file.module

<?php

/**
 * @file
 * Defines a "managed_file" Form API field and a "file" field for Field module.
 */

use Drupal\file\Plugin\Core\Entity\File;
use Drupal\Component\Utility\NestedArray;
use Drupal\Core\Template\Attribute;
use Symfony\Component\HttpFoundation\JsonResponse;
use Drupal\file\FileUsage\DatabaseFileUsageBackend;
use Drupal\file\FileUsage\FileUsageInterface;
use Drupal\Core\Ajax\AjaxResponse;
use Drupal\Core\Ajax\ReplaceCommand;

// Load all Field module hooks for File.
require_once __DIR__ . '/file.field.inc';

/**
 * Implements hook_help().
 */
function file_help($path, $arg) {
  switch ($path) {
    case 'admin/help#file':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('The File module defines a <em>File</em> field type for the Field module, which lets you manage and validate uploaded files attached to content on your site (see the <a href="@field-help">Field module help page</a> for more information about fields). For more information, see the online handbook entry for <a href="@file">File module</a>.', array('@field-help' => url('admin/help/field'), '@file' => 'http://drupal.org/documentation/modules/file')) . '</p>';
      $output .= '<h3>' . t('Uses') . '</h3>';
      $output .= '<dl>';
      $output .= '<dt>' . t('Attaching files to content') . '</dt>';
      $output .= '<dd>' . t('The File module allows users to attach files to content (e.g., PDF files, spreadsheets, etc.), when a <em>File</em> field is added to a given content type using the <a href="@fieldui-help">Field UI module</a>. You can add validation options to your File field, such as specifying a maximum file size and allowed file extensions.', array('@fieldui-help' => url('admin/help/field_ui'))) . '</dd>';
      $output .= '<dt>' . t('Managing attachment display') . '</dt>';
      $output .= '<dd>' . t('When you attach a file to content, you can specify whether it is <em>listed</em> or not. Listed files are displayed automatically in a section at the bottom of your content; non-listed files are available for embedding in your content, but are not included in the list at the bottom.') . '</dd>';
      $output .= '<dt>' . t('Managing file locations') . '</dt>';
      $output .= '<dd>' . t("When you create a File field, you can specify a directory where the files will be stored, which can be within either the <em>public</em> or <em>private</em> files directory. Files in the public directory can be accessed directly through the web server; when public files are listed, direct links to the files are used, and anyone who knows a file's URL can download the file. Files in the private directory are not accessible directly through the web server; when private files are listed, the links are Drupal path requests. This adds to server load and download time, since Drupal must start up and resolve the path for each file download request, but allows for access restrictions.") . '</dd>';
      $output .= '</dl>';
      return $output;
  }
}

/**
 * Implements hook_menu().
 */
function file_menu() {
  $items = array();

  $items['file/ajax'] = array(
    'page callback' => 'file_ajax_upload',
    'access arguments' => array('access content'),
    'theme callback' => 'ajax_base_page_theme',
    'type' => MENU_CALLBACK,
  );
  $items['file/progress'] = array(
    'page callback' => 'file_ajax_progress',
    'access arguments' => array('access content'),
    'theme callback' => 'ajax_base_page_theme',
    'type' => MENU_CALLBACK,
  );

  return $items;
}

/**
 * Implements hook_element_info().
 *
 * The managed file element may be used anywhere in Drupal.
 */
function file_element_info() {
  $file_path = drupal_get_path('module', 'file');
  $types['managed_file'] = array(
    '#input' => TRUE,
    '#process' => array('file_managed_file_process'),
    '#value_callback' => 'file_managed_file_value',
    '#element_validate' => array('file_managed_file_validate'),
    '#pre_render' => array('file_managed_file_pre_render'),
    '#theme' => 'file_managed_file',
    '#theme_wrappers' => array('form_element'),
    '#progress_indicator' => 'throbber',
    '#progress_message' => NULL,
    '#upload_validators' => array(),
    '#upload_location' => NULL,
    '#size' => 22,
    '#multiple' => FALSE,
    '#extended' => FALSE,
    '#attached' => array(
      'library' => array(array('file','drupal.file')),
    ),
  );
  return $types;
}

/**
 * Loads file entities from the database.
 *
 * @param array $fids
 *   (optional) An array of entity IDs. If omitted, all entities are loaded.
 * @param $reset
 *   Whether to reset the internal file_load_multiple() cache.
 *
 * @return array
 *   An array of file entities, indexed by fid.
 *
 * @see hook_file_load()
 * @see file_load()
 * @see entity_load()
 * @see Drupal\Core\Entity\Query\EntityQueryInterface
 */
function file_load_multiple(array $fids = NULL, $reset = FALSE) {
  return entity_load_multiple('file', $fids, $reset);
}

