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bug#32605: [w64] (random) never returns negative
From: |
Andy Moreton |
Subject: |
bug#32605: [w64] (random) never returns negative |
Date: |
Sat, 14 Aug 2021 19:47:22 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (windows-nt) |
On Sat 14 Aug 2021, Eli Zaretskii wrote:
>> From: Andy Moreton <andrewjmoreton@gmail.com>
>> Date: Sat, 14 Aug 2021 14:40:35 +0100
>>
>> >> On 32bit builds both options are roughly equivalent.
>> >> On 64bit builds option (b) is better as option (a) does unnecessary work.
>> >
>> > The above assumes we will never call 'random' except via 'get_random'.
>> > Is that something we want to bet on?
>>
>> Option (b) fixes bugs in the current code. Currently 'get_random' is the
>> only caller of 'random'. If inefficiency is a problem after later code
>> changes, then then this issue can be revisited.
>>
>> Another option is to replace the imlementation of 'random' in w32.c with
>> a different PRNG that can generate 31 bits more efficiently than using 3
>> calls to 'rand_as183'.
>>
>> Yet another possibility is to use 'getrandom' from gnulib instead of all
>> of this Windows specific code, but that may bring a fresh set of
>> concerns to be considered.
>
> Thanks, I've decided to go with a hybrid approach that doesn't change
> how 32-bit builds behaved up to now.
That looks fine, and the bug reported by the OP now appears fixed in
testing on 32bit and 64bit builds.
AndyM
- bug#32605: [w64] (random) never returns negative, (continued)
- bug#32605: [w64] (random) never returns negative, Andy Moreton, 2021/08/13
- bug#32605: [w64] (random) never returns negative, Eli Zaretskii, 2021/08/14
- bug#32605: [w64] (random) never returns negative, Andy Moreton, 2021/08/14
- bug#32605: [w64] (random) never returns negative, Eli Zaretskii, 2021/08/14
- bug#32605: [w64] (random) never returns negative, Andy Moreton, 2021/08/14
- bug#32605: [w64] (random) never returns negative, Eli Zaretskii, 2021/08/14
- bug#32605: [w64] (random) never returns negative, Andy Moreton, 2021/08/14
- bug#32605: [w64] (random) never returns negative, Eli Zaretskii, 2021/08/14
- bug#32605: [w64] (random) never returns negative, Andy Moreton, 2021/08/14
- bug#32605: [w64] (random) never returns negative, Eli Zaretskii, 2021/08/14
- bug#32605: [w64] (random) never returns negative,
Andy Moreton <=
- bug#32605: [w64] (random) never returns negative, Eli Zaretskii, 2021/08/15