Re: [PATCH 1/2] [GSOC] ref-filter: add %(raw) atom

From: Phillip Wood <phillip.wood123@gmail.com>
Date: May 29, 2021, 17:23 UTC
Message-ID: <e7db3342-7022-98db-e0d2-a880f874565e@gmail.com>
In-Reply-To: <60b25ca7a01c2_265088208af@natae.notmuch>

On 29/05/2021 16:24, Felipe Contreras wrote:

Show 21 quoted lines

> Phillip Wood wrote:
>> On 27/05/2021 17:36, Felipe Contreras wrote:
>>> ZheNing Hu via GitGitGadget wrote:
>>> [...]
>>>> +static int memcasecmp(const void *vs1, const void *vs2, size_t n)
>>>
>>> Why void *? We can delcare as char *.
>>
>> If you look at how this function is used you'll see
>> 	int (*cmp_fn)(const void *, const void *, size_t);
>> 	cmp_fn = s->sort_flags & REF_SORTING_ICASE
>> 			? memcasecmp : memcmp;
> 
> Yeah, but why?
> 
> We know we are comparing two char *. Presumably the reason is that
> memcmp and memcasecmp use void *, but that could be remedied with:
> 
> 	cmp_fn = (int (*)(const char *, const char *, size_t))memcmp;
> 
> That way the same cmp_fn could be used for the two cases.

But that is still undefined behavior - the ugly cast just silences any compiler warning without making the code safe. It calls memcmp using a pointer of a different type. The type of cmp_fn and the two functions assigned to it must match.

Best Wishes

Phillip

Show 11 quoted lines

> Either way I don't care particularly much. It also could be possible to
> use void * and do the casting in tolower().
>   
>>> (and I personally prefer lower to upper)
>>
>> We should be using tolower() as that is what POSIX specifies for
>> strcasecmp() [1] which we are trying to emulate and there are cases[2] where
>> 	(tolower(c1) == tolower(c2)) != (toupper(c1) == toupper(c2))
> 
> That's true.
>