Re: Redefining inet_net_ntop - Mailing list pgsql-hackers

From Craig Ringer
Subject Re: Redefining inet_net_ntop
Date
Msg-id CAMsr+YHUtepk=0U=4+QN0SidXDCeoTQuwcYToQBo=-jGycpZJA@mail.gmail.com
Whole thread Raw
In response to Re: Redefining inet_net_ntop  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Redefining inet_net_ntop
List pgsql-hackers
On 27 January 2018 at 04:27, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Emre Hasegeli <emre@hasegeli.com> writes:
>> port.h declares inet_net_ntop and we always compile our own from
>> port/inet_net_ntop.c .

> There is another copy of it under backend/utils/adt/inet_cidr_ntop.c.
> The code looks different but does 90% the same thing.  Their naming
> and usage is confusing.

> I recently needed to format IP addresses as DNS PTR records in the
> database, and got annoyed by having no functions that outputs IPv6
> addresses in easily parseable format like
> 0000:0000:0000:0000:0000:0000:0000:0000.  I was going to send a patch
> to unify those C functions and add another SQL function to get
> addresses in such format.  Is this a good plan?  Where should those C
> functions be on the tree if they are not port of anything anymore?

Almost certainly, the thing to do is absorb updated code from bind,
not roll our own.

Definitely.

I asked because I didn't see any comments explaining why we had it and why we built it even when the local system has support for it.

I noticed because I was building an extension in C++ (yeah, fun) and it breaks because <inet/arpa.h>'s definition of inet_net_ntop is annotated with _THROW , which expands to throw() when building in c++. But this makes the prototype incompatible with the one we (re)declare in port.h without _THROW and causes  #include "postgres.h" to fail.

Sure, I can add a hack to c.h to define _THROW as a no-op when not on glibc and all that, assuming I get far enough with this extension to bother. But it made me ask why we have this duplication in the first place, hence this post.

--
 Craig Ringer                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

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