[PATCH v8] linux: Add openat2 (BZ 31664)

[Carlos O'Donell]

On 12/9/25 5:25 AM, Adhemerval Zanella Netto wrote:
> 
> 
> On 08/12/25 11:18, Florian Weimer wrote:
>> * Adhemerval Zanella:
>>
>>> The openat2 syscall was added on Linux 5.6, as an extension of openat.
>>> Unlike other open-like functions, the kernel only provides the LFS
>>> variant (so files larger than 4GB always succeed, unlike other
>>> functions with an offset larger than off_t).  Also, similar to other
>>> open functions, the new symbol is a cancellable entrypoint.
>>>
>>> The test case added only stress tests for some of the syscalls' provided
>>> functionality, and it is based on an existing kernel self-test.
>>>
>>> A fortify wrapper is added to verify the argument size if not larger
>>> than the current support open_how struct.
>>>
>>> Gnulib added an openat2 module, which uses read-only for the open_how
>>> argument [1].  There is no clear indication whether the kernel will
>>> indeed use the argument as in-out, how it would do so, or for which
>>> kind of functionality [2]. Also, adding a potentially different prototype
>>> than gnulib only would add extra unnecessary friction and extra
>>> wrappers to handle it.
>>>
>>> Checked on x86_64-linux-gnu and aarch64-linux-gnu.
>>>
>>> [1] https://gitweb.git.savannah.gnu.org/gitweb/?p=gnulib.git;a=commit;h=0b97ffdf32bdab909d02449043447237273df75e
>>> [2] https://sourceware.org/pipermail/libc-alpha/2025-September/169740.html
>>>
>>> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
>>
>> Adhemerval, Carlos, is this patch accepted, or does it need further
>> review?
> 
> I think it should be ok for inclusion, Carlos pointed out some minor
> typos in the v7 [1] and stated that I should keep the RB.
> 
> I will commit this shortly.
> 
> [1] https://sourceware.org/pipermail/libc-alpha/2025-November/172687.html
> 

Yes, v7 looked good to me with just minor typos.

Please push v8 when you get a chance so we have the new ABI/API for the release before the freeze.

-- 
Cheers,
Carlos.