[Mesa-dev] [PATCH] egl/dri2: refactor dri2_query_surface, swrastGetDrawableInfo

[Emil Velikov]

On 8 August 2017 at 10:00, Eric Engestrom <eric.engestrom at imgtec.com> wrote:
> On Tuesday, 2017-08-08 11:31:36 +0300, Tapani Pälli wrote:
>> Currently swrastGetDrawableInfo always initializes w and h, patch
>> refactors function as x11_get_drawable_info that returns success and
>> sets the values only if no error happened. Add swrastGetDrawableInfo
>> wrapper function as expected by DRI extension.
>>
>> Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
>> Reported-by: Emil Velikov <emil.velikov at collabora.com>
>
> Couple notes below, but with that:
> Reviewed-by: Eric Engestrom <eric.engestrom at imgtec.com>
>
>> ---
>>  src/egl/drivers/dri2/platform_x11.c | 23 ++++++++++++++++-------
>>  1 file changed, 16 insertions(+), 7 deletions(-)
>>
>> diff --git a/src/egl/drivers/dri2/platform_x11.c b/src/egl/drivers/dri2/platform_x11.c
>> index 4ce819f..80f2477 100644
>> --- a/src/egl/drivers/dri2/platform_x11.c
>> +++ b/src/egl/drivers/dri2/platform_x11.c
>> @@ -99,8 +99,8 @@ swrastDestroyDrawable(struct dri2_egl_display * dri2_dpy,
>>     xcb_free_gc(dri2_dpy->conn, dri2_surf->swapgc);
>>  }
>>
>> -static void
>> -swrastGetDrawableInfo(__DRIdrawable * draw,
>> +static bool
>> +x11_get_drawable_info(__DRIdrawable * draw,
>>                        int *x, int *y, int *w, int *h,
>>                        void *loaderPrivate)
>>  {
>> @@ -110,12 +110,12 @@ swrastGetDrawableInfo(__DRIdrawable * draw,
>>     xcb_get_geometry_cookie_t cookie;
>>     xcb_get_geometry_reply_t *reply;
>>     xcb_generic_error_t *error;
>> +   bool ret = false;
>
> Don't initialise `ret` here...
>
>>
>> -   *x = *y = *w = *h = 0;
>>     cookie = xcb_get_geometry (dri2_dpy->conn, dri2_surf->drawable);
>>     reply = xcb_get_geometry_reply (dri2_dpy->conn, cookie, &error);
>>     if (reply == NULL)
>> -      return;
>> +      return false;
>>
>>     if (error != NULL) {
>>        _eglLog(_EGL_WARNING, "error in xcb_get_geometry");
>
> but set it here:
>
> +   ret = false;
>
>> @@ -125,8 +125,18 @@ swrastGetDrawableInfo(__DRIdrawable * draw,
>>        *y = reply->y;
>>        *w = reply->width;
>>        *h = reply->height;
>> +      ret = true;
>>     }
>>     free(reply);
>> +   return ret;
>> +}
>> +
>> +static void
>> +swrastGetDrawableInfo(__DRIdrawable * draw,
>> +                      int *x, int *y, int *w, int *h,
>> +                      void *loaderPrivate)
>> +{
>
> +   *x = *y = *w = *h = 0;
>
> All the callers (swrast & drisw) expect these to be set unconditionally,
> so we should initialise them here.
>
Initialize preemptively or set when x11_get_drawable_info() fails -
either one will do.
With Eric's suggestions
Reviewed-by: Emil Velikov <emil.velikov at collabora.com>

> (Note that __glXDRIGetDrawableInfo() is the only impl to not honour that;
> might need to be fixed.)
>
AFAICT the function returns false on error, we should be fine.
Plus it's a legacy DRI1 codepath, so personally I will be a bit
cautious about subtle changes in behaviour

-Emil