[LTP] [PATCH v2 1/2] openat2: define _GNU_SOURCE and include <fcntl.h>

[Li Wang]

On Wed, Feb 04, 2026 at 11:27:53PM +0100, Petr Vorel wrote:
> Hi Li,
> 
> ...
> > > lapi/openat2.h uses struct open_how directly, shouldn't be included lapi/fcntl.h
> > > there?
> 
> > From my understand lapi/* are appendix for missing stuff in header file.
> 
> Yes, but we agreed in the past, that it's better to include relevant libc/kernel
> header in the lapi header [1]:
> 
> 	LAPI header should always include original header.
> 
> [1] https://github.com/linux-test-project/ltp/blob/master/doc/old/C-Test-API.asciidoc#lapi-headers
> 
> I thought we had a discussion about it, but now I see nobody acked the change in
> ML (cfbc41d775), therefore I somehow pushed this approach without consensus with
> others. I'm sorry for that, we can revise that. At the moment quite a few lapi
> headers use this approach (likely majority).
> 
> IMHO it's better to include it than expect that all tests which use lapi header
> will include relevant header *before* (otherwise tests can happily always depend
> on fallback instead of using a real value from a system header).

Yes, I generally agree with this, and here is my understand:

1. Testcase should include original <header.h> (but not "lapi/header.h")
   if *only* need the original <header.h> file.

2. LAPI-header should always include original <header.h>, it handling
   the missing/conflicting part there.
   Thus, we can treat "lapi/header.h" as a patched <header.h> and only
   use it intead of the original <header.h> in testcase if needed.

3. We avoid including both original <header.h> and "lapi/header.h" in
   testase at the same time.

> It's a minor detail, but being consistent helps for newcomers to understand
> LTP code.
> 
> And *if* we agree on it, it should be now doc/developers/ground_rules.rst.
> 
> Also there is a different approach where should be fallbacks. We use some lapi
> headers (e.g. lapi/openat2.h but there are more) which don't have public
> equivalent in libc (/usr/include/bits/openat2.h cannot be used directly, but via
> <fcntl.h>). Therefore I would put content of lapi/openat2.h into lapi/fcntl.h,
> but that's a minor detail.

I am ok with it, the advantage merge lapi/openat2.h into lapi/fcntl.h is
keep things more centralized.

But also, keep lapi/openat2.h seperated is more modular, and it should
contains <fcntl.h> as well.

> > Test cases should only include standard header files, and lapi should
> > only be used in case of missing or conflicting header files.

> But lapi/openat2.h also uses struct open_how. I would either include <fcntl.h>
> in both sources or just in lapi/openat2.h. Having it only in tests looks to me
> as not ideal.

Right, thanks for bring up this topic.

-- 
Regards,
Li Wang