Adjust public APIS for ENGINE removal

[nhorman]

Removal of engines means we have numerous APIs which will have an ENGINE parameter that is no longer used.

We need to determine a method for which this parameter is handled or eliminated

My current proposal is:

1. Public API functions which are deprecated should not be modified. For those the api should be left alone, including the ENGINE parameter. Use of the ENGINE parameter becomes vestigual and is documented as not being used, and that passing any value other than NULL will result in an error.

2. Functions which are not deprecated can have their ENGINE parameter removed entirely and docs updated accordingly. Given that this is being done on a major release boundary, API alterations should be allowed for this

3. The canonical ENGINE apis (ENGINE_init/get_id/etc), should be eliminated entirely

[t8m]

2. Functions which are not deprecated can have their ENGINE parameter removed entirely and docs updated accordingly. Given that this is being done on a major release boundary, API alterations should be allowed for this

This doesn't make much sense to me.

[t-j-h]

This is old and outdated and should be closed unactioned.

[esyr]

This is old and outdated and should be closed unactioned.

What is the current agreement wrt publicly facing APIs, then?

[t8m]

Basically 1) it is: Public API functions which are deprecated should not be modified. For those the api should be left alone, including the ENGINE parameter. Use of the ENGINE parameter becomes vestigial and is documented as not being used, and that passing any value other than NULL will result in an error.

And yeah, functions that are in the ENGINE API are handled by the stubs.

[mbroz]

My plan was to just go through the remaining list, there are aready some stubs in engine.h (in feature branch), I hope this was not a mistake:

ossl_err_load_ENGINE_strings
EVP_PKEY_set1_engine
EVP_PKEY_get0_engine
RAND_set_rand_engine
TS_CONF_set_crypto_device
TS_CONF_set_default_engine
ERR_load_ENGINE_strings
SSL_CTX_set_client_cert_engine

But for other API calls, it should not be changed or removed.

[mbroz]

What about these API calls? I think it should be removed and replaced by stubs in engine.h as well, as these do not make sense without ENGINES...

DH_get0_engine
DSA_get0_engine
EC_KEY_get0_engine
RSA_get0_engine
and
OSSL_STORE_LOADER_get0_engine

(Note that we removed EVP_PKEY_get0_engine above already....)

@t8m @t-j-h ?

[jogme]

IMO all the *_get0_engine() should be considered

[t8m]

Yes, I'd replace them with stubs in engine.h.