Subj : EMS[CS]: Re: using LoadLibrary and GetProcAddress with MS DLL
To   : borland.public.cpp.borlandcpp
From : Christian Schoett
Date : Fri Mar 18 2005 09:49 am

Thank you very much again, Ed!

> > 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?
>
I am ashamed because the problem, as in about 99% of all cases, sat in front
of my PC ...

The problem was that the linker couldn't find the object files of my
projects and threw a warning but nevertheless created the .lib file
(although only 1KB big). Of course, the exported functions were not found
afterwards.

However, I will try your example and let you know the result.

>       FuncType One = (FuncType) GetProcAddress(dll_hand, "@One$qv");
>       FuncType Two = (FuncType) GetProcAddress(dll_hand, "@Two$qv");
>
I didn't have to decorate the function names in my .lib within BCC. I can
use the same names as in VC.

Kind regards, Chris


"Ed Mulroy [TeamB]" <dont_email_me@invalid.com> schrieb im Newsbeitrag
news:4239bd19$1@newsgroups.borland.com...
> That is because I told you something which was wrong.
>
> To show the actual text of exports which have mangled names the
> command is:
>     tdump -m -ee dllname.dll
>
> and not this, which is what I said before
>     tdump -ee dllname.dll
>
> The '-m' is required so that tdump will show the mangling.
>
> Below is a simple example of an explicitly loaded DLL with
> name-mangled exports.  Please let me know of 1-how the example worked
> on your machine and 2-if you are still having problems.
>
>   -----TEST1.CPP-----
>   #include <windows.h>
>
>   void WINAPI MsgBox(const char *s, const char *title="Main Program")
>     {
>     MessageBox(HWND_DESKTOP, s, title, MB_OK);
>     }
>
>   int WINAPI WinMain(HINSTANCE, HINSTANCE, LPSTR, int)
>     {
>     MsgBox("Before loading DLL");
>
>     HMODULE dll_hand = LoadLibrary("DLL1.DLL");
>
>     if (dll_hand)
>       {
>       typedef void (*FuncType)();
>
>       FuncType One = (FuncType) GetProcAddress(dll_hand, "@One$qv");
>       FuncType Two = (FuncType) GetProcAddress(dll_hand, "@Two$qv");
>
>       if (One)
>         One();
>       else
>         MsgBox("Unable to load address of One()", "Error");
>
>       if (Two)
>         Two();
>       else
>         MsgBox("Unable to load address of Two()", "Error");
>
>       FreeLibrary(dll_hand);
>       }
>     else
>       {
>       MsgBox("Error: Could not load DLL1.DLL");
>       }
>
>     return 0;
>     }
>   -----DLL1.CPP-----
>     #include <windows.h>
>
>     BOOL WINAPI DllEntryPoint(HINSTANCE, DWORD, LPVOID)
>       {
>       return TRUE;
>       }
>
>     static void WINAPI MBox(const char *msg)
>       {
>       MessageBox(HWND_DESKTOP, msg, "From the DLL",  MB_OK);
>       }
>
>     void __declspec(dllexport) One()
>       {
>       MBox("Function One()");
>       }
>
>     void __declspec(dllexport) Two()
>       {
>       MBox("Function Two()");
>       }
>   -----Commands to build-----
>   bcc32 -W -v test1
>   bcc32 -WD -v dll1
>   ---------------------------
>
>
> .  Ed
>
> > Christian Schoett wrote in message
> > news:42397d44@newsgroups.borland.com...
> >
> > 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?
>
>

.