CODEWITHSUNDEEP
c++visual-c++dlldllexportdumpbin
Satyrn
Satyrn

Reputation: 63

awkward DLL exports section

I have a section of C++ code in MSVC2010 that creates a DLL wrapper. The section of code looks something like this...

extern "C" __declspec(dllexport) DWORD myDllExportFunction()
{
    return (DWORD)SomeFunction(SomeParameter);
}

or...

_declspec(dllexport) int64 _stdcall myDllExportFunction2(<someType> someParameter){
{
    return new (DWORD)SomeExternalFunction(SomeParameter);
}

I would expect my exports section from doing a dumpbin on this dll to contain just the fully qualified function name however it looks more like this.

 _myDllExportFunction@12 = _myDllExportFunction@12

I have no idea why this equal sign is there or what it means. I have a strong feeling that the function is not accessible by programs which import the dll as it is not doing what it is supposed to.

for sake of providing enough information I have included some of my compiler and linker switches

Compiler Options:

/Zi /nologo /Wall /WX- /O2 /Ob2 /Oi /Oy- /D "_WINDLL" /D "_MBCS" /D "_AFXDLL" /Gm- /EHsc /GS /fp:precise /Zc:wchar_t /Zc

Linker Options:

/MANIFESTUAC:"level='asInvoker' uiAccess='false'" /DEBUG /PDB:"C:\....\MyProj.pdb" /SUBSYSTEM:CONSOLE /OPT:REF /OPT:ICF /PGD:"C:\....\MyProj.pgd" /TLBID:1 /DYNAMICBASE:NO /NXCOMPAT:NO /IMPLIB:"MyProj.lib" /MACHINE:X86 /ERRORREPORT:QUEUE

Note: /IMPLIB:"MyProj.lib" -> This import library has all of the exports that I want to have in my DLL in the format that I want them to be in the dll.

Is there any setting in my projects options that would cause this? Was there any changes to dllexport in the past years that I might have missed? Is there any information that I could provide you that would help you understand my problem?

Upvotes: 2

Views: 906

Answers (4)

Praetorian
Praetorian

Reputation: 109119

There are a few different options to prevent name mangling.

  • Change the declaration specifier for the exported function from __stdcall to __cdecl. So the function signature should look like this

    extern "C" DWORD __declspec(dllexport) __cdecl myDllExportFunction()

If you must use the __stdcall calling convention use one of the following two methods to get around name mangling. In both cases you do not need to add __declspec(dllexport) to the function definition (but it's OK if you do).

  • Add a .def file to the project containing the lines

LIBRARY YourLibraryName
EXPORTS
    myDllExportFunction

  • In the project properties, go to Linker -> Command Line and in the edit box for Additional Options add /export:myDllExportFunction

Upvotes: 0

Ben Voigt
Ben Voigt

Reputation: 283634

If you want to control the names of exported functions (for example, to remove mangling), you'll need to use a linker module definition (.def) file.

Upvotes: 0

Puppy
Puppy

Reputation: 146910

You have mangled the name by declaring it __stdcall, presumably in a separate declaration. You must give it the __cdecl calling convention to avoid name mangling.

Upvotes: 0

John Dibling
John Dibling

Reputation: 101456

Try turning off debug information generation.

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Upvotes: 2

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