Re: [patch] random.3: wfix: RAND_MAX is for rand(3)

["Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>]

On 6/8/20 1:04 PM, John Marshall wrote:
> POSIX fixes random()'s range at 2^31-1; RAND_MAX may be smaller on some
> platforms (even though with glibc or musl on Linux they are the same).
> ---
> 
> On Sat, Jun 06, 2020 at 12:45:58PM +0000, Walter Harms wrote:
>> that RAND_MAX is 2^31-1 in some cases does not matter. IMHO
>> it is wrong to mention RAND_MAX in the random page. it can
>> simply be replaced with (2**31-1)
> 
> Thanks for confirming, Walter. I forgot to mention I was happy to
> provide a patch -- suggested fix in this git-format-patch message.
> 
>     John
> 
>  man3/random.3 | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/man3/random.3 b/man3/random.3
> index 76b076f42..e3550f802 100644
> --- a/man3/random.3
> +++ b/man3/random.3
> @@ -69,7 +69,7 @@ The
>  function uses a nonlinear additive feedback random
>  number generator employing a default table of size 31 long integers to
>  return successive pseudo-random numbers in
> -the range from 0 to \fBRAND_MAX\fR.
> +the range from 0 to 2^31\ \-\ 1.
>  The period of this random number generator is very large, approximately
>  .IR "16\ *\ ((2^31)\ \-\ 1)" .
>  .PP
> @@ -125,7 +125,9 @@ or be the result of a previous call of
>  The
>  .BR random ()
>  function returns a value between 0 and
> -.BR RAND_MAX .
> +.BR INT32_MAX ,
> +i.e.,
> +.IR "(2^31)\ \-\ 1" .
>  The
>  .BR srandom ()
>  function returns no value.

Hello John,

Thanks. I applied this patch. I also agree with Walter. There's no
real need to mention INT32_MAX, so I removed that piece.

Cheers,

Michael




-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/