MDL-69078 questions: check for UTF-8 encoding of the import file

Signed-off-by: Daniel Ziegenberg <[email protected]>

question/format.php

@@ -95,6 +95,40 @@ class qformat_default {
         return ($file->get_mimetype() == $this->mime_type());
     }
 
+    /**
+     * Validate the given file.
+     *
+     * For more expensive or detailed integrity checks.
+     *
+     * @param stored_file $file the file to check
+     * @return string the error message that occurred while validating the given file
+     */
+    public function validate_file(stored_file $file): string {
+        return '';
+    }
+
+    /**
+     * Check if the given file has the required utf8 encoding.
+     *
+     * @param stored_file $file the file to check
+     * @return string the error message if the file encoding is not UTF-8
+     */
+    protected function validate_is_utf8_file(stored_file $file): string {
+        if (!mb_check_encoding($file->get_content(), "UTF-8")) {
+            return get_string('importwrongfileencoding', 'question',  $this->get_name());
+        }
+        return '';
+    }
+
+    /**
+     * Return the localized pluginname string for the question format.
+     *
+     * @return string the pluginname string for the question format
+     */
+    protected function get_name(): string {
+        return get_string('pluginname', get_class($this));
+    }
+
     // Accessor methods
 
     /**