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Re: new long doubles option: gcc libquadmath

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From:
demerphq
Date:
September 22, 2014 08:31
Subject:
Re: new long doubles option: gcc libquadmath
Message ID:
CANgJU+VahJqMO1MGUCRi8QESvSU8XjTDDR1H2Euj3V8TuoQrew@mail.gmail.com
On 21 September 2014 14:39, Jarkko Hietaniemi <jhi@iki.fi> wrote:

> On Saturday-201409-20, 0:05, demerphq wrote:
>
>>     I know you're being facetious, and crypto uses integer math so we're
>>
>
> Moi?  Facetious?  I don't even know that word.


Josh said that, not me.


>
>
>      not talking about leaking private key material, but as a general
>>     principle, transporting garbage should be avoided.  It was bad when
>>     Microsoft Word bumped a document file's logical EOF to match its
>>     physical EOF (thus carrying around a partial block of who-knows-what
>>     prior data, which very well could have included your credit card
>>     number), and it's bad now. Any unused bits in the in-memory format
>>     should be zeroed before transmission or storage.
>>
>>
>> I agree. Sereal will zero the extra bytes. (Cant remember this second if
>> that is going to be the next release, or the current one.)
>>
>
> As does Perl's pack/unpack code for long double.
> ... checking ...
> Wait, I can see explicit zeroing only in the pack() case (search for
> "unused bits" in pp_pack.c.  Will investigate whether the unpack()
> does it somehow more sneakily.
>

Nod. My concern on what you said in a separate post about "ld" meaning
"larger than double" instead of a specific size, and having to use
$CONFG{longdblkind}
to find out what kind it is makes me a bit concerned about things like
Storable and Sereal. We will make Sereal "work" for some reasonable
definition of work, but Storable seems a bigger concern.

Yves


-- 
perl -Mre=debug -e "/just|another|perl|hacker/"

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