cocos2dxandroid執行Luac編譯後的lua程式碼
阿新 • • 發佈：2019-01-28
執行環境
win7 64
cocos2d-2.1rc0-x-2.1.2
lua 5.1
通常我們編寫好的lua程式碼都是明文形式，誰都可以檢視修改，為了防止自己的勞動成果不被別人輕易的盜取，可以使用luac（lua庫中自帶）對其進行加密，轉換為二進位制檔案。這樣lua程式碼就無法直接檢視，但是這裡會有一個問題：在windows下能夠很好的執行，在android上就會黑屏，提示錯誤：
[LUA ERROR] binary string: unexpected end in precompiled chunk
追根溯源
在bool AppDelegate::applicationDidFinishLaunching()中檢視lua載入程式碼：
01.#if
(CC_TARGET_PLATFORM == CC_PLATFORM_ANDROID)
02.CCString* pstrFileContent = CCString::createWithContentsOfFile(
"program/main.lua" );
03.if
(pstrFileContent)
04.{
05.pEngine->executeString(pstrFileContent->getCString());
06.}
07.#else
08.std::string path = CCFileUtils::sharedFileUtils()->fullPathForFilename(
"program/main.lua" );
09.pEngine->addSearchPath( path.substr(
0, path.find_last_of(
"/" ) ).c_str() );
10.pEngine->executeScriptFile( path.c_str() );
11.#endif
這裡executeString()載入lua檔案，繼續檢視原始碼發現真正幹活的是：
1.LUALIB_API
int luaL_loadbuffer (lua_State *L,
const char
*buff, size_t size,
2.const
char*name) {
3.LoadS ls;
4.ls.s = buff;
5.ls.size = size;
6.return
lua_load(L, getS, &ls, name);
7.}
在回頭看看函式executeScriptFile()的執行過程：
01.LUALIB_API
int luaL_loadfile (lua_State *L,
const char
*filename) {
02.LoadF lf;
03.int
status, readstatus;
04.int
c;
05.int
fnameindex = lua_gettop(L) + 1;
/* index of filename on the stack */
06.lf.extraline =
0;
07.if
(filename == NULL) {
08.lua_pushliteral(L,
"=stdin");
09.lf.f = stdin;
10.}
11.else
{
12.lua_pushfstring(L,
"@%s", filename);
13.lf.f = fopen(filename,
"r");
14.if
(lf.f == NULL) return
errfile(L, "open", fnameindex);
15.}
16.c = getc(lf.f);
17.if
(c == '#') {
/* Unix exec. file? */
18.lf.extraline =
1;
19.while
((c = getc(lf.f)) != EOF && c != '
20.') ;
/* skip first line */
21.if
(c == '
22.') c = getc(lf.f);
23.}
24.if
(c == LUA_SIGNATURE[0] && filename) {
/* binary file? */
25.lf.f = freopen(filename,
"rb", lf.f); /* reopen in binary mode */
26.if
(lf.f == NULL) return
errfile(L, "reopen", fnameindex);
27./* skip eventual `#!...' */
28.while
((c = getc(lf.f)) != EOF && c != LUA_SIGNATURE[0]) ;
29.lf.extraline =
0;
30.}
31.ungetc(c, lf.f);
32.status = lua_load(L, getF, &lf, lua_tostring(L, -1));
// 關鍵，與luaL_loadbuffer()中的一樣
33.readstatus = ferror(lf.f);
34.if
(filename) fclose(lf.f); /* close file (even in case of errors) */
35.if
(readstatus) {
36.lua_settop(L, fnameindex);
/* ignore results from `lua_load' */
37.return
errfile(L, "read", fnameindex);
38.}
39.lua_remove(L, fnameindex);
40.return
status;
41.}
注意看程式碼的中文註釋部分，這裡就能解釋為什麼用luac編譯的檔案在window下面可以好好地執行（IOS上面也OK），而android上就不能。luaL_loadfile()中通過c == LUA_SIGNATURE[0]判斷lua檔案是否加密，如果是，則重新以“rb”方式開啟。
解決辦法
修改scriptingluacocos2dx_supportCocos2dxLuaLoader.cpp中的loader_Android()函式
修改前：
01.int
loader_<a href=
target="_blank"
class="keylink">Android</a>(lua_State *L)
02.{
03.std::string filename(luaL_checkstring(L,
1));
04.filename.append(".lua");
05.
