class MimeTypeGuesser

File.php in drupal/core/vendor/symfony/http-foundation/Symfony/Component/HttpFoundation/File/File.php

FileTest.php in drupal/core/vendor/symfony/http-foundation/Symfony/Component/HttpFoundation/Tests/File/FileTest.php

MimeTypeTest.php in drupal/core/vendor/symfony/http-foundation/Symfony/Component/HttpFoundation/Tests/File/MimeType/MimeTypeTest.php

class MimeTypeGuesser implements MimeTypeGuesserInterface {

  /**
   * The singleton instance
   *
   * @var MimeTypeGuesser
   */
  private static $instance = null;

  /**
   * All registered MimeTypeGuesserInterface instances
   *
   * @var array
   */
  protected $guessers = array();

  /**
   * Returns the singleton instance
   *
   * @return MimeTypeGuesser
   */
  public static function getInstance() {
    if (null === self::$instance) {
      self::$instance = new self();
    }
    return self::$instance;
  }

  /**
   * Registers all natively provided mime type guessers
   */
  private function __construct() {
    if (FileBinaryMimeTypeGuesser::isSupported()) {
      $this
        ->register(new FileBinaryMimeTypeGuesser());
    }
    if (FileinfoMimeTypeGuesser::isSupported()) {
      $this
        ->register(new FileinfoMimeTypeGuesser());
    }
  }

  /**
   * Registers a new mime type guesser
   *
   * When guessing, this guesser is preferred over previously registered ones.
   *
   * @param MimeTypeGuesserInterface $guesser
   */
  public function register(MimeTypeGuesserInterface $guesser) {
    array_unshift($this->guessers, $guesser);
  }

  /**
   * Tries to guess the mime type of the given file
   *
   * The file is passed to each registered mime type guesser in reverse order
   * of their registration (last registered is queried first). Once a guesser
   * returns a value that is not NULL, this method terminates and returns the
   * value.
   *
   * @param string $path The path to the file
   *
   * @return string         The mime type or NULL, if none could be guessed
   *
   * @throws FileException  If the file does not exist
   */
  public function guess($path) {
    if (!is_file($path)) {
      throw new FileNotFoundException($path);
    }
    if (!is_readable($path)) {
      throw new AccessDeniedException($path);
    }
    if (!$this->guessers) {
      throw new \LogicException('Unable to guess the mime type as no guessers are available (Did you enable the php_fileinfo extension?)');
    }
    foreach ($this->guessers as $guesser) {
      if (null !== ($mimeType = $guesser
        ->guess($path))) {
        return $mimeType;
      }
    }
  }

}