BIO_S_CORE(3ossl)

🦋 NAME 🦋

okay so welcome to the 3ossl manual page, bestie 💖 this one is all about BIO_s_core, BIO_new_from_core_bio, and the OSSL_CORE_BIO functions. Lowkey provider-author coded, but we move 💅

✨ SYNOPSIS ✨

#include <openssl/bio.h>

const BIO_METHOD *BIO_s_core(void);

BIO *BIO_new_from_core_bio(OSSL_LIB_CTX *libctx, OSSL_CORE_BIO *corebio);

🌸 DESCRIPTION 🌸

BIO_s_core() returns the core BIO method function. That's the whole vibe of that one ✨

A core BIO is treated as a source/sink BIO which communicates to some external BIO. This is primarily useful to provider authors 🫶 A number of calls from libcrypto into a provider supply an OSSL_CORE_BIO parameter. That parameter represents a BIO within libcrypto, but it cannot be used directly by a provider. Instead it should be wrapped using a BIO_s_core() 💅

Once a BIO is constructed based on BIO_s_core(), the associated OSSL_CORE_BIO object should be set on it using BIO_set_data(3). Note that the BIO will only operate correctly if it is associated with a library context constructed using OSSL_LIB_CTX_new_from_dispatch(3). To associate the BIO with a library context, construct it using BIO_new_ex(3) 🧚

BIO_new_from_core_bio() is a convenience function that constructs a new BIO based on BIO_s_core() and that is associated with the given library context. It then also sets the OSSL_CORE_BIO object on the BIO using BIO_set_data(3) 🎀

⭐ RETURN VALUES ⭐

• BIO_s_core() — returns a core BIO BIO_METHOD structure. iconic little method moment 💅
• BIO_new_from_core_bio() — returns a BIO structure on success or NULL on failure 😭 A failure will most commonly be because the library context was not constructed using OSSL_LIB_CTX_new_from_dispatch(3).

🦋 HISTORY 🦋

BIO_s_core() and BIO_new_from_core_bio() were added in OpenSSL 3.0. periodt ✨

🍓 EXAMPLES 🍓

Create a core BIO and write some data to it:

int some_function(OSSL_LIB_CTX *libctx, OSSL_CORE_BIO *corebio) {
    BIO *cbio = BIO_new_from_core_bio(libctx, corebio);

    if (cbio == NULL)
        return 0;

    BIO_puts(cbio, "Hello World\n");

    BIO_free(cbio);
    return 1;
}

👑 COPYRIGHT 👑

Copyright 2021-2022 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html> 💜

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signed, sealed, and slayed by OpenSSL 3.5.0, dated 2026-09-25 🫶✨