Safe I/O 2 - Electric Boogaloo! (#404)

* Safe I/O initial commit

* Formatting

* Formatting 2

* God help us all.

* fix diffs part 1

* fix diffs 2

* Fix invalid filter file

* Update NorthstarLauncher.vcxproj

* Remove newline at EOF

* fix the damn thing

* God help the diffs

* diff hate

* diff hate the 2nd

* Add comments since this code is unreadable

Now, this code may look readable, but I barely understand what I did here myself.

* Remove char limit and file definitions

* Fix build

* organization stuff

* Fix build

* More funcs, more stuff

* format fix

* oops, this is wrong.

* fix a thing

* Add max folder size (250MB) and add getallfiles

* Fix build also size cap

* reduce max folder size to 50MB

* he forgor

* i give up

* aync edition?????

* Fix max size bypass

* fix it

* Remove logs

* Add max folder size launch arg

* boop

* FUCK SHIT

* FUCKKKKKKKKKKK

* Fix build

* Fix crash

* Fix error FINAL!!!

* fix scriptjson.h not being found

* fix scriptjson.h not appearing correctly

* shit diffself

* format fix

* Fix indentation (thank you vscode)

* Fix indentation again

* adadasa

* shit diffself

adadasa

Fix indentation (thank you vscode)

Fix indentation again

* format fix

* Revert "shit diffself"

This reverts commit b49a62b5b36784df1c01663cdec2e4e403279618.

* Revert "Merge branch 'safe-io-rewrite' of https://github.com/EladNLG/NorthstarLauncher into safe-io-rewrite"

This reverts commit 761eb8a1cb11ccf1dadf55f5be9a08700fe1d560, reversing
changes made to 65549b2f799660d7fe7b5a53e81425922b996ea9.

* Fix the diff finally

* more diff fixes

* Fix more diffs

* Allow non-ascii characters that aren't NUL

* format fix :(

* this is untested and I don't wanna update the safe i/o test thing

* fix build :(

* fix mayhaps?

* fix build

* Fix lotsa stuff :D

* FIxed :D

* Rewrite error messages, rename CheckFileName to IsPathSafe

* Shout out to clang-format!

* oops, wrong error message :3

* SHOUT OUT TO CLANG-FORMAT!!!

* Revert "SHOUT OUT TO CLANG-FORMAT!!!"

This reverts commit c536384073528b4eee7c330dfab320a5527ff240.

* :(

* oop

* Add failure callback (launcher)

* unnecessary comment

* holy shit format fix
boooooo. BOOOOOO!

* restrict path to ASCII

* Fix ascii check I hate you all

* reformat

* Clang-format my beloved :)

* Move the thing

* Apply suggestions from code review

Co-authored-by: Rémy Raes <contact@remyraes.com>

* clang-format no like code suggestions :(

* name change

* doc'd

* - Replace the mutex map with a single mutex for all file actions
- Fix Load calls sometimes failing and not calling NSHandleLoadResult
- Add NSGetTotalSpaceRemaining which checks how much space a mod has, in KB
- Add contstant MAX_FOLDER_SIZE which holds the maximum save folder size, in KB

* add safe-io stuff to cmake

* surrounds IsPathSafe with a try/catch

---------

Co-authored-by: Rémy Raes <contact@remyraes.com>
Co-authored-by: uniboi <kami.0.katze@gmail.com>