/**
 * Loads a single file entity from the database.
 *
 * @param $fid
 *   A file ID.
 * @param $reset
 *   Whether to reset the internal file_load_multiple() cache.
 *
 * @return \Drupal\file\FileInterface
 *   A file entity or FALSE if the file was not found.
 *
 * @see hook_file_load()
 * @see file_load_multiple()
 */
function file_load($fid, $reset = FALSE) {
  $files = file_load_multiple(array($fid), $reset);
  return reset($files);
}

/**
 * Returns the file usage service.
 *
 * @return Drupal\file\FileUsage\FileUsageInterface.
 */
function file_usage() {
  return drupal_container()->get('file.usage');
}

/**
 * Copies a file to a new location and adds a file record to the database.
 *
 * This function should be used when manipulating files that have records
 * stored in the database. This is a powerful function that in many ways
 * performs like an advanced version of copy().
 * - Checks if $source and $destination are valid and readable/writable.
 * - Checks that $source is not equal to $destination; if they are an error
 *   is reported.
 * - If file already exists in $destination either the call will error out,
 *   replace the file or rename the file based on the $replace parameter.
 * - Adds the new file to the files database. If the source file is a
 *   temporary file, the resulting file will also be a temporary file. See
 *   file_save_upload() for details on temporary files.
 *
 * @param Drupal\file\File $source
 *   A file entity.
 * @param $destination
 *   A string containing the destination that $source should be copied to.
 *   This must be a stream wrapper URI.
 * @param $replace
 *   Replace behavior when the destination file already exists:
 *   - FILE_EXISTS_REPLACE - Replace the existing file. If a managed file with
 *       the destination name exists then its database entry will be updated. If
 *       no database entry is found then a new one will be created.
 *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
 *       unique.
 *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
 *
 * @return
 *   File object if the copy is successful, or FALSE in the event of an error.
 *
 * @see file_unmanaged_copy()
 * @see hook_file_copy()
 */
function file_copy(File $source, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
  if (!file_valid_uri($destination)) {
    if (($realpath = drupal_realpath($source->getFileUri())) !== FALSE) {
      watchdog('file', 'File %file (%realpath) could not be copied because the destination %destination is invalid. This is often caused by improper use of file_copy() or a missing stream wrapper.', array('%file' => $source->getFileUri(), '%realpath' => $realpath, '%destination' => $destination));
    }
    else {
      watchdog('file', 'File %file could not be copied because the destination %destination is invalid. This is often caused by improper use of file_copy() or a missing stream wrapper.', array('%file' => $source->getFileUri(), '%destination' => $destination));
    }
    drupal_set_message(t('The specified file %file could not be copied because the destination is invalid. More information is available in the system log.', array('%file' => $source->getFileUri())), 'error');
    return FALSE;
  }

  if ($uri = file_unmanaged_copy($source->getFileUri(), $destination, $replace)) {
    $file = $source->createDuplicate();
    $file->setFileUri($uri);
    $file->setFilename(drupal_basename($uri));
    // If we are replacing an existing file re-use its database record.
    if ($replace == FILE_EXISTS_REPLACE) {
      $existing_files = entity_load_multiple_by_properties('file', array('uri' => $uri));
      if (count($existing_files)) {
        $existing = reset($existing_files);
        $file->fid = $existing->id();
        $file->setFilename($existing->getFilename());
      }
    }
    // If we are renaming around an existing file (rather than a directory),
    // use its basename for the filename.
    elseif ($replace == FILE_EXISTS_RENAME && is_file($destination)) {
      $file->setFilename(drupal_basename($destination));
    }

    $file->save();

    // Inform modules that the file has been copied.
    module_invoke_all('file_copy', $file, $source);

    return $file;
  }
  return FALSE;
}

/**
 * Moves a file to a new location and update the file's database entry.
 *
 * Moving a file is performed by copying the file to the new location and then
 * deleting the original.
 * - Checks if $source and $destination are valid and readable/writable.
 * - Performs a file move if $source is not equal to $destination.
 * - If file already exists in $destination either the call will error out,
 *   replace the file or rename the file based on the $replace parameter.
 * - Adds the new file to the files database.
 *
 * @param Drupal\file\File $source
 *   A file entity.
 * @param $destination
 *   A string containing the destination that $source should be moved to.
 *   This must be a stream wrapper URI.
 * @param $replace
 *   Replace behavior when the destination file already exists:
 *   - FILE_EXISTS_REPLACE - Replace the existing file. If a managed file with
 *       the destination name exists then its database entry will be updated and
 *       $source->delete() called after invoking hook_file_move().
 *       If no database entry is found then the source files record will be
 *       updated.
 *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
 *       unique.
 *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
 *
 * @return Drupal\file\File
 *   Resulting file entity for success, or FALSE in the event of an error.
 *
 * @see file_unmanaged_move()
 * @see hook_file_move()
 */
function file_move(File $source, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
  if (!file_valid_uri($destination)) {
    if (($realpath = drupal_realpath($source->getFileUri())) !== FALSE) {
      watchdog('file', 'File %file (%realpath) could not be moved because the destination %destination is invalid. This may be caused by improper use of file_move() or a missing stream wrapper.', array('%file' => $source->getFileUri(), '%realpath' => $realpath, '%destination' => $destination));
    }
    else {
      watchdog('file', 'File %file could not be moved because the destination %destination is invalid. This may be caused by improper use of file_move() or a missing stream wrapper.', array('%file' => $source->getFileUri(), '%destination' => $destination));
    }
    drupal_set_message(t('The specified file %file could not be moved because the destination is invalid. More information is available in the system log.', array('%file' => $source->getFileUri())), 'error');
    return FALSE;
  }

