freebsd-dev/lib/libc/string/bzero.3

.\" Copyright (c) 1990, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek.
.\"
.\" 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. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS 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 REGENTS OR 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
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
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.\"	@(#)bzero.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd August 24, 2015
.Dt BZERO 3
.Os
.Sh NAME
.Nm bzero ,
.Nm explicit_bzero
.Nd write zeroes to a byte string
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In strings.h
.Ft void
.Fn bzero "void *b" "size_t len"
.Ft void
.Fn explicit_bzero "void *b" "size_t len"
.Sh DESCRIPTION
The
.Fn bzero
function
writes
.Fa len
zero bytes to the string
.Fa b .
If
.Fa len
is zero,
.Fn bzero
does nothing.
.Pp
The
.Fn explicit_bzero
variant behaves the same, but will not be removed by a compiler's dead store
optimization pass, making it useful for clearing sensitive memory such as a
password.
.Sh SEE ALSO
.Xr memset 3 ,
.Xr swab 3
.Sh HISTORY
A
.Fn bzero
function
appeared in
.Bx 4.3 .
Its prototype existed previously in
.In string.h
before it was moved to
.In strings.h
for
.St -p1003.1-2001
compliance.
.Pp
The
.Fn explicit_bzero
function first appeared in
.Ox 5.5
and
.Fx 11.0 .
.Pp
.St -p1003.1-2008
removes the specification of
.Fn bzero
and it is marked as LEGACY in
.St -p1003.1-2004 .
For portability with other systems new programs should use
.Xr memset 3 .
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.\" Copyright (c) 1990, 1991, 1993`
			`.\" The Regents of the University of California. All rights reserved.`
			`.\"`
			`.\" This code is derived from software contributed to Berkeley by`
			`.\" Chris Torek.`
			`.\"`
			`.\" 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.`
Renumber clauses to reduce diffs to other versions NetBSD, OpenBSD, and Android's Bionic number the clauses 1 through 3, so follow suit to make comparison easier. 2013-05-28 20:57:40 +00:00			`.\" 3. Neither the name of the University nor the names of its contributors`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.\" may be used to endorse or promote products derived from this software`
			`.\" without specific prior written permission.`
			`.\"`
			.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
			`.\" ANY EXPRESS 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 REGENTS OR 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.`
			`.\"`
			`.\" @(#)bzero.3 8.1 (Berkeley) 6/4/93`
$Id$ -> $FreeBSD$ 1999-08-28 00:22:10 +00:00			`.\" $FreeBSD$`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.\"`
Update bzero(3) manpage to following the Posix Standard. Reviewed by: wblock, pfg Approved by: bapt (mentor) Differential Revision: D3380 2015-08-24 01:51:10 +00:00			`.Dd August 24, 2015`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Dt BZERO 3`
mdoc(7) police: removed HISTORY info from the .Os call. 2001-07-10 13:41:46 +00:00			`.Os`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh NAME`
Add explicit_bzero(3) and its kernel counterpart. Obtained from: OpenBSD MFC after: 2 weeks 2014-10-07 04:54:11 +00:00			`.Nm bzero ,`
			`.Nm explicit_bzero`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Nd write zeroes to a byte string`
Introduce ".Lb" macro to libc manpages. More libraries manpages updates following. 2000-04-21 09:42:15 +00:00			`.Sh LIBRARY`
			`.Lb libc`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh SYNOPSIS`
- Let their manual pages show the reader that the bzero(3) and bcopy(3) functions are prototyped in <strings.h> and not in <string.h> anymore. - Add a sentence about that to the respective HISTORY sections. In the C source files: - Include <string.h> or <strings.h> depending on what function is to be compiled. - Use ANSI-C function definitions. 2002-09-01 21:53:46 +00:00			`.In strings.h`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Ft void`
			`.Fn bzero "void *b" "size_t len"`
Add explicit_bzero(3) and its kernel counterpart. Obtained from: OpenBSD MFC after: 2 weeks 2014-10-07 04:54:11 +00:00			`.Ft void`
			`.Fn explicit_bzero "void *b" "size_t len"`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh DESCRIPTION`
			`The`
			`.Fn bzero`
			`function`
			`writes`
			`.Fa len`
			`zero bytes to the string`
			`.Fa b .`
			`If`
			`.Fa len`
			`is zero,`
			`.Fn bzero`
			`does nothing.`
Add explicit_bzero(3) and its kernel counterpart. Obtained from: OpenBSD MFC after: 2 weeks 2014-10-07 04:54:11 +00:00			`.Pp`
			`The`
			`.Fn explicit_bzero`
			`variant behaves the same, but will not be removed by a compiler's dead store`
			`optimization pass, making it useful for clearing sensitive memory such as a`
			`password.`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh SEE ALSO`
			`.Xr memset 3 ,`
			`.Xr swab 3`
			`.Sh HISTORY`
			`A`
			`.Fn bzero`
			`function`
Remove whitespace at EOL. 2001-07-15 07:53:42 +00:00			`appeared in`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Bx 4.3 .`
- Let their manual pages show the reader that the bzero(3) and bcopy(3) functions are prototyped in <strings.h> and not in <string.h> anymore. - Add a sentence about that to the respective HISTORY sections. In the C source files: - Include <string.h> or <strings.h> depending on what function is to be compiled. - Use ANSI-C function definitions. 2002-09-01 21:53:46 +00:00			`Its prototype existed previously in`
mdoc(7): Use the new feature of the .In macro. 2003-09-08 19:57:22 +00:00			`.In string.h`
- Let their manual pages show the reader that the bzero(3) and bcopy(3) functions are prototyped in <strings.h> and not in <string.h> anymore. - Add a sentence about that to the respective HISTORY sections. In the C source files: - Include <string.h> or <strings.h> depending on what function is to be compiled. - Use ANSI-C function definitions. 2002-09-01 21:53:46 +00:00			`before it was moved to`
mdoc(7): Use the new feature of the .In macro. 2003-09-08 19:57:22 +00:00			`.In strings.h`
- Let their manual pages show the reader that the bzero(3) and bcopy(3) functions are prototyped in <strings.h> and not in <string.h> anymore. - Add a sentence about that to the respective HISTORY sections. In the C source files: - Include <string.h> or <strings.h> depending on what function is to be compiled. - Use ANSI-C function definitions. 2002-09-01 21:53:46 +00:00			`for`
			`.St -p1003.1-2001`
			`compliance.`
Add explicit_bzero(3) and its kernel counterpart. Obtained from: OpenBSD MFC after: 2 weeks 2014-10-07 04:54:11 +00:00			`.Pp`
			`The`
			`.Fn explicit_bzero`
			`function first appeared in`
			`.Ox 5.5`
			`and`
			`.Fx 11.0 .`
Update bzero(3) manpage to following the Posix Standard. Reviewed by: wblock, pfg Approved by: bapt (mentor) Differential Revision: D3380 2015-08-24 01:51:10 +00:00			`.Pp`
			`.St -p1003.1-2008`
			`removes the specification of`
			`.Fn bzero`
			`and it is marked as LEGACY in`
			`.St -p1003.1-2004 .`
			`For portability with other systems new programs should use`
			`.Xr memset 3 .`