System Requirements


Quick install

$ php install <(int)version> <(bool)debug>

Downloading & Compiling


use Versyx\Codepad\Downloader;
use Versyx\Codepad\Compiler;

require __DIR__ . '/../config/bootstrap.php';

$debug = true;
$version = "7.1.30";
init(new Downloader($debug), new Compiler($debug), $version);

function init(Downloader $downloader, Compiler $compiler, string $version)
    try {
        $php = $downloader->setVersion($version)->download();
        $compiler->compile($php->getVersion(), $php->getTarget());
    } catch (\Exception $e) {
        echo $e->getMessage();


Creating the chrooted Jail

The jailer module is incomplete, in the meantime please follow these instructions:

Create the jail:

$ mkdir /opt/phpjail
$ cd /opt/phpjail

Create the filesystem

$ mkdir bin etc dev lib lib64 usr
$ mkdir etc/alternatives

Create mount points for PHP versions

$ mkdir php-7.0.33 php-7.1.30 php-7.2.19...

Set permissions

$ chmod -R 0711 /opt/phpjail
$ chown -R root:root /opt/phpjail

Mount filesystem in read-only mode

mount -o bind,ro /bin /opt/phpjail/bin
mount -o bind,ro /dev /opt/phpjail/dev
mount -o bind,ro /lib /opt/phpjail/lib
mount -o bind,ro /lib64 /opt/phpjail/lib64
mount -o bind,ro /usr /opt/phpjail/usr
mount -o bind,ro /etc/alternatives /opt/phpjail/etc/alternatives
mount -o bind,ro /tmp/php-7.0.33 /opt/phpjail/php-7.0.33
mount -o bind,ro /tmp/php-7.1.30 /opt/phpjail/php-7.1.30
mount -o bind,ro /tmp/php-7.2.19 /opt/phpjail/php-7.2.19

Enabling the worker

You’ll need to allow www-data to run the worker script as a privileged user, add entries for each compiled version to /etc/sudoers like so:

www-data ALL =(ALL) NOPASSWD: /opt/phpjail/php-7.3.6/bin/php /var/www/codepad/http/worker.php 7.3.6
www-data ALL =(ALL) NOPASSWD: /opt/phpjail/php-7.0.33/bin/php /var/www/codepad/http/worker.php 7.0.33

This will restrict www-data’s sudo privileges to only running the worker.

How it Works

The PHP code and version is base64 encoded and submitted to http/manager.php, the manager then base64 decodes the data and runs a check on the code input against disabled functions, if the check comes back clean, a new process is created with stream resources:

$proc = proc_open("sudo /opt/phpjail/php-$ver/bin/php /var/www/" . env("APP_NAME) . "/http/worker.php $ver", [
    0 => ["pipe", "rb"],
    1 => ["pipe", "wb"],
    2 => ["pipe", "wb"]
], $pipes);

The PHP code is passed to http/worker.php from the manager via STDIN, the worker then creates a temporary file in /opt/phpjail, sets its permissions to 0444 and then executes the file using the selected PHP version instance, which is chrooted to /opt/phpjail as user nobody. If the code takes longer than five seconds to execute, the process will terminate.

$starttime = microtime(true);
$unused = [];
$ph = proc_open('chroot --userspec=nobody /opt/phpjail /php-' . $argv[1] .'/bin/php ' . escapeshellarg(basename($file)), $unused, $unused);
$terminated = false;
while (($status = proc_get_status($ph)) ['running']) {
    usleep(100 * 1000);
    if (!$terminated && microtime(true) - $starttime > MAX_RUNTIME_SECONDS) {
        $terminated = true;
        echo 'max runtime reached (' . MAX_RUNTIME_SECONDS . ' seconds), terminating...';


Example Deployment

example deployment