[Mesa-dev] [PATCH v2] glsl/blob: handle NULL ptr in blob_write_string/blob_read_string

[Timothy Arceri]

On 05/04/17 16:41, gregory hainaut wrote:
> On Wed, 5 Apr 2017 09:09:45 +1000
> Timothy Arceri <tarceri at itsqueeze.com> wrote:
>
>> On 05/04/17 02:29, Gregory Hainaut wrote:
>>> Context:
>>> Nouveau uses NULL strings for unnamed parameter of texture gather
>>> offsets opcode.
>>>
>>> Fix piglit crashes of the 'texturegatheroffsets' tests on Nouveau
>>>
>>> v2: based on Nicolai feedback
>>
>> Hi Gregory,
>>
>> Nicolai suggested you change the caller of create a new helper function
>> for the case where string can be NULL. e.g blob_write_optional_string()
>>
>> The change below causes an extra read/write which is not required for
>> ever other use of this function. Please create the additional function
>> as a wrapper around blob_write_string()
>>
>> Thanks,
>> Tim
>>
>
> Hello Timothy,
>
> I will change it.
>
> However what do you want to do if blob_write_string is called
> with a null pointer ? Do you prefer
> * Crash
> * Assert
> * Report an internal error message
>
> I'm leading toward the latter but I'm afraid it might either corrupt
> the cache (if we skip the string write or use an empty string). Well we
> could just report an error before the crash too.

Feel free to add an assert. It shouldn't happen unless we have a bug.

If we do have a bug the corrupt cache item will be ignored after any 
newer builds of Mesa that include a fix.

>
> Best regards,
> Gregory
>