Issue #2588421 by neclimdul: CckLinks double unserialized attributes array

core/modules/link/src/Plugin/migrate/process/d6/CckLink.php

@@ -45,8 +45,11 @@ public static function create(ContainerInterface $container, array $configuratio
    * {@inheritdoc}
    */
   public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
-    // Drupal 6 link attributes are double serialized.
-    $attributes = unserialize(unserialize($value['attributes']));
+    $attributes = unserialize($value['attributes']);
+    // Drupal 6 link attributes might be double serialized.
+    if (!is_array($attributes)) {
+      $attributes = unserialize($attributes);
+    }
 
     // Massage the values into the correct form for the link.
     $route['uri'] = $value['url'];

core/modules/migrate_drupal/tests/fixtures/drupal6.php

@@ -2021,6 +2021,12 @@
   'field_test_value' => NULL,
   'field_test_format' => NULL,
 ))
+->values(array(
+  'vid' => '12',
+  'nid' => '9',
+  'field_test_value' => 'text for default value',
+  'field_test_format' => '1',
+))
 ->execute();
 $connection->schema()->createTable('content_field_test_text_single_checkbox', array(
@@ -2077,6 +2083,11 @@
   'nid' => '2',
   'field_test_text_single_checkbox_value' => NULL,
 ))
+->values(array(
+  'vid' => '12',
+  'nid' => '9',
+  'field_test_text_single_checkbox_value' => '0',
+))
 ->execute();
 $connection->schema()->createTable('content_field_test_two', array(
@@ -2146,6 +2157,12 @@
   'delta' => '0',
   'field_test_two_value' => NULL,
 ))
+->values(array(
+  'vid' => '12',
+  'nid' => '9',
+  'delta' => '0',
+  'field_test_two_value' => NULL,
+))
 ->values(array(
   'vid' => '1',
   'nid' => '1',
@@ -3233,6 +3250,34 @@
   'field_test_imagefield_list' => NULL,
   'field_test_imagefield_data' => NULL,
 ))
+->values(array(
+  'nid' => '9',
+  'vid' => '12',
+  'uid' => '0',
+  'field_test_three_value' => '101.00',
+  'field_test_identical1_value' => NULL,
+  'field_test_identical2_value' => NULL,
+  'field_test_link_url' => 'http://www.example.com/buy-one-upon-a-time',
+  'field_test_link_title' => 'Buy it now',
+  'field_test_link_attributes' => 'a:1:{s:6:"target";s:6:"_blank";}',
+  'field_test_date_value' => NULL,
+  'field_test_datestamp_value' => NULL,
+  'field_test_datetime_value' => NULL,
+  'field_test_email_email' => NULL,
+  'field_test_filefield_fid' => NULL,
+  'field_test_filefield_list' => NULL,
+  'field_test_filefield_data' => NULL,
+  'field_test_four_value' => '101',
+  'field_test_integer_selectlist_value' => NULL,
+  'field_test_float_single_checkbox_value' => '3',
+  'field_test_decimal_radio_buttons_value' => NULL,
+  'field_test_phone_value' => NULL,
+  'field_test_exclude_unset_value' => 'text for default value',
+  'field_test_exclude_unset_format' => '1',
+  'field_test_imagefield_fid' => NULL,
+  'field_test_imagefield_list' => NULL,
+  'field_test_imagefield_data' => NULL,
+))
 ->execute();
 $connection->schema()->createTable('content_type_test_page', array(
@@ -21406,6 +21451,23 @@
   'tnid' => '0',
   'translate' => '0',
 ))
+->values(array(
+  'nid' => '9',
+  'vid' => '12',
+  'type' => 'story',
+  'language' => '',
+  'title' => 'Once upon a time',
+  'uid' => '1',
+  'status' => '1',
+  'created' => '1444671588',
+  'changed' => '1444671588',
+  'comment' => '2',
+  'promote' => '1',
+  'moderate' => '0',
+  'sticky' => '0',
+  'tnid' => '0',
+  'translate' => '0',
+))
 ->execute();
 $connection->schema()->createTable('node_access', array(
@@ -21541,6 +21603,13 @@
   'last_comment_uid' => '1',
   'comment_count' => '0',
 ))
+->values(array(
+  'nid' => '9',
+  'last_comment_timestamp' => '1444671588',
+  'last_comment_name' => NULL,
+  'last_comment_uid' => '1',
+  'comment_count' => '0',
+))
 ->execute();
 $connection->schema()->createTable('node_counter', array(
@@ -21773,6 +21842,17 @@
   'timestamp' => '1390095701',
   'format' => '1',
 ))
+->values(array(
+  'nid' => '9',
+  'vid' => '12',
+  'uid' => '1',
+  'title' => 'Once upon a time',
+  'body' => 'Come on kid, go to sleep.',
+  'teaser' => 'Come on kid, go to sleep.',
+  'log' => '',
+  'timestamp' => '1444671588',
+  'format' => '1',
+))
 ->execute();
 $connection->schema()->createTable('node_type', array(