ReshadePluginsCore/libs/Unity/MonoLoader.cpp

#include "MonoLoader.hpp"
#include <spdlog/spdlog.h>
#include <spdlog/sinks/basic_file_sink.h>

HMODULE MonoLoader::WaitForMono(const char* monoName) {
    HMODULE mono = nullptr;
    while (!mono) {
        mono = GetModuleHandleA(monoName);
        std::this_thread::sleep_for(std::chrono::milliseconds(200));
    }
    return mono;
}

bool MonoLoader::Initialize(std::shared_ptr<spdlog::logger> log, const char* monoName) {
    if (log) logger = log;

    HMODULE mono = WaitForMono(monoName);
    if (!mono) {
        logger->error("Mono module not found.");
        return false;
    }
    logger->info("Mono DLL found at {:p}", (void*)mono);

    mono_get_root_domain = (MonoDomain * (*)())GetProcAddress(mono, "mono_get_root_domain");
    mono_thread_attach = (MonoThread * (*)(MonoDomain*))GetProcAddress(mono, "mono_thread_attach");
    mono_domain_assembly_open = (MonoAssembly * (*)(MonoDomain*, const char*))GetProcAddress(mono, "mono_domain_assembly_open");
    mono_assembly_get_image = (MonoImage * (*)(MonoAssembly*))GetProcAddress(mono, "mono_assembly_get_image");
    mono_class_from_name = (MonoClass * (*)(MonoImage*, const char*, const char*))GetProcAddress(mono, "mono_class_from_name");
    mono_class_get_method_from_name = (MonoMethod * (*)(MonoClass*, const char*, int))GetProcAddress(mono, "mono_class_get_method_from_name");
    mono_compile_method = (void* (*)(MonoMethod*))GetProcAddress(mono, "mono_compile_method");
    mono_assembly_foreach = (void(*)(void(*)(MonoAssembly*, void*), void*))GetProcAddress(mono, "mono_assembly_foreach");
    mono_assembly_get_name = (mono_assembly_get_name_t)GetProcAddress(mono, "mono_assembly_get_name");
    mono_assembly_name_get_name = (mono_assembly_name_get_name_t)GetProcAddress(mono, "mono_assembly_name_get_name");
    mono_class_get_methods = (mono_class_get_methods_t)GetProcAddress(mono, "mono_class_get_methods");
    mono_method_get_name = (mono_method_get_name_t)GetProcAddress(mono, "mono_method_get_name");
    mono_method_signature = (mono_method_signature_t)GetProcAddress(mono, "mono_method_signature");
    mono_signature_get_param_count = (mono_signature_get_param_count_t)GetProcAddress(mono, "mono_signature_get_param_count");
    mono_class_get_field_from_name = (mono_class_get_field_from_name_t)GetProcAddress(mono, "mono_class_get_field_from_name");
    mono_runtime_invoke = (mono_runtime_invoke_t) GetProcAddress(mono, "mono_runtime_invoke");
    mono_field_get_offset = (mono_field_get_offset_t)GetProcAddress(mono, "mono_field_get_offset");
    mono_field_set_value = (mono_field_set_value_t)GetProcAddress(mono, "mono_field_set_value");
    mono_field_get_value = (mono_field_get_value_t)GetProcAddress(mono, "mono_field_get_value");

    if (!mono_get_root_domain || !mono_thread_attach || !mono_domain_assembly_open || !mono_assembly_get_image ||
        !mono_class_from_name || !mono_class_get_method_from_name || !mono_compile_method || !mono_assembly_foreach ||
        !mono_assembly_get_name || !mono_assembly_name_get_name || !mono_class_get_methods || !mono_method_get_name ||
        !mono_method_signature || !mono_signature_get_param_count || !mono_class_get_field_from_name ||
        !mono_runtime_invoke || !mono_field_get_offset || !mono_field_set_value || !mono_field_get_value) {
        logger->error("Failed to resolve one or more Mono exports.");
        return false;
    }

    g_monoDomain = mono_get_root_domain();
    if (!g_monoDomain) {
        logger->error("Mono root domain is null.");
        return false;
    }

    mono_thread_attach(g_monoDomain);
    logger->info("Attached to Mono domain {:p}", (void*)g_monoDomain);
    return true;
}

