Feeds data into an existing #GHmac.
The HMAC must still be open, that is glib.hmac.Hmac.getString or glib.hmac.Hmac.getDigest must not have been called on hmac.
buffer used to compute the checksum
Feeds data into an existing #GHmac.
The HMAC must still be open, that is glib.hmac.Hmac.getString or glib.hmac.Hmac.getDigest must not have been called on hmac.