sha256_init
ATTRIBUTE_WARN_UNUSED_RET int sha256_init(sha256_context *ctx);
return sha256_init((sha256_context*)hctx);
ret = sha256_init(&ctx); EG(ret, err);
ret = sha256_init(&ctx); EG(ret, err);
LEGACY_EVP_MD_METH_TABLE(sha256_init, sha256_update, sha256_final, NULL,