IPC between exe and dll PLEASE HELP

[ZwOOp]

Hi there again all fellow programmers. I have soon finished my little helper program in C++ so that I can get on to a more familiar language (Java so that’s why I suck on pointers ) and finish the project. I want to thank for all the help in this forum.



I have now get stuck on the IPC can someone please take a look at this I’m sure it is yeast some lame ass newbie error that I have done wrong.



This little C++ project is structured like this…

It has 1 .DLL file and one .EXE file they both import a .h file.

I now what to communicate between the .DLL and the .EXE file using WM_COPYDATA.



The error I get when debugging the code is [Unhandled exception in prog.exe (USER32.DLL): 0xC0000005: Access Violation]



(OBS there is more code then what is listed below but that is not of interest here)



This is the code in the .h file

//The structure that I want to send to the .EXE file

typedef struct ipcMsg{

                      int msgType;

                      HWND hwnd;

                      TCHAR text[100];

                      TCHAR className[100];

                      HWND parenthwnd;

} *LPWM_IPCMSG;

This is the code in the .DLL file

//A shared section between the .EXE file and .DLL file

#pragma data_seg ("shared")

LPWM_IPCMSG copyDataStruct = NULL;

TCHAR textOut[MAX_TEXT_LENGTH] = {'\0'};

CWPSTRUCT *cwp = NULL;

#pragma data_seg ()

#pragma comment(linker,"/SECTION:shared,RWS")

 

//Then there is a function WH_CALLWNDPROC

//LPARAM in the WH_CALLWNDPROC function points to a CWPSTRUCT

cwp = (CWPSTRUCT*) lParam;

//Lets put some data in my structure (lParam is a pointer to a null terminates string that newer is longer that 100 char)

lstrcat(copyDataStruct->text, (char*) cwp->lParam);

//Initiating the COPYDATASTRUCT that WM_COPYDATA points to, we set the data field of COPYDATASTRUCT 

//to point at the copyDataStruct and because it is placed in the shared memory space the .EXE should have access to it (OR???)

COPYDATASTRUCT data = {0, sizeof(copyDataStruct), (PVOID) copyDataStruct};

//And then we send it away to the .EXE window

SendMessage(hObserver, WM_COPYDATA, (WPARAM) hDllInstance, (LPARAM) &data);

And finally the code in the .EXE file that import the .h file

//This code is in the WndProc function

static LPWM_IPCMSG dataCopy = NULL;

static HWND hwndList;

hwndList = CreateWindow(TEXT("listbox"), …Some stuff

switch(message)

 {

case WM_COPYDATA:

//We extract the structure I want to use

dataCopy = (LPWM_IPCMSG)((COPYDATASTRUCT*)lParam)->lpData;

//and then we insert the string in the listbox by sending a pointer to a null terminated string, I use the one in the dataCopy structure, this is actually not a 

//pointer but not sure how to do this

SendMessage(hwndList[0], LB_INSERTSTRING, 0, (LPARAM) dataCopy->text);

return TRUE;

}

Now what access am I violating

 

[ZwOOp]

Solved