backupscript/src/Twig/AppExtension.php

<?php

namespace App\Twig;

use Symfony\Component\DependencyInjection\ContainerInterface;
use Twig\Extension\AbstractExtension;
use Twig\TwigFilter;

class AppExtension extends AbstractExtension
{
    public function getFilters()
    {
        return array(
            new TwigFilter('formatBytes', array($this, 'formatBytes')),
        );
    }

    /**
     * Format a file size to be human readable
     * 
     * @param int $bytes     Number of bytes
     * @param int $precision Precision
     * 
     * @return string Formatted string
     */
    public function formatBytes($bytes, $precision = 2)
    {
        $size = ['B','kB','MB','GB','TB','PB','EB','ZB','YB'];
        $fact = (int)(floor((strlen((string)$bytes) - 1) / 3));
        return sprintf("%.{$precision}f", $bytes / pow(1024, $fact)) . $size[$fact];
    }

}