Re: gdi32: Fix 64-bit pointer issues when copying upside-down bitmaps.

[Marcus Meissner]

On Fri, Feb 25, 2011 at 11:41:31PM +1100, Peter Urbanec wrote:
> ---
>  dlls/gdi32/dib.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)

> diff --git a/dlls/gdi32/dib.c b/dlls/gdi32/dib.c
> index 0619304..595eb9b 100644
> --- a/dlls/gdi32/dib.c
> +++ b/dlls/gdi32/dib.c
> @@ -885,7 +885,7 @@ INT WINAPI GetDIBits(
>               */
>              if (bmp->dib->dsBmih.biHeight < 0)
>              {
> -                sbits += (srcwidthb * (abs(bmp->dib->dsBmih.biHeight) - 2 * startscan - 1));
> +                sbits += (srcwidthb * (LONG)(abs(bmp->dib->dsBmih.biHeight) - 2 * startscan - 1));

Please enlighten us to the problem you are fixing? I see no 64bit pointer relation...?

Ciao, Marcus

gdi32: Fix 64-bit pointer issues when copying upside-down bitmaps.

[Peter Urbanec]

On 26/02/11 00:05, Marcus Meissner wrote:
> diff --git a/dlls/gdi32/dib.c b/dlls/gdi32/dib.c
> > index 0619304..595eb9b 100644
> > --- a/dlls/gdi32/dib.c
> > +++ b/dlls/gdi32/dib.c
> > @@ -885,7 +885,7 @@ INT WINAPI GetDIBits(
> >                */
> >               if (bmp->dib->dsBmih.biHeight<  0)
> >               {
> > -                sbits += (srcwidthb * (abs(bmp->dib->dsBmih.biHeight) - 2 * startscan - 1));
> > +                sbits += (srcwidthb * (LONG)(abs(bmp->dib->dsBmih.biHeight) - 2 * startscan - 1));
> > Please enlighten us to the problem you are fixing? I see no 64bit pointer relation...?

When running gdi32_test bitmap on Gentoo64, I see:

Unhandled exception: page fault on read access to 0x100240000 in 64-bit 
code (0x00007f7f8a708530).

Backtrace:
=>0 0x00007f7f8a708530 in libc.so.6 (+0x127530) (0x000000000022f9b0)
   1 0x00007f7f88b607c4 GetDIBits+0x11f9(hdc=0x25c, hbitmap=0x750, 
startscan=0x1, lines=0x1, bits=0x22fa1c, info=0x22fa20, coloruse=0) 
[/home/eyeon/source/wine/dlls/gdi32/dib.c:914] in gdi32 (0x000000000022f9b0)
   2 0x00007f7f891face5 
test_GetDIBits_single_pixel_destination+0x2d2(bpp=0x10) 
[/home/eyeon/source/wine/dlls/gdi32/tests/bitmap.c:3026] in gdi32_test 
(0x000000000022f9b0)
   3 0x00007f7f891fb123 func_bitmap+0xc2() 
[/home/eyeon/source/wine/dlls/gdi32/tests/bitmap.c:3082] in gdi32_test 
(0x000000000022f9b0)

A little more tracing revealed that the above line without the (LONG) 
cast turned sbits from 0x240004 to 0x100240000, which in turn caused the 
page fault in memcpy(). With the (LONG) cast in place, I see sbits 
changing from 0x240004 to 0x240000, as expected.

Using gcc (Gentoo 4.5.2 p1.0, pie-0.4.5) 4.5.2 with -O0

The addition of the cast fixes the issue and allows the winetest to succeed.

Cheers,

     Peter Urbanec