lua_pushlstring[-0, +1, m]
const char *lua_pushlstring (lua_State *L, const char *s, size_t len);
Pushes the string pointed to by s with size len onto the stack. Lua makes (or reuses) an internal copy of the given string, so the memory at s can be freed or reused immediately after the function returns. The string can contain any binary data, including embedded zeros.
Returns a pointer to the internal copy of the string.