array(
      'fid' => array(
        'description' => 'The {file_managed}.fid being referenced in this field.',
        'type' => 'int',
        'not null' => FALSE,
        'unsigned' => TRUE,
      ),
      'display' => array(
        'description' => 'Flag to control whether this file should be displayed when viewing content.',
        'type' => 'int',
        'size' => 'tiny',
        'unsigned' => TRUE,
        'not null' => TRUE,
        'default' => 1,
      ),
      'description' => array(
        'description' => 'A description of the file.',
        'type' => 'text',
        'not null' => FALSE,
      ),
    ),
    'indexes' => array(
      'fid' => array('fid'),
    ),
    'foreign keys' => array(
      'fid' => array(
        'table' => 'file_managed',
        'columns' => array('fid' => 'fid'),
      ),
    ),
  );
}
/**
 * Implements hook_requirements().
 *
 * Display information about getting upload progress bars working.
 */
function file_requirements($phase) {
  $requirements = array();
  // Check the server's ability to indicate upload progress.
  if ($phase == 'runtime') {
    $implementation = file_progress_implementation();
    $apache = strpos($_SERVER['SERVER_SOFTWARE'], 'Apache') !== FALSE;
    $fastcgi = strpos($_SERVER['SERVER_SOFTWARE'], 'mod_fastcgi') !== FALSE || strpos($_SERVER["SERVER_SOFTWARE"], 'mod_fcgi') !== FALSE;
    $description = NULL;
    if (!$apache) {
      $value = t('Not enabled');
      $description = t('Your server is not capable of displaying file upload progress. File upload progress requires an Apache server running PHP with mod_php.');
      $severity = REQUIREMENT_INFO;
    }
    elseif ($fastcgi) {
      $value = t('Not enabled');
      $description = t('Your server is not capable of displaying file upload progress. File upload progress requires PHP be run with mod_php and not as FastCGI.');
      $severity = REQUIREMENT_INFO;
    }
    elseif (!$implementation && extension_loaded('apc')) {
      $value = t('Not enabled');
      $description = t('Your server is capable of displaying file upload progress through APC, but it is not enabled. Add apc.rfc1867 = 1 to your php.ini configuration. Alternatively, it is recommended to use PECL uploadprogress, which supports more than one simultaneous upload.');
      $severity = REQUIREMENT_INFO;
    }
    elseif (!$implementation) {
      $value = t('Not enabled');
      $description = t('Your server is capable of displaying file upload progress, but does not have the required libraries. It is recommended to install the PECL uploadprogress library (preferred) or to install APC.');
      $severity = REQUIREMENT_INFO;
    }
    elseif ($implementation == 'apc') {
      $value = t('Enabled (APC RFC1867)');
      $description = t('Your server is capable of displaying file upload progress using APC RFC1867. Note that only one upload at a time is supported. It is recommended to use the PECL uploadprogress library if possible.');
      $severity = REQUIREMENT_OK;
    }
    elseif ($implementation == 'uploadprogress') {
      $value = t('Enabled (PECL uploadprogress)');
      $severity = REQUIREMENT_OK;
    }
    $requirements['file_progress'] = array(
      'title' => t('Upload progress'),
      'value' => $value,
      'severity' => $severity,
      'description' => $description,
    );
  }
  return $requirements;
}