Re: [edk2-devel] [PATCH v3 1/3] CryptoPkg/BaseCryptLib: Add EVP (Envelope) Digest interface

["Laszlo Ersek" <lersek@redhat.com>]

On 09/16/20 14:39, Laszlo Ersek wrote:
> On 09/16/20 14:07, Yao, Jiewen wrote:
>> I overlooked the behavior that NULL DigestValue will take side effect to free Context.
>>
>> Hi Christopher
>> May I understand why we need free the context?
>> This does not align with other existing HASH or HMAC functions.
> 
> I requested that.
> 
> It makes no sense to keep a finalized context.
> 
> In other words, it makes no sense to separate finalization from freeing.
> A context that has been finalized is unusable for anything except freeing.

To clarify my point about (DigestValue==NULL): the freeing of the
context is not tied to (DigestValue==NULL). When finalizing the context,
the context should *always* be freed. (DigestValue==NULL) only decides
whether we *only* free the context, or we store the computed digest *in
addition to* freeing the context.

So the unconditional part of the finalization is the freeing; the
conditional part is the storing of the digest.

Thanks
Laszlo