  if ($uri = file_unmanaged_move($source->getFileUri(), $destination, $replace)) {
    $delete_source = FALSE;

    $file = clone $source;
    $file->setFileUri($uri);
    // If we are replacing an existing file re-use its database record.
    if ($replace == FILE_EXISTS_REPLACE) {
      $existing_files = entity_load_multiple_by_properties('file', array('uri' => $uri));
      if (count($existing_files)) {
        $existing = reset($existing_files);
        $delete_source = TRUE;
        $file->fid = $existing->id();
      }
    }
    // If we are renaming around an existing file (rather than a directory),
    // use its basename for the filename.
    elseif ($replace == FILE_EXISTS_RENAME && is_file($destination)) {
      $file->setFilename(drupal_basename($destination));
    }

    $file->save();

    // Inform modules that the file has been moved.
    module_invoke_all('file_move', $file, $source);

    // Delete the original if it's not in use elsewhere.
    if ($delete_source && !file_usage()->listUsage($source)) {
      $source->delete();
    }

    return $file;
  }
  return FALSE;
}

/**
 * Checks that a file meets the criteria specified by the validators.
 *
 * After executing the validator callbacks specified hook_file_validate() will
 * also be called to allow other modules to report errors about the file.
 *
 * @param Drupal\file\File $file
 *   A file entity.
 * @param $validators
 *   An optional, associative array of callback functions used to validate the
 *   file. The keys are function names and the values arrays of callback
 *   parameters which will be passed in after the file entity. The
 *   functions should return an array of error messages; an empty array
 *   indicates that the file passed validation. The functions will be called in
 *   the order specified.
 *
 * @return
 *   An array containing validation error messages.
 *
 * @see hook_file_validate()
 */
function file_validate(File $file, $validators = array()) {
  // Call the validation functions specified by this function's caller.
  $errors = array();
  foreach ($validators as $function => $args) {
    if (function_exists($function)) {
      array_unshift($args, $file);
      $errors = array_merge($errors, call_user_func_array($function, $args));
    }
  }

  // Let other modules perform validation on the new file.
  return array_merge($errors, module_invoke_all('file_validate', $file));
}

/**
 * Checks for files with names longer than can be stored in the database.
 *
 * @param Drupal\file\File $file
 *   A file entity.
 *
 * @return
 *   An array. If the file name is too long, it will contain an error message.
 */
function file_validate_name_length(File $file) {
  $errors = array();

  if (!$file->getFilename()) {
    $errors[] = t("The file's name is empty. Please give a name to the file.");
  }
  if (strlen($file->getFilename()) > 240) {
    $errors[] = t("The file's name exceeds the 240 characters limit. Please rename the file and try again.");
  }
  return $errors;
}

/**
 * Checks that the filename ends with an allowed extension.
 *
 * @param Drupal\file\File $file
 *   A file entity.
 * @param $extensions
 *   A string with a space separated list of allowed extensions.
 *
 * @return
 *   An array. If the file extension is not allowed, it will contain an error
 *   message.
 *
 * @see hook_file_validate()
 */
function file_validate_extensions(File $file, $extensions) {
  $errors = array();

  $regex = '/\.(' . preg_replace('/ +/', '|', preg_quote($extensions)) . ')$/i';
  if (!preg_match($regex, $file->getFilename())) {
    $errors[] = t('Only files with the following extensions are allowed: %files-allowed.', array('%files-allowed' => $extensions));
  }
  return $errors;
}

/**
 * Checks that the file's size is below certain limits.
 *
 * @param Drupal\file\File $file
 *   A file entity.
 * @param $file_limit
 *   An integer specifying the maximum file size in bytes. Zero indicates that
 *   no limit should be enforced.
 * @param $user_limit
 *   An integer specifying the maximum number of bytes the user is allowed.
 *   Zero indicates that no limit should be enforced.
 *
 * @return
 *   An array. If the file size exceeds limits, it will contain an error
 *   message.
 *
 * @see hook_file_validate()
 */
function file_validate_size(File $file, $file_limit = 0, $user_limit = 0) {
  global $user;
  $errors = array();

  if ($file_limit && $file->getSize() > $file_limit) {
    $errors[] = t('The file is %filesize exceeding the maximum file size of %maxsize.', array('%filesize' => format_size($file->getSize()), '%maxsize' => format_size($file_limit)));
  }

