[ros-dev] [ros-diffs] [tkreuzer] 26396: NtGdiGetObject: - return 0 if buffer != 0 and count == 0 - don't write beyond umode buffer size (max count bytes!) - use SEH only once - No need for Ret & RetCount, use only RetCount - document the function

[Timo Kreuzer]

Hmm. I got different results with a BRUSH. I'll have a look at that 
later, must work now.


Ged wrote:
>> + * @remarks
>> + *   The function will always return the complete size of the object's 
>> data,
>> + *   but will copy only a maximum of count bytes to the specified buffer.
>>     
>
>
>
> This isn't necessarily true, and the function is slightly flawed because of
> it. It's a rather weird API in terms of it's results.
> Your rewrite doesn't take into account the following cases, according to XP:
>
> ................................................................
>
> BITMAP behaviour
>
> GetObjectW(hBmp, -1, &bmp)  returns 24 and fills the struct
> GetObjectW(hBmp, 0, &bmp)   returns 0 and doesn't fill the struct
> GetObjectW(hBmp, 1, &bmp)   returns 0 and doesn't fill the struct
> GetObjectW(hBmp, sizeof(BITMAP), &bmp)   returns 24 and fills the struct
> GetObjectW(hBmp, 5000, &bmp)   returns 24 and fills the struct
>
> DIBSECTION behaviour
>
> GetObjectW(hBmp, -1, &dib)  returns 24 and fills the struct
> GetObjectW(hBmp, 0, &dib)   returns 0 and doesn't fill the struct
> GetObjectW(hBmp, 1, &dib)   returns 0 and doesn't fill the struct
> GetObjectW(hBmp, sizeof(BITMAP), &dib)   returns 24 and fills the struct
> GetObjectW(hBmp, sizeof(DIBSECTION), &dib)   returns 24 and fills the struct
> GetObjectW(hBmp, 5000, &dib)   returns 24 and fills the struct
>
> Non struct behaviour
>
> The function will always return 24, no matter what size is passed.
>
> ................................................................
>
> So, we can conclude that if size is less than 0, it works.
> If size if between 0 and 23, it doesn't, and anything above works.
> If we pass NULL, as the struct, we return 24, but obviously don't fill the
> struct.
>
> I would have grabbed you on IRC, but you weren't around ;)
>
> Ged.
>
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