Re: [PATCH v3 7/8] gzip: move bitbuffer into gunzip state

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 26/04/2024 6:57 am, Jan Beulich wrote:
> On 26.04.2024 07:55, Jan Beulich wrote:
>> On 25.04.2024 21:23, Andrew Cooper wrote:
>>> On 24/04/2024 5:34 pm, Daniel P. Smith wrote:
>>>> --- a/xen/common/gzip/inflate.c
>>>> +++ b/xen/common/gzip/inflate.c
>>>> @@ -1017,8 +1014,8 @@ static int __init inflate(struct gunzip_state *s)
>>>>      /* Undo too much lookahead. The next read will be byte aligned so we
>>>>       * can discard unused bits in the last meaningful byte.
>>>>       */
>>>> -    while (bk >= 8) {
>>>> -        bk -= 8;
>>>> +    while (s->bk >= 8) {
>>>> +        s->bk -= 8;
>>>>          s->inptr--;
>>>>      }
>>> Isn't it just me, but isn't this just:
>>>
>>>     s->inptr -= (s->bk >> 3);
>>>     s->bk &= 7;
>>>
>>> ?
>> I'd say yes, if only there wasn't the comment talking of just a single byte,
>> and even there supposedly some of the bits.

The comments in this file leave a lot to be desired...

I'm reasonably confident they were not adjusted when a piece of
userspace code was imported into Linux.

This cannot ever have been just a byte's worth of bits, seeing as the
bit count is from 8 or more.  Right now it's an unsigned long's worth of
bits.
> Talking of the comment: Considering what patch 1 supposedly does, how come
> that isn't Xen-style (yet)?

I had been collecting some minor fixes like this to fold into patch 1
when I committed the whole series.

I'll see if I can fold them elsewhere.

~Andrew