5 files changed, 608 insertions, 0 deletions

diff --git a/NorthstarDLL/CMakeLists.txt b/NorthstarDLL/CMakeLists.txt
index f6ff8014..126812e9 100644
--- a/NorthstarDLL/CMakeLists.txt
+++ b/NorthstarDLL/CMakeLists.txt
@@ -78,6 +78,8 @@ add_library(NorthstarDLL SHARED
             "mods/compiled/modscriptsrson.cpp"
             "mods/modmanager.cpp"
             "mods/modmanager.h"
+            "mods/modsavefiles.cpp"
+            "mods/modsavefiles.h"
             "plugins/plugin_abi.h"
             "plugins/pluginbackend.cpp"
             "plugins/pluginbackend.h"
@@ -97,6 +99,7 @@ add_library(NorthstarDLL SHARED
             "scripts/scripthttprequesthandler.cpp"
             "scripts/scripthttprequesthandler.h"
             "scripts/scriptjson.cpp"
+            "scripts/scriptjson.h"
             "scripts/scriptutility.cpp"
             "server/auth/bansystem.cpp"
             "server/auth/bansystem.h"
diff --git a/NorthstarDLL/mods/modsavefiles.cpp b/NorthstarDLL/mods/modsavefiles.cpp
new file mode 100644
index 00000000..6676ec34
--- /dev/null
+++ b/NorthstarDLL/mods/modsavefiles.cpp
@@ -0,0 +1,573 @@
+#include "pch.h"
+#include <filesystem>
+#include <sstream>
+#include <fstream>
+#include "squirrel/squirrel.h"
+#include "util/utils.h"
+#include "mods/modmanager.h"
+#include "modsavefiles.h"
+#include "rapidjson/document.h"
+#include "rapidjson/writer.h"
+#include "rapidjson/stringbuffer.h"
+#include "config/profile.h"
+#include "core/tier0.h"
+#include "rapidjson/error/en.h"
+#include "scripts/scriptjson.h"
+
+SaveFileManager* g_pSaveFileManager;
+int MAX_FOLDER_SIZE = 52428800; // 50MB (50 * 1024 * 1024)
+fs::path savePath;
+
+/// <summary></summary>
+/// <param name="dir">The directory we want the size of.</param>
+/// <param name="file">The file we're excluding from the calculation.</param>
+/// <returns>The size of the contents of the current directory, excluding a specific file.</returns>
+uintmax_t GetSizeOfFolderContentsMinusFile(fs::path dir, std::string file)
+{
+	uintmax_t result = 0;
+	for (const auto& entry : fs::directory_iterator(dir))
+	{
+		if (entry.path().filename() == file)
+			continue;
+		// fs::file_size may not work on directories - but does in some cases.
+		// per cppreference.com, it's "implementation-defined".
+		try
+		{
+			result += fs::file_size(entry.path());
+		}
+		catch (fs::filesystem_error& e)
+		{
+			if (entry.is_directory())
+			{
+				result += GetSizeOfFolderContentsMinusFile(entry.path(), "");
+			}
+		}
+	}
+	return result;
+}
+
+uintmax_t GetSizeOfFolder(fs::path dir)
+{
+	uintmax_t result = 0;
+	for (const auto& entry : fs::directory_iterator(dir))
+	{
+		// fs::file_size may not work on directories - but does in some cases.
+		// per cppreference.com, it's "implementation-defined".
+		try
+		{
+			result += fs::file_size(entry.path());
+		}
+		catch (fs::filesystem_error& e)
+		{
+			if (entry.is_directory())
+			{
+				result += GetSizeOfFolderContentsMinusFile(entry.path(), "");
+			}
+		}
+	}
+	return result;
+}
+
+// Saves a file asynchronously.
+template <ScriptContext context> void SaveFileManager::SaveFileAsync(fs::path file, std::string contents)
+{
+	auto mutex = std::ref(fileMutex);
+	std::thread writeThread(
+		[mutex, file, contents]()
+		{
+			try
+			{
+				mutex.get().lock();
+
+				fs::path dir = file.parent_path();
+				// this actually allows mods to go over the limit, but not by much
+				// the limit is to prevent mods from taking gigabytes of space,
+				// we don't need to be particularly strict.
+				if (GetSizeOfFolderContentsMinusFile(dir, file.filename().string()) + contents.length() > MAX_FOLDER_SIZE)
