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	1	.\" Copyright (c) 1990, 1991, 1993
	2	.\" The Regents of the University of California. All rights reserved.
	3	.\"
	4	.\" This code is derived from software contributed to Berkeley by
	5	.\" the American National Standards Committee X3, on Information
	6	.\" Processing Systems.
	7	.\"
	8	.\" Redistribution and use in source and binary forms, with or without
	9	.\" modification, are permitted provided that the following conditions
	10	.\" are met:
	11	.\" 1. Redistributions of source code must retain the above copyright
	12	.\" notice, this list of conditions and the following disclaimer.
	13	.\" 2. Redistributions in binary form must reproduce the above copyright
	14	.\" notice, this list of conditions and the following disclaimer in the
	15	.\" documentation and/or other materials provided with the distribution.
	16	.\" 4. Neither the name of the University nor the names of its contributors
	17	.\" may be used to endorse or promote products derived from this software
	18	.\" without specific prior written permission.
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	.\" SUCH DAMAGE.
	31	.\"
	32	.\" @(#)rand.3 8.1 (Berkeley) 6/4/93
	33	.\" $FreeBSD: src/lib/libc/stdlib/rand.3,v 1.16 2007/01/09 00:28:10 imp Exp $
	34	.\"
	35	.Dd May 25, 1999
	36	.Dt RAND 3
	37	.Os
	38	.Sh NAME
	39	.Nm rand ,
	40	.Nm rand_r ,
	41	.Nm srand ,
	42	.Nm sranddev
	43	.Nd bad random number generator
	44	.Sh LIBRARY
	45	.Lb libc
	46	.Sh SYNOPSIS
	47	.In stdlib.h
	48	.Ft int
	49	.Fo rand
	50	.Fa void
	51	.Fc
	52	.Ft int
	53	.Fo rand_r
	54	.Fa "unsigned *seed"
	55	.Fc
	56	.Ft void
	57	.Fo srand
	58	.Fa "unsigned seed"
	59	.Fc
	60	.Ft void
	61	.Fo sranddev
	62	.Fa void
	63	.Fc
	64	.Sh DESCRIPTION
	65	.Bf -symbolic
	66	These interfaces are obsoleted by
	67	.Xr arc4random 3 .
	68	.Ef
	69	.Pp
	70	The
	71	.Fn rand
	72	function computes a sequence of pseudo-random integers in the range
	73	of 0 to
	74	.Dv RAND_MAX
	75	(as defined by the header file
	76	.In stdlib.h ) .
	77	.Pp
	78	The
	79	.Fn srand
	80	function sets its argument
	81	.Fa seed
	82	as the seed for a new sequence of
	83	pseudo-random numbers to be returned by
	84	.Fn rand .
	85	These sequences are repeatable by calling
	86	.Fn srand
	87	with the same seed value.
	88	.Pp
	89	If no
	90	.Fa seed
	91	value is provided, the functions are automatically
	92	seeded with a value of 1.
	93	.Pp
	94	The
	95	.Fn sranddev
	96	function initializes a seed, using the
	97	.Xr random 4
	98	random number device which returns good random numbers.
	99	However, the
	100	.Fn rand
	101	function still remains unsuitable for cryptographic use.
	102	.Pp
	103	The
	104	.Fn rand_r
	105	function
	106	provides the same functionality as
	107	.Fn rand .
	108	A pointer to the context value
	109	.Fa seed
	110	must be supplied by the caller.
	111	.Sh SEE ALSO
	112	.Xr arc4random 3 ,
	113	.Xr random 3 ,
	114	.Xr random 4
	115	.Sh STANDARDS
	116	The
	117	.Fn rand
	118	and
	119	.Fn srand
	120	functions
	121	conform to
	122	.St -isoC .
	123	.Pp
	124	The
	125	.Fn rand_r
	126	function is as proposed in the POSIX.4a Draft #6 document.