freebsd-nq/lib/libc/stdlib/rand.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
.\" the American National Standards Committee X3, on Information
.\" Processing Systems.
.\"
.\" 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
.\" 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.
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.\"     @(#)rand.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd April 2, 2013
.Dt RAND 3
.Os
.Sh NAME
.Nm rand ,
.Nm srand ,
.Nm sranddev ,
.Nm rand_r
.Nd bad random number generator
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft void
.Fn srand "unsigned seed"
.Ft void
.Fn sranddev void
.Ft int
.Fn rand void
.Ft int
.Fn rand_r "unsigned *ctx"
.Sh DESCRIPTION
.Bf -symbolic
The functions described in this manual page are not cryptographically
secure.
Cryptographic applications should use
.Xr arc4random 3
instead.
.Ef
.Pp
These interfaces are obsoleted by
.Xr random 3 .
.Pp
The
.Fn rand
function computes a sequence of pseudo-random integers in the range
of 0 to
.Dv RAND_MAX
(as defined by the header file
.In stdlib.h ) .
.Pp
The
.Fn srand
function sets its argument
.Fa seed
as the seed for a new sequence of
pseudo-random numbers to be returned by
.Fn rand .
These sequences are repeatable by calling
.Fn srand
with the same seed value.
.Pp
If no
.Fa seed
value is provided, the functions are automatically
seeded with a value of 1.
.Pp
The
.Fn sranddev
function initializes a seed using pseudo-random numbers obtained from the kernel.
.Pp
The
.Fn rand_r
function
provides the same functionality as
.Fn rand .
A pointer to the context value
.Fa ctx
must be supplied by the caller.
.Pp
For better generator quality, use
.Xr random 3
or
.Xr lrand48 3 .
.Sh SEE ALSO
.Xr arc4random 3 ,
.Xr lrand48 3 ,
.Xr random 3 ,
.Xr random 4
.Sh STANDARDS
The
.Fn rand
and
.Fn srand
functions
conform to
.St -isoC .
.Pp
The
.Fn rand_r
function is as proposed in the POSIX.4a Draft #6 document.
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`
			`.\" the American National Standards Committee X3, on Information`
			`.\" Processing Systems.`
			`.\"`
			`.\" 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. 2013-06-13 00:19:30 +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.`
			`.\"`
			`.\" @(#)rand.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			`.\"`
Replace access to /dev/random with the kernel pseudo-random number source sysctl(KERN_ARND) and remove the fallback code. Obtained from: OpenBSD Reviewed by: secteam MFC after: 1 month 2013-04-02 23:41:20 +00:00			`.Dd April 2, 2013`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Dt RAND 3`
			`.Os`
			`.Sh NAME`
			`.Nm rand ,`
Added Posix rand_r function. 1999-05-24 23:30:14 +00:00			`.Nm srand ,`
Add sranddev() since srand() is not vary much with seed, typical time 2001-04-23 02:29:10 +00:00			`.Nm sranddev ,`
Added Posix rand_r function. 1999-05-24 23:30:14 +00:00			`.Nm rand_r`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Nd bad random number generator`
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`
Move to using .In instead of .Fd #include <> for include mark-up. Inspired by comment from: dd 2001-09-07 14:46:36 +00:00			`.In stdlib.h`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Ft void`
			`.Fn srand "unsigned seed"`
Add sranddev() since srand() is not vary much with seed, typical time 2001-04-23 02:29:10 +00:00			`.Ft void`
			`.Fn sranddev void`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Ft int`
			`.Fn rand void`
Added Posix rand_r function. 1999-05-24 23:30:14 +00:00			`.Ft int`
			`.Fn rand_r "unsigned *ctx"`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh DESCRIPTION`
			`.Bf -symbolic`