+				{
+					// tbh, you're either trying to fill the hard drive or use so much data, you SHOULD be congratulated.
+					spdlog::error(fmt::format("Mod spamming save requests? Folder limit bypassed despite previous checks. Not saving."));
+					mutex.get().unlock();
+					return;
+				}
+
+				std::ofstream fileStr(file);
+				if (fileStr.fail())
+				{
+					mutex.get().unlock();
+					return;
+				}
+
+				fileStr.write(contents.c_str(), contents.length());
+				fileStr.close();
+
+				mutex.get().unlock();
+				// side-note: this causes a leak?
+				// when a file is added to the map, it's never removed.
+				// no idea how to fix this - because we have no way to check if there are other threads waiting to use this file(?)
+				// tried to use m.try_lock(), but it's unreliable, it seems.
+			}
+			catch (std::exception ex)
+			{
+				spdlog::error("SAVE FAILED!");
+				mutex.get().unlock();
+				spdlog::error(ex.what());
+			}
+		});
+
+	writeThread.detach();
+}
+
+// Loads a file asynchronously.
+template <ScriptContext context> int SaveFileManager::LoadFileAsync(fs::path file)
+{
+	int handle = ++m_iLastRequestHandle;
+	auto mutex = std::ref(fileMutex);
+	std::thread readThread(
+		[mutex, file, handle]()
+		{
+			try
+			{
+				mutex.get().lock();
+
+				std::ifstream fileStr(file);
+				if (fileStr.fail())
+				{
+					spdlog::error("A file was supposed to be loaded but we can't access it?!");
+
+					g_pSquirrel<context>->AsyncCall("NSHandleLoadResult", handle, false, "");
+					mutex.get().unlock();
+					return;
+				}
+
+				std::stringstream stringStream;
+				stringStream << fileStr.rdbuf();
+
+				g_pSquirrel<context>->AsyncCall("NSHandleLoadResult", handle, true, stringStream.str());
+
+				fileStr.close();
+				mutex.get().unlock();
+				// side-note: this causes a leak?
+				// when a file is added to the map, it's never removed.
+				// no idea how to fix this - because we have no way to check if there are other threads waiting to use this file(?)
+				// tried to use m.try_lock(), but it's unreliable, it seems.
+			}
+			catch (std::exception ex)
+			{
+				spdlog::error("LOAD FAILED!");
+				g_pSquirrel<context>->AsyncCall("NSHandleLoadResult", handle, false, "");
+				mutex.get().unlock();
+				spdlog::error(ex.what());
+			}
+		});
+
+	readThread.detach();
+	return handle;
+}
+
+// Deletes a file asynchronously.
+template <ScriptContext context> void SaveFileManager::DeleteFileAsync(fs::path file)
+{
+	// P.S. I don't like how we have to async delete calls but we do.
+	auto m = std::ref(fileMutex);
+	std::thread deleteThread(
+		[m, file]()
+		{
+			try
+			{
+				m.get().lock();
+
+				fs::remove(file);
+
+				m.get().unlock();
+				// side-note: this causes a leak?
+				// when a file is added to the map, it's never removed.
+				// no idea how to fix this - because we have no way to check if there are other threads waiting to use this file(?)
+				// tried to use m.try_lock(), but it's unreliable, it seems.
+			}
+			catch (std::exception ex)
+			{
+				spdlog::error("DELETE FAILED!");
+				m.get().unlock();
+				spdlog::error(ex.what());
+			}
+		});
+
+	deleteThread.detach();
+}
+
+// Checks if a file contains null characters.
+bool ContainsInvalidChars(std::string str)
+{
+	// we don't allow null characters either, even if they're ASCII characters because idk if people can
+	// use it to circumvent the file extension suffix.
+	return std::any_of(str.begin(), str.end(), [](char c) { return c == '\0'; });
+}
+
+// Checks if the relative path (param) remains inside the mod directory (dir).
+// Paths are restricted to ASCII because encoding is fucked and we decided we won't bother.
