sasl_verifyfile_t
r = ((sasl_verifyfile_t *)(verifyfile_cb->proc))
ret = ((sasl_verifyfile_t *)(vf->proc))(vf->context,
result = ((sasl_verifyfile_t *)(verifyfile_cb->proc))(verifyfile_cb->context,
result = ((sasl_verifyfile_t *)(verifyfile_cb->proc))(verifyfile_cb->context,