minor fixes

Author: gsmolk

src/catalog.c

@@ -929,7 +929,7 @@ get_closest_backup(timelineInfo *tlinfo)
 				 * should be considered.
 				 */
 				if (!XLogRecPtrIsInvalid(backup->stop_lsn) &&
-					!XRecOffIsValid(backup->stop_lsn) &&
+					XRecOffIsValid(backup->stop_lsn) &&
 					backup->stop_lsn <= tlinfo->switchpoint &&
 					(backup->status == BACKUP_STATUS_OK ||
 					backup->status == BACKUP_STATUS_DONE))
@@ -950,10 +950,11 @@ get_closest_backup(timelineInfo *tlinfo)
 
 /*
  * Find oldest backup in given timeline
- * to determine what WAL segments belonging to this timeline,
- * are not reachable from any backup.
+ * to determine what WAL segments of this timeline
+ * are reachable from backups belonging to it.
  *
- * Returns NULL if such backup is not found.
+ * If such backup doesn't exist, it means that
+ * there is no backups on this timeline. Return NULL.
  */
 pgBackup*
 get_oldest_backup(timelineInfo *tlinfo)

src/delete.c

@@ -634,7 +634,7 @@ do_retention_wal(bool dry_run)
 
 		/*
 		 * If closest backup exists, then timeline is reachable from
-		 * at least one backup and none files should not be removed.
+		 * at least one backup and no file should be removed.
 		 */
 		if (tlinfo->closest_backup)
 			continue;