+bool IsPathSafe(const std::string param, fs::path dir)
+{
+	try
+	{
+		auto const normRoot = fs::weakly_canonical(dir);
+		auto const normChild = fs::weakly_canonical(dir / param);
+
+		auto itr = std::search(normChild.begin(), normChild.end(), normRoot.begin(), normRoot.end());
+		// we return if the file is safe (inside the directory) and uses only ASCII chars in the path.
+		return itr == normChild.begin() && std::none_of(
+											   param.begin(),
+											   param.end(),
+											   [](char c)
+											   {
+												   unsigned char unsignedC = static_cast<unsigned char>(c);
+												   return unsignedC > 127 || unsignedC < 0;
+											   });
+	}
+	catch (fs::filesystem_error err)
+	{
+		return false;
+	}
+}
+
+// void NSSaveFile( string file, string data )
+ADD_SQFUNC("void", NSSaveFile, "string file, string data", "", ScriptContext::SERVER | ScriptContext::CLIENT | ScriptContext::UI)
+{
+	Mod* mod = g_pSquirrel<context>->getcallingmod(sqvm);
+	if (mod == nullptr)
+	{
+		g_pSquirrel<context>->raiseerror(sqvm, "Has to be called from a mod function!");
+		return SQRESULT_ERROR;
+	}
+
+	fs::path dir = savePath / fs::path(mod->m_ModDirectory).filename();
+	std::string fileName = g_pSquirrel<context>->getstring(sqvm, 1);
+	if (!IsPathSafe(fileName, dir))
+	{
+		g_pSquirrel<context>->raiseerror(
+			sqvm,
+			fmt::format(
+				"File name invalid ({})! Make sure it does not contain any non-ASCII character, and results in a path inside your mod's "
+				"save folder.",
+				fileName,
+				mod->Name)
+				.c_str());
+		return SQRESULT_ERROR;
+	}
+
+	std::string content = g_pSquirrel<context>->getstring(sqvm, 2);
+	if (ContainsInvalidChars(content))
+	{
+		g_pSquirrel<context>->raiseerror(
+			sqvm, fmt::format("File contents may not contain NUL/\\0 characters! Make sure your strings are valid!", mod->Name).c_str());
+		return SQRESULT_ERROR;
+	}
+
+	fs::create_directories(dir);
+	// this actually allows mods to go over the limit, but not by much
+	// the limit is to prevent mods from taking gigabytes of space,
+	// this ain't a cloud service.
+	if (GetSizeOfFolderContentsMinusFile(dir, fileName) + content.length() > MAX_FOLDER_SIZE)
+	{
+		g_pSquirrel<context>->raiseerror(
+			sqvm,
+			fmt::format(
+				"The mod {} has reached the maximum folder size.\n\nAsk the mod developer to optimize their data usage,"
+				"or increase the maximum folder size using the -maxfoldersize launch parameter.",
+				mod->Name)
+				.c_str());
+		return SQRESULT_ERROR;
+	}
+
+	g_pSaveFileManager->SaveFileAsync<context>(dir / fileName, content);
+
+	return SQRESULT_NULL;
+}
+
+// void NSSaveJSONFile(string file, table data)
+ADD_SQFUNC("void", NSSaveJSONFile, "string file, table data", "", ScriptContext::SERVER | ScriptContext::CLIENT | ScriptContext::UI)
+{
+	Mod* mod = g_pSquirrel<context>->getcallingmod(sqvm);
+	if (mod == nullptr)
+	{
+		g_pSquirrel<context>->raiseerror(sqvm, "Has to be called from a mod function!");
+		return SQRESULT_ERROR;
+	}
+
+	fs::path dir = savePath / fs::path(mod->m_ModDirectory).filename();
+	std::string fileName = g_pSquirrel<context>->getstring(sqvm, 1);
+	if (!IsPathSafe(fileName, dir))
+	{
+		g_pSquirrel<context>->raiseerror(
+			sqvm,
+			fmt::format(
+				"File name invalid ({})! Make sure it does not contain any non-ASCII character, and results in a path inside your mod's "
+				"save folder.",
+				fileName,
+				mod->Name)
+				.c_str());
+		return SQRESULT_ERROR;
+	}
+
+	// Note - this cannot be done in the async func since the table may get garbage collected.
+	// This means that especially large tables may still clog up the system.
