Question

我遇到一个问题，我有一个配置文件，我用boost :: property_tree解析它：info_parser。

我使用此代码来完成工作：

struct _Config
{
    std::string info[2];
    boost::property_tree::ptree pt;
    _Config()
    {
        //check if config file exists, if not create it, etc, do other stuff not related to the issue
        //this code reproduces the issue
        //DEFAULT VALUE, can be changed by configuration later
        info[0] = "If updating this file make sure to update all settings accordingly.";
        info[1] = "This program has been created by Name 'Nickname' Lastname";
    }
    void Save()
    {
        boost::property_tree::info_parser::write_info(".\\config.cfg", pt);
    }
    void Load()
    {
        boost::property_tree::info_parser::read_info(".\\config.cfg", pt);
        {
            //check if variable already exists in config file, if yes load it to
            {
                //try to load entry
                boost::optional<std::string> v = pt.get_optional<std::string>("Info.a");
                if (v.is_initialized())
                    //overwrite default value
                    info[0] = v.get();
            }
            //if entry does not exist it will be created now, else the loaded value will be saved
            pt.put<std::string>("Info.a", info[0]);
        }
        //again for next variable
        {
            {
                boost::optional<std::string> v = pt.get_optional<std::string>("Info.b");
                if (v.is_initialized())
                    info[1] = v.get();
            }
            pt.put<std::string>("Info.b", info[1]);
        }
        Save();
    }
    ~_Config()
    {
        Save();
        pt.clear();
    }
} Config;

现在，我的部分第一次看起来像这样：

Info
{
    a "If updating this file make sure to update all settings accordingly."
    b "This program has been created by Name 'Nickname' Lastname"
}

再次启动时，我的配置在保存时变为：

Info
{
    a If updating this file make sure to update all settings accordingly.
    b This program has been created by Name 'Nickname' Lastname
}

但重新启动代码后，信息部分变得一团糟，我的程序中断了：

Info
{
    a If
    updating this
    file make
    sure to
    update all
    accordingly. ""
    b This
    program has
    been created
    by Name
    'Nickname' Lastname
}

如何确保空格是可接受的字符并且不删除引号？我还注意到我在配置文件中发表的任何评论都没有保存，是否有保存它们的选项？

我在32位应用程序中使用Windows 1.5 x64上的Visual Studio 2013的boost 1.55。

Answer 1

这是Undefined Behaviour，具体是

static initialization fiasco

这里的表现非常微妙！

Valgrind告诉我，info_parser::is_simple_data<char>正在访问已释放的字符串。该字符串将是本地静态。两者都是从__run_exit_handlers()调用的，但不是按任何特定顺序调用的！有关说明，请参阅链接的C ++ FAQ条目。

解决方案，不要依赖RAII的全球静力学：

int main()
{
    _Config Config;
    Config.Load();
}

很好，看到 Live On Coliru

boost :: property_tree :: info_parser打破值的空格

1 个答案:

static initialization fiasco