84d9c625bf
- Fix for possible unset uid/gid in toproto
- Fix for default mtree style
- Update libelf
- Importing libexecinfo
- Resynchronize GCC, mpc, gmp, mpfr
- build.sh: Replace params with show-params.
This has been done as the make target has been renamed in the same
way, while a new target named params has been added. This new
target generates a file containing all the parameters, instead of
printing it on the console.
- Update test48 with new etc/services (Fix by Ben Gras <ben@minix3.org)
get getservbyport() out of the inner loop
Change-Id: Ie6ad5226fa2621ff9f0dee8782ea48f9443d2091
82 lines
2.6 KiB
Groff
82 lines
2.6 KiB
Groff
.\" $NetBSD: explicit_memset.3,v 1.2 2013/08/28 15:46:23 riastradh Exp $
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.\"
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.\" Copyright (c) 2013 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This documentation is derived from text contributed to The NetBSD
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.\" Foundation by Taylor R. Campbell.
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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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, 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 OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd August 28, 2013
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.Dt EXPLICIT_MEMSET 3
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.Os
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.Sh NAME
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.Nm explicit_memset
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.Nd guarantee writing a byte 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 string.h
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.Ft void *
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.Fn explicit_memset "void *b" "int c" "size_t len"
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.Sh DESCRIPTION
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The
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.Fn explicit_memset
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function writes
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.Fa len
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bytes of value
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.Fa c
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(converted to an unsigned char) to the string
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.Fa b .
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It is guaranteed not to be optimized away by the compiler even if
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.Fa b
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is no longer used and is about to be freed or go out of scope.
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.Sh RETURN VALUES
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The
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.Fn explicit_memset
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function returns the original value of
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.Fa b .
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.Sh EXAMPLES
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Create a buffer on the stack for a secret key, use it, and then zero it
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in memory before throwing it away.
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.Bd -literal -offset indent
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void
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f(void)
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{
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uint8_t key[32];
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crypto_random(key, sizeof(key));
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do_crypto_stuff(key, sizeof(key));
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\&...
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explicit_memset(key, 0, sizeof(key));
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}
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.Ed
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.Sh SEE ALSO
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.Xr consttime_memequal 3 ,
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.Xr memset 3
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.Sh HISTORY
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The
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.Fn explicit_memset
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function appeared in
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.Nx 7.0 .
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