06.CCString* pFileContent = CCString::createWithContentsOfFile(filename.c_str());
07.
08.if
(pFileContent)
09.{
10.if
(luaL_loadstring(L, pFileContent->getCString()) != 0)
11.{
12.luaL_error(L, "error loading module %s from file %s :
13.%s",
14.lua_tostring(L,
1), filename.c_str(), lua_tostring(L, -1));
15.}
16.}
17.else
18.{
19.CCLog("can not get file data of %s", filename.c_str());
20.}
21.
22.return
1;
23.}
修改後：
01.int
loader_Android(lua_State* L)
02.{
03.unsigned
char* pData = nullptr;
04.unsigned
long size = 0;
05.
06./* modify for read lua script from bytecode */
07.std::string filename(luaL_checkstring(L,
1));
08.std::string rel_name = filename.append(".lua");
09.
10.pData = CCFileUtils::sharedFileUtils()->getFileData(rel_name.c_str(),
"rb", &size);
11.if
(pData) {
12.if
(luaL_loadbuffer(L, (char*)pData,size,rel_name.c_str()) !=
0 ) {
13.luaL_error(L,
"error loading module s from file s :s",
14.lua_tostring(L,
1), rel_name.c_str(), lua_tostring(L, -1));
15.}
16.}
17.else
{
18.CCLog("can not get file data of %s", filename.c_str());
19.}
20.
21.CC_SAFE_DELETE_ARRAY(pData);
22.
23.return
1;
24.}
另外，由於在cpp中第一次載入lua並沒有呼叫loader_Android()，這是因為uaL_loadbuffer只會把檔案載入成為一個chunk，而不會執行該chunk，所以還要在加一條呼叫語名lua_pcall，如下：
01.int
loader_Android(lua_State* L)
02.{
03.unsigned
char* pData = nullptr;
04.unsigned
long size = 0;
05.
06./* modify for read lua script from bytecode */
07.std::string filename(luaL_checkstring(L,
1));
08.std::string rel_name = filename.append(".lua");
09.
10.pData = CCFileUtils::sharedFileUtils()->getFileData(rel_name.c_str(),
"rb", &size);
11.if
(pData) {
12.if
(luaL_loadbuffer(L, (char*)pData,size,rel_name.c_str()) !=
0 || lua_pcall(L, 0, LUA_MULTRET,
0) ) { // 修改處
13.luaL_error(L,
"error loading module s from file s :s",
14.lua_tostring(L,
1), rel_name.c_str(), lua_tostring(L, -1));
15.}
16.}
17.else
{
18.CCLog("can not get file data of %s", filename.c_str());
19.}
20.
21.CC_SAFE_DELETE_ARRAY(pData);
22.
23.return
1;
24.}
或者我們可以偷雞一下，
1.pEngine->executeString("require "program/main"");
// 注意這裡的"
最後我們的AppDelegate::applicationDidFinishLaunching()大概就是這樣的，
01.const
char* luaFile = "program/main.lua";
02.#if
(CC_TARGET_PLATFORM == CC_PLATFORM_ANDROID)
03.std::string path = CCFileUtils::sharedFileUtils()->fullPathForFilename(luaFile);
04.CCLog("path = %s", path.c_str());
05.std::string subPath = path.substr(0, path.find_last_of("/"));
06.CCLog("sub path = %s", subPath.c_str());
07.
08.pEngine->addSearchPath(subPath.c_str());
09.
10.std::vector<std::string> searchPaths = CCFileUtils::sharedFileUtils()->getSearchPaths();
11.searchPaths.insert(searchPaths.begin(), subPath);
12.CCFileUtils::sharedFileUtils()->setSearchPaths(searchPaths);
13.
14.pEngine->executeString("require "program/main"");
// 注意這裡的"
15.#else
16.std::string path = CCFileUtils::sharedFileUtils()->fullPathForFilename(luaFile);
17.pEngine->addSearchPath( path.substr(
0, path.find_last_of(
"/" ) ).c_str() );
18.pEngine->executeScriptFile( path.c_str() );
19.#endif
注：這裡筆者偷雞了一下。