  // Save a query by only calling spaceUsed() when a limit is provided.
  if ($user_limit && (Drupal::entityManager()->getStorageController('file')->spaceUsed($user->uid) + $file->getSize()) > $user_limit) {
    $errors[] = t('The file is %filesize which would exceed your disk quota of %quota.', array('%filesize' => format_size($file->getSize()), '%quota' => format_size($user_limit)));
  }

  return $errors;
}

/**
 * Checks that the file is recognized by image_get_info() as an image.
 *
 * @param Drupal\file\File $file
 *   A file entity.
 *
 * @return
 *   An array. If the file is not an image, it will contain an error message.
 *
 * @see hook_file_validate()
 */
function file_validate_is_image(File $file) {
  $errors = array();

  $info = image_get_info($file->getFileUri());
  if (!$info || empty($info['extension'])) {
    $errors[] = t('Only JPEG, PNG and GIF images are allowed.');
  }

  return $errors;
}

/**
 * Verifies that image dimensions are within the specified maximum and minimum.
 *
 * Non-image files will be ignored. If a image toolkit is available the image
 * will be scaled to fit within the desired maximum dimensions.
 *
 * @param Drupal\file\File $file
 *   A file entity. This function may resize the file affecting its size.
 * @param $maximum_dimensions
 *   An optional string in the form WIDTHxHEIGHT e.g. '640x480' or '85x85'. If
 *   an image toolkit is installed the image will be resized down to these
 *   dimensions. A value of 0 indicates no restriction on size, so resizing
 *   will be attempted.
 * @param $minimum_dimensions
 *   An optional string in the form WIDTHxHEIGHT. This will check that the
 *   image meets a minimum size. A value of 0 indicates no restriction.
 *
 * @return
 *   An array. If the file is an image and did not meet the requirements, it
 *   will contain an error message.
 *
 * @see hook_file_validate()
 */
function file_validate_image_resolution(File $file, $maximum_dimensions = 0, $minimum_dimensions = 0) {
  $errors = array();

  // Check first that the file is an image.
  if ($info = image_get_info($file->getFileUri())) {
    if ($maximum_dimensions) {
      // Check that it is smaller than the given dimensions.
      list($width, $height) = explode('x', $maximum_dimensions);
      if ($info['width'] > $width || $info['height'] > $height) {
        // Try to resize the image to fit the dimensions.
        if ($image = image_load($file->getFileUri())) {
          image_scale($image, $width, $height);
          image_save($image);
          $file->filesize = $image->info['file_size'];
          drupal_set_message(t('The image was resized to fit within the maximum allowed dimensions of %dimensions pixels.', array('%dimensions' => $maximum_dimensions)));
        }
        else {
          $errors[] = t('The image is too large; the maximum dimensions are %dimensions pixels.', array('%dimensions' => $maximum_dimensions));
        }
      }
    }

    if ($minimum_dimensions) {
      // Check that it is larger than the given dimensions.
      list($width, $height) = explode('x', $minimum_dimensions);
      if ($info['width'] < $width || $info['height'] < $height) {
        $errors[] = t('The image is too small; the minimum dimensions are %dimensions pixels.', array('%dimensions' => $minimum_dimensions));
      }
    }
  }

  return $errors;
}

/**
 * Saves a file to the specified destination and creates a database entry.
 *
 * @param $data
 *   A string containing the contents of the file.
 * @param $destination
 *   A string containing the destination URI. This must be a stream wrapper URI.
 *   If no value is provided, a randomized name will be generated and the file
 *   will be saved using Drupal's default files scheme, usually "public://".
 * @param $replace
 *   Replace behavior when the destination file already exists:
 *   - FILE_EXISTS_REPLACE - Replace the existing file. If a managed file with
 *       the destination name exists then its database entry will be updated. If
 *       no database entry is found then a new one will be created.
 *   - FILE_EXISTS_RENAME - Append _{incrementing number} until the filename is
 *       unique.
 *   - FILE_EXISTS_ERROR - Do nothing and return FALSE.
 *
 * @return \Drupal\file\FileInterface
 *   A file entity, or FALSE on error.
 *
 * @see file_unmanaged_save_data()
 */
function file_save_data($data, $destination = NULL, $replace = FILE_EXISTS_RENAME) {
  global $user;

  if (empty($destination)) {
    $destination = file_default_scheme() . '://';
  }
  if (!file_valid_uri($destination)) {
    watchdog('file', 'The data could not be saved because the destination %destination is invalid. This may be caused by improper use of file_save_data() or a missing stream wrapper.', array('%destination' => $destination));
    drupal_set_message(t('The data could not be saved because the destination is invalid. More information is available in the system log.'), 'error');
    return FALSE;
  }

  if ($uri = file_unmanaged_save_data($data, $destination, $replace)) {
    // Create a file entity.
    $file = entity_create('file', array(
      'uri' => $uri,
      'uid' => $user->uid,
      'status' => FILE_STATUS_PERMANENT,
    ));
    // If we are replacing an existing file re-use its database record.
    if ($replace == FILE_EXISTS_REPLACE) {
      $existing_files = entity_load_multiple_by_properties('file', array('uri' => $uri));
      if (count($existing_files)) {
        $existing = reset($existing_files);
        $file->fid = $existing->id();
        $file->setFilename($existing->getFilename());
      }
    }
    // If we are renaming around an existing file (rather than a directory),
    // use its basename for the filename.
    elseif ($replace == FILE_EXISTS_RENAME && is_file($destination)) {
      $file->setFilename(drupal_basename($destination));
    }

