[PATCH 2/3] tests: Don't pass INT_MAX to virFileReadAll()

[Michal Prívozník]

On 6/14/21 2:26 PM, Peter Krempa wrote:
> On Mon, Jun 14, 2021 at 14:14:47 +0200, Michal Prívozník wrote:
>> On 6/14/21 1:31 PM, Tim Wiederhake wrote:
>>> On Mon, 2021-06-14 at 13:06 +0200, Michal Privoznik wrote:
>>>> In a few occasions in tests we pass INT_MAX to
>>>> virFileReadLimFD(). This is not safe because virFileReadAll()
>>>> will call virFileReadLimFD() under the hood which takes the limit
>>>> and adds 1 to it.
>>>
>>> Calling virFileReadAll with "INT_MAX - 1" looks funny. Is it possible
>>> to check for "maxlen >= INT_MAX" in virFileReadLimFD instead?
>>
>> Actually, I don't understand why we need to add 1 in the first place.
>> I'll push the other two patches and send v2 for this that removes the +1.
> 
> It's so that it guarantees that a file of 'maxlen' length is read
> completely and the terminating '\0' is in the resulting string.
> 
> Removing the '+ 1' would change this kind of semantics, which may
> require audit of all callers.
> 

I'm not sure that's correct behaviour. I mean, if I specify that the
limit should be X, then at the most X bytes should be read, not X+1.

Also, virFileReadLimFD() uses saferead_lim() which upon successful
return makes sure the returned string is properly terminated.

Michal