPI_tuptable->vals), SPI_tuptable->tupdesc, 1, &isnull);
SPI_finished();
if (isnull)
  PG_RETURN_NULL();
return dat;