BIO_new(3)

BIO_new(3) | OpenSSL | BIO_new(3)

# NAME

BIO_new_ex, BIO_new, BIO_up_ref, BIO_free, BIO_vfree, BIO_free_all - BIO allocation and freeing functions

# SYNOPSIS

     #include <openssl/bio.h>
     BIO *BIO_new_ex(OSSL_LIB_CTX *libctx, const BIO_METHOD *type);
     BIO *BIO_new(const BIO_METHOD *type);
     int BIO_up_ref(BIO *a);
     int BIO_free(BIO *a);
     void BIO_vfree(BIO *a);
     void BIO_free_all(BIO *a);

# DESCRIPTION

The BIO_new_ex() function returns a new BIO using method type associated with the library context libctx (see OSSL_LIB_CTX(3)). The library context may be NULL to indicate the default library context. type MUST NOT be NULL.

The BIO_new() is the same as BIO_new_ex() except the default library context is always used.

BIO_up_ref() increments the reference count associated with the BIO object.

BIO_free() frees up a single BIO, BIO_vfree() also frees up a single BIO but it does not return a value. If a is NULL nothing is done. Calling BIO_free() may also have some effect on the underlying I/O structure, for example it may close the file being referred to under certain circumstances. For more details see the individual BIO_METHOD descriptions.

BIO_free_all() frees up an entire BIO chain, it does not halt if an error occurs freeing up an individual BIO in the chain. If a is NULL nothing is done.

# RETURN VALUES

BIO_new_ex() and BIO_new() return a newly created BIO or NULL if the call fails.

BIO_up_ref() and BIO_free() return 1 for success and 0 for failure.

BIO_free_all() and BIO_vfree() do not return values.

# NOTES

If BIO_free() is called on a BIO chain it will only free one BIO resulting in a memory leak.

Calling BIO_free_all() on a single BIO has the same effect as calling BIO_free() on it other than the discarded return value.

# HISTORY

BIO_set() was removed in OpenSSL 1.1.0 as BIO type is now opaque.

BIO_new_ex() was added in OpenSSL 3.0.

# EXAMPLES

Create a memory BIO:

     BIO *mem = BIO_new(BIO_s_mem());

# COPYRIGHT

Copyright 2000-2021 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>.

2025-07-01 | 3.5.1