Lua Dump in C++

Question

I want to export a binary Chunk with lua_dump or luaU_dump..

The error: the return is only <-LuaR

Don't have a compile error or static problems with the code, only the <-LuaR return

What can i do? to result the problem?

private:
const char* buildLua(QString luaScript)
{
    const Proto* f;
    char *byteCode = 0L;
    size_t byteCodeLen = 0;
    wdata wd = { &byteCodeLen, &byteCode };
    string ts = luaScript.toStdString();
    const char* cs;
    lua_State *L = luaL_newstate();
    f=combine(L,0);
    luaL_loadstring(L,ts.c_str());
    luaL_openlibs(L);
    lua_lock(L);
    luaU_dump(L,f,kpt_lua_Writer,&wd,1);
    lua_unlock(L);
    lua_close(L);
    cs = byteCode;
    return cs;
}

static const char* kpt_lua_Reader(lua_State *L, void *ud, size_t *size)
{
    UNUSED(L);
    if ((*(int*)ud)--)
    {
        *size=sizeof(FUNCTION)-1;
        return FUNCTION;
    }
    else
    {
        *size=0;
        return NULL;
    }
}

static int kpt_lua_Writer(lua_State * /*l*/, const void *p, size_t sz, void *ud)
{
    wdata *wd = (wdata *)ud;

    char *newData;

    if((newData = (char *)realloc(*(wd->data), (*(wd->len)) + sz))) {
        memcpy(newData + (*(wd->len)), p, sz);
        *(wd->data) = newData;
        *(wd->len) += sz;
    } else {
        free(newData);
        return 1;
    }

    return 0;
}

static const Proto* combine(lua_State* L, int n)
{
    if (n==1)
        return toproto(L,-1);
    else
    {
        Proto* f;
        int i=n;
        if (lua_load(L,kpt_lua_Reader,&i,"=(keppedev)",NULL)!=LUA_OK) fatal(lua_tostring(L,-1));
        f=toproto(L,-1);
        for (i=0; i<n; i++)
        {
            f->p[i]=toproto(L,i-n-1);
            if (f->p[i]->sizeupvalues>0) f->p[i]->upvalues[0].instack=0;
        }
        f->sizelineinfo=0;
        return f;
    }
}

static void fatal(const char* message)
{
    QWidget *widget = new QWidget();
    QMessageBox::warning(widget,"Keppe Develop",message);
}

http://www.keppe.org/img/LuaR.png

Answer 1

There is no need to use the internals of Lua. In any case, you should call luaL_loadstring or luaL_loadbuffer , not luaL_dostring , which executes the code in the string:

lua_State *L = luaL_newstate();
luaL_loadstring(L,s.c_str());
lua_dump(L,writer,NULL);
lua_close(L);

However, you should test the return values of both luaL_loadstring and lua_dump .

Answer 2

The compiler error is cause by an invalid function prototype where frmDevelop::writer is implemented.

extern "C"
{
static int frmDevelop::writer(lua_State *L, const void *p, size_t size, void *u)
{
  // ...
}
}

You only need the static qualifier at the point of declaration in class frmDevelop . Also, extern "C" here isn't right since you're telling the compiler to not mangle the function name. But the compiler cannot honor that request because you're using a C++ feature(writer is part of frmDevelop and so you need the :: scope operator) -- extern "C" just gets ignored for frmDevelop::writer .

Change writer's implementation from:

extern "C"
static int frmDevelop::writer(lua_State *L, const void *p, size_t size, void *u)
{ /* ... */ }

to

int frmDevelop::writer(lua_State *L, const void *p, size_t size, void *u)
{ /* ... */ }

and that'll fix the compile error you're getting.

Answer 3

I am fixing it self with the Code

Source File (Contain)

void frmDevelop::on_actionBuild_Project_triggered()
{
    if (!isInLuaMode) return;
    const char* output = buildLua(cedit->document()->toPlainText());
    int length = strlen(output);
}

Header File (Contain)

private:
const char* buildLua(QString luaScript)
    {
        string ts = luaScript.toStdString();
        lua_State *L = luaL_newstate();
        FILE* D = fopen("test.luac","wb");
        luaL_openlibs(L);
        luaL_loadstring(L,ts.c_str());
        lua_lock(L);
        int re = lua_dump(L,kpt_lua_Writer,D);
        lua_unlock(L);
        lua_close(L);
        fclose(D);
        return QString::number(re).toStdString().c_str();
    }

    static int kpt_lua_Writer(lua_State * /*l*/, const void *p, size_t sz, void *u)
    {
        return (fwrite(p,sz,1,(FILE*)u)!=1) && (sz!=0);
    }

test.luac must replace with your File Name :D