API: crypto: return value of `odp_crypto_cipher_capability`/`odp_crypto_auth_capability`

[lumag]

Currently we enforce that crypto capabilities retrieval functions always return same value for 'number of capability structures'. This helps one to use following code sequence easily:

int num_caps = odp_crypto_cipher_capability(ODP_CIPHER_ALG_AES_CBC, NULL, 0);
odp_crypto_cipher_capability_t capa[num_caps];
int ret = odp_crypto_cipher_capability(ODP_CIPHER_ALG_AES_CBC, capa, num_caps);
int i;

for (i = 0; i < num_capa; i++)
    do_something(&capa[i]);

For ODP-DPDK this might lead to inclusion of duplicate or overlapping entries in capabilties structure. Options to consider:

• leave API as is, document that caps might include overlapping entries
• change requirement so that ret <= num_capa, forcing users to loop till ret in the second loop
• ???

[Bill-Fischofer-Linaro]

@lumag is this issue still current?

[lumag]

@Bill-Fischofer-Linaro sure it is.