    $file->save();
    return $file;
  }
  return FALSE;
}

/**
 * Examines a file entity and returns appropriate content headers for download.
 *
 * @param Drupal\file\File $file
 *   A file entity.
 *
 * @return
 *   An associative array of headers, as expected by
 *   \Symfony\Component\HttpFoundation\StreamedResponse.
 */
function file_get_content_headers(File $file) {
  $name = mime_header_encode($file->getFilename());
  $type = mime_header_encode($file->getMimeType());

  return array(
    'Content-Type' => $type,
    'Content-Length' => $file->getSize(),
    'Cache-Control' => 'private',
  );
}

/**
 * Implements hook_theme().
 */
function file_theme() {
  return array(
    // file.module.
    'file_link' => array(
      'variables' => array('file' => NULL, 'icon_directory' => NULL, 'description' => NULL),
    ),
    'file_icon' => array(
      'variables' => array('file' => NULL, 'icon_directory' => NULL),
    ),
    'file_managed_file' => array(
      'render element' => 'element',
    ),

    // file.field.inc.
    'file_widget' => array(
      'render element' => 'element',
    ),
    'file_widget_multiple' => array(
      'render element' => 'element',
    ),
    'file_formatter_table' => array(
      'variables' => array('items' => NULL),
    ),
    'file_upload_help' => array(
      'variables' => array('description' => NULL, 'upload_validators' => NULL, 'cardinality' => NULL),
    ),
  );
}

/**
 * Implements hook_file_download().
 *
 * This function takes an extra parameter $field_type so that it may
 * be re-used by other File-like modules, such as Image.
 */
function file_file_download($uri, $field_type = 'file') {
  global $user;

  // Get the file record based on the URI. If not in the database just return.
  $files = entity_load_multiple_by_properties('file', array('uri' => $uri));
  if (count($files)) {
    foreach ($files as $item) {
      // Since some database servers sometimes use a case-insensitive comparison
      // by default, double check that the filename is an exact match.
      if ($item->getFileUri() === $uri) {
        $file = $item;
        break;
      }
    }
  }
  if (!isset($file)) {
    return;
  }

  // Find out which (if any) fields of this type contain the file.
  $references = file_get_file_references($file, NULL, FIELD_LOAD_CURRENT, $field_type);

  // Stop processing if there are no references in order to avoid returning
  // headers for files controlled by other modules. Make an exception for
  // temporary files where the host entity has not yet been saved (for example,
  // an image preview on a node/add form) in which case, allow download by the
  // file's owner.
  if (empty($references) && ($file->isPermanent() || $file->getOwner()->id() != $user->uid)) {
    return;
  }

  // Default to allow access.
  $denied = FALSE;
  // Loop through all references of this file. If a reference explicitly allows
  // access to the field to which this file belongs, no further checks are done
  // and download access is granted. If a reference denies access, eventually
  // existing additional references are checked. If all references were checked
  // and no reference denied access, access is granted as well. If at least one
  // reference denied access, access is denied.
  foreach ($references as $field_name => $field_references) {
    foreach ($field_references as $entity_type => $entities) {
      foreach ($entities as $entity) {
        $field = field_info_field($field_name);
        // Check if access to this field is not disallowed.
        if (!field_access('view', $field, $entity_type, $entity)) {
          $denied = TRUE;
          continue;
        }

        // Invoke hook and collect grants/denies for download access.
        // Default to FALSE and let entities overrule this ruling.
        $grants = array('system' => FALSE);
        foreach (module_implements('file_download_access') as $module) {
          $grants = array_merge($grants, array($module => module_invoke($module, 'file_download_access', $field, $entity, $file)));
        }
        // Allow other modules to alter the returned grants/denies.
        $context = array(
          'entity' => $entity,
          'field' => $field,
          'file' => $file,
        );
        drupal_alter('file_download_access', $grants, $context);

        if (in_array(TRUE, $grants)) {
          // If TRUE is returned, access is granted and no further checks are
          // necessary.
          $denied = FALSE;
          break 3;
        }

        if (in_array(FALSE, $grants)) {
          // If an implementation returns FALSE, access to this entity is denied
          // but the file could belong to another entity to which the user might
          // have access. Continue with these.
          $denied = TRUE;
        }
      }
    }
  }

