Random C# / Mono / .NET assembly patcher using Mono.Cecil.

It patches any C# assembly (PE32 executable (console) Intel 80386 Mono/.Net assembly) with any given assembly patches.

The patches are in form of C# assemblies, making it easy to use for quick and (as long as the input assembly isn't obfuscated) version-independent patching / modding / prototyping.

Finally, MonoMod patches itself into the input assembly entry point. In case the user runs the patched assembly in a shell, the used MonoMod version gets printed.

You drop the MonoMod.exe, Mono.Cecil.dll and your patches into a folder. Then, in your favorite shell (cmd, bash):

MonoMod.exe Assembly.exe

MonoMod then scans the directory the file is in for files named Assembly.*.mm.dll (in case of FEZ.exe: FEZ.Mod.mm.dll). Finally, it produces an Assembly.mm.exe, which is the patched version of the assembly.

Black magic, Mono.Cecil and a lot of luck. Oh, and many, many hacks and workarounds.

You decompile the input assembly to get a tree of all types and methods. Use that tree to create another assembly which contains pieces of that tree with custom code.

To further simplify patching, MonoMod offers following features:

• For types and methods, to be ignored by MonoMod (because of a superclass that is defined in another assembly and thus shouldn't be patched), use the MonoModIgnore attribute.
• For types that must have another name than the original type but should still get patched into the input assembly by MonoMod, prefix the type with "patch_".
• To call the original method, create a stub method of the same signature with the prefix "orig_".

##For gamedevs and others: How can I check my game etc. has been modded? MonoMod creates a type called "WasHere" in the namespace "MonoMod" in your assembly. You can simply call

if (Assembly.GetExecutingAssembly().GetType("MonoMod.WasHere") != null) {
    //We Interrupt This Programme
}

to check if your game has been modded.

Yes.

• Any patch that doesn't compile due to any reasons (feel free to add your workaround here).
• Any patch that crashes MonoMod (feel free to add your fix here).
• Any patch that causes issues at IL level (feel free to add your black magic here).
• Any patch that is blacklisted or accessing anything blacklisted (feel free to contact me about adding your field / method / ... to the blacklist).
• Anyone can compile a "black" (blacklist- and WasHere-free) version of MonoMod, avoiding the one limitation listed above.

Ask the creator of the input assembly, the patches and your lawyer (actually not your lawyer).

Yes. Do so freely, as long as you don't charge the user any costs for using / downloading MonoMod.

##Is it possible to patch patches? Yes, but the orig_ methods will be ignored by MonoMod.

##Is it possible to patch patched patches? ...

##Is it possible to make my PC burn? Maybe. I've heard AMD CPUs start smoking at 400°C.