my ($block_size) = 10_000_000;       # 10MB block size
     my ($timeout) = 0;     # Don't wait.
     my ($rfd)     = '';    # Initialize with string only

     # SYNOPSIS:
     open ($filehandle, "FILE or PIPE");
     CheckHandle ($filehandle);

     sub CheckHandle
     {
          my ($filehandle) = @_;
          vec ($rfd, fileno($filehandle), 1) = 1;

          # Wait for something to happen, and make sure
          # that it happened to the right filehandle.
          if (select ($rfd, undef, undef, $timeout) >= 0
                && vec($rfd, fileno($filehandle), 1))
          {
                 # Something came in!
                 my ($buffer);
                 read ($filehandle, $buffer, $block_size);

                 return $buffer;
          }

          return;
     }