MDL-54567 backup: Process the calculations_freeze item upon restore

backup/moodle2/backup_stepslib.php

@@ -930,8 +930,11 @@ class backup_gradebook_structure_step extends backup_structure_step {
         $grade_setting = new backup_nested_element('grade_setting', 'id', array(
             'name', 'value'));
 
+        $gradebook_attributes = new backup_nested_element('attributes', null, array('calculations_freeze'));
 
         // Build the tree
+        $gradebook->add_child($gradebook_attributes);
+
         $gradebook->add_child($grade_categories);
         $grade_categories->add_child($grade_category);
 
@@ -946,14 +949,15 @@ class backup_gradebook_structure_step extends backup_structure_step {
         $gradebook->add_child($grade_settings);
         $grade_settings->add_child($grade_setting);
 
+        // Define sources
+
         // Add attribute with gradebook calculation freeze date if needed.
+        $attributes = new stdClass();
         $gradebookcalculationfreeze = get_config('core', 'gradebook_calculations_freeze_' . $this->get_courseid());
         if ($gradebookcalculationfreeze) {
-            $gradebook->add_attributes(array('calculations_freeze'));
-            $gradebook->get_attribute('calculations_freeze')->set_value($gradebookcalculationfreeze);
+            $attributes->calculations_freeze = $gradebookcalculationfreeze;
         }
-
-        // Define sources
+        $gradebook_attributes->set_source_array([$attributes]);
 
         //Include manual, category and the course grade item
         $grade_items_sql ="SELECT * FROM {grade_items}

backup/moodle2/restore_stepslib.php

@@ -121,6 +121,21 @@ class restore_gradebook_structure_step extends restore_structure_step {
             return false;
         }
 
+        // Identify the backup we're dealing with.
+        $backuprelease = floatval($this->get_task()->get_info()->backup_release); // The major version: 2.9, 3.0, ...
+        $backupbuild = 0;
+        preg_match('/(\d{8})/', $this->get_task()->get_info()->moodle_release, $matches);
+        if (!empty($matches[1])) {
+            $backupbuild = (int) $matches[1]; // The date of Moodle build at the time of the backup.
+        }
+
+        // On older versions the freeze value has to be converted.
+        // We do this from here as it is happening right before the file is read.
+        // This only targets the backup files that can contain the legacy freeze.
+        if ($backupbuild > 20150618 && ($backuprelease < 3.0 || $backupbuild < 20160527)) {
+            $this->rewrite_step_backup_file_for_legacy_freeze($fullpath);
+        }
+
         // Arrived here, execute the step
         return true;
      }
@@ -129,7 +144,7 @@ class restore_gradebook_structure_step extends restore_structure_step {
         $paths = array();
         $userinfo = $this->task->get_setting_value('users');
 
-        $paths[] = new restore_path_element('gradebook', '/gradebook');
+        $paths[] = new restore_path_element('attributes', '/gradebook/attributes');
         $paths[] = new restore_path_element('grade_category', '/gradebook/grade_categories/grade_category');
         $paths[] = new restore_path_element('grade_item', '/gradebook/grade_items/grade_item');
         if ($userinfo) {
@@ -141,7 +156,7 @@ class restore_gradebook_structure_step extends restore_structure_step {
         return $paths;
     }
 
-    protected function process_gradebook($data) {
+    protected function process_attributes($data) {
         // For non-merge restore types:
         // Unset 'gradebook_calculations_freeze_' in the course and replace with the one from the backup.
         $target = $this->get_task()->get_target();
@@ -581,6 +596,85 @@ class restore_gradebook_structure_step extends restore_structure_step {
             }
         }
     }
+
+    /**
+     * Rewrite step definition to handle the legacy freeze attribute.
+     *
+     * In previous backups the calculations_freeze property was stored as an attribute of the
+     * top level node <gradebook>. The backup API, however, do not process grandparent nodes.
+     * It only processes definitive children, and their parent attributes.
+     *
+     * We had:
+     *
+     * <gradebook calculations_freeze="20160511">
+     *   <grade_categories>
+     *     <grade_category id="10">
+     *       <depth>1</depth>
+     *       ...
+     *     </grade_category>
+     *   </grade_categories>
+     *   ...
+     * </gradebook>
+     *
+     * And this method will convert it to:
+     *
+     * <gradebook >
+     *   <attributes>
+     *     <calculations_freeze>20160511</calculations_freeze>
+     *   </attributes>
+     *   <grade_categories>
+     *     <grade_category id="10">
+     *       <depth>1</depth>
+     *       ...
+     *     </grade_category>
+     *   </grade_categories>
+     *   ...
+     * </gradebook>
+     *
+     * Note that we cannot just load the XML file in memory as it could potentially be huge.
+     * We can also completely ignore if the node <attributes> is already in the backup
+     * file as it never existed before.
+     *
+     * @param string $filepath The absolute path to the XML file.
+     * @return void
+     */
+    protected function rewrite_step_backup_file_for_legacy_freeze($filepath) {
+        $foundnode = false;
+        $newfile = make_request_directory(true) . DIRECTORY_SEPARATOR . 'file.xml';
+        $fr = fopen($filepath, 'r');
+        $fw = fopen($newfile, 'w');
+        if ($fr && $fw) {
+            while (($line = fgets($fr, 4096)) !== false) {
+                if (!$foundnode && strpos($line, '<gradebook ') === 0) {
+                    $foundnode = true;
+                    $matches = array();
+                    $pattern = '@calculations_freeze=.([0-9]+).@';
+                    if (preg_match($pattern, $line, $matches)) {
+                        $freeze = $matches[1];
+                        $line = preg_replace($pattern, '', $line);
+                        $line .= "  <attributes>\n    <calculations_freeze>$freeze</calculations_freeze>\n  </attributes>\n";
+                    }
+                }
+                fputs($fw, $line);
+            }
+            if (!feof($fr)) {
+                throw new restore_step_exception('Error while attempting to rewrite the gradebook step file.');
+            }
+            fclose($fr);
+            fclose($fw);
+            if (!rename($newfile, $filepath)) {
+                throw new restore_step_exception('Error while attempting to rename the gradebook step file.');
+            }
+        } else {
+            if ($fr) {
+                fclose($fr);
+            }
+            if ($fw) {
+                fclose($fw);
+            }
+        }
+    }
+
 }
 
 /**