Question

我有一个c ++类，使用stat读取有关文件的信息。它在各自的文件上设置dir和reg true就好了，但是当我在我的ubuntu PC上的已知sym链接上测试时，lnk仍然是假的（＆＃34; /vmlinuz.old"）。它在这种情况下设定为真。我的代码必须在此处引用：http://linux.die.net/man/2/stat（漫步到底部）

class file_info
{
  public:
    string size;
    string owner;
    string group;
    string path;

    string acc_time;
    string mod_time;
    string cre_time;

    bool read;
    bool write;
    bool exec;

    bool dir;
    bool lnk;
    bool reg;
    bool fail;

  private:
    struct stat f_stat;

    void set_size()
    {
      string raw_size = to_string(f_stat.st_size);
      unsigned int len = raw_size.size();
      size = "";

      if (len <= 3)
      {
        size += raw_size;
        size += "Bytes";
        return;
      }

      size += raw_size[len - 1];
      size += ".";
      size += raw_size[len - 2];

      if ((len > 3) && (len < 6))         size += "KB";
      else if ((len >= 6) && (len < 9))   size += "MB";
      else if ((len >= 9) && (len < 12))  size += "GB";
      else if ((len >= 12) && (len < 15)) size += "TB";
      else if ((len >= 15) && (len < 18)) size += "PB";
      else if ((len >= 18) && (len < 21)) size += "EB";
      else size = "OL";
    }

  private:
    void get_info()
    {
      switch (f_stat.st_mode & S_IFMT)
      {
        case S_IFDIR: dir = true; break;
        case S_IFREG: reg = true; break;
        case S_IFLNK: lnk = true; break;
        default: fail = true; break;
      }

      if (!fail)
      {
        if (f_stat.st_mode & S_IRUSR) read = true;
        if (f_stat.st_mode & S_IWUSR) write = true;
        if (f_stat.st_mode & S_IXUSR) exec = true;

        struct passwd *pw = getpwuid(f_stat.st_uid);
        struct group *gr = getgrgid(f_stat.st_gid);

        if (pw != NULL) owner = pw->pw_name;
        if (gr != NULL) group = gr->gr_name;

        set_size();       
        acc_time = ctime(&f_stat.st_atime);
        mod_time = ctime(&f_stat.st_mtime);
        cre_time = ctime(&f_stat.st_ctime);

        acc_time.erase(acc_time.end() - 1, acc_time.end());
        mod_time.erase(mod_time.end() - 1, mod_time.end());
        cre_time.erase(cre_time.end() - 1, cre_time.end());
      }
    }

  public:
    file_info(string file): dir(false),
                            lnk(false),
                            reg(false),
                            fail(false),
                            read(false),
                            write(false),
                            exec(false)
    {
      path = file;

      if (stat(file.c_str(), &f_stat))
      {
        fail = true;
      }
      else
      {
        get_info();
      }
    } 
};

Answer 1

如果我没有弄错，你使用stat（）系统调用来检查文件是否是符号链接，使用S_IFLNK标志。以下是手册页中的引用：

stat() stats the file pointed to by path and fills in buf.

lstat() is identical to stat(), except that if path is a symbolic link,
then the link itself is stat-ed, not the file that it refers to.

尝试使用lstat（）而不是stat（）。 stat（）跟在链接之后，并返回链接链接到的文件确实是目录或常规文件。

Answer 2

stat()返回有关符号链接指向的文件的信息...尝试lstat()

c ++类不检测sym链接

2 个答案: