[Mesa-dev] [PATCH 2/2] st/mesa: simplify returning GL_VENDOR

[Marek Olšák]

On Wed, Jun 7, 2017 at 10:28 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> On Wed, Jun 7, 2017 at 4:22 PM, Marek Olšák <maraeo at gmail.com> wrote:
>> On Wed, Jun 7, 2017 at 10:12 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>>> This creates string lifetime issues... should probably document that
>>> the pointer returned by get_vendor and get_name are supposed to last
>>> for the lifetime of the screen.
>>
>> Was the lifetime of the string not always guaranteed?
>>
>> Most drivers use a statically-declared string or a literal string. I
>> think the lifetime has always been at least the same as the lifetime
>> of pipe_screen.
>
> Previously it was stored in st_context, so the lifetime only had to be
> for "a little while", until the next line of code saved it off. The
> nouveau implementation is, for better or worse, currently:
>
> static const char *
> nouveau_screen_get_name(struct pipe_screen *pscreen)
> {
>    struct nouveau_device *dev = nouveau_screen(pscreen)->device;
>    static char buffer[128];
>
>    util_snprintf(buffer, sizeof(buffer), "NV%02X", dev->chipset);
>    return buffer;
> }
>
> So while the pointer will remain valid, it will potentially change for
> different screens that are created within the same process space.
> (Which could happen with EGL, or maybe other odd scenarios.)

I think that should be fixed in drivers. You can, for example, put the
string into your screen structure.

Marek