Re: xen-analysis ECLAIR support

[Luca Fancellu <Luca.Fancellu@xxxxxxx>]

> On 25 Aug 2023, at 09:18, Michal Orzel <michal.orzel@xxxxxxx> wrote:
> 
> Hi Stefano,
> 
> On 25/08/2023 00:24, Stefano Stabellini wrote:
>> 
>> 
>> Hi Luca,
>> 
>> We are looking into adding ECLAIR support for xen-analysis so that we
>> can use the SAF-n-safe tags also with ECLAIR.
>> 
>> One question that came up is about multi-line statements. For instance,
>> in a case like the following:
>> 
>> diff --git a/xen/common/inflate.c b/xen/common/inflate.c
>> index 8fa4b96d12..8bdc9208da 100644
>> --- a/xen/common/inflate.c
>> +++ b/xen/common/inflate.c
>> @@ -1201,6 +1201,7 @@ static int __init gunzip(void)
>>     magic[1] = NEXTBYTE();
>>     method   = NEXTBYTE();
>> 
>> +    /* SAF-1-safe */
>>     if (magic[0] != 037 ||
>>         ((magic[1] != 0213) && (magic[1] != 0236))) {
>>         error("bad gzip magic numbers");
>> 
>> 
>> Would SAF-1-safe cover both 037, and also 0213 and 0213?
>> Or would it cover only 037?
>> 
>> We haven't use SAFE-n-safe extensively through the codebase yet but
>> my understanding is that SAFE-n-safe would cover the entire statement of
>> the following line, even if it is multi-line. Is that also your
>> understanding? Does it work like that with cppcheck?
> Looking at the docs and the actual script, only the single line below SAF 
> comment is excluded.
> So in your case you would require:
> 
> /* SAF-1-safe */
> if (magic[0] != 037 ||
>    /* SAF-1-safe */
>    ((magic[1] != 0213) && (magic[1] != 0236))) {
>    error("bad gzip magic numbers");

Yes correct

> 
> I guess this was done so that it is clear that someone took all the parts of 
> the statements into account
> and all of them fall into the same justification (which might not be the 
> case).
> 
> BTW. I don't think we have also covered the case where there is more than one 
> violation in a single line
> that we want to deviate (e.g. sth like /* SAF-1-safe, SAF-2-safe */

You are right, but it should work adding multiple comments in this way:

/* SAF-1-safe */
/* SAF-2-safe */
<code where violation 1 and 2 are in the same line>

> 
> ~Michal