$max_size = '100000'; #set your max size value
$totalbytes=0;
open (IMAGESAVE,">$image_upload_directory/$final_name");
while ($bytesread=read ($file,$data,1024)) {
	$totalbytes+=$bytesread;
	if ($totalbytes > $max_size) {
		unlink ("$image_upload_directory/$file_name");
		&FileTooLarge; #call your error sub 
		exit;
	}
	print IMAGESAVE $data;
}
close IMAGESAVE;