[Mesa-dev] [PATCH] mesa: Fix FB blitting in case of zero size src or dst rect

[Anuj Phogat]

On Fri, Mar 8, 2013 at 8:02 AM, Paul Berry <stereotype441 at gmail.com> wrote:
> On 7 March 2013 14:15, Anuj Phogat <anuj.phogat at gmail.com> wrote:
>>
>> Framebuffer blitting operation should be skipped if any of the
>> dimensions (width/height) of src/dst rect are zero.
>>
>> Fixes: fbblit(negative.nullblit.zeroSize) in Intel oglconform
>> https://bugs.freedesktop.org/show_bug.cgi?id=59495
>>
>> Note: Candidate for all the stable branches.
>>
>> Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
>> ---
>>  src/mesa/main/fbobject.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/mesa/main/fbobject.c b/src/mesa/main/fbobject.c
>> index d6acc58..58a2d0b 100644
>> --- a/src/mesa/main/fbobject.c
>> +++ b/src/mesa/main/fbobject.c
>> @@ -2876,7 +2876,9 @@ _mesa_BlitFramebuffer(GLint srcX0, GLint srcY0,
>> GLint srcX1, GLint srcY1,
>>     readFb = ctx->ReadBuffer;
>>     drawFb = ctx->DrawBuffer;
>>
>> -   if (!readFb || !drawFb) {
>> +   if (!readFb || !drawFb ||
>> +       (srcX1 - srcX0) == 0 || (srcY1 - srcY0) == 0 ||
>> +       (dstX1 - dstX0) == 0 || (dstY1 - dstY0) == 0) {
>>        /* This will normally never happen but someday we may want to
>>         * support MakeCurrent() with no drawables.
>>         */
>
>
> This seems too early.  All of the error checking (which appears below this
> check) should still occur if the src/dst dimensions are zero.  We should add
> the check to this conditional instead (near the end of the function, at line
> 3193):
>
>    if (!mask) {
>       return;
>    }
right. I'll move it to end of function.