
static void do_copy (int infile, int tmp_file, long len)
   {
     int to_do;
     char buffer [SIZE_BUFFER];
     do
          {
          to_do = (int) (min ((long) SIZE_BUFFER, len));
          read (infile, buffer, to_do);
          write (tmp_file, buffer, to_do);
         } while (len -= to_do);
     return ;
   }


