sub readn
{
   my ($socket, $bytes ) = @_;
   my $offset = 0;
   
   my $buf = "";
   while ($offset < $bytes)
   {
      my $nread;
      my $nleft = $bytes-$offset;
      
      $nread = sysread($socket,$buf,$nleft,$offset);

      ## undef is like the -1 C return
      kill 'USR1',$$ unless (defined $nread);  

      last if ($nread ==0);                 ## EOF
      
      $offset += $nread;
   }

   return $buf;
}