From: Timo Sirainen <timo.sirainen@open-xchange.com>
Date: Mon, 10 Aug 2020 17:02:22 +0000 (+0300)
Subject: lib-index: mail_transaction_log_indexid_changed() - Clarify refcount handling
X-Git-Tag: 2.3.14.rc1~318
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=268de25bd48f1d102e2fd3b6813793489c449167;p=thirdparty%2Fdovecot%2Fcore.git

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 e0b0766b4e..7a0b6810e1 100644
--- 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);
+		}
 	}
 }