重写require后调用"lua_getfield(）"时崩溃

Crashes when calling `lua_getfield()` after overriding the require

本文关键字：quot 崩溃 getfield require 重写 lua 调用      更新时间：2023-10-16

这个问题与@Henri_Menke对这个问题的回答有关：如何在C++中获得预加载的模块名称

我正在尝试用我自己的版本覆盖require函数，这样我就可以在Lua脚本中获得预加载的模块名称。

这是我的代码：

#include "lua.hpp"
void main()
{
lua_State *L = luaL_newstate();
luaL_openlibs(L);
lua_settop(L, 0);
luaL_dostring(L, "local require_original = requiren"
"function require(name, ...)n"
"current_module = namen"
"require_original(name, ...)n"
"current_module = niln"
"endn"); //if I comment out this chunk, it works fine
luaL_dostring(L, "package.preload['test'] = function ()n"
"local test = {}n"
"print('While loading:', current_module)n"
"function test.update() print('Updated!') endn"
"return testn"
"endn");
lua_getglobal(L, "require");
lua_pushstring(L, "test");
if (lua_pcall(L, 1, LUA_MULTRET, 0))
{
std::cout << "Error: " << lua_tostring(L, -1) << std::endl;
lua_pop(L, 1);
}
int top = lua_gettop(L);
lua_getfield(L, -1, "update"); //crashes here
if (lua_isfunction(L, -1))
{
lua_pushnil(L);
if (lua_pcall(L, 1, LUA_MULTRET, 0))
{
std::cout << "Error: " << lua_tostring(L, -1) << std::endl;
lua_pop(L, 1);
}
}
lua_close(L);
}

但是，它在调用lua_getfield(L, -1, "update");时崩溃。

当我注释掉Lua脚本的第一块(第一个luaL_dostring(时，它不再崩溃。

我不明白如果我使用自己版本的require，它为什么会崩溃。

我该怎么解决这个问题？

我忘记从重写的require函数返回模块表。很抱歉。

#include <iostream>
#include "lua.hpp"
int main() {
lua_State *L = luaL_newstate();
luaL_openlibs(L);
lua_settop(L, 0);
luaL_dostring(L, "local require_original = requiren"
"function require(name, ...)n"
"current_module = namen"
"local val = table.pack(require_original(name, ...))n"
"current_module = niln"
"return table.unpack(val,1,val.n)n"
"endn"); //if I comment out this chunk, it works fine
luaL_dostring(L, "package.preload['test'] = function ()n"
"local test = {}n"
"print('While loading:', current_module)n"
"function test.update() print('Updated!') endn"
"return testn"
"endn");
lua_getglobal(L, "require");
lua_pushstring(L, "test");
if (lua_pcall(L, 1, LUA_MULTRET, 0))
{
std::cout << "Error: " << lua_tostring(L, -1) << std::endl;
lua_pop(L, 1);
}
int top = lua_gettop(L);
lua_getfield(L, -1, "update"); //crashes here
if (lua_isfunction(L, -1))
{
lua_pushnil(L);
if (lua_pcall(L, 1, LUA_MULTRET, 0))
{
std::cout << "Error: " << lua_tostring(L, -1) << std::endl;
lua_pop(L, 1);
}
}
lua_close(L);
}

$ clang++ -Wall -Wextra -Wpedantic -I /usr/include/lua5.2 test.cpp -llua5.2
test.cpp:28:9: warning: unused variable 'top' [-Wunused-variable]
int top = lua_gettop(L);
^
1 warning generated.
$ ./a.out 
While loading:  test
Updated!
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