Tracking memory allocation

Robert Shearman rob at
Thu Oct 26 08:08:56 CDT 2006

Jeff L wrote:
> Robert Shearman wrote:
>> Jeff L wrote:
>>> It seems that this would not be a unique problem in wine, is there a 
>>> standard way to handle memory tracking so that if memory is freed, 
>>> at a later time we can check to see if the pointer is still valid?
>> It sounds like you could benefit from using the handle table 
>> functions in ntdll.
> Looks promising.  There don't appear to be examples of how to use the 
> functions.  I assume that I declare memory to be of type 
> RTL_HANDLE_TABLE and call RtlInitializeHandleTable to initialise it.  
> Then there is a call to RtlpAllocateSomeHandles to get the space for 
> the handles.  After this RtlAllocateHandle gets a handle off the free 
> list and RtlFreeHandle to release the handle.
> How do you access the memory pointed to by the handle?  I was thinking 
> that I would need to stash the address I am managing into the handle.  
> It looks like I can do that with the RTL_HANDLE pointer retuned by 
> RtlAllocateHandle but from then on it does not look like I can get the 
> address of the handle as RtlIsValidHandle etc do not return it.

Yes, it does. You can look at dlls/ntdll/tests/rtl.c to see how the 
functions can be used.

> If I run out of handles, how do I reallocate the table or add to it?

You can't. It is intended to be a fixed size table.

> Are the functions thread safe if I anchor the handletable off a static 
> variable in the dll?  I am going to need a persistent table for the 
> life of the dll.  Hence it has the potential to be used by multiple 
> threads.

No. You need to protect the accessing of the handle table and handles 
with a critical section.

Rob Shearman

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