[pywin32-bugs] [ pywin32-Bugs-1203980 ] Universal Gateway mishandles ByRef Variant arguments

[SourceForge.net <no...@so...>]

Bugs item #1203980, was opened at 2005-05-18 09:39
Message generated for change (Comment added) made by mhammond
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=551954&aid=1203980&group_id=78018

Please note that this message will contain a full copy of the comment thread,
including the initial issue submission, for this request,
not just the latest update.
Category: None
Group: None
>Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: George van den Driessche (gbmvdd)
Assigned to: Nobody/Anonymous (nobody)
Summary: Universal Gateway mishandles ByRef Variant arguments

Initial Comment:
Symptoms
========

PyWin32 is installed from pywin32-204.win32-py2.3.exe. 
Using win32com.server to add commands to Visual 
Studio .NET 2003, dispatch to 
IDTCommandTarget.QueryStatus fails, saying "Cant 
convert vectors!". Execution never reaches the Python 
COM server's implementation of the QueryStatus 
method.



Cause
=====

in univgw_dataconv.cpp, in dataconv_ReadFromInTuple
(), there is a bug in the handling of ByRef Variant 
arguments. Such an argument is not dereferenced 
before being passed to PyCom_PyObjectFromVariant(), 
so that the code attempts to construct a Python object 
from data that does not constitute a Variant.

In the worst case this could cause an access violation 
and the premature death of the host process.



Solution
========

Applying the following patch to univgw_dataconv.cpp 
solves the problem, allowing Python commands to be 
added to Visual Studio:

-------- diff --------
711,713c711,720
< 				// A pointer 
to a _real_ variant.
< 				VARIANT 
*pVar = (VARIANT *)pb;
< 				obArg = 
PyCom_PyObjectFromVariant(pVar);
---
> 
> 				// A _real_ 
variant.
> 				if (bIsByRef)
> 				{
> 				
	obArg = PyCom_PyObjectFromVariant(*
(VARIANT**)pb);
> 				}
> 				else
> 				{
> 				
	obArg = PyCom_PyObjectFromVariant
((VARIANT*)pb);
> 				}
-------- diff --------

I have tested the above diff using a debug build of 
pywin32 running on Python 2.4.1.


Remarks
=======

The above diff brings the code for handling ByRef 
Variants into line with the nearby code for handling 
ByRef Int64s, and also with the corresponding code for 
handling ByRef Variants in dataconv_WriteFromOutTuple
().


----------------------------------------------------------------------

>Comment By: Mark Hammond (mhammond)
Date: 2005-06-27 21:03

Message:
Logged In: YES 
user_id=14198

checked into CVS - thanks.

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=551954&aid=1203980&group_id=78018