struct FindAssemblyData {
    MonoLoader* loader;
    const std::string* targetName;
    MonoAssembly* result = nullptr;
};

void MonoLoader::FindAssemblyCallback(MonoAssembly* assembly, void* userData) {
    auto data = reinterpret_cast<FindAssemblyData*>(userData);
    if (!assembly || !data || !data->targetName) return;

    const void* nameStruct = data->loader->mono_assembly_get_name(assembly);
    const char* nameCStr = data->loader->mono_assembly_name_get_name(nameStruct);

    if (nameCStr && *data->targetName == nameCStr) {
        data->result = assembly;
    }
}

MonoAssembly* MonoLoader::FindAssembly(const std::string& name) {
    if (!mono_assembly_foreach || !mono_assembly_get_name || !mono_assembly_name_get_name) {
        logger->error("Mono exports not resolved, cannot enumerate assemblies.");
        return nullptr;
    }

    FindAssemblyData data;
    data.loader = this;
    data.targetName = &name;
    data.result = nullptr;

    mono_assembly_foreach(MonoLoader::FindAssemblyCallback, &data);
    return data.result;
}

MonoClass* MonoLoader::FindClass(const std::string& assemblyName, const std::string& namespaceName, const std::string& className) {
    MonoAssembly* assembly = FindAssembly(assemblyName);
    if (!assembly) return nullptr;

    MonoImage* image = mono_assembly_get_image(assembly);
    if (!image) return nullptr;

    return mono_class_from_name(image, namespaceName.c_str(), className.c_str());
}

uint8_t* MonoLoader::GetCompiledMethod(MonoClass* monoClass, const std::string& methodName, int paramCount) {
    if (!monoClass) return nullptr;
    MonoMethod* method = mono_class_get_method_from_name(monoClass, methodName.c_str(), paramCount);
    if (!method) return nullptr;
    return (uint8_t*)mono_compile_method(method);
}

MonoThread* MonoLoader::AttachCurrentThread() {
    MonoThread* monoThread = mono_thread_attach(mono_get_root_domain());
    if (!monoThread) return nullptr;
    return monoThread;
}

void MonoLoader::DetachCurrentThread(MonoThread* thread) {
    if (!thread || !mono_thread_detach) return;
    mono_thread_detach(thread);
}

MonoMethod* MonoLoader::GetMethod(MonoClass* monoClass, const std::string& methodName, int paramCount) {
    if (!monoClass) return nullptr;
    MonoMethod* method = mono_class_get_method_from_name(monoClass, methodName.c_str(), paramCount);
    if (!method) return nullptr;
    return method;
}

MonoObject* MonoLoader::InvokeMethod(MonoMethod* method, MonoObject* obj, void** params, MonoObject** exception) {
    if (!method) return nullptr;
    MonoThread* thread = AttachCurrentThread();
    if (!thread) return nullptr;
    MonoObject* invoke = mono_runtime_invoke(method, obj, params, exception);
    DetachCurrentThread(thread);
    return invoke;
}

void MonoLoader::DumpMethods(MonoClass* monoClass, std::shared_ptr<spdlog::logger> logger) {
    if (!monoClass) {
        logger->error("DumpMethods: monoClass is null.");
        return;
    }

    if (!g_monoDomain) {
        logger->error("DumpMethods: Mono domain is null.");
        return;
    }

    mono_thread_attach(g_monoDomain);

    if (!mono_class_get_methods || !mono_method_get_name || !mono_method_signature || !mono_signature_get_param_count) {
        logger->error("DumpMethods: Required Mono exports not resolved.");
        return;
    }

    logger->info("---- Dumping methods ----");

    void* iter = nullptr;
    MonoMethod* method = nullptr;

    while ((method = mono_class_get_methods(monoClass, &iter)) != nullptr) {
        const char* name = mono_method_get_name(method);

        MonoMethodSignature* sig = mono_method_signature(method);
        uint32_t paramCount = 0;

        if (sig) paramCount = mono_signature_get_param_count(sig);

        logger->info("Method: {} | Params: {}", name ? name : "null", paramCount);
    }

    logger->info("-------------------------");
}