153 lines
4.7 KiB
Groff
153 lines
4.7 KiB
Groff
.\" $OpenBSD: BUF_MEM_new.3,v 1.19 2024/07/24 08:57:58 tb Exp $
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.\" OpenSSL doc/crypto/buffer.pod 18edda0f Sep 20 03:28:54 2000 +0000
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.\" not merged: 74924dcb, 58e3457a, 21b0fa91, 7644a9ae
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.\" OpenSSL doc/crypto/BUF_MEM_new.pod 53934822 Jun 9 16:39:19 2016 -0400
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.\" not merged: c952780c, 91da5e77
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.\" OpenSSL doc/man3/BUF_MEM_new.pod 498180de Dec 12 15:35:09 2016 +0300
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.\"
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.\" This file was written by Ralf S. Engelschall <rse@openssl.org>.
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.\" Copyright (c) 1999, 2000, 2016 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: July 24 2024 $
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.Dt BUF_MEM_NEW 3
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.Os
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.Sh NAME
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.Nm BUF_MEM_new ,
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.Nm BUF_MEM_free ,
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.Nm BUF_MEM_grow ,
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.Nm BUF_MEM_grow_clean
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.Nd simple character arrays structure
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.Sh SYNOPSIS
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.In openssl/buffer.h
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.Ft BUF_MEM *
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.Fo BUF_MEM_new
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.Fa void
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.Fc
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.Ft void
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.Fo BUF_MEM_free
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.Fa "BUF_MEM *a"
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.Fc
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.Ft int
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.Fo BUF_MEM_grow
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.Fa "BUF_MEM *str"
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.Fa "size_t len"
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.Fc
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.Ft int
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.Fo BUF_MEM_grow_clean
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.Fa "BUF_MEM *str"
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.Fa "size_t len"
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.Fc
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.Sh DESCRIPTION
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The buffer library handles simple character arrays.
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Buffers are used for various purposes in the library, most notably
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memory BIOs.
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.Pp
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The library uses the
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.Vt BUF_MEM
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structure defined in buffer.h:
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.Bd -literal
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typedef struct buf_mem_st {
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size_t length; /* current number of bytes */
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char *data;
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size_t max; /* size of buffer */
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} BUF_MEM;
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.Ed
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.Pp
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.Fa length
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is the current size of the buffer in bytes;
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.Fa max
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is the amount of memory allocated to the buffer.
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There are three functions which handle these and one miscellaneous function.
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.Pp
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.Fn BUF_MEM_new
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allocates a new buffer of zero size.
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.Pp
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.Fn BUF_MEM_free
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frees up an already existing buffer.
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The data is zeroed before freeing up in case the buffer contains
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sensitive data.
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If
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.Fa a
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is a
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.Dv NULL
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pointer, no action occurs.
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.Pp
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.Fn BUF_MEM_grow
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changes the size of an already existing buffer to
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.Fa len .
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Any data already in the buffer is preserved if it increases in size.
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.Pp
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.Fn BUF_MEM_grow_clean
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is similar to
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.Fn BUF_MEM_grow ,
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but it sets any freed or additionally allocated memory to zero.
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.Sh RETURN VALUES
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.Fn BUF_MEM_new
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returns the buffer or
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.Dv NULL
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on error.
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.Pp
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.Fn BUF_MEM_grow
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and
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.Fn BUF_MEM_grow_clean
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return zero on error or the new size (i.e.\&
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.Fa len ) .
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.Sh SEE ALSO
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.Xr BIO_new 3 ,
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.Xr BIO_s_mem 3
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.Sh HISTORY
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.Fn BUF_MEM_new ,
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.Fn BUF_MEM_free ,
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and
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.Fn BUF_MEM_grow
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first appeared in SSLeay 0.6.0.
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All these functions have been available since
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.Ox 2.4 .
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.Pp
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.Fn BUF_MEM_grow_clean
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first appeared in OpenSSL 0.9.7 and has been available since
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.Ox 3.2 .
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