a027d64fa7
NetBSD, OpenBSD, and Android's Bionic number the clauses 1 through 3, so follow suit to make comparison easier.
126 lines
3.3 KiB
Groff
126 lines
3.3 KiB
Groff
.\" 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.
|
|
.\"
|
|
.\" @(#)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.
|