[PATCH] check_native: Get rid of alloca

[Andreas Schwab]

On Jun 01 2023, Florian Weimer wrote:

> * Andreas Schwab:
>
>> On Jun 01 2023, Florian Weimer via Libc-alpha wrote:
>>
>>> * Adhemerval Zanella Netto via Libc-alpha:
>>>
>>>> +static void
>>>> +iclose (int *fd)
>>>> +{
>>>> +  if (*fd >= 0)
>>>> +    __close_nocancel_nostatus (*fd);
>>>> +}
>>>> +
>>>>  void
>>>>  __check_native (uint32_t a1_index, int *a1_native,
>>>>  		uint32_t a2_index, int *a2_native)
>>>>  {
>>>> -  int fd = __socket (PF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
>>>> +  int __attribute__ ((__cleanup__ (iclose))) fd
>>>> +    = __socket (PF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
>>>> +  if (fd < 0)
>>>> +    return;
>>>
>>> I think introducing attribute cleanup where equivalent functionality can
>>> be implemented otherwise requires a discussion first.
>>
>> The cleanup attribute requires compiling the function and all callees
>> with -fasynchronous-unwind-tables.
>
> I think GCC will still call the destructor on normal scope exit (if no
> exception is thrown), even with -fno-exceptions.  That should be
> sufficient here?

The cancellation could be asynchronous.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
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