Initial commit, hook into StarWarsI.exe

lua_hook.cpp

@@ -0,0 +1,116 @@
+#include "lua_hook.h"
+#include "minhook/include/MinHook.h"
+#include <windows.h>
+
+#if defined _M_X64
+#pragma comment(lib, "MinHook.x64.lib")
+#elif defined _M_IX86
+#pragma comment(lib, "MinHook.x86.lib")
+#endif
+
+// Opaque Lua state - never dereferenced, just passed around
+struct lua_State;
+typedef int (*lua_CFunction)(lua_State*);
+
+// Function pointer types
+typedef lua_State* (*fn_lua_open)();
+typedef void (*fn_lua_pushstring)(lua_State*, const char*);
+typedef void (*fn_lua_pushcclosure)(lua_State*, lua_CFunction, int);
+typedef void (*fn_lua_settable)(lua_State*, int);
+typedef const char* (*fn_lua_tostring)(lua_State*, int);
+
+// Resolved function pointers
+static fn_lua_open real_lua_open = nullptr;
+static fn_lua_pushstring pfn_pushstring = nullptr;
+static fn_lua_pushcclosure pfn_pushcclosure = nullptr;
+static fn_lua_settable pfn_settable = nullptr;
+static fn_lua_tostring pfn_tostring = nullptr;
+
+// Helper, equivalent of lua_setglobal
+static void register_global(lua_State* L, const char* name, lua_CFunction fn) {
+	pfn_pushstring(L, name);
+	pfn_pushcclosure(L, fn, 0);
+	pfn_settable(L, LUA_GLOBALSINDEX);
+}
+
+// =========================
+// Custom Lua file functions
+// =========================
+
+// WriteToFile(path, text) - appends text to a file
+static int L_WriteToFile(lua_State* L) {
+	const char* path = pfn_tostring(L, 1);
+	const char* text = pfn_tostring(L, 2);
+
+	if (!path || !text) {
+		return 0;
+	}
+
+	HANDLE hFile = CreateFileA(
+		path,
+		GENERIC_WRITE,
+		FILE_SHARE_READ,
+		NULL,
+		OPEN_ALWAYS,
+		FILE_ATTRIBUTE_NORMAL,
+		NULL);
+
+	if (hFile != INVALID_HANDLE_VALUE) {
+		DWORD written;
+
+		SetFilePointer(hFile, 0, NULL, FILE_END);
+		WriteFile(hFile, text, lstrlenA(text), &written, NULL);
+		WriteFile(hFile, "\n", 1, &written, NULL);
+		CloseHandle(hFile);
+	}
+
+	return 0;
+}
+
+// =========================
+// Hooks
+// =========================
+
+// Fired every time the game creates a new Lua state
+static lua_State* Hook_lua_open() {
+	lua_State* L = real_lua_open();
+
+	if (!L) {
+		return L;
+	}
+
+	// Register custom Lua functions
+	register_global(L, "WriteToFile", L_WriteToFile);
+
+	return L;
+}
+
+bool LuaHook_Init() {
+	uintptr_t base = (uintptr_t)GetModuleHandleA(nullptr);
+
+	pfn_pushstring = (fn_lua_pushstring)(base + RVA_lua_pushstring);
+	pfn_pushcclosure = (fn_lua_pushcclosure)(base + RVA_lua_pushcclosure);
+	pfn_settable = (fn_lua_settable)(base + RVA_lua_settable);
+	pfn_tostring = (fn_lua_tostring)(base + RVA_lua_tostring);
+
+	void* const target = (void*)(base + RVA_lua_open);
+
+	if (MH_Initialize() != MH_OK) {
+		return false;
+	}
+
+	if (MH_CreateHook(target, &Hook_lua_open, (void**)&real_lua_open) != MH_OK) {
+		return false;
+	}
+
+	if (MH_EnableHook(target) != MH_OK) {
+		return false;
+	}
+
+	return true;
+}
+
+void LuaHook_Shutdown() {
+	MH_DisableHook(MH_ALL_HOOKS);
+	MH_Uninitialize();
+}