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Re: [PATCH] dlfcn: Avoid one-element flexible array in Dl_serinfo
* Paul Eggert:
> On 5/23/19 2:34 AM, Florian Weimer wrote:
>> +# ifdef __GNUC__
>> + /* This avoids an unwanted array subscript check by the compiler,
>> + while preserving the size of the type. */
>> + __extension__ union
>> + {
>> + Dl_serpath dls_serpath[0]; /* Actually longer, dls_cnt elements. */
>> + Dl_serpath __dls_serpath_pad[1];
>> + };
>> +# else /* !__GNUC__ */
>> Dl_serpath dls_serpath[1]; /* Actually longer, dls_cnt elements. */
>> +# endif /* !__GNUC__ */
>
> Since this is actually a flexible array member, shouldn't we be using
> C99's support for that if available, instead? Something like the
> attached untested patch, say. We've been using a FLEXIBLE_ARRAY_MEMBER
> macro in Gnulib for quite some time to do this sort of thing.
This changes the size of the type and is not source-code-compatible. I
have not investigated whether the change is still reasonably safe, but
usually, wo do not make such changes.
Thanks,
Florian