jkuchar/BigFileTools

<?php

namespace BigFileTools\Driver;

use BigFileTools\Utils;
use Brick\Math\BigInteger;

class NativeSeekDriver implements ISizeDriver
{
    /**
     * Returns file size by seeking at the end of file
     * @see http://www.php.net/manual/en/function.filesize.php#79023
     * @see http://www.php.net/manual/en/function.filesize.php#102135
     * @param string $path Full path to file
     * @return BigInteger
     * @throws Exception
     */
    public function getFileSize($path)
    {
        // This should work for large files on 64bit platforms and for small files everywhere
        $fp = fopen($path, "rb");
        if (!$fp) {
            throw new Exception("Cannot open specified file for reading.");
        }

        $flockResult = flock($fp, LOCK_SH);
        $seekResult = fseek($fp, 0, SEEK_END);
        $position = ftell($fp);
        flock($fp, LOCK_UN);
        fclose($fp);

        if($flockResult === false) {
            throw new Exception("Couldn't get file lock. Operation abandoned.");
        }

        if($seekResult !== 0) {
            throw new Exception("Seeking to end of file failed");
        }

        if($position === false) {
            throw new Exception("Cannot determine position in file. ftell() failed.");
        }

        // PHP uses internally (in C) UNSIGNED integer for file size.
        // PHP uses signed implicitly
        // convert signed (max val +2^31) -> unsigned integer will extend range for 32-bit to (+2^32)
        return BigInteger::of(
            sprintf("%u", $position)
        );
    }
}