BUG: VMD_Post_Absolute_Pointer_Message Bug in VMOUSE

RESOLUTION

• The value in VMOUSE_FOCUS_VM is never initialized. In your initialization code, you should default it to the current VM by using something like this:
  

     VMMcall Get_SYS_VM_Handle
     mov [VMOUSE_FOCUS_VM],ebx

• The hook call VMMCall Hook_Device_PM_API does not currently have a corresponding unhook call. Therefore your VxD will need to be static.

Sample Code

;******************************
; Microsoft Corp. (C) 1991-1996
;******************************
; Your driver may already have the following code to track MOUSE
; Ownership. This code needs to be there because even as advertized, VMD_
; Post_Absolute_Message won't handle MS-DOS VMs. So your VxD needs to track
; mouse ownership and selectively call VMD_Post_Absolute_Pointer_Message
;=======================================================
VxD_Locked_Data_Seg
lpfnPreviousVMOUSEPMAPI   dd   0   ; VMOUSE's PM_API_Proc
               ; will be non-zero if you hook vmouse.

UserEventHandle   dd   0
User_Mouse_Event_Segment   dd   0
User_Mouse_Event_Offset      dd   0
VxD_Locked_Data_Ends
;In the Device_Init (or sys_dynamic_Device_init, if it
;is a dyna-loaded VxD (loaded by vmouse)) proc of your VxD,
   VxDCall   VMD_Get_Version      ; get version of
 VMOUSE
   cmp   eax, 400h      ; Q: correct support ABS coords?
   jne   done         ;   Y: Get out
   mov   eax, VMD_Device_ID      ; N: hook vmouse's service.
   mov   esi, OFFSET32 FTG_PM_API
   VMMCall   Hook_Device_PM_API      ; Hook VMOUSE's PM
 API
   mov   [lpfnPreviousVMOUSEPMAPI], esi   ; Save old address
done:
; Now on to FTG_PM_API. This will watch for Mouse.drv telling VMOUSE
; about User.exe's entry point. This entry point used to be called
; by your Mouse.drv in Windows 3.1.
BeginProc FTG_PM_API
   movzx   eax, [ebp.Client_AX]
   cmp   eax, VMDAPI_SET_MOUSE_EVENT_CALLBACK
   jne   @F
   movzx   eax, [ebp.Client_DX]
   mov   [USER_Mouse_Event_Offset], eax
   mov   eax, [ebp.Client_ECX]
   mov   [USER_Mouse_Event_Segment], ax
   jmp   goto_previous
@@:
   cmp   eax, VMDAPI_SET_MOUSE_FOCUS
   jne   goto_previous
   mov   eax, [ebp.Client_EBX]      ; contains the VM handle
   mov   [VMOUSE_FOCUS_VM], eax
goto_previous:
   jmp   [lpfnPreviousVMOUSEPMAPI]
EndProc FTG_PM_API
; Now on to mouse focus tracking. FTG needs to track mouse
; focus, because if the mouse focus is on SYS_VM, then it
; wants to handle the absolute device in one way, otherwise
; in a different way.
; Add to your CONTROL_PROC, the following line:
   Control_Dispatch Set_Device_Focus, FTG_Set_Device_Focus
; On to FTG_Set_Device_Focus
BeginProc FTG_Set_Device_Focus
   or   edx, edx      ; Q: Critical set focus ?
   jz   fsdf_set      ;    Y: set it
   cmp   edx, VMD_Device_ID   ;    N: Q: Is it for VMD ?
   jne   fsdf_exit
fsdf_set:
   mov   [VMOUSE_FOCUS_VM], ebx
fsdf_exit:
   ret
EndProc FTG_Set_Device_Focus
;***********************************************************
; All the previous code needed to be there in your VxD anyway because,
; even as advertized, VMD_Post_Absolute_Pointer_Message, didn't work for
; MS-DOS VMs. The following code will circumvent VMD_Post_Abso...
;==================================================================
; Say that you are at this decision point
; Q: Should I call VMOUSE or should I do the relative motion stuff
;    or whatever for the MS-DOS VMs ?
   mov   ebx, [VMOUSE_FOCUS_VM]
   VMMCall   Test_Sys_VM_Handle   ; Q: Is this System VM ?
   jnz   Handle_DOS_VMs      ;    N: do what you would have done.
; Handle Windows VM absolute motion here.
; Assumption: You are at interrupt time. AND
;
; Buttons = button state (button state as desired by User.exe's
;          mouse_event procedure.)
;       (without the absolute bit set).
; XPos = X position
; YPos = Y position
;
   xor   eax, eax
   cmp   [lpfnpreviousVMOUSEPMAPI], eax   ; Q: good vmouse ?
   je   call_it
   cmp   [UserEventHandle], eax      ; Q: Event scheduled already?
   jne   handled_it
   mov   esi, OFFSET32 CallUserProc
   mov   eax, TIME_CRITICAL_BOOST
   mov   ecx, PEF_Wait_For_STI OR PEF_Always_Sched
   VMMCall   Call_Priority_VM_Event
   mov   [UserEventHandle], esi
   jmp   handled_it
call_it:
   mov   al, [Buttons]
   mov   esi, [XPos]
   mov   edi, [YPos]
   VxDCall   VMD_Post_Absolute_Pointer_Message

handled_it:               ; handled hardware int.

   ....

; Now on to the final part. Call User.exe's mouse_event proc
BeginProc CallUserProc
   movzx   ecx, [USER_Mouse_Event_Segment]
   jecxz   cup_done
   Push_Client_State
   VMMCall   Begin_Nest_Exec
   movzx   eax, [Buttons]      ; buttons
   or   ax, 8000h      ; set absolute bit
   mov   [ebp.Client_EAX], eax
   mov   eax, [XPos]      ; send X position
   mov   [ebp.Client_EBX], eax
   mov   eax, [YPos]      ; send Y position
   mov   [ebp.Client_ECX], eax

   movzx   eax, [ButtonCount]   ; How many buttons ?
   mov   [ebp.Client_EDX], eax   ; send # buttons
   xor   eax, eax
   mov   [ebp.Client_EDI], eax   ; These need to be 0
   mov   [ebp.Client_ESI], eax

   mov   edx, [USER_Mouse_Event_Offset]   ; ECX Still contains SEGMENT

   VMMCall   Simulate_Far_Call
   VMMCall   Resume_Exec

   VMMCall   End_Nest_Exec
   Pop_Client_State

cup_done:
   mov   [UserEventHandle], 0      ; Reset flag so new messages
                                   ; can go in
   ret

EndProc CallUserProc