Re: [ros-dev] About GDIOBJHDR header changes

[Timo Kreuzer]

Alex Ionescu wrote:
>   Let's begin with the GDI Base Object, which is a
> header at the top of
>  every GDI Object. The structure is called _BASEOBJECT (what you refer
>  to as "GDIOBJHDR") and is defined as follows:
>
>  struct _BASEOBJECT
>  {
>      HANDLE hHmgr;
>      ULONG ulShareCount;
>      LONG cExclusiveLock;
>      ULONG BaseFlags;
>      PW32THREAD Tid;
>  }; 
Your structure is 20 bytes long, I can say for sure that for all gdi
objects I have seen the header is 16 bytes. Maybe you mean
struct _BASEOBJECT
{
    HANDLE hHmgr;
    ULONG ulShareCount;
    USHORT cExclusiveLock;
    USHORT BaseFlags;
    PW32THREAD Tid;
};
This would match my findings with having 0x8000 in the BaseFlags field

>  
>  The pointer to a _BASEOBJECT is known as a POBJ.
>
>  Now, how to get to this object? Well, dxg and win32k.sys now both
>  implement different Hmhr's (Handle Managers).
>
>  In Win32K land, the handles come from gpentHmgr, and each handle is
>  indexed from it. The resulting structure is called an _ENTRY, and is
>  defined as follows:
>
>  struct _ENTRY
>  {
>      union
>      {
>          POBJ pobj;
>          HANDLE hFree;
>      };
>      union
>      {
>           ULONG ulObj;
>           struct
>           {
>                  USHORT Count:15;
>                  USHORT Lock:1;
>                  HANDLE Pid;
>           };
>      } ObjectOwner;
>      USHORT FullUnique;
>      UCHAR Objt;
>      UCHAR Flags;
>      PVOID pUser;
>  }; 
I remember a discussion about this some time ago, when I suggested
something similar to this one and you were the one who disagreed and now
you come up with this one ;-) (Everyone remember we have to deal with
endianess.)
I agree on most of it, but the second union: the structure consists of
16 bits + 32 bits.
Can you explain the fields of the second union please.

Regards,
Timo