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function hook_clamav_file_is_scannable in ClamAV 2.x

Same name and namespace in other branches
  1. 8 clamav.api.php \hook_clamav_file_is_scannable()
  2. 7 clamav.api.php \hook_clamav_file_is_scannable()

Alter whether a file should be scanned by the ClamAV anti-virus scanner.

By default, all files are considered scannable.

Examples of use-cases where a scan may not be not wanted include:

  • Files considered "safe". Certain file-types have often been considered "safe", for example, it was thought that image files could not contain a virus (although this has since been proved incorrect).
  • Extremely large files. Invoking the scanner adds overhead, and the larger the file, the longer it could take to scan. Scanning a large file could cause the Drupal process to time-out.
  • Alternative backend storage. If a file is being saved directly into an alternative backend storage (for example, a CDN or a cloud file-storage system), it may already be checked for viruses in the alternative handler, in which case duplicate checking would be unnecessary.
  • Deliberate storage of a virus. Some organisations have a business need to store infected files. Security researchers, anti-virus organisations, and many others have a genuine requirement to allow an infected file to be saved, although they may also require other parts of the site to be protected.

There are many genuine use-cases where virus-scanning should be conditionally disabled for certain files. Modules can choose to require the file is scanned, stop the file from being scanned, or not affect the result.

Modules are processed in weight order. The "heaviest" module has the final decision on whether the file is scanned.

Parameters

Drupal\file\FileInterface $file: The file to scan.

Return value

int|null

1 invocation of hook_clamav_file_is_scannable()
Scanner::isScannable in src/Scanner.php
Check whether a specific file should be scanned by ClamAV.

File

./clamav.api.php, line 60
Hooks provided by the ClamAV module.

Code

function hook_clamav_file_is_scannable(Drupal\file\FileInterface $file) {

  // Don't scan image files.
  if ($mime_type = $file
    ->getMimeType()) {
    if (strpos($mime_type, '/') && (list($classification) = explode('/', $mime_type))) {
      if ($classification == 'image') {
        return Scanner::FILE_IS_NOT_SCANNABLE;
      }
    }
  }
  return Scanner::FILE_SCANNABLE_IGNORE;
}