+	std::string content = EncodeJSON<context>(sqvm);
+	if (ContainsInvalidChars(content))
+	{
+		g_pSquirrel<context>->raiseerror(
+			sqvm, fmt::format("File contents may not contain NUL/\\0 characters! Make sure your strings are valid!", mod->Name).c_str());
+		return SQRESULT_ERROR;
+	}
+
+	fs::create_directories(dir);
+	// this actually allows mods to go over the limit, but not by much
+	// the limit is to prevent mods from taking gigabytes of space,
+	// this ain't a cloud service.
+	if (GetSizeOfFolderContentsMinusFile(dir, fileName) + content.length() > MAX_FOLDER_SIZE)
+	{
+		g_pSquirrel<context>->raiseerror(
+			sqvm,
+			fmt::format(
+				"The mod {} has reached the maximum folder size.\n\nAsk the mod developer to optimize their data usage,"
+				"or increase the maximum folder size using the -maxfoldersize launch parameter.",
+				mod->Name)
+				.c_str());
+		return SQRESULT_ERROR;
+	}
+
+	g_pSaveFileManager->SaveFileAsync<context>(dir / fileName, content);
+
+	return SQRESULT_NULL;
+}
+
+// int NS_InternalLoadFile(string file)
+ADD_SQFUNC("int", NS_InternalLoadFile, "string file", "", ScriptContext::SERVER | ScriptContext::CLIENT | ScriptContext::UI)
+{
+	Mod* mod = g_pSquirrel<context>->getcallingmod(sqvm, 1); // the function that called NSLoadFile :)
+	if (mod == nullptr)
+	{
+		g_pSquirrel<context>->raiseerror(sqvm, "Has to be called from a mod function!");
+		return SQRESULT_ERROR;
+	}
+
+	fs::path dir = savePath / fs::path(mod->m_ModDirectory).filename();
+	std::string fileName = g_pSquirrel<context>->getstring(sqvm, 1);
+	if (!IsPathSafe(fileName, dir))
+	{
+		g_pSquirrel<context>->raiseerror(
+			sqvm,
+			fmt::format(
+				"File name invalid ({})! Make sure it does not contain any non-ASCII character, and results in a path inside your mod's "
+				"save folder.",
+				fileName,
+				mod->Name)
+				.c_str());
+		return SQRESULT_ERROR;
+	}
+
+	g_pSquirrel<context>->pushinteger(sqvm, g_pSaveFileManager->LoadFileAsync<context>(dir / fileName));
+
+	return SQRESULT_NOTNULL;
+}
+
+// bool NSDoesFileExist(string file)
+ADD_SQFUNC("bool", NSDoesFileExist, "string file", "", ScriptContext::SERVER | ScriptContext::CLIENT | ScriptContext::UI)
+{
+	Mod* mod = g_pSquirrel<context>->getcallingmod(sqvm);
+
+	fs::path dir = savePath / fs::path(mod->m_ModDirectory).filename();
+	std::string fileName = g_pSquirrel<context>->getstring(sqvm, 1);
+	if (!IsPathSafe(fileName, dir))
+	{
+		g_pSquirrel<context>->raiseerror(
+			sqvm,
+			fmt::format(
+				"File name invalid ({})! Make sure it does not contain any non-ASCII character, and results in a path inside your mod's "
+				"save folder.",
+				fileName,
+				mod->Name)
+				.c_str());
+		return SQRESULT_ERROR;
+	}
+
+	g_pSquirrel<context>->pushbool(sqvm, fs::exists(dir / (fileName)));
+	return SQRESULT_NOTNULL;
+}
+
+// int NSGetFileSize(string file)
+ADD_SQFUNC("int", NSGetFileSize, "string file", "", ScriptContext::SERVER | ScriptContext::CLIENT | ScriptContext::UI)
+{
+	Mod* mod = g_pSquirrel<context>->getcallingmod(sqvm);
+
+	fs::path dir = savePath / fs::path(mod->m_ModDirectory).filename();
+	std::string fileName = g_pSquirrel<context>->getstring(sqvm, 1);
+	if (!IsPathSafe(fileName, dir))
+	{
+		g_pSquirrel<context>->raiseerror(
+			sqvm,
+			fmt::format(
+				"File name invalid ({})! Make sure it does not contain any non-ASCII character, and results in a path inside your mod's "
+				"save folder.",
+				fileName,
+				mod->Name)
+				.c_str());
+		return SQRESULT_ERROR;
+	}
+	try
+	{
+		// throws if file does not exist
+		// we don't want stuff such as "file does not exist, file is unavailable" to be lethal, so we just try/catch fs errors
