Re: [PATCH 13/10] tests for various pack index features

["Shawn O. Pearce" <spearce@spearce.org>]

Olivier Galibert <galibert@pobox.com> wrote:
> On Wed, Apr 11, 2007 at 08:57:09AM -0400, Nicolas Pitre wrote:
> > Hmmm what we need is a random data generator that always produces the 
> > same thing.  I'll hack something to replace urandom.
> 
> Don't hack something, ues the standard reference, the Mersenne Twister.
> 
>   http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
> 
> PRNGs are the same as cryptosystems, it's very easy to hack up
> something and get it very, very wrong.  And it's unnecessary, since
> there are very good ones available.

Indeed.  But Mersenne Twister doesn't have code to produce a random
file of size X given an initial constant seed of Y, does it?
A small program to produce X random bytes starting with seed Y
still needs to be hacked up.

Probably the smart thing to do here is to embed a copy of MT with
constant seeds so we always get the same data file produced on
every system, no matter what the implementation of the C library's
rand routine is.

Although MT is not GPL. It has its own license, one with a small
advertising clause...

-- 
Shawn.