vendor/symfony/http-foundation/File/MimeTypeFileBinaryMimeTypeGuesser.php

<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\HttpFoundation\File\MimeType;

use Symfony\Component\HttpFoundation\File\Exception\AccessDeniedException;
use Symfony\Component\HttpFoundation\File\Exception\FileNotFoundException;

/**
 * Guesses the mime type with the binary "file" (only available on *nix).
 *
 * @author Bernhard Schussek <bschussek@gmail.com>
 */
class FileBinaryMimeTypeGuesser implements MimeTypeGuesserInterface
{
    private $cmd;

    /**
     * The $cmd pattern must contain a "%s" string that will be replaced
     * with the file name to guess.
     *
     * The command output must start with the mime type of the file.
     *
     * @param string $cmd The command to run to get the mime type of a file
     */
    public function __construct($cmd = 'file -b --mime %s 2>/dev/null')
    {
        $this->cmd = $cmd;
    }

    /**
     * Returns whether this guesser is supported on the current OS.
     *
     * @return bool
     */
    public static function isSupported()
    {
        static $supported = null;

        if (null !== $supported) {
            return $supported;
        }

        if ('\\' === \DIRECTORY_SEPARATOR || !\function_exists('passthru') || !\function_exists('escapeshellarg')) {
            return $supported = false;
        }

        ob_start();
        passthru('command -v file', $exitStatus);
        $binPath = trim(ob_get_clean());

        return $supported = 0 === $exitStatus && '' !== $binPath;
    }

    /**
     * {@inheritdoc}
     */
    public function guess($path)
    {
        if (!is_file($path)) {
            throw new FileNotFoundException($path);
        }

        if (!is_readable($path)) {
            throw new AccessDeniedException($path);
        }

        if (!self::isSupported()) {
            return;
        }

        ob_start();

        // need to use --mime instead of -i. see #6641
        passthru(sprintf($this->cmd, escapeshellarg($path)), $return);
        if ($return > 0) {
            ob_end_clean();

            return;
        }

        $type = trim(ob_get_clean());

        if (!preg_match('#^([a-z0-9\-]+/[a-z0-9\-\.]+)#i', $type, $match)) {
            // it's not a type, but an error message
            return;
        }

        return $match[1];
    }
}