Add FreeBSD PF Firewall to libbsd

[Chris Johns]

On 3/08/2016 5:00 PM, Christian Mauderer wrote:
> Am 03.08.2016 um 08:46 schrieb Chris Johns:
>> On 03/08/2016 16:15, Christian Mauderer wrote:
>>> Basically it boils down to the following: Currently I use an
>>> __attribute__ on every variable that has to be initialized. That makes
>>> updates a little more difficult because we would have to look out for
>>> changed variables. In addition it is difficult for function static
>>> variables.
>>
>> Ok, this makes sense.
>>
>>> A solution that would be simpler to maintain would be to manipulate the
>>> object file. I would use objcopy to rename all sections with initialized
>>> variables to put them into the linker set. This would be a little less
>>> obvious if you read only the c code but it would solve both problems
>>> mentioned above.
>>
>> Having transparent source is more important.
> 
> If you mean by "transparent" that it is less changed from FreeBSD then I
> agree.
> 

Yes this is what I mean. Source we take from FreeBSD with no changes is
transparent. As we add changes the opacity level increases. I have added
reporting to freebsd-to-rtems.py to provide us with a metric we can use
to monitor this.

> If you mean it should be more obvious where the section comes from
> (simpler to read - more transparent to the reader) I would not. The
> method with adding an attribute to every variable involves a lot of
> manual work and therefore is more likely to introduce bugs.

I agree, being as close to the FreeBSD source is important.

>>
>>> But it makes it necessary that the build system adds
>>> the object file manipulation step before it links the application. That
>>> is the point where I'm currently stuck.
>>
>> Should I wait for this to happen before adding any new control logic to
>> the build system?
> 
> I think that my main problem is to understand enough of waf so I can add
> the object file manipulation. As soon as I managed that I should be able
> to adapt it to a new control logic too without too much effort. So feel
> free to make the changes whenever you can fit them into your schedule.

OK. I will then take a look when I can.

Chris