99 lines
2.7 KiB
Groff
99 lines
2.7 KiB
Groff
.\" Copyright (c) 1990, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" Chris Torek.
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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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.\" 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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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)bzero.3 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd August 24, 2015
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.Dt BZERO 3
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.Os
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.Sh NAME
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.Nm bzero ,
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.Nm explicit_bzero
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.Nd write zeroes to a byte string
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In strings.h
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.Ft void
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.Fn bzero "void *b" "size_t len"
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.Ft void
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.Fn explicit_bzero "void *b" "size_t len"
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.Sh DESCRIPTION
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The
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.Fn bzero
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function
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writes
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.Fa len
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zero bytes to the string
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.Fa b .
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If
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.Fa len
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is zero,
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.Fn bzero
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does nothing.
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.Pp
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The
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.Fn explicit_bzero
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variant behaves the same, but will not be removed by a compiler's dead store
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optimization pass, making it useful for clearing sensitive memory such as a
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password.
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.Sh SEE ALSO
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.Xr memset 3 ,
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.Xr swab 3
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.Sh HISTORY
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A
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.Fn bzero
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function
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appeared in
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.Bx 4.3 .
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Its prototype existed previously in
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.In string.h
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before it was moved to
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.In strings.h
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for
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.St -p1003.1-2001
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compliance.
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.Pp
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The
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.Fn explicit_bzero
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function first appeared in
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.Ox 5.5
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and
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.Fx 11.0 .
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.Pp
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.St -p1003.1-2008
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removes the specification of
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.Fn bzero
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and it is marked as LEGACY in
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.St -p1003.1-2004 .
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For portability with other systems new programs should use
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.Xr memset 3 .
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