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.\" $OpenBSD: BIO_new.3,v 1.5 2016/11/18 18:43:05 schwarze Exp $
.\" OpenSSL ca3a82c3 Mar 25 11:31:18 2015 -0400
.\"
.\" This file was written by Dr. Stephen Henson <steve@openssl.org>.
.\" Copyright (c) 2000, 2015, 2016 The OpenSSL Project. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\"
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\"
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in
.\" the documentation and/or other materials provided with the
.\" distribution.
.\"
.\" 3. All advertising materials mentioning features or use of this
.\" software must display the following acknowledgment:
.\" "This product includes software developed by the OpenSSL Project
.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
.\"
.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
.\" endorse or promote products derived from this software without
.\" prior written permission. For written permission, please contact
.\" openssl-core@openssl.org.
.\"
.\" 5. Products derived from this software may not be called "OpenSSL"
.\" nor may "OpenSSL" appear in their names without prior written
.\" permission of the OpenSSL Project.
.\"
.\" 6. Redistributions of any form whatsoever must retain the following
.\" acknowledgment:
.\" "This product includes software developed by the OpenSSL Project
.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)"
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
.\" OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd $Mdocdate: November 18 2016 $
.Dt BIO_NEW 3
.Os
.Sh NAME
.Nm BIO_new ,
.Nm BIO_set ,
.Nm BIO_free ,
.Nm BIO_vfree ,
.Nm BIO_free_all
.Nd BIO allocation and freeing functions
.Sh SYNOPSIS
.In openssl/bio.h
.Ft BIO *
.Fo BIO_new
.Fa "BIO_METHOD *type"
.Fc
.Ft int
.Fo BIO_set
.Fa "BIO *a"
.Fa "BIO_METHOD *type"
.Fc
.Ft int
.Fo BIO_free
.Fa "BIO *a"
.Fc
.Ft void
.Fo BIO_vfree
.Fa "BIO *a"
.Fc
.Ft void
.Fo BIO_free_all
.Fa "BIO *a"
.Fc
.Sh DESCRIPTION
The
.Fn BIO_new
function returns a new BIO using method
.Fa type .
.Pp
.Fn BIO_set
sets the method of an already existing BIO.
.Pp
.Fn BIO_free
frees up a single BIO;
.Fn BIO_vfree
also frees up a single BIO, but it does not return a value.
If
.Fa a
is a
.Dv NULL
pointer, no action occurs.
Calling
.Fn 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
.Vt BIO_METHOD
descriptions.
.Pp
.Fn 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
.Fa a
is a
.Dv NULL
pointer, no action occurs.
.Pp
Some BIOs (such as memory BIOs) can be used immediately after calling
.Fn BIO_new .
Others (such as file BIOs) need some additional initialization, and
frequently a utility function exists to create and initialize such BIOs.
.Pp
If
.Fn BIO_free
is called on a BIO chain, it will only free one BIO,
resulting in a memory leak.
.Pp
Calling
.Fn BIO_free_all
on a single BIO has the same effect as calling
.Fn BIO_free
on it other than the discarded return value.
.Pp
Normally the
.Fa type
argument is supplied by a function which returns a pointer to a
.Vt BIO_METHOD .
There is a naming convention for such functions:
a source/sink BIO is normally called
.Fn BIO_s_*
and a filter BIO
.Fn BIO_f_* .
.Sh RETURN VALUES
.Fn BIO_new
returns a newly created BIO or
.Dv NULL
if the call fails.
.Pp
.Fn BIO_set
and
.Fn BIO_free
return 1 for success and 0 for failure.
.Sh EXAMPLES
Create a memory BIO:
.Pp
.Dl BIO *mem = BIO_new(BIO_s_mem());
|
