Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Tue, 04 Sep 2012 11:41:18 +0200
From: Igmar Palsenberg <>
Subject: Re: 'Proper' software writing

On 9/4/12 3:50 AM, Rich Felker wrote:
> On Mon, Sep 03, 2012 at 03:55:47PM +0200, Igmar Palsenberg wrote:
>> Hi,
>> When attempting to fix my own piece of software I've come to the
>> conclusing that writing somewhat portable software (glibc vs musl) is a
>> huge PITA.
> Yes. Actually it's also a huge PITA between other implementations too,
> but the breakage is all a lot more subtle. Basically the surest way to
> write portable software is to use _POSIX_C_SOURCE or _XOPEN_SOURCE and
> write purely to the standards, not using any extension functionality,
> but often you want or even need at least some extensions that are
> pretty much universally available, and then there's no well-defined
> way to get them...
This code is Linux only. I basically can use _GNU_SOURCE, but that pulls
in way to much, and not to mention
things you don't want in decent software. For now, I've settled for
_XOPEN_SOURCE and _BSD_SOURCE, and redefine the stuff I need (dladdr(),
some network related defines).

That seems to work for me. I've broken my glibc build, but that's a fix
for later :)
>> - Why use _BSD_SOURCE and _GNU_SOURCE at all ? What is the argument of
>> not exposing *ALL* stuff that is in musl ?
> All is probably too much; there's a lot of ugly cruft (like lowercase
> macros named major and minor getting exposed whenever you include
> stdlib.h) in the "expose it all" _GNU_SOURCE profile. This is bad
> enough if you're requesting it, but really bad if it's just there by
> default.
> I'm well aware that your frustration is the first/biggest FAQ people
> have when trying to use musl and that it's a bad first experience.
I like clean software. Musl helps with that, so that you actually
*think* before coding. Musl and -Werror are my best friends for now.
I've had more bad experiences with GNU software then with Musl. Musl I
can usually fix myself, GNU tools are usually a whole different story.
> Right now there's a big ongoing thread about what to do about it, and
> we're doing some research on applications and the headers themselves
> to figure out what a sane, clean, default profile to expose would be.
>> - Is there a way to do proper feature detection ? I tried autoscan from
>> autotools, but the outcome wanted to make me cry. It missed about all
>>    that is important.
> Gregor has a really good guide to using autotools properly, and some
> tricks to make generated autoconf scripts lighter/faster by
> dummying-out useless ones:
Thanks. I'll look into that.



Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.