Subj : EMS[CS]: Re: using LoadLibrary and GetProcAddress with MS DLL
To   : borland.public.cpp.borlandcpp
From : Christian Schoett
Date : Thu Mar 17 2005 01:52 pm

Ed, Thank you for your quick answer.

The target is 32bit and the compiler is Borland C++ Builder. I noticed that
I chose the wrong group to post my question, sorry for that.

I have inspected code and exports again and recompiled everything. Please do
not ask why, but now it works ...

I have however encountered another problem now. Let me try to explain what I
want to do:

before:
application links import library (Microsoft or Borland obtained through
'implib') and accesses the DLL functions directly. Works fine

now:
application links custom library that loads DLL at runtime and assigns
functions via GetProcAddress. The application interface looks exactly the
same like the old one but now I can execute some supplementary code within
my custom library before calling the DLL. Of course the library file is much
bigger than the old one

Now my problem:
1. I create a test application with the C files that will go into the
library. Everything works fine.
2. I create the library and then link it to a test application. The linker
comes up with unresolved externals for all the library functions.

Did I miss sometehing when creating the library. Do I have to do something
else than just adding the library file to my test project?

Kind regards, Chris


"Ed Mulroy [TeamB]" <dont_email_me@invalid.com> schrieb im Newsbeitrag
news:423970da@newsgroups.borland.com...
> As Borland C++ can create programs for either of 16 bit Windows or 32
> bit Windows, when you ask a question please mention which of those is
> the target type in your situation.
>
> It sounds as if your diagnosis is correct.  The symptoms you describe
> are exactly what occurs when the name given to GetProcAddress does not
> match that found in the DLL.
>
> Just for the heck of it, make one more pass through the code to insure
> that the handle returned from LoadLibrary is both checked for NULL
> (Win32) or for a value <= HINSTANCE_ERROR (16 bit Windows) and that
> handle is actually the one passed as the first argument to
> GetProcAddress.
>
> Look at the contents of the *.def file, the module definition file.
> In it are the public names of the exported functions.  Those names are
> what should be given to GetProcAddress.
>
> You can also see the exact text of the public names exported from a
> DLL by giving a command like this:
>
> A command like this will also show the exact text of a DLL's exported
> names :
>
>   tdump -ee DllName.DLL
>
> Side note:
>
> An import library is just an alternate means to implicitly link to a
> DLL.  You can do it by adding either of a module definition file or an
> import library to the project.  The results should be the same from
> either.
>
> .  Ed
>
> > Christian Schoett wrote in message
> > news:42394141$1@newsgroups.borland.com...
> >
> > I have a DLL created with Visual C. It uses a .def file to export
> > the
> > functions.  Until now, I used implib to create a .lib file that can
> > be
> > linked to applications created with Borland C++ Builder. Now I
> > want to load the DLL dynamically from a static library created
> > with Borland builder using 'LoadLibrary' and 'GetProcaddress'.
> > 'LoadLibrary' is successful but 'GetProcAddress' always returns
> > NULL for all functions. I guess it has something to do with the
> > name mangling but may someone has a hint how to solve this
> > problem.
>
>

.