DefToLib

This is a script for MSVC/MSBuild that generates a .lib file from just a .def file, which is particularly useful for importing undocumented functions.

Background

Using just lib.exe for x64/ARM64 works fine because it assumes __cdecl which x64/ARM64 always use. It does not work for x86, however. This is because DLL-exported functions in x86 will most of the time use __stdcall, which lib.exe is not set up to handle. For no-name (ordinal) functions, you can bypass this by appending the __stdcall decoration in the .def file. However, for named functions, this will result in the wrong name being imported by the resulting binary.

How to use

1. Clone this repository into your project. For example, <ProjectRoot>\libs\DefToLib.
2. In your .vcxproj file, add the following line after <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />:

   <Import Project="libs\DefToLib\DefToLib.targets" Condition="Exists('libs\DefToLib\DefToLib.targets')" />

   Adjust the path as necessary to match your project structure.
3. In your project's root directory, create a defs directory (<ProjectRoot>\defs).
4. Any .def file inside that directory will automatically be compiled and linked to your project. Make sure to read the Syntax section before making any .def files.

Syntax

In the EXPORTS section of your .def file, any function you need to import needs to have a comment at the end of the line with the format ;argsize=XX, where XX is the size of the arguments visible in the __stdcall decoration.

Example:

LIBRARY WINBRAND
EXPORTS
    BrandingLoadImage ;argsize=24