Listing 5 Derives exception classes from the standard exception hierarchy

// ddir3.cpp
#include <stdio.h>
#include <stdlib.h>
#include <io.h>
#include <string.h>
#include <sys/stat.h>
#include <dirent.h>
#include <dir.h>
#include <iostream.h>
#include <fstream.h>
#include <strstream.h>
#include <cstring.h>
#include <except.h>

// Exception classes
class Dir_err : public runtime
{
public:
   Dir_err(const string& s) : runtime(s){}
};

class Bad_dir : public Dir_err
{
public:
   Bad_dir(const string& s) : Dir_err(s){}
};

class Dir_open_err : public Dir_err
{
public:
   Dir_open_err(const string& s) : Dir_err(s){}
};

class File_del_err : public Dir_err
{
public:
   File_del_err(const string& s) : Dir_err(s){}
};

class Dir_del_err : public Dir_err
{
public:
   Dir_del_err(const string& s) : Dir_err(s){}
};

// Put response file in root directory
char response_file[L_tmpnam+1] = "\\";
// (Change this to "/" for UNIX)
main(int argc, char **argv)
{
   char *old_path = getcwd(NULL,MAXDIR);
   void rd(char *);

   // Initialize response file for DOS "del" command
   tmpnam(response_file+1);
   ofstream(response_file) << "Y\n";

   // Delete the directories
   while (--argc)
   {
      try
      {
         rd(*++argv);
      }

      // Catch exceptions
      catch(const Bad_dir& x)
      {
         cerr << "Invalid directory: "
             << x.what() << endl;
      }
      catch(const Dir_open_err& x)
      {
         cerr << "Error opening directory: "
             << x.what() << endl;
      }
      catch(const File_del_err& x)
      {
         cerr << "Error deleting file: "
             << x.what() << endl;
      }
      catch(const Dir_del_err& x)
      {
         cerr << "Error deleting directory: "
             << x.what() << endl;
      }
      catch(const Dir_err& x)
      {
         cerr << "Directory error:"
             << x.what() << endl;
      }
   }

   // Clean-up
   remove(response_file);
   chdir(old_path);
   return 0;
}

void rd(char* dir)
{
   // Log onto the directory that is to be deleted
   if (chdir(dir))
      throw Bad_dir(dir);
   cout << strlwr(dir) << endl;

   // Delete all normal files via OS shell
   const size_t SH_CMD_LEN = 14;
   char sh_cmd[L_tmpnam+SH_CMD_LEN+1];
   ostrstream(sh_cmd,sizeof sh_cmd) << "del *.* <"
                              << response_file
                              << " >>null"
                              << ends;
   system(sh_cmd);

   // Delete any remaining directory entries
   DIR *dirp;
   struct dirent *entry;
   if ((dirp = opendir(".")) == NULL)
      throw Dir_open_err(dir);
   while ((entry = readdir(dirp)) != NULL)
   {
      struct stat finfo;

      if (entry->d_name[0] == '.')
         continue;
      stat(entry->d_name,&finfo);
      if (finfo.st_mode & S_IFDIR)
         rd(entry->d_name);      // Subdirectory
      else
      {
         // Enable delete of file, then do it
         chmod(entry->d_name,S_IWRITE);
         if (unlink(entry->d_name))
            throw File_del_err(entry->d_name);
      }
   }
   closedir(dirp);

   // Remove the directory from its parent
   chdir("..");
   if (rmdir(dir))
      throw Dir_del_err(dir);
}

// End of File