Re: [Qemu-trivial] [Qemu-devel] [PATCH] libcacard: fix wrong array expansion logic

[Michael Tokarev <mjt@tls.msk.ru>]

26.05.2014 10:25, Markus Armbruster wrote:
> Michael Tokarev <mjt@tls.msk.ru> writes:
> 
>> The currrent code in libcacard/vcard_emul_nss.c:vcard_emul_options()
>> has a weird bug in variable usage around expanding opts->vreader
>> array.
>>
>> There's a helper variable, vreaderOpt, which is first needlessly
>> initialized to NULL, next, conditionally, only we have to expand
>> opts->vreader, receives array expansion from g_renew() (initially
>> realloc), and next, even if we don't actually perform expansion,
> 
> I don't get the "(initially realloc)" part.  The sentence makes sense to
> me just fine without it, though.

I was in context of your patch which changes realloc() to g_renew().
And I failed to mention that this my patch is on top of yuors,
too - think of this comment as such a mention ;)

>> the value of this variable is assigned to the actual array,
>> opts->vreader, which was supposed to be expanded.
>>
>> So, since we expand the array by READER_STEP increments, only
>> once in READER_STEP (=4) the code will work, in other 3/4 times
>> it will fail badly.
>>
>> Fix this by not using this temp variable when expanding the
>> array, and by dropping the useless =NULL initializer too -
>> if it wasn't in place initially, compiler warned us about
> 
> "would have warned us"?

Oh yeah.  I tried to remember the right English construct, but
failed.  This tense always escpapes my mind for some reason :)


> Much more straightforward now.  Thanks!
> 
> Reviewed-by: Markus Armbruster <armbru@redhat.com>

Thank you.  I'll fix the comment.  And I'm now ready to push
whole -trivial.

/mjt