Passing pointers through windows messages?

[BeanDog]

I am trying to ascertain whether a process running in a separate .exe, not just a separate thread, has completed (multithreading is not an option in this case). In the calling module, the following code executes:

volatile bool* IsDone = new bool;
*IsDone = false;
PostMessage(IndexWin, WM_INDEXER_PURGE_INDEX, (int)(IsDone), 0);
while(!(*IsDone))
{
Sleep(250);
Application->ProcessMessages();
}

So, we make a volatile bool (so it can be changed asynchronously), set it equal to false, and post a message to the other module using the pointer to the bool as the WPARAM. We then process messages until the other module
sets the bool equal to true.

In the other module, the following code is run:
volatile bool* IsDone = (bool*)Msg.WParam;
*IsDone = true;

I get an access violation from the second module when it tries to change the bool's value (writing to whatever address). Why? Is there a way to pass a pointer this way?



~BenDilts( void );




~BenDilts( void );
benbeandogdilts@cs.com

 

[Cagliostro]

Yes. You can send a handle to an allocated memory. This memory shoyld be allocated with sequrity options(there should exist some security attributes structure) as non share exclusive as usualy. Try to se how to work with that structure. John Fill

ivfmd@mail.md

 

[scalp]

Have a look in the 'Win32 Programmers reference' help file (came with builder) for the function call CreateSemaphore. If you are creating the new process from within the initial process (CreateProcess), the semaphore seems to encapsulate the functionality you are looking for with the bool stuff.

hth
scalp

 

[Cagliostro]

don't forget about using files, memory mapped files, dlls, COM objects. John Fill

ivfmd@mail.md