  // Access specifically denied.
  if ($denied) {
    return -1;
  }

  // Access is granted.
  $headers = file_get_content_headers($file);
  return $headers;
}

/**
 * Implements file_cron()
 */
function file_cron() {
  $result = Drupal::entityManager()->getStorageController('file')->retrieveTemporaryFiles();
  foreach ($result as $row) {
    if ($file = file_load($row->fid)) {
      $references = file_usage()->listUsage($file);
      if (empty($references)) {
        if (file_exists($file->getFileUri())) {
          $file->delete();
        }
        else {
          watchdog('file system', 'Could not delete temporary file "%path" during garbage collection', array('%path' => $file->getFileUri()), WATCHDOG_ERROR);
        }
      }
      else {
        watchdog('file system', 'Did not delete temporary file "%path" during garbage collection because it is in use by the following modules: %modules.', array('%path' => $file->getFileUri(), '%modules' => implode(', ', array_keys($references))), WATCHDOG_INFO);
      }
    }
  }
}

/**
 * Ajax callback: Processes file uploads and deletions.
 *
 * This rebuilds the form element for a particular field item. As long as the
 * form processing is properly encapsulated in the widget element the form
 * should rebuild correctly using FAPI without the need for additional callbacks
 * or processing.
 *
 * @see file_menu()
 */
function file_ajax_upload() {
  $form_parents = func_get_args();
  $form_build_id = (string) array_pop($form_parents);

  if (empty($_POST['form_build_id']) || $form_build_id != $_POST['form_build_id']) {
    // Invalid request.
    drupal_set_message(t('An unrecoverable error occurred. The uploaded file likely exceeded the maximum file size (@size) that this server supports.', array('@size' => format_size(file_upload_max_size()))), 'error');
    $response = new AjaxResponse();
    return $response->addCommand(new ReplaceCommand(NULL, theme('status_messages')));
  }

  list($form, $form_state) = ajax_get_form();

  if (!$form) {
    // Invalid form_build_id.
    drupal_set_message(t('An unrecoverable error occurred. Use of this form has expired. Try reloading the page and submitting again.'), 'error');
    $response = new AjaxResponse();
    return $response->addCommand(new ReplaceCommand(NULL, theme('status_messages')));
  }

  // Get the current element and count the number of files.
  $current_element = $form;
  foreach ($form_parents as $parent) {
    $current_element = $current_element[$parent];
  }
  $current_file_count = isset($current_element['#file_upload_delta']) ? $current_element['#file_upload_delta'] : 0;

  // Process user input. $form and $form_state are modified in the process.
  drupal_process_form($form['#form_id'], $form, $form_state);

  // Retrieve the element to be rendered.
  foreach ($form_parents as $parent) {
    $form = $form[$parent];
  }

  // Add the special Ajax class if a new file was added.
  if (isset($form['#file_upload_delta']) && $current_file_count < $form['#file_upload_delta']) {
    $form[$current_file_count]['#attributes']['class'][] = 'ajax-new-content';
  }
  // Otherwise just add the new content class on a placeholder.
  else {
    $form['#suffix'] .= '<span class="ajax-new-content"></span>';
  }

  $form['#prefix'] .= theme('status_messages');
  $output = drupal_render($form);
  $js = drupal_add_js();
  $settings = drupal_merge_js_settings($js['settings']['data']);

  $response = new AjaxResponse();
  return $response->addCommand(new ReplaceCommand(NULL, $output, $settings));
}

/**
 * Ajax callback: Retrieves upload progress.
 *
 * @param $key
 *   The unique key for this upload process.
 */
function file_ajax_progress($key) {
  $progress = array(
    'message' => t('Starting upload...'),
    'percentage' => -1,
  );

  $implementation = file_progress_implementation();
  if ($implementation == 'uploadprogress') {
    $status = uploadprogress_get_info($key);
    if (isset($status['bytes_uploaded']) && !empty($status['bytes_total'])) {
      $progress['message'] = t('Uploading... (@current of @total)', array('@current' => format_size($status['bytes_uploaded']), '@total' => format_size($status['bytes_total'])));
      $progress['percentage'] = round(100 * $status['bytes_uploaded'] / $status['bytes_total']);
    }
  }
  elseif ($implementation == 'apc') {
    $status = apc_fetch('upload_' . $key);
    if (isset($status['current']) && !empty($status['total'])) {
      $progress['message'] = t('Uploading... (@current of @total)', array('@current' => format_size($status['current']), '@total' => format_size($status['total'])));
      $progress['percentage'] = round(100 * $status['current'] / $status['total']);
    }
  }

  return new JsonResponse($progress);
}

/**
 * Determines the preferred upload progress implementation.
 *
 * @return
 *   A string indicating which upload progress system is available. Either "apc"
 *   or "uploadprogress". If neither are available, returns FALSE.
 */
function file_progress_implementation() {
  static $implementation;
  if (!isset($implementation)) {
    $implementation = FALSE;

