c++ - 在 Linux 上加密目录中的文件的问题

Question

我已经测试了程序的加密部分，它对单个文件工作得很好，甚至像“file1、file2、file3”这样的东西，但它不适用于目录。代码对我来说看起来不错，但是在执行时会出现段错误。

它应该加密目录中的文件并将它们写入具有新扩展名(旧名称+“.wbf”)的同一目录中，并在相反的情况下删除扩展名进行解密。我只会发布处理文件的代码部分，处理单个文件的 do_crypt 函数工作得很好，我认为这不是我的问题的根源。

    // PHP explode function

    vector<string> explode (string text, char separator)

    {

        vector<string> split;

        int last_trip = 0, pos = 0;

        text += separator;

        for (pos = 0; pos < text.size(); pos++)

        {

            if (text[pos] != separator)

            {

                // continue with iteration

            }

            else

            {

                split.push_back(text.substr(last_trip, pos - last_trip));

                last_trip = pos + 1;

            }

        }

        return split;

    };

    // LINUX -- directory listing function
    string LS (string dir)
    {
        DIR *dp;
        vector<string> files;
        struct dirent *dirp;
        if ((dp = opendir(dir.c_str())) = NULL)
        {
            cout << "Error (" << errno << ") opening " << dir << endl;
            //return errno;
        }
        while ((dirp = readdir(dp)) != NULL)
        {
            files.push_back(string(dirp->d_name));
        }
        closedir(dp);
        string explosive = "";
        for (int i = 0; i < files.size(); i++)
        {
            explosive += files[i];
            if (i != (files.size() - 1)) { explosive += ','; } 
        }
        return 0;
    }

// various functions for encryption

int main (int argc, char* argv[])

{

    cout << "\t! ENCRYPTR -- File encryption utility written by WBlinder, 2010. !" << endl << endl;

    cout << "\t\t\t\tOPTIONS:" << endl;

    cout << "\t\t\t1\tCRYPT A FILE" << endl << "\t\t\t2\tDECRYPT A FILE" << endl << endl;

    cout << "choice > ";

    int opt;

    cin >> opt;

    string sin, sout;

    string dummy; getline(cin, dummy);

    /*cout << "input files > ";

    cout.clear(); cin.clear();

    getline(cin, sin);

    vector<string> fin = explode(sin, ',');

    cout << "output files > ";

    getline(cin, sout);

    vector <string> fout = explode(sout, ',');

    if (sin.size() != sout.size())

    {

        cout << "NO. INPUT FILES UNEQUAL NO. OUTPUT FILES" << endl;

        return 1;

    }*/
    string dir;
    cout << "dir > "; 
    getline (cin, dir);
    vector<string> input = explode(dir, ',');
    vector<string> output = input;
    switch (opt)
    {
        case 1:
            for (int i = 0; i < output.size(); i++)
            {
                output[i] = output[i] + ".wbf";
            }
            break;
        case 2:
            for (int i = 0; i < output.size(); i++)
            {
                output[i] = output[i].substr(0, (output[i].size() - 4));
            }
            break;
    }

    cout << "password > ";

    getline(cin, key);

    cout << "N > ";

    cin >> N;

    cout << "(768 => fairly secure\t3072 => secure)\nextra rounds > ";

    cin >> drop;

    for (int brick = 0; brick < input.size(); brick++)

    {

        do_crypt(opt, dir + input[brick], dir + output[brick]);

    }

    /*string text;

    cout << "text to split: ";

    getline (cin, text);

    vector<string> tnt = explode(text, '.');

    for (int i = 0; i < tnt.size(); i++)

    {

        cout << i << ": " << tnt[i] << endl;

    }*/

}

Answer 1

你的LS有很多问题功能。首先，你应该让它直接返回 vector<string>而不是将数据打包在 string 中使用逗号分隔值。这将使您免于调用 explode函数，如果目录包含一个带逗号的文件名(在 Linux 上是有效名称)，则不会中断。

但更大的问题(导致)您的段错误是 return 0线。由于您的函数被声明为返回 string对象，并且自 string类具有来自 const char* 的隐式构造函数, 这被编译器解释为 return string(NULL) .当用 NULL 调用时指针此构造函数引发 logic_error异常(exception)。由于您没有捕获异常，C++ 运行时调用 abort功能。此函数在设计上会导致段错误以停止执行(如果启用，则生成核心转储以允许事后调试)。

你至少应该重写你的 LS像这样的功能:

string LS (string dir)
{
    DIR *dp;
    vector<string> files;
    struct dirent *dirp;
    if ((dp = opendir(dir.c_str())) == NULL)
    {
        cout << "Error (" << errno << ") opening " << dir << endl;
        return string();
    }
    while ((dirp = readdir(dp)) != NULL)
    {
        files.push_back(string(dirp->d_name));
    }
    closedir(dp);
    string explosive = "";
    for (int i = 0; i < files.size(); i++)
    {
        explosive += files[i];
        if (i != (files.size() - 1)) { explosive += ','; } 
    }
    return explosive;
}

或者更好的是，更改其签名以返回 vector<string>并像这样重写它:

vector<string> LS (string dir)
{
    DIR *dp;
    vector<string> files;
    struct dirent *dirp;
    if ((dp = opendir(dir.c_str())) != NULL)
    {
        while ((dirp = readdir(dp)) != NULL)
        {
            files.push_back(string(dirp->d_name));
        }
        closedir(dp);
    }
    else
    {
        cout << "Error (" << errno << ") opening " << dir << endl;
    }
    return files;
}