crypto/hmac: Allow to build hmac over multiple qcrypto_gnutls_hmac_bytes[v] calls

If the buffers that should be considered for building the hmac are not
available at the same time, the current API is unsuitable. Extend it so
that passing a NULL pointer as result_len is used as indicator that
further buffers will be passed in succeeding calls to
qcrypto_gnutls_hmac_bytes[v].

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <2d3539c247a6c323491a3821f0e5b6fc382a4686.1756706188.git.jan.kiszka@siemens.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
5 files changed