Add a prominent warning about these functions' unsuitability for cryptographic purposes, and recommend using arc4random(3) instead. 2012-09-04 21:40:53 +00:00			`The functions described in this manual page are not cryptographically`
			`secure.`
			`Cryptographic applications should use`
			`.Xr arc4random 3`
			`instead.`
			`.Ef`
			`.Pp`
mdoc(7) police: expand plain text xrefs. 2001-08-08 11:48:28 +00:00			`These interfaces are obsoleted by`
			`.Xr random 3 .`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Pp`
			`The`
			`.Fn rand`
			`function computes a sequence of pseudo-random integers in the range`
			`of 0 to`
			`.Dv RAND_MAX`
			`(as defined by the header file`
mdoc(7): Use the new feature of the .In macro. 2003-09-08 19:57:22 +00:00			`.In stdlib.h ) .`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Pp`
			`The`
			`.Fn srand`
Added Posix rand_r function. 1999-05-24 23:30:14 +00:00			`function sets its argument`
			`.Fa seed`
			`as the seed for a new sequence of`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`pseudo-random numbers to be returned by`
			`.Fn rand .`
			`These sequences are repeatable by calling`
			`.Fn srand`
			`with the same seed value.`
			`.Pp`
Added Posix rand_r function. 1999-05-24 23:30:14 +00:00			`If no`
Remove whitespace at EOL. 2001-07-15 07:53:42 +00:00			`.Fa seed`
Added Posix rand_r function. 1999-05-24 23:30:14 +00:00			`value is provided, the functions are automatically`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`seeded with a value of 1.`
Added Posix rand_r function. 1999-05-24 23:30:14 +00:00			`.Pp`
Add sranddev() since srand() is not vary much with seed, typical time 2001-04-23 02:29:10 +00:00			`The`
			`.Fn sranddev`
Replace access to /dev/random with the kernel pseudo-random number source sysctl(KERN_ARND) and remove the fallback code. Obtained from: OpenBSD Reviewed by: secteam MFC after: 1 month 2013-04-02 23:41:20 +00:00			`function initializes a seed using pseudo-random numbers obtained from the kernel.`
Add sranddev() since srand() is not vary much with seed, typical time 2001-04-23 02:29:10 +00:00			`.Pp`
mdoc(7) police: "The .Fn function". 2002-12-18 12:45:11 +00:00			`The`
Added Posix rand_r function. 1999-05-24 23:30:14 +00:00			`.Fn rand_r`
mdoc(7) police: "The .Fn function". 2002-12-18 12:45:11 +00:00			`function`
Added Posix rand_r function. 1999-05-24 23:30:14 +00:00			`provides the same functionality as`
			`.Fn rand .`
			`A pointer to the context value`
			`.Fa ctx`
			`must be supplied by the caller.`
Add cross-references to lrand48(3) and arc4random(3) from rand(3) and random(3). Submitted by: Valentin Nechayev <netch netch kiev ua> MFC after: 1 week 2010-10-06 09:05:47 +00:00			`.Pp`
			`For better generator quality, use`
			`.Xr random 3`
			`or`
			`.Xr lrand48 3 .`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh SEE ALSO`
Missed space. Submitted by: brueffer MFC after: 1 week 2010-10-06 09:24:33 +00:00			`.Xr arc4random 3 ,`
Add cross-references to lrand48(3) and arc4random(3) from rand(3) and random(3). Submitted by: Valentin Nechayev <netch netch kiev ua> MFC after: 1 week 2010-10-06 09:05:47 +00:00			`.Xr lrand48 3 ,`
Add sranddev() since srand() is not vary much with seed, typical time 2001-04-23 02:29:10 +00:00			`.Xr random 3 ,`
urandom(4) -> random(4) PR: 27858 Submitted by: Yoshihiro Koya <Yoshihiro.Koya@math.yokohama-cu.ac.jp> Approved by: markm 2001-06-07 02:31:03 +00:00			`.Xr random 4`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh STANDARDS`
			`The`
			`.Fn rand`
			`and`
			`.Fn srand`
			`functions`
			`conform to`
.St -ansiC -> .St -isoC 2001-02-26 13:23:47 +00:00			`.St -isoC .`
Added Posix rand_r function. 1999-05-24 23:30:14 +00:00			`.Pp`
			`The`
			`.Fn rand_r`
			`function is as proposed in the POSIX.4a Draft #6 document.`