+		g_pSquirrel<context>->pushinteger(sqvm, (int)(fs::file_size(dir / fileName) / 1024));
+	}
+	catch (std::filesystem::filesystem_error const& ex)
+	{
+		spdlog::error("GET FILE SIZE FAILED! Is the path valid?");
+		g_pSquirrel<context>->raiseerror(sqvm, ex.what());
+		return SQRESULT_ERROR;
+	}
+	return SQRESULT_NOTNULL;
+}
+
+// void NSDeleteFile(string file)
+ADD_SQFUNC("void", NSDeleteFile, "string file", "", ScriptContext::SERVER | ScriptContext::CLIENT | ScriptContext::UI)
+{
+	Mod* mod = g_pSquirrel<context>->getcallingmod(sqvm);
+
+	fs::path dir = savePath / fs::path(mod->m_ModDirectory).filename();
+	std::string fileName = g_pSquirrel<context>->getstring(sqvm, 1);
+	if (!IsPathSafe(fileName, dir))
+	{
+		g_pSquirrel<context>->raiseerror(
+			sqvm,
+			fmt::format(
+				"File name invalid ({})! Make sure it does not contain any non-ASCII character, and results in a path inside your mod's "
+				"save folder.",
+				fileName,
+				mod->Name)
+				.c_str());
+		return SQRESULT_ERROR;
+	}
+
+	g_pSaveFileManager->DeleteFileAsync<context>(dir / fileName);
+	return SQRESULT_NOTNULL;
+}
+
+// The param is not optional because that causes issues :)
+ADD_SQFUNC("array<string>", NS_InternalGetAllFiles, "string path", "", ScriptContext::CLIENT | ScriptContext::UI | ScriptContext::SERVER)
+{
+	// depth 1 because this should always get called from Northstar.Custom
+	Mod* mod = g_pSquirrel<context>->getcallingmod(sqvm, 1);
+	fs::path dir = savePath / fs::path(mod->m_ModDirectory).filename();
+	std::string pathStr = g_pSquirrel<context>->getstring(sqvm, 1);
+	fs::path path = dir;
+	if (pathStr != "")
+		path = dir / pathStr;
+	if (!IsPathSafe(pathStr, dir))
+	{
+		g_pSquirrel<context>->raiseerror(
+			sqvm,
+			fmt::format(
+				"File name invalid ({})! Make sure it does not contain any non-ASCII character, and results in a path inside your mod's "
+				"save folder.",
+				pathStr,
+				mod->Name)
+				.c_str());
+		return SQRESULT_ERROR;
+	}
+	try
+	{
+		g_pSquirrel<context>->newarray(sqvm, 0);
+		for (const auto& entry : fs::directory_iterator(path))
+		{
+			g_pSquirrel<context>->pushstring(sqvm, entry.path().filename().string().c_str());
+			g_pSquirrel<context>->arrayappend(sqvm, -2);
+		}
+		return SQRESULT_NOTNULL;
+	}
+	catch (std::exception ex)
+	{
+		spdlog::error("DIR ITERATE FAILED! Is the path valid?");
+		g_pSquirrel<context>->raiseerror(sqvm, ex.what());
+		return SQRESULT_ERROR;
+	}
+}
+
+ADD_SQFUNC("bool", NSIsFolder, "string path", "", ScriptContext::CLIENT | ScriptContext::UI | ScriptContext::SERVER)
+{
+	Mod* mod = g_pSquirrel<context>->getcallingmod(sqvm);
+	fs::path dir = savePath / fs::path(mod->m_ModDirectory).filename();
+	std::string pathStr = g_pSquirrel<context>->getstring(sqvm, 1);
+	fs::path path = dir;
+	if (pathStr != "")
+		path = dir / pathStr;
+	if (!IsPathSafe(pathStr, dir))
+	{
+		g_pSquirrel<context>->raiseerror(
+			sqvm,
+			fmt::format(
+				"File name invalid ({})! Make sure it does not contain any non-ASCII character, and results in a path inside your mod's "
+				"save folder.",
+				pathStr,
+				mod->Name)
+				.c_str());
+		return SQRESULT_ERROR;
+	}
+	try
+	{
+		g_pSquirrel<context>->pushbool(sqvm, fs::is_directory(path));
+		return SQRESULT_NOTNULL;
+	}
+	catch (std::exception ex)
+	{
+		spdlog::error("DIR READ FAILED! Is the path valid?");
+		spdlog::info(path.string());
+		g_pSquirrel<context>->raiseerror(sqvm, ex.what());
+		return SQRESULT_ERROR;
+	}
+}
+
+// side note, expensive.
+ADD_SQFUNC("int", NSGetTotalSpaceRemaining, "", "", ScriptContext::CLIENT | ScriptContext::UI | ScriptContext::SERVER)
+{
