function file_validate_extensions

Checks that the filename ends with an allowed extension.

Parameters

\Drupal\file\FileInterface $file: A file entity.

string $extensions: A string with a space separated list of allowed extensions.

Return value

array An empty array if the file extension is allowed or an array containing an error message if it's not.

See also

hook_file_validate()

File

core/modules/file/file.module, line 308

Code

function file_validate_extensions(FileInterface $file, $extensions) {
    $errors = [];
    $regex = '/\\.(' . preg_replace('/ +/', '|', preg_quote($extensions)) . ')$/i';
    // Filename may differ from the basename, for instance in case files migrated
    // from D7 file entities. Because of that new files are saved temporarily with
    // a generated file name, without the original extension, we will use the
    // generated filename property for extension validation only in case of
    // temporary files; and use the file system file name in case of permanent
    // files.
    $subject = $file->isTemporary() ? $file->getFilename() : $file->getFileUri();
    if (!preg_match($regex, $subject)) {
        $errors[] = t('Only files with the following extensions are allowed: %files-allowed.', [
            '%files-allowed' => $extensions,
        ]);
    }
    return $errors;
}