Date: Sat, 3 Jan 2009 10:33:22 -0200 From: "Fernan Aguero" <fernan.aguero@gmail.com> To: "Anton Berezin" <tobez@tobez.org> Cc: freebsd-perl@freebsd.org Subject: Re: Storable byteorder incompatibilities in different FreeBSD installations Message-ID: <520894aa0901030433i7a103ba7i4236ae17b83c6eae@mail.gmail.com> In-Reply-To: <20090102164439.GF40649@heechee.tobez.org> References: <520894aa0901020758o79bb1233teee539f6d599d10a@mail.gmail.com> <20090102164439.GF40649@heechee.tobez.org>
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Hi Anton,
On Fri, Jan 2, 2009 at 2:44 PM, Anton Berezin <tobez@tobez.org> wrote:
> On Fri, Jan 02, 2009 at 01:58:06PM -0200, Fernan Aguero wrote:
>
>> I've been bitten by binary incompatibilitiess (bytorder, and/or byte
>> sizes of ints, longs, and whatnot) between two perl installations
>> (both on FreeBSD, using latest perl5.8 from ports).
>
> [...]
>
>> Binary incompatibilities when reading the Storable binary data have
>> been observed in the past when running the web application from Linux
>> boxes (Ubuntu, i386 or amd64).
>
>> So why is it that building Perl outside of the ports system makes the
>> test program report '1234' which is what I would expect from an i386
>> box, while it gives '12345678' when running from within the ports
>> system? Why this unusual byteorder?
>
> This is because of PERL_64BITINT (aka -Duse64bitint) is the
> default with the port.
That is only useful in i386. In amd64, it doesn't change anything.
With or Without that define, the outcome is always:
perl -MConfig -le "print @Config{byteorder}"
12345678
perl -MConfig -le "print @Config{shortsize}"
2
perl -MConfig -le "print @Config{intsize}"
4
perl -MConfig -le "print @Config{longsize}"
8
perl -MConfig -le "print @Config{longlongsize}"
8
[tested in FreeBSD-7.1 RC1, amd64]
In FreeBSD-6.3, i386, unchecking PERL_64BITINT would give:
perl -MConfig -le "print @Config{byteorder}"
1234
perl -MConfig -le "print @Config{longsize}"
4
[all others being equal]
In FreeBSD-6.3, i386 with PERL_64BITINT:
perl -MConfig -le "print @Config{byteorder}"
12345678
perl -MConfig -le "print @Config{longsize}"
4
[all others being equal]
Apart from the byteorder issue, the other issue which I raised in my
post, was also the incompatibility in 'longsize' between two perl
instances built from ports, in different boxes.
In this case, the perl built in a FBSD-6.3, i386 box has a longsize of
4, whereas the same perl built in FBSD-7.1, amd64 has a longsize of 8.
In both cases they were compiled with PERL_64BITINT (the default for
the port), and in both cases the byteorder is the same!
How can I build a perl with a byteorder of 12345678, and a longsize of
4, in an amd64 platform? Is that possible at all?
Looking at the output of perl -V in these different Perls, in the
Compiler section I see (from the diff attached in my previous message,
this is from a build in i386)
- intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
+ intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=12345678
Can we toggle these compiler options?
>> And now for a pragmatic and urgent question:
>> iv) how can I use the ports system to build a Perl in different FBSD
>> boxes that would result in the same binary configuration (byteorder,
>> shortsize, intsize, etc.) to guarantee it would produce compatible
>> (i.e. readable from other FBSD boxes) dumps of Perl data structures?
>
> Uncheck PERL_64BITINT in the configuration dialog. (make rmconfig
> first)
>
> Apart from that, do you actually use "nstore" variants of Storable
> functions? If you use it consistently in you application, you
> might find out that the problem disappears, and it would not
> matter what platform you use.
I know about nstore, and I am switching my code to use nstore for
future releases. But, as it stands now, I've already made the mistake
of using plain 'store' in all my production code, which means I have
lots of data already written in the DB that I need to be able to read
with binary-compatible perl/Storable instances. I can do that
currently using the perl instance I have in FBSD-6, i386. But I was
wondering if it's possible to make the port build a perl with a
different 'binary' configuration.
You might want to think about this problem in the following terms:
i) you have lots of data dumped from perl in a specific binary format
ii) your old hardware is gone/lost
iii) you need to build a perl in a new box, perhaps in a different
platform, that would read these Storable dumps.
Is this possible using the FreeBSD perl port?
In my case, this would be translated to: can I build a perl instance
with a byteorder of 12345678, and a longsize of 4 in a FreeBSD-7.1,
amd64 box?
Cheers,
Fernan
> Cheers,
> \Anton.
--
fernan
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