libxtables backward compatibility

libxtables backward compatibility

[Neal P. Murphy]

I've search hither and yon and have found no (obvious) answers.

Are newer versions of libxtables.so backward-compatible with older versions?

Specifically, should programs linked to--and expecting to use--libxtables.so.7 (iptables v1.4.14) work with versions libxtables.so.10 (v1.4.21) and libxtables.so.11 (v1.6)? I suspect yes, since I haven't seen problems symlinking .10 to .7. But a definitive answer would be nice to have.

If they aren't compatible, I'll plan on including .7 and .10 binaries in the update packet.

(I know about nftables and look forward to deploying its flexibility, but we're still on linux 3.4; I'm working on updating to 3.14. Our next release will use linux 4.4 (or newer) and nftables. But that is a major change; we have a lot of rule generators in several syntaxes that will need to be modernized. The user interface will also need to be reworked.)

Thanks,
Neal

Re: libxtables backward compatibility

[Jan Engelhardt]

On Sunday 2016-07-03 22:00, Neal P. Murphy wrote:

>Specifically, should programs linked to--and expecting to use--libxtables.so.7
>work with versions libxtables.so.10 and libxtables.so.11? I suspect yes

Absolutely not. Never has been in any shared library system.

Re: libxtables backward compatibility

[Neal P. Murphy]

On Sun, 3 Jul 2016 22:59:36 +0200 (CEST)
Jan Engelhardt <jengelh@inai.de> wrote:

> 
> On Sunday 2016-07-03 22:00, Neal P. Murphy wrote:
> 
> >Specifically, should programs linked to--and expecting to use--libxtables.so.7
> >work with versions libxtables.so.10 and libxtables.so.11? I suspect yes
> 
> Absolutely not. Never has been in any shared library system.

Drat. So I'll include all three versions in the next update. Unless the older versions of iptables are not compatible with newer versions of linux. (I begin to see why some products stay with a specific set of pkg versions for longer periods of time: keeping one or two things updated can turn into a full-time job updating all of the related pkgs.)

Thanks,
Neal

Re: libxtables backward compatibility

[Jan Engelhardt]

On Sunday 2016-07-03 23:29, Neal P. Murphy wrote:
>> On Sunday 2016-07-03 22:00, Neal P. Murphy wrote:
>> 
>> >Specifically, should programs linked to--and expecting to use--libxtables.so.7
>> >work with versions libxtables.so.10 and libxtables.so.11? I suspect yes
>> 
>> Absolutely not. Never has been in any shared library system.
>
>(I begin to see why some products stay with a specific set of pkg versions for
>longer periods of time: keeping one or two things updated can turn into a
>full-time job updating all of the related pkgs.)

This is why anyone caring about their time is offloading automatable task to
software, like openbuildservice.org does for me.

Re: libxtables backward compatibility

[Neal P. Murphy]

On Sun, 3 Jul 2016 23:56:38 +0200 (CEST)
Jan Engelhardt <jengelh@inai.de> wrote:

> 
> On Sunday 2016-07-03 23:29, Neal P. Murphy wrote:
> >> On Sunday 2016-07-03 22:00, Neal P. Murphy wrote:
> >> 
> >> >Specifically, should programs linked to--and expecting to use--libxtables.so.7
> >> >work with versions libxtables.so.10 and libxtables.so.11? I suspect yes
> >> 
> >> Absolutely not. Never has been in any shared library system.
> >
> >(I begin to see why some products stay with a specific set of pkg versions for
> >longer periods of time: keeping one or two things updated can turn into a
> >full-time job updating all of the related pkgs.)
> 
> This is why anyone caring about their time is offloading automatable task to
> software, like openbuildservice.org does for me.

That would be a great service to be able to use.

Alas, Smoothwall isn't there yet; it doesn't use packages. Maybe some day. Regardless, I still have to manually update the build process when bumping gcc, glibc, binutils and similar utilities; LFS is a good guide, but it still takes a long time to figure out how to make those packages build. Never mind poring through the build logs to find which packages ignore "-m32 -march=i586" (there are plenty of x86 CPUs in use that don't have the CMOV instructions, thus i586 is required). And never mind finding all of a package's dependencies, and adding new ones to the build.

Neal