Solved

Problems with GetProcAddress and LoadLibrary

Posted on 2004-10-04
3
1,050 Views
Last Modified: 2012-06-22
Hi,

I have been bothered by this bug for a few days and I wish if anyone could give me a little hints or help, I will be very appreciating..

I have been trying to build a DLL for a hook.. so I started by building a regular DLL and I ran into troubles of not having the dllMain() which created problems..
So I start over again and built a similar DLL using the extension DLL.

I built the export function as the following:

extern "C" BOOL __declspec(dllexport) __stdcall InitHook(){
  ......
  ......
}

I don't see a header file for the extension DLL so I did not declare it in any header file.. is that valid?

Then I built a dialog box based application and try to call the DLL function.. I tried both implicit and explicit..

declare the BOOL __declspec(dllimport) __stdcall InitHook(); in the header file of the dialog box based application, added the .lib file to the resource, and put the .dll in the %SystemRoot%\system32 folder..

but it didn't work by having error LNK2019: unresolved external symbol..

so I turned to another explicit:

typedef BOOL (WINAPI* LPHOOK)();

hDLL = LoadLibrary("MyHook.dll");
HINSTANCE hDLL;
LPHOOK lp_InitHook;
if (hDLL){
  lp_InitHook = (LPHOOK)GetProcAddress(hDLL,"InitHook");
}

something like that..
but, although it complies okay.. it only returned a valid hDLL but with a NULL lp_InitHook..

I have been trying a lot of different methods but I am not sure what is still missing..
Any help or suggestion is welcome.. please help..
Thanks a million..
0
Comment
Question by:ewong_111
  • 2
3 Comments
 
LVL 86

Accepted Solution

by:
jkr earned 500 total points
ID: 12221531
>>extern "C" BOOL __declspec(dllexport) __stdcall InitHook()

You need to leave out the '__stdcall', since that will cause a different name decoration. It should just be

extern "C" BOOL __declspec(dllexport) InitHook()
0
 
LVL 86

Expert Comment

by:jkr
ID: 12221551
>>a different name decoration

Just to clarify - the '__stdcall' attibute will export the function like

_InitHook@<some_ordinal>

You can verify that using

dumpbin.exe /exports MyHook.dll

or using the dependency walker from www.dependencywalker.com
0
 
LVL 2

Author Comment

by:ewong_111
ID: 12221793
jkr.. u are really the genius here.. :)
0

Featured Post

Free Tool: Port Scanner

Check which ports are open to the outside world. Helps make sure that your firewall rules are working as intended.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

  Included as part of the C++ Standard Template Library (STL) is a collection of generic containers. Each of these containers serves a different purpose and has different pros and cons. It is often difficult to decide which container to use and …
Basic understanding on "OO- Object Orientation" is needed for designing a logical solution to solve a problem. Basic OOAD is a prerequisite for a coder to ensure that they follow the basic design of OO. This would help developers to understand the b…
The viewer will learn additional member functions of the vector class. Specifically, the capacity and swap member functions will be introduced.
The viewer will be introduced to the technique of using vectors in C++. The video will cover how to define a vector, store values in the vector and retrieve data from the values stored in the vector.

791 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question