Re: [PATCH v3] libctf: ctf_member_next needs to return (ssize_t)-1 on error

[Torbjorn SVENSSON <torbjorn.svensson@foss.st.com>]

On 2023-09-26 16:51, Nick Alcock wrote:
> On 13 Sep 2023, Torbjorn SVENSSON outgrape:
>> On 2023-09-13 20:37, Nick Alcock wrote:
>>> On 13 Sep 2023, Torbjörn SVENSSON verbalised:
> Honestly I suspect all we need is a better name:
> 
> ctf_set_int_errno(...);
> ctf_set_type_errno(...)
> 
> and then use one or the other, consistently. (Neither needs to call the
> other: they're only two lines long!)

Ok. I've updated the patch (V4) to be like you suggested above.
> 
>> I suppose the ctf_set_errno_unsigned could even be a macro in the ctf-impl.h header file.
> 
> I'd make both of them inline functions personally (I bet it would reduce
> code size!)

I do not see any major difference in code size for the ld.exe binary 
after the change.

> 
>>>> +int
>>>> +ctf_set_errno_signed (ctf_dict_t *fp, int err)
>>>> +{
>>>> +  fp->ctf_errno = err;
>>>> +  /* Don't rely on CTF_ERR here as it will not properly sign extend on 64-bit
>>>> +     Windows ABI.  */
>>>> +  return -1;
>>>> +}
>>> ... that Windows is not really the problem here. It's more
>>> /* Don't rely on CTF_ERR here; it is a ctf_id_t (unsigned long), and
>>>      it will be truncated to a non--1 value on platforms on which int
>>>      and unsigned long are different sizes.  */
>>> perhaps? (At least, I think that's what's going on.)
>>
>> The problem happens when the signed integral type is wider than unsigned long.
> 
> ... sizeof(signed int) > sizeof(unsigned long int)?! Is that even
> possible? I would have assumed from the C type hierarchy and the integer
> conversion rank rules would have required that unsigned long int was at
> least as big as any non-long integral type, but I don't see anywhere
> it's required in the standard, dammit...

I don't know about the 'sizeof(signed int) > sizeof(unsigned long int)' 
part, but what I said was _integral type_, not _int_. In the case where 
I saw the problem, it was ssize_t but I'm not sure what that maps to, 
but it's wider than unsigned long int apparently in this case.

>>> This probably needs testing on a wide variety of platforms with
>>> different type sizes. I'll add throwing this through my entire test
>>> matrix to my todo list, and fix any bugs observed: but the basic idea
>>> looks sound to me.
>>
>> Do you want to run this full matrix before or after submitting the patch?
>> If it's before; when do you think you will have time to do that?
>>
>> Let me know how you want to proceed.
> 
> OK, I'm back from various conferences so I can throw tests past this at
> any time, it's largely automated. So once I stop faffing about and
> changing my mind and we converge on something I'll throw it past every
> test I've got. (It takes a day or so.)

If you do not see any problem with the V4 patch, then please go ahead 
and run the tests that you have to get a verdict.

Kind regards,
Torbjörn