Windows: How to create custom appcompat shims (Application Fixes)?

Question

Windows has the capability to apply shims to mis-behaving applications. Shims are used to intercept API calls and change it. For example, shims can be used to:

• change the incoming paramters
• lie about the return values
• change it to call something else

The Application Compatibility Tookit has quite a few existing shims you can apply to your own mis-behaving application. Here's an example of one that ignores your API call and instead calls a completely different API instead:

i need a shim that isn't one of the hundreds of shims Microsoft already wrote. i need a custom shim.

In my case i want to intercept calls to:

GetSystemMetrics(0x1000)

so that it returns 0. i can't find any information on how to give Windows my own DLL that will have the fix i need. i don't even know if you can create custom shims.

Does Windows support custom shims?

Answer 1

I'm not aware of any way of someone other than Microsoft implementing an appcompat shim.

You might want to investigate Detours, it might provide the functionality you want.