Creating an MSVC import library from a DLL that uses stdcall

Question

I have a dll that exports

extern "C" __declspec(dllexport) int __stdcall Foo( void );

A dump of the dll shows

******************************************************************************
Section:             Exports
File Offset:         00001400 (5120)
  Flags:             00000000
  Time Stamp:        00000000
  Major Version:     0000
  Minor Version:     0000

Exports from simple.dll
  3 exported name(s), 3 export addresse(s).  Ordinal base is 1.
  Sorted by Name:
    RVA      Ord. Hint Name
    -------- ---- ---- ----
    00002104    3 0000 std::nothrow
    00001258    2 0001 Foo
    000020F8    1 0002 ___CPPdebugHook

******************************************************************************

I started with the following def file:

LIBRARY simple.dll 
EXPORTS
  Foo

This created a lib file with the following exports:

Exports
       ordinal    name
                  _Foo

When I link with this library, the msvc linker complains that it can't find _Foo@0. To correct this problem, I added an alias to the def file.

LIBRARY simple.dll 
EXPORTS
  Foo
  Foo@0=Foo

Which results in a lib file with exports

Exports
       ordinal    name
                  _Foo
                  _Foo@0

Now the project links without any problem. However, when I try to run it, I get the message

"The procedure entry point Foo@0 could not be located in the dynamic link library simple.dll"

So it appears that even though I told lib.exe that Foo@0 is an alias for Foo, it still creates an import library that tries to load "Foo@0" by name.

Is there a way to get the import library to load "Foo" when I asked for "Foo@0"?

Thanks,

David

Malcolmmalcom

Answer 1

You had the right idea trying to use an alias ...

"it seems LIB does not accept aliased forms (it will simply ignore the part after the equal-sign); 2) it assumes all functions in the DEF file __cdecl. The second point lies in the fact that the import library it produces will map each symbol in the DLL to an internal name with an underscore prefixed, i.e., the linker using the import library will try to resolve an undefined symbol _Function to the symbol Function in the DLL. It takes no special care of the __stdcall calling convention. With some techniques we could use LIB to produce import libraries for __stdcall functions, but the caller could only call them by ordinal, not by name. The details are left as an exercise :-)." (http://wyw.dcweb.cn/stdcall.htm)

Instead of using an alias use an ordinal: (using your example):

LIBRARY simple.dll 
EXPORTS
     Foo
     Foo@0    @2 ;(from your dumpbin)

Worked for me :)

Ebba

Works like a charm! Exactly what I needed. It's amazing that Microsoft makes it so difficult to create an import library. Thanks!! – Malcolmmalcom