(Dependency Walker) missing explicit type on function

Question

Apologies in advance for noob mistakes. This is my first question here. First, some background:

I am trying to create a module for a program using dependency walker to find C++ functions in a .dll that I don't have the lib or any source code for. You can also assume that I can't get support from the original developer. Basically, I checked another file that accesses it to see what the minimum functions were to get it working. Here is an example of the undecorated names that are output:

void foo::bar::baz(float)
float foo::bar::qux(void)
foo::bar::bar(void)
class foo::bar & foo::bar::operator=(class foo::bar const &)

The top two functions obviously take float or void and return float or void. I got a similar function working using something like:

HINSTANCE THEDLL = LoadLibrary("C:\\dllFolder\\theDll.dll");
typedef float (*quxType)(void);
quxType qux = (quxType)GetProcAddress(THEDLL, "quxMangledName");

So those are not a problem.

Now, the third on the list looks like another function that takes void, but it doesn't have an explicit return type. Does this mean I should just use an implicit type for it, is it void, or is it not really a function? If not, what is it?

I have no idea what to do with the fourth one. Is it even possible to handle without the associated .h file?

I looked around, but I couldn't find any information on what to do when the function doesn't look like a normal function with an explicit return type. Despite using basically the same code that I used to get a function working in a similar .dll, I keep getting an access violation crash when I try to use function #2 here (I really just need function #2). So I am guessing that the .dll needs more information or needs something initialized first, which is why I am interested in the others on the list.

I realize this is a complicated problem, so there probably won't be a "Right answer" solution to get it working, but if I am making any obvious mistakes, or if there are any general suggestions for how to attack the problem (even alternatives to dependency walker), let me know.

Answer 1

The 3rd one is the default constructor of bar. The 4th one is the copy assignment operator of bar.

I think you need to instantiate the class first, in order to call the 2nd method. Otherwise the method would be called with an invalid 'this' that causes access violation.

The problem is how you instantiate it? If you can find a factory function that returns a bar in the DLL, you can try to use it.

If you don't see a factory function and you don't have the lib file, you can refer to answers here on how to create a lib from a DLL: How to make a .lib file when have a .dll file and a header file

You also need to create header file for the class, with the correct order and types of members. This way you don't have to use LoadLibrary and GetProcAddress, just use the class as normal.

You may still use LoadLibrary and GetProcAddress without the lib and header though, this blog shows how to manually allocate memory, call constructor, gets an object and pass that object to call a method: http://recxltd.blogspot.com/2012/02/working-with-c-dll-exports-without.html