What is this?

ClrHook is a lightweight native library that enables drop-in managed .NET plugins to load at runtime without modifying the target application.

It provides a unified plugin model across runtimes by wrapping CoreCLR’s built-in Host Startup Hook feature, and backporting equivalent behavior to Mono so that plugins work transparently on both runtimes.

Requirements

• Linux x64 or OSX Arm64
• Mono or CoreCLR runtime based application

Usage

1. Build coreclr (see build.sh or your preferred build method).
2. Launch your Mono application with coreclr injected, e.g.:

   # Linux
   LD_PRELOAD=/path/to/coreclr.so ./TheGame
   # OSX
   DYLD_INSERT_LIBRARIES=./clrhook.dylib ./TheGame

   Initial run will create the directory structures, so close the application and proceed.
3. Place your plugin DLLs in the coreclr/plugins/ directory. Each plugin should have a class StartupHook with a static Initialize method (see clr docs).
4. Run again and check the output for plugin load status and logs.

Plugin Examples

• Demo Plugin
• Terraria

Notes

• Tested on Linux x64 & OSX Arm64 (Apple Silicon) on games:
  • Terraria via Steam - Mono based runtime embedded (MonoKickstart/FNA)
  • Stardew Valley via Steam - Coreclr based runtime (MonoGame)
• Plugins must be compatible with the target application's Mono version and runtime configuration.
• This tool is is provided without warranty. Use at your own risk, as with anything...