Re: [xml] EXSLT random() function

[Roumen Petrov <bugtrack roumenpetrov info>]

Chuck Bearden wrote:
> Chuck Bearden wrote:
>   
> > Daniel Veillard wrote:
> > [...]
> >     
> > >  Use the source, it's available !
> > >
> > > static double
> > > exsltMathRandom (void) {
> > >     double ret;
> > >     int num;
> > >
> > >     num = rand();
> > >     ret = (double)num / (double)RAND_MAX;
> > >     return(ret);
> > > }
> > >
> > > and man rand() states
> > >
> > > --------------------
> > >        The  rand()  function  returns  a  pseudo-random  integer between 0 and
> > >        RAND_MAX.
> > >
> > >        The srand() function sets its argument as the seed for a  new  sequence
> > >        of  pseudo-random  integers  to be returned by rand().  These sequences
> > >        are repeatable by calling srand() with the same seed value.
> > >
> > >        If no seed value is provided,  the  rand()  function  is  automatically
> > >        seeded with a value of 1.
> > > --------------------
> > >       
> > Thank you for your informative reply.  I actually know less than you 
> > think I do :-)  I did look at the source, and the syntax and logic were 
> > clear enough, but I haven't worked in C, and it didn't occur to me that 
> > I could 'man rand' since it is in the standard library.  It's all 
> > perfectly clear when you know the conventions, and now I've learned a 
> > bit.  The concern about portability makes perfect sense, and if time() 
> > is portable, then the solution in your follow-up reply makes sense to me 
> > as well.
> >     
>
> P.S.: I will even try to create and test a patch for this, if you like.
> Chuck
>   
May be to seed is enough to use bytes read from a file an to left 
entropy to be generated from external source(program).
- /dev/urandom - nonblocking random device
- /dev/random - blocking random device
- $ openssl rand - could generate a number of bytes with default output 
$HOME/.rnd
- $ ssh-rand-helper
- egd
- prngd
etc.

Roumen