lib-index: mail_transaction_log_indexid_changed() - Clarify refcount handling

Although the old code worked as well, it wasn't so obvious since the
behavior was slightly different when the log->head had extra references.
Clarify the behavior by always unreferencing after the new log file is
created.

diff --git a/src/lib-index/mail-transaction-log.c b/src/lib-index/mail-transaction-log.c
index e0b0766b4e7035936329aadc86054bc45c89d0a4..7a0b6810e1e27c00d5ed5ae90a09f09b6bfac0e6 100644 (file)
--- a/src/lib-index/mail-transaction-log.c
+++ b/src/lib-index/mail-transaction-log.c
@@ -202,9 +202,16 @@ void mail_transaction_log_indexid_changed(struct mail_transaction_log *log)
 
        if (log->head != NULL &&
            log->head->hdr.indexid != log->index->indexid) {
-               if (--log->head->refcount == 0)
-                       mail_transaction_log_file_free(&log->head);
+               struct mail_transaction_log_file *old_head = log->head;
+
                (void)mail_transaction_log_create(log, FALSE);
+               if (--old_head->refcount == 0) {
+                       if (old_head == log->head) {
+                               /* failed to create a new log */
+                               log->head = NULL;
+                       }
+                       mail_transaction_log_file_free(&old_head);
+               }
        }
 }