drupal/core/modules/file/file.install

<?php

/**
 * @file
 * Install, update and uninstall functions for File module.
 */

/**
 * Implements hook_schema().
 */
function file_schema() {
  $schema['file_usage'] = [
    'description' => 'Track where a file is used.',
    'fields' => [
      'fid' => [
        'description' => 'File ID.',
        'type' => 'int',
        'unsigned' => TRUE,
        'not null' => TRUE,
      ],
      'module' => [
        'description' => 'The name of the module that is using the file.',
        'type' => 'varchar_ascii',
        'length' => DRUPAL_EXTENSION_NAME_MAX_LENGTH,
        'not null' => TRUE,
        'default' => '',
      ],
      'type' => [
        'description' => 'The name of the object type in which the file is used.',
        'type' => 'varchar_ascii',
        'length' => 64,
        'not null' => TRUE,
        'default' => '',
      ],
      'id' => [
        'description' => 'The primary key of the object using the file.',
        'type' => 'varchar_ascii',
        'length' => 64,
        'not null' => TRUE,
        'default' => 0,
      ],
      'count' => [
        'description' => 'The number of times this file is used by this object.',
        'type' => 'int',
        'unsigned' => TRUE,
        'not null' => TRUE,
        'default' => 0,
      ],
    ],
    'primary key' => ['fid', 'type', 'id', 'module'],
    'indexes' => [
      'type_id' => ['type', 'id'],
      'fid_count' => ['fid', 'count'],
      'fid_module' => ['fid', 'module'],
    ],
  ];
  return $schema;
}

/**
 * Implements hook_requirements().
 *
 * Display information about getting upload progress bars working.
 */
function file_requirements($phase) {
  $requirements = [];

  // Check the server's ability to indicate upload progress.
  if ($phase == 'runtime') {
    $description = NULL;
    $implementation = file_progress_implementation();
    $server_software = \Drupal::request()->server->get('SERVER_SOFTWARE');

    // Test the web server identity.
    if (preg_match("/Nginx/i", $server_software)) {
      $is_nginx = TRUE;
      $is_apache = FALSE;
      $fastcgi = FALSE;
    }
    elseif (preg_match("/Apache/i", $server_software)) {
      $is_nginx = FALSE;
      $is_apache = TRUE;
      $fastcgi = strpos($server_software, 'mod_fastcgi') !== FALSE || strpos($server_software, 'mod_fcgi') !== FALSE;
    }
    else {
      $is_nginx = FALSE;
      $is_apache = FALSE;
      $fastcgi = FALSE;
    }

    if (!$is_apache && !$is_nginx) {
      $value = t('Not enabled');
      $description = t('Your server is not capable of displaying file upload progress. File upload progress requires an Apache server running PHP with mod_php or Nginx with PHP-FPM.');
    }
    elseif ($fastcgi) {
      $value = t('Not enabled');
      $description = t('Your server is not capable of displaying file upload progress. File upload progress requires PHP be run with mod_php or PHP-FPM and not as FastCGI.');
    }
    elseif (!$implementation) {
      $value = t('Not enabled');
      $description = t('Your server is capable of displaying file upload progress, but does not have the required libraries. It is recommended to install the <a href="http://pecl.php.net/package/uploadprogress">PECL uploadprogress library</a>.');
    }
    elseif ($implementation == 'uploadprogress') {
      $value = t('Enabled (<a href="http://pecl.php.net/package/uploadprogress">PECL uploadprogress</a>)');
    }
    $requirements['file_progress'] = [
      'title' => t('Upload progress'),
      'value' => $value,
      'description' => $description,
    ];
  }

  return $requirements;
}

/**
 * Implements hook_update_last_removed().
 */
function file_update_last_removed() {
  return 8700;
}