    // We prefer the PECL extension uploadprogress because it supports multiple
    // simultaneous uploads. APC only supports one at a time.
    if (extension_loaded('uploadprogress')) {
      $implementation = 'uploadprogress';
    }
    elseif (extension_loaded('apc') && ini_get('apc.rfc1867')) {
      $implementation = 'apc';
    }
  }
  return $implementation;
}

/**
 * Implements hook_file_predelete().
 */
function file_file_predelete(File $file) {
  // TODO: Remove references to a file that is in-use.
}

/**
 * Render API callback: Expands the managed_file element type.
 *
 * Expands the file type to include Upload and Remove buttons, as well as
 * support for a default value.
 *
 * This function is assigned as a #process callback in file_element_info().
 */
function file_managed_file_process($element, &$form_state, $form) {
  // Append the '-upload' to the #id so the field label's 'for' attribute
  // corresponds with the file element.
  $element['#id'] .= '-upload';

  // This is used sometimes so let's implode it just once.
  $parents_prefix = implode('_', $element['#parents']);

  $fids = isset($element['#value']['fids']) ? $element['#value']['fids'] : array();

  // Set some default element properties.
  $element['#progress_indicator'] = empty($element['#progress_indicator']) ? 'none' : $element['#progress_indicator'];
  $element['#files'] = !empty($fids) ? file_load_multiple($fids) : FALSE;
  $element['#tree'] = TRUE;

  $ajax_settings = array(
    'path' => 'file/ajax/' . implode('/', $element['#array_parents']) . '/' . $form['form_build_id']['#value'],
    'wrapper' => $element['#id'] . '-ajax-wrapper',
    'effect' => 'fade',
    'progress' => array(
      'type' => $element['#progress_indicator'],
      'message' => $element['#progress_message'],
    ),
  );

  // Set up the buttons first since we need to check if they were clicked.
  $element['upload_button'] = array(
    '#name' => $parents_prefix . '_upload_button',
    '#type' => 'submit',
    '#value' => t('Upload'),
    '#validate' => array(),
    '#submit' => array('file_managed_file_submit'),
    '#limit_validation_errors' => array($element['#parents']),
    '#ajax' => $ajax_settings,
    '#weight' => -5,
  );

  // Force the progress indicator for the remove button to be either 'none' or
  // 'throbber', even if the upload button is using something else.
  $ajax_settings['progress']['type'] = ($element['#progress_indicator'] == 'none') ? 'none' : 'throbber';
  $ajax_settings['progress']['message'] = NULL;
  $ajax_settings['effect'] = 'none';
  $element['remove_button'] = array(
    '#name' => $parents_prefix . '_remove_button',
    '#type' => 'submit',
    '#value' => $element['#multiple'] ? t('Remove selected') : t('Remove'),
    '#validate' => array(),
    '#submit' => array('file_managed_file_submit'),
    '#limit_validation_errors' => array($element['#parents']),
    '#ajax' => $ajax_settings,
    '#weight' => 1,
  );

  $element['fids'] = array(
    '#type' => 'hidden',
    '#value' => $fids,
  );

  // Add progress bar support to the upload if possible.
  if ($element['#progress_indicator'] == 'bar' && $implementation = file_progress_implementation()) {
    $upload_progress_key = mt_rand();

    if ($implementation == 'uploadprogress') {
      $element['UPLOAD_IDENTIFIER'] = array(
        '#type' => 'hidden',
        '#value' => $upload_progress_key,
        '#attributes' => array('class' => array('file-progress')),
        // Uploadprogress extension requires this field to be at the top of the
        // form.
        '#weight' => -20,
      );
    }
    elseif ($implementation == 'apc') {
      $element['APC_UPLOAD_PROGRESS'] = array(
        '#type' => 'hidden',
        '#value' => $upload_progress_key,
        '#attributes' => array('class' => array('file-progress')),
        // Uploadprogress extension requires this field to be at the top of the
        // form.
        '#weight' => -20,
      );
    }

    // Add the upload progress callback.
    $element['upload_button']['#ajax']['progress']['path'] = 'file/progress/' . $upload_progress_key;
  }

  // The file upload field itself.
  $element['upload'] = array(
    '#name' => 'files[' . $parents_prefix . ']',
    '#type' => 'file',
    '#title' => t('Choose a file'),
    '#title_display' => 'invisible',
    '#size' => $element['#size'],
    '#multiple' => $element['#multiple'],
    '#theme_wrappers' => array(),
    '#weight' => -10,
  );

  if (!empty($fids) && $element['#files']) {
    foreach ($element['#files'] as $delta => $file) {
      if ($element['#multiple']) {
        $element['file_' . $delta]['selected'] = array(
          '#type' => 'checkbox',
          '#title' => theme('file_link', array('file' => $file)) . ' ',
        );
      }
      else {
        $element['file_' . $delta]['filename'] = array(
          '#type' => 'markup',
          '#markup' => theme('file_link', array('file' => $file)) . ' ',
          '#weight' => -10,
        );
      }
    }
  }

