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Diffstat (limited to 'lib/libc/stdlib/rand.3')
-rw-r--r-- | lib/libc/stdlib/rand.3 | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/lib/libc/stdlib/rand.3 b/lib/libc/stdlib/rand.3 new file mode 100644 index 0000000..ee24dba --- /dev/null +++ b/lib/libc/stdlib/rand.3 @@ -0,0 +1,121 @@ +.\" 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. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. 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 May 25, 1999 +.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 +These interfaces are obsoleted by +.Xr random 3 . +.Ef +.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 the +.Xr random 4 +random number device which returns good random numbers. +However, the +.Fn rand +function still remains unsuitable for cryptographic use. +.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. +.Sh SEE ALSO +.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. |