101 lines
3.7 KiB
Groff
101 lines
3.7 KiB
Groff
.\" $OpenBSD: BIO_s_null.3,v 1.10 2023/04/11 16:58:43 schwarze Exp $
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.\" full merge up to: OpenSSL e9b77246 Jan 20 19:58:49 2017 +0100
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.\"
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.\" This file was written by Dr. Stephen Henson <steve@openssl.org>.
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.\" Copyright (c) 2000 The OpenSSL Project. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\"
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\"
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in
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.\" the documentation and/or other materials provided with the
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.\" distribution.
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.\"
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.\" 3. All advertising materials mentioning features or use of this
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.\" software must display the following acknowledgment:
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.\" "This product includes software developed by the OpenSSL Project
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.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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.\"
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.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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.\" endorse or promote products derived from this software without
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.\" prior written permission. For written permission, please contact
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.\" openssl-core@openssl.org.
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.\"
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.\" 5. Products derived from this software may not be called "OpenSSL"
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.\" nor may "OpenSSL" appear in their names without prior written
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.\" permission of the OpenSSL Project.
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.\"
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.\" 6. Redistributions of any form whatsoever must retain the following
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.\" acknowledgment:
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.\" "This product includes software developed by the OpenSSL Project
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.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
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.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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.\" OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd $Mdocdate: April 11 2023 $
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.Dt BIO_S_NULL 3
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.Os
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.Sh NAME
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.Nm BIO_s_null
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.\" .Nm BIO_s_log is intentionally undocumented because it is unused
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.Nd null data sink
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.Sh SYNOPSIS
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.In openssl/bio.h
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.Ft const BIO_METHOD *
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.Fo BIO_s_null
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.Fa void
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.Fc
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.Sh DESCRIPTION
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.Fn BIO_s_null
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returns the null sink BIO method.
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Data written to the null sink is discarded, reads return EOF.
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.Pp
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A null sink BIO behaves in a similar manner to the
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.Xr null 4
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device.
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.Pp
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A null BIO can be placed on the end of a chain to discard any data
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passed through it.
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.Pp
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A null sink is useful if, for example, an application wishes
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to digest some data by writing through a digest bio
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but not send the digested data anywhere.
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Since a BIO chain must normally include a source/sink BIO,
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this can be achieved by adding a null sink BIO to the end of the chain.
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.Sh RETURN VALUES
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.Fn BIO_s_null
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returns the null sink BIO method.
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.Pp
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When called on a null sink BIO object,
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.Xr BIO_method_type 3
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returns the constant
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.Dv BIO_TYPE_NULL
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and
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.Xr BIO_method_name 3
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returns a pointer to the static string
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.Qq NULL ,
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not to be confused with a NUL string nor with a
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.Dv NULL
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pointer.
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.Sh SEE ALSO
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.Xr BIO_new 3
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.Sh HISTORY
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.Fn BIO_s_null
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first appeared in SSLeay 0.6.0 and has been available since
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.Ox 2.4 .
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