hookfxr

Reroutes entrypoint DLLs for CoreCLR apphosts by proxying through hostfxr.dll, allowing .NET Core applications to be modified without overwriting any files.

Usage

Place hostfxr.dll and the accompanying hookfxr.ini into the same directory as your .NET Core application. In the ini file, specify the DLL you want to reroute the entrypoint to, for example:

[hookfxr]
target_assembly=MyApp.dll

When you run your application, hostfxr.dll will intercept the entrypoint and redirect it to MyApp.dll instead of the original that was shipped with the application. Refer to the ini file for more options.

Other features

• .deps.json of target assembly can be merged into the one of the origin assembly, by setting merge_deps_json=true in hookfxr.ini. This allows the runtime to resolve native assemblies of the origin assembly and the target assembly.
• The path of the origin assembly is now written into the HOOKFXR_ORIGINAL_APP_PATH environment variable before the runtime is loaded. Your loader can access this variable to know what target assembly it needs to load.

Limitations

• Only supports .NET Core global framework-dependent deployments. Self-contained deployments are currently not supported.
• Currently only supports Windows. On other platforms, just run your code directly.
• Requires a custom version of libnethost built from this branch of runtime that exposes additional functionality and is built against a static CRT.