iw6-mod/src/client/component/mods.cpp

#include <std_include.hpp>
#include "loader/component_loader.hpp"
#include "game/game.hpp"
#include "game/dvars.hpp"

#include "mods.hpp"

#include <utils/hook.hpp>

namespace mods
{
	namespace
	{
		utils::hook::detour sys_create_file_hook;

		void db_build_os_path_from_source(const char* zone_name, game::FF_DIR source, unsigned int size, char* filename)
		{
			char user_map[MAX_PATH]{};

			switch (source)
			{
			case game::FFD_DEFAULT:
				(void)sprintf_s(filename, size, "%s\\%s.ff", std::filesystem::current_path().string().c_str(), zone_name);
				break;
			case game::FFD_MOD_DIR:
				assert(mods::is_using_mods());

				(void)sprintf_s(filename, size, "%s\\%s\\%s.ff", std::filesystem::current_path().string().c_str(), (*dvars::fs_gameDirVar)->current.string, zone_name);
				break;
			case game::FFD_USER_MAP:
				strncpy_s(user_map, zone_name, _TRUNCATE);

				(void)sprintf_s(filename, size, "%s\\%s\\%s\\%s.ff", std::filesystem::current_path().string().c_str(), "usermaps", user_map, zone_name);
				break;
			default:
				assert(false && "inconceivable");
				break;
			}
		}

		game::Sys_File sys_create_file_stub(const char* dir, const char* filename)
		{
			auto result = sys_create_file_hook.invoke<game::Sys_File>(dir, filename);

			if (result.handle != INVALID_HANDLE_VALUE)
			{
				return result;
			}

			if (!is_using_mods())
			{
				return result;
			}

			// .ff extension was added previously
			if (!std::strcmp(filename, "mod.ff") && mods::db_mod_file_exists())
			{
				char file_path[MAX_PATH]{};
				db_build_os_path_from_source("mod", game::FFD_MOD_DIR, sizeof(file_path), file_path);
				result.handle = game::Sys_OpenFileReliable(file_path);
			}

			return result;
		}

		void db_load_x_assets_stub(game::XZoneInfo* zone_info, unsigned int zone_count, game::DBSyncMode sync_mode)
		{
			std::vector<game::XZoneInfo> zones(zone_info, zone_info + zone_count);

			if (db_mod_file_exists())
			{
				zones.emplace_back("mod", game::DB_ZONE_COMMON | game::DB_ZONE_CUSTOM, 0);
			}

			game::DB_LoadXAssets(zones.data(), static_cast<unsigned int>(zones.size()), sync_mode);
		}

		const auto skip_extra_zones_stub = utils::hook::assemble([](utils::hook::assembler& a)
		{
			const auto skip = a.newLabel();
			const auto original = a.newLabel();

			a.pushad64();
			a.test(ebp, game::DB_ZONE_CUSTOM); // allocFlags
			a.jnz(skip);

			a.bind(original);
			a.popad64();
			a.mov(rdx, 0x140835F28);
			a.mov(rcx, rsi);
			a.call_aligned(strcmp);
			a.jmp(0x1403217C0);

			a.bind(skip);
			a.popad64();
			a.mov(r15d, 0x80);
			a.not_(r15d);
			a.and_(ebp, r15d);
			a.jmp(0x1403217F6);
		});
	}

	bool is_using_mods()
	{
		return (*dvars::fs_gameDirVar) && *(*dvars::fs_gameDirVar)->current.string;
	}

	bool db_mod_file_exists()
	{
		if (!*(*dvars::fs_gameDirVar)->current.string)
		{
			return false;
		}

		char filename[MAX_PATH]{};
		db_build_os_path_from_source("mod", game::FFD_MOD_DIR, sizeof(filename), filename);

		if (auto zone_file = game::Sys_OpenFileReliable(filename); zone_file != INVALID_HANDLE_VALUE)
		{
			::CloseHandle(zone_file);
			return true;
		}

		return false;
	}

	class component final : public component_interface
	{
	public:
		static_assert(sizeof(game::Sys_File) == 8);

		void post_unpack() override
		{
			dvars::fs_gameDirVar = reinterpret_cast<game::dvar_t**>(SELECT_VALUE(0x145856D38, 0x147876000));

			// Remove DVAR_INIT from fs_game
			utils::hook::set<std::uint32_t>(SELECT_VALUE(0x14041C085 + 2, 0x1404DDA45 + 2), SELECT_VALUE(game::DVAR_FLAG_NONE, game::DVAR_FLAG_SERVERINFO));

			if (game::environment::is_sp())
			{
				return;
			}

			// Don't load eng_ + patch_ with loadzone
			utils::hook::nop(0x1403217B1, 15);
			utils::hook::jump(0x1403217B1, skip_extra_zones_stub, true);

			// Add custom zone paths
			sys_create_file_hook.create(game::Sys_CreateFile, sys_create_file_stub);

			// Load mod.ff
			utils::hook::call(0x1405E7113, db_load_x_assets_stub); // R_LoadGraphicsAssets According to myself but I don't remember where I got it from
		}
	};
}

REGISTER_COMPONENT(mods::component)