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

[Ilia Mirkin]

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.)

  -ilia