  // Add the extension list to the page as JavaScript settings.
  if (isset($element['#upload_validators']['file_validate_extensions'][0])) {
    $extension_list = implode(',', array_filter(explode(' ', $element['#upload_validators']['file_validate_extensions'][0])));
    $element['upload']['#attached']['js'] = array(
      array(
        'type' => 'setting',
        'data' => array('file' => array('elements' => array('#' . $element['#id'] . '-upload' => $extension_list)))
      )
    );
  }

  // Prefix and suffix used for Ajax replacement.
  $element['#prefix'] = '<div id="' . $element['#id'] . '-ajax-wrapper">';
  $element['#suffix'] = '</div>';

  return $element;
}

/**
 * Render API callback: Determines the value for a managed_file type element.
 *
 * This function is assigned as a #value_callback in file_element_info().
 */
function file_managed_file_value(&$element, $input = FALSE, $form_state = NULL) {
  // Find the current value of this field.
  $fids = !empty($input['fids']) ? explode(' ', $input['fids']) : array();
  foreach ($fids as $key => $fid) {
    $fids[$key] = (int) $fid;
  }

  // Process any input and save new uploads.
  if ($input !== FALSE) {
    $input['fids'] = $fids;
    $return = $input;

    // Uploads take priority over all other values.
    if ($files = file_managed_file_save_upload($element)) {
      if ($element['#multiple']) {
        $fids = array_merge($fids, array_keys($files));
      }
      else {
        $fids = array_keys($files);
      }
    }
    else {
      // Check for #filefield_value_callback values.
      // Because FAPI does not allow multiple #value_callback values like it
      // does for #element_validate and #process, this fills the missing
      // functionality to allow File fields to be extended through FAPI.
      if (isset($element['#file_value_callbacks'])) {
        foreach ($element['#file_value_callbacks'] as $callback) {
          $callback($element, $input, $form_state);
        }
      }

      // Load files if the FIDs have changed to confirm they exist.
      if (!empty($input['fids'])) {
        $fids = array();
        foreach ($input['fids'] as $key => $fid) {
          if ($file = file_load($fid)) {
            $fids[] = $file->id();
          }
        }
      }
    }
  }

  // If there is no input, set the default value.
  else {
    if ($element['#extended']) {
      $default_fids = isset($element['#default_value']['fids']) ? $element['#default_value']['fids'] : array();
      $return = isset($element['#default_value']) ? $element['#default_value'] : array('fids' => array());
    }
    else {
      $default_fids = isset($element['#default_value']) ? $element['#default_value'] : array();
      $return = array('fids' => array());
    }

    // Confirm that the file exists when used as a default value.
    if (!empty($default_fids)) {
      $fids = array();
      foreach ($default_fids as $key => $fid) {
        if ($file = file_load($fid)) {
          $fids[] = $file->id();
        }
      }
    }
  }

  $return['fids'] = $fids;
  return $return;
}

/**
 * Render API callback: Validates the managed_file element.
 *
 * This function is assigned as a #element_validate callback in
 * file_element_info().
 */
function file_managed_file_validate(&$element, &$form_state) {
  // If referencing an existing file, only allow if there are existing
  // references. This prevents unmanaged files from being deleted if this
  // item were to be deleted.
  $clicked_button = end($form_state['triggering_element']['#parents']);
  if ($clicked_button != 'remove_button' && !empty($element['fids']['#value'])) {
    $fids = $element['fids']['#value'];
    foreach ($fids as $fid) {
      if ($file = file_load($fid)) {
        if ($file->isPermanent()) {
          $references = file_usage()->listUsage($file);
          if (empty($references)) {
            form_error($element, t('The file used in the !name field may not be referenced.', array('!name' => $element['#title'])));
          }
        }
      }
      else {
        form_error($element, t('The file referenced by the !name field does not exist.', array('!name' => $element['#title'])));
      }
    }
  }

  // Check required property based on the FID.
  if ($element['#required'] && empty($element['fids']['#value']) && !in_array($clicked_button, array('upload_button', 'remove_button'))) {
    form_error($element['upload'], t('!name field is required.', array('!name' => $element['#title'])));
  }

  // Consolidate the array value of this field to array of FIDs.
  if (!$element['#extended']) {
    form_set_value($element, $element['fids']['#value'], $form_state);
  }
}

/**
 * Form submission handler for upload / remove buttons of managed_file elements.
 *
 * @see file_managed_file_process()
 */
function file_managed_file_submit($form, &$form_state) {
  // Determine whether it was the upload or the remove button that was clicked,
  // and set $element to the managed_file element that contains that button.
  $parents = $form_state['triggering_element']['#array_parents'];
  $button_key = array_pop($parents);
  $element = NestedArray::getValue($form, $parents);