PHP script to generate a file with random data of given name and size?

Question

Does anyone know of one? I need to test some upload/download scripts and need some really large files generated. I was going to integrate the test utility with my debug script.

Answer 1

generate_file() from "Marco Demaio" is not memory friendly so I created file_rand().

function file_rand($filename, $filesize) {
    if ($h = fopen($filename, 'w')) {
        if ($filesize > 1024) {
            for ($i = 0; $i < floor($filesize / 1024); $i++) {
                fwrite($h, bin2hex(openssl_random_pseudo_bytes(511)) . PHP_EOL);
            }
            $filesize = $filesize - (1024 * $i);
        }
        $mod = $filesize % 2;
        fwrite($h, bin2hex(openssl_random_pseudo_bytes(($filesize - $mod) / 2)));
        if ($mod) {
            fwrite($h, substr(uniqid(), 0, 1));
        }
        fclose($h);
        umask(0000);
        chmod($filename, 0644);
    }
}

As you can see linebreaks are added every 1024 bytes to avoid problems with functions that are limited to 1024-9999 bytes. e.g. fgets() with <= PHP 4.3. And it makes it easier to open the file with an text editor having the same issue with super long lines.

Answer 2

generate_file() from @Marco Demaio caused this below when generating 4GB file.

Warning: str_repeat(): Result is too big, maximum 2147483647 allowed in /home/xxx/test_suite/handler.php on line 38

I found below function from php.net and it's working like charm. I have tested it upto

17.6 TB (see update below)

in less than 3 seconds.

function CreatFileDummy($file_name,$size = 90294967296 ) {   
// 32bits 4 294 967 296 bytes MAX Size
    $f = fopen('dummy/'.$file_name, 'wb');
    if($size >= 1000000000)  {
        $z = ($size / 1000000000);       
        if (is_float($z))  {
            $z = round($z,0);
            fseek($f, ( $size - ($z * 1000000000) -1 ), SEEK_END);
            fwrite($f, "\0");
        }       
        while(--$z > -1) {
            fseek($f, 999999999, SEEK_END);
            fwrite($f, "\0");
        }
    }
    else {
        fseek($f, $size - 1, SEEK_END);
        fwrite($f, "\0");
    }
    fclose($f);

return true;
}

Update:

I was trying to hit 120TB, 1200 TB and more but filesize was limited to 17.6 TB. After some googling I found that it is max_volume_size for ReiserFS file system which was on my server. May be PHP can handle 1200TB also in just few seconds. :)