Scripting: Lua requires should be relative to the file they were run from

src/script/engines/lua.c

@@ -49,6 +49,8 @@ static int _luaPairsTable(lua_State* lua);
 static int _luaGetList(lua_State* lua);
 static int _luaLenList(lua_State* lua);
 
+static int _luaRequireShim(lua_State* lua);
+
 #if LUA_VERSION_NUM < 503
 #define lua_pushinteger lua_pushnumber
 #endif
@@ -78,6 +80,8 @@ struct mScriptEngineContextLua {
 	struct mScriptEngineContext d;
 	lua_State* lua;
 	int func;
+	char lastDirectory[PATH_MAX];
+	int require;
 	char* lastError;
 };
 
@@ -163,6 +167,9 @@ struct mScriptEngineContext* _luaCreate(struct mScriptEngine2* engine, struct mS
 #endif
 	lua_pop(luaContext->lua, 1);
 
+	lua_getglobal(luaContext->lua, "require");
+	luaContext->require = luaL_ref(luaContext->lua, LUA_REGISTRYINDEX);
+
 	return &luaContext->d;
 }
 
@@ -330,7 +337,7 @@ struct mScriptValue* _luaCoerce(struct mScriptEngineContextLua* luaContext, bool
 		}
 		return _luaCoerceFunction(luaContext);
 	case LUA_TTABLE:
-		// This function pops the value internally via luaL_ref
+		// This function pops the value internally
 		if (!pop) {
 			break;
 		}
@@ -481,12 +488,11 @@ bool _luaLoad(struct mScriptEngineContext* ctx, const char* filename, struct VFi
 		luaContext->lastError = NULL;
 	}
 	char name[PATH_MAX + 1];
+	char dirname[PATH_MAX] = {0};
 	if (filename) {
 		if (*filename == '*') {
 			snprintf(name, sizeof(name), "=%s", filename + 1);
 		} else {
-#ifdef _WIN32
-			wchar_t dirname[PATH_MAX] = {0};
 			const char* lastSlash = strrchr(filename, '/');
 			const char* lastBackslash = strrchr(filename, '\\');
 			if (lastSlash && lastBackslash) {
@@ -497,10 +503,8 @@ bool _luaLoad(struct mScriptEngineContext* ctx, const char* filename, struct VFi
 				lastSlash = lastBackslash;
 			}
 			if (lastSlash) {
-				MultiByteToWideChar(CP_UTF8, 0, filename, lastSlash - filename, dirname, PATH_MAX);
-				AddDllDirectory(dirname);
+				strncpy(dirname, filename, lastSlash - filename);
 			}
-#endif
 			snprintf(name, sizeof(name), "@%s", filename);
 		}
 		filename = name;
@@ -509,6 +513,11 @@ bool _luaLoad(struct mScriptEngineContext* ctx, const char* filename, struct VFi
 	switch (ret) {
 	case LUA_OK:
 		luaContext->func = luaL_ref(luaContext->lua, LUA_REGISTRYINDEX);
+		if (dirname[0]) {
+			strncpy(luaContext->lastDirectory, dirname, sizeof(luaContext->lastDirectory));
+		} else {
+			memset(luaContext->lastDirectory, 0, sizeof(luaContext->lastDirectory));
+		}
 		return true;
 	case LUA_ERRSYNTAX:
 		luaContext->lastError = strdup(lua_tostring(luaContext->lua, -1));
@@ -522,8 +531,21 @@ bool _luaLoad(struct mScriptEngineContext* ctx, const char* filename, struct VFi
 
 bool _luaRun(struct mScriptEngineContext* context) {
 	struct mScriptEngineContextLua* luaContext = (struct mScriptEngineContextLua*) context;
+
+	if (luaContext->lastDirectory[0]) {
+		// Shim require to look in the previous location
+		lua_pushstring(luaContext->lua, luaContext->lastDirectory);
+		lua_pushcclosure(luaContext->lua, _luaRequireShim, 1);
+		lua_setglobal(luaContext->lua, "require");
+	}
+
 	lua_rawgeti(luaContext->lua, LUA_REGISTRYINDEX, luaContext->func);
-	return _luaInvoke(luaContext, NULL);
+	bool ret = _luaInvoke(luaContext, NULL);
+
+	// Restore previous value of require
+	lua_rawgeti(luaContext->lua, LUA_REGISTRYINDEX, luaContext->require);
+	lua_setglobal(luaContext->lua, "require");
+	return ret;
 }
 
 const char* _luaGetError(struct mScriptEngineContext* context) {
@@ -962,3 +984,68 @@ static int _luaLenList(lua_State* lua) {
 	lua_pushinteger(lua, mScriptListSize(list));
 	return 1;
 }
+
+static int _luaRequireShim(lua_State* lua) {
+	struct mScriptEngineContextLua* luaContext = _luaGetContext(lua);
+
+	const char* path = lua_tostring(lua, lua_upvalueindex(1));
+	const char* oldpath;
+	const char* oldcpath;
+
+	lua_getglobal(luaContext->lua, "package");
+
+	lua_pushliteral(luaContext->lua, "path");
+	lua_pushliteral(luaContext->lua, "path");
+	lua_gettable(luaContext->lua, -3);
+	oldpath = strdup(lua_tostring(luaContext->lua, -1));
+	lua_pushliteral(luaContext->lua, ";");
+	lua_pushstring(luaContext->lua, path);
+	lua_pushliteral(luaContext->lua, "/?.lua;");
+	lua_pushstring(luaContext->lua, path);
+	lua_pushliteral(luaContext->lua, "/?/init.lua");
+	lua_concat(luaContext->lua, 6);
+	lua_settable(luaContext->lua, -3);
+
+#ifdef _WIN32
+#define DLL "dll"
+#elif defined(__APPLE__)
+#define DLL "dylib"
+#else
+#define DLL "so"
+#endif
+	lua_pushliteral(luaContext->lua, "cpath");
+	lua_pushliteral(luaContext->lua, "cpath");
+	lua_gettable(luaContext->lua, -3);
+	oldcpath = strdup(lua_tostring(luaContext->lua, -1));
+	lua_pushliteral(luaContext->lua, ";");
+	lua_pushstring(luaContext->lua, path);
+	lua_pushliteral(luaContext->lua, "/?." DLL ";");
+	lua_pushstring(luaContext->lua, path);
+	lua_pushliteral(luaContext->lua, "/?/init." DLL);
+	lua_concat(luaContext->lua, 6);
+	lua_settable(luaContext->lua, -3);
+
+	lua_pop(luaContext->lua, 1);
+
+	lua_rawgeti(luaContext->lua, LUA_REGISTRYINDEX, luaContext->require);
+	lua_rotate(luaContext->lua, -2, 1);
+	int ret = lua_pcall(luaContext->lua, 1, 0, 0);
+
+	lua_getglobal(luaContext->lua, "package");
+
+	lua_pushliteral(luaContext->lua, "path");
+	lua_pushstring(luaContext->lua, oldpath);
+	lua_settable(luaContext->lua, -3);
+
+	lua_pushliteral(luaContext->lua, "cpath");
+	lua_pushstring(luaContext->lua, oldcpath);
+	lua_settable(luaContext->lua, -3);
+
+	lua_pop(luaContext->lua, 1);
+
+	if (ret) {
+		lua_error(luaContext->lua);
+	}
+
+	return 0;
+}