+	Mod* mod = g_pSquirrel<context>->getcallingmod(sqvm);
+	fs::path dir = savePath / fs::path(mod->m_ModDirectory).filename();
+	g_pSquirrel<context>->pushinteger(sqvm, (MAX_FOLDER_SIZE - GetSizeOfFolder(dir)) / 1024);
+	return SQRESULT_NOTNULL;
+}
+
+// ok, I'm just gonna explain what the fuck is going on here because this
+// is the pinnacle of my stupidity and I do not want to touch this ever
+// again, yet someone will eventually have to maintain this.
+template <ScriptContext context> std::string EncodeJSON(HSquirrelVM* sqvm)
+{
+	// new rapidjson
+	rapidjson_document doc;
+	doc.SetObject();
+
+	// get the SECOND param
+	SQTable* table = sqvm->_stackOfCurrentFunction[2]._VAL.asTable;
+	// take the table and copy it's contents over into the rapidjson_document
+	EncodeJSONTable<context>(table, &doc, doc.GetAllocator());
+
+	// convert JSON document to string
+	rapidjson::StringBuffer buffer;
+	rapidjson::Writer<rapidjson::StringBuffer> writer(buffer);
+	doc.Accept(writer);
+
+	// return the converted string
+	return buffer.GetString();
+}
+
+ON_DLL_LOAD("engine.dll", ModSaveFFiles_Init, (CModule module))
+{
+	savePath = fs::path(GetNorthstarPrefix()) / "save_data";
+	g_pSaveFileManager = new SaveFileManager;
+	int parm = Tier0::CommandLine()->FindParm("-maxfoldersize");
+	if (parm)
+		MAX_FOLDER_SIZE = std::stoi(Tier0::CommandLine()->GetParm(parm));
+}
+
+int GetMaxSaveFolderSize()
+{
+	return MAX_FOLDER_SIZE;
+}
diff --git a/NorthstarDLL/mods/modsavefiles.h b/NorthstarDLL/mods/modsavefiles.h
new file mode 100644
index 00000000..a50fe62c
--- /dev/null
+++ b/NorthstarDLL/mods/modsavefiles.h
@@ -0,0 +1,16 @@
+#pragma once
+int GetMaxSaveFolderSize();
+bool ContainsInvalidChars(std::string str);
+
+class SaveFileManager
+{
+  public:
+	template <ScriptContext context> void SaveFileAsync(fs::path file, std::string content);
+	template <ScriptContext context> int LoadFileAsync(fs::path file);
+	template <ScriptContext context> void DeleteFileAsync(fs::path file);
+	// Future proofed in that if we ever get multi-threaded SSDs this code will take advantage of them.
+	std::mutex fileMutex;
+
+  private:
+	int m_iLastRequestHandle = 0;
+};
diff --git a/NorthstarDLL/scripts/scriptjson.h b/NorthstarDLL/scripts/scriptjson.h
new file mode 100644
index 00000000..09926bef
--- /dev/null
+++ b/NorthstarDLL/scripts/scriptjson.h
@@ -0,0 +1,14 @@
+#pragma once
+
+#include "pch.h"
+#include "rapidjson/document.h"
+#include "rapidjson/writer.h"
+#include "rapidjson/stringbuffer.h"
+
+template <ScriptContext context> void EncodeJSONTable(
+	SQTable* table,
+	rapidjson::GenericValue<rapidjson::UTF8<char>, rapidjson::MemoryPoolAllocator<SourceAllocator>>* obj,
+	rapidjson::MemoryPoolAllocator<SourceAllocator>& allocator);
+
+template <ScriptContext context> void
+DecodeJsonTable(HSquirrelVM* sqvm, rapidjson::GenericValue<rapidjson::UTF8<char>, rapidjson::MemoryPoolAllocator<SourceAllocator>>* obj);
diff --git a/NorthstarDLL/squirrel/squirrel.cpp b/NorthstarDLL/squirrel/squirrel.cpp
index 0dd23cd7..43dd0cad 100644
--- a/NorthstarDLL/squirrel/squirrel.cpp
+++ b/NorthstarDLL/squirrel/squirrel.cpp
@@ -1,4 +1,5 @@
 #include "squirrel.h"
+#include "mods/modsavefiles.h"
 #include "logging/logging.h"
 #include "core/convar/concommand.h"
 #include "mods/modmanager.h"
@@ -255,6 +256,7 @@ template <ScriptContext context> void SquirrelManager<context>::VMCreated(CSquir
 
 		defconst(m_pSQVM, pair.first.c_str(), bWasFound);
 	}
+	defconst(m_pSQVM, "MAX_FOLDER_SIZE", GetMaxSaveFolderSize() / 1024);
 	g_pSquirrel<context>->messageBuffer = new SquirrelMessageBuffer();
 	g_pPluginManager->InformSQVMCreated(context, newSqvm);
 }