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Message-ID: <5045CCBE.7030709@palsenberg.com>
Date: Tue, 04 Sep 2012 11:41:18 +0200
From: Igmar Palsenberg <musl@...senberg.com>
To: musl@...ts.openwall.com
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:
>
> https://bitbucket.org/GregorR/autoconf-lean
>
Thanks. I'll look into that.
Regards,
Igmar
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