int TSystem::CopyFile(const char *f, const char *t, Bool_t overwrite)
{
   //Method to copy any file from anywhere to anywhere
   //(if the necessary TFile and TSystem plugins are available).
   // Copy a file. If overwrite is true and file already exists the
   // file will be overwritten. Returns 0 when successful, -1 in case
   // of failure, -2 in case the file already exists and overwrite was false.

   if (!AccessPathName(t) && !overwrite)
      return -2;

   //save current directory
   TDirectory* dir_sav = gDirectory;
   
   TUrl path(f,kTRUE);
   path.SetOptions("filetype=raw");
   TFile* from = TFile::Open(path.GetUrl(),"READ");
   if (!from || from->IsZombie()){
      dir_sav->cd();
      return -1;
   }
//   from->ls();

   path.SetUrl(t,kTRUE);
   path.SetOptions("filetype=raw");
   TString open_option("CREATE");
   if(overwrite) open_option.Prepend("RE");
   TFile* to = TFile::Open(path.GetUrl(), open_option.Data());
   if (!to || to->IsZombie()){
      dir_sav->cd();
      return -2;
   }
//   to->ls();

   //set buffer size depending on size of file to copy
   //as a default use 1MB buffer (good for large files and rfio-hpss system);
   //use a 1KB buffer for files smaller than 1MB
   int bufsize = 1024*1024;
   Long64_t filesize = from->GetSize();
   if( filesize >0 && filesize<1024*1024 ) bufsize=1024;
   char* buf = new char[bufsize];
   
   int ret = 0;
   Long64_t bytes_read, bytes_wrote, bytes_left, last_bytes_read, last_bytes_wrote;
   bytes_read = bytes_wrote = bytes_left = last_bytes_read = last_bytes_wrote = 0;
   
//   printf("Filesize=%lld Buffersize=%d\n",filesize,bufsize);
   
//   int op = 1;
   
   while (bufsize && !ret && !from->ReadBuffer(buf, bufsize)) {
      
      bytes_read = from->GetBytesRead() - last_bytes_read;
      last_bytes_read = from->GetBytesRead();
      ret = (int)to->WriteBuffer(buf, bytes_read);
      bytes_wrote = to->GetBytesWritten() - last_bytes_wrote;
      last_bytes_wrote = to->GetBytesWritten();
      if(bytes_wrote != bytes_read)
         ret = -3;
      //adjust buffer size
      bytes_left = filesize - last_bytes_read;
      if(bytes_left < bufsize) bufsize = (int)bytes_left;
      
//       printf("----------------------------------%d-----------------------------------\n",op++);
//       printf("bytes_read=%lld last_bytes_read=%lld total_bytes_read=%lld\n",
//             bytes_read, last_bytes_read, from->GetBytesRead());
//       printf("bytes_wrote=%lld last_bytes_wrote=%lld total_bytes_wrote=%lld\n",
//             bytes_wrote, last_bytes_wrote, to->GetBytesWritten());
//       printf("bytes_left=%lld bufsize=%d\n",
//             bytes_left, bufsize);
   }

//       printf("----------------------------------END-----------------------------------\n");
//       printf("bytes_read=%lld last_bytes_read=%lld total_bytes_read=%lld\n",
//             bytes_read, last_bytes_read, from->GetBytesRead());
//       printf("bytes_wrote=%lld last_bytes_wrote=%lld total_bytes_wrote=%lld\n",
//             bytes_wrote, last_bytes_wrote, to->GetBytesWritten());
//       printf("bytes_left=%lld bufsize=%d\n",
//             bytes_left, bufsize);
      
   delete from;
   delete to;
   delete [] buf;

   //reset working directory
   dir_sav->cd();
   
   return ret;
}