function hook_file_download

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7 system.api.php hook_file_download($uri)
4.7 core.php hook_file_download($file)
5 core.php hook_file_download($file)
6 core.php hook_file_download($filepath)
8 system.api.php hook_file_download($uri)

Control access to private file downloads and specify HTTP headers.

This hook allows modules enforce permissions on file downloads when the private file download method is selected. Modules can also provide headers to specify information like the file's name or MIME type.

Parameters

$uri: The URI of the file.

Return value

If the user does not have permission to access the file, return -1. If the user has permission, return an array with the appropriate headers. If the file is not controlled by the current module, the return value should be NULL.

See also

file_download()

Related topics

5 functions implement hook_file_download()

Note: this list is generated by pattern matching, so it may include some functions that are not actually implementations of this hook.

file_file_download in modules/file/file.module
Implements hook_file_download().
file_test_file_download in modules/simpletest/tests/file_test.module
Implements hook_file_download().
image_file_download in modules/image/image.module
Implements hook_file_download().
image_module_test_file_download in modules/image/tests/image_module_test.module
user_file_download in modules/user/user.module
Implements hook_file_download().
3 invocations of hook_file_download()
file_download in includes/file.inc
Menu handler for private file transfers.
image_file_download in modules/image/image.module
Implements hook_file_download().
image_style_deliver in modules/image/image.module
Page callback: Generates a derivative, given a style and image path.

File

modules/system/system.api.php, line 2920
Hooks provided by Drupal core and the System module.

Code

function hook_file_download($uri) {
  // Check if the file is controlled by the current module.
  if (!file_prepare_directory($uri)) {
    $uri = FALSE;
  }
  if (strpos(file_uri_target($uri), variable_get('user_picture_path', 'pictures') . '/picture-') === 0) {
    if (!user_access('access user profiles')) {
      // Access to the file is denied.
      return -1;
    }
    else {
      $info = image_get_info($uri);
      return array('Content-Type' => $info['mime_type']);
    }
  }
}

Comments

Can someone explain what the purpose of checking file_prepare_directory in the example implementation is?

Note, in D6, this function returns a simple array listing the headers as strings. In D7, it returns an associative array, with the header fields as keys and the header values as values.

@bkosborne I've looked into the code and can't see the point of this. It appears, to me, to be a bug in the documentation.

Example for check some logic when content type field is file attached to a node
function hook_file_download($uri){
global $user;
$result = db_query('SELECT id
FROM `file_managed` m, file_usage u
WHERE m.fid = u.fid
AND u.`type` = :type
AND uri = :uri', array(':type' => "node", ':uri' => $uri))
->fetchField();
if($result){
$node = node_load($result);
// doing some logic ....
return array('Content-Type' => file_get_mimetype($uri));
}

<?php
/**
* Implements hook_file_download().
*/
function mymodule_file_download($uri){
 
$query = db_select('file_usage', 'fu');
 
$query->addField('fu', 'id');
 
$query->join('file_managed', 'fm', 'fm.fid = fu.fid');
 
$query->condition('fm.uri', $uri, '=');
 
$query->condition('fu.type', 'node', '=');
 
$result= $query->execute();

  foreach(

$result as $record){
   
// If this file is used in a research node where Display File(s) is not checked, don't allow user to view file
   
$node_wrapper = entity_metadata_wrapper('node', node_load($record->id));
    if (
$node_wrapper->type->value() == 'research' && $node_wrapper->field_research_displaydocs->raw() != 1) {
      return -
1;
    }
  }

 

$info = image_get_info($uri);
  return array(
'Content-Type' => $info['mime_type']);
}
?>

Sorry for the formatting issues!

file_prepare_directory checks to see if this private file is controlled by this module. It's a way of figuring out if this file is interesting to you and if you want to control access to it. I think most of the time you would not check this because most of the time you're trying to modify file access that was set by another module.