Try to do things whit PHP stream_filter

stream-fiter-test.php

<?php
error_reporting(E_ALL);
ini_set('display_errors', 'On');

/**
 * http://stackoverflow.com/questions/27103269/what-is-a-bucket-brigade
 * http://stackoverflow.com/questions/38147616/consumed-bytes-for-php-user-filterfilter
 */

class append_filter extends php_user_filter {
    function filter($in, $out, &$consumed, $closing) {
        echo 'Start New filter whit closing = '.($closing?'TRUE':'FALSE');
        $total_read = 0;
        while ($bucket = stream_bucket_make_writeable($in)) {
            $total_read += $bucket->datalen;

            #$bucket->data = str_replace('a', '', $bucket->data);
            #$bucket->data = str_replace('a', 'ae', $bucket->data);

            $consumed += $bucket->datalen; # By the example
            #$consumed += strlen($bucket->data);
            #$consumed = 0;
            #$consumed = rand(0, $bucket->datalen*2);
            #$consumed -= $bucket->datalen;
            # or just don't change it at all

            stream_bucket_append($out, $bucket);
        }
        echo "; consumed ".(is_null($consumed)?'NULL':$consumed)." of $total_read \n";
        return PSFS_PASS_ON;
    }
}
stream_filter_register("append", "append_filter");

if(!isset($argv[1]) || !file_exists($argv[1])) die('First argument must be a file.');
$in_file = strpos($argv[1], '.gz') ? 'compress.zlib://'.$argv[1] : $argv[1];
$fin = fopen($in_file, 'rb');

stream_filter_append($fin, 'append', STREAM_FILTER_READ);
stream_copy_to_stream($fin, fopen('/tmp/debug.out', 'wb'));