lib-storge: Call mail_storage.list_index_corrupted() when needed

The callback is called whenever mailbox list index appears to be corrupted
with LAYOUT=index. The storage is responsible for adding to the index any
mailboxes that are missing.

src/lib-storage/list/mailbox-list-index-notify.c

@@ -778,6 +778,9 @@ int mailbox_list_index_notify_next(struct mailbox_list_notify *notify,
 
 	if (!inotify->initialized)
 		mailbox_list_index_notify_read_init(inotify);
+	if (mailbox_list_index_handle_corruption(notify->list) < 0)
+		return -1;
+
 	while (mailbox_list_index_notify_try_next(inotify)) {
 		if ((inotify->notify_rec.events & inotify->notify.mask) != 0) {
 			*rec_r = &inotify->notify_rec;

src/lib-storage/list/mailbox-list-index-sync.c

@@ -230,9 +230,11 @@ int mailbox_list_index_sync_begin(struct mailbox_list *list,
 	struct mail_index_view *view;
 	struct mail_index_transaction *trans;
 	const struct mail_index_header *hdr;
+	bool fix_attempted = FALSE;
 
 	i_assert(!ilist->syncing);
 
+retry:
 	if (mailbox_list_index_index_open(list) < 0)
 		return -1;
 
@@ -248,6 +250,14 @@ int mailbox_list_index_sync_begin(struct mailbox_list *list,
 		mail_index_sync_rollback(&index_sync_ctx);
 		return -1;
 	}
+	if (ilist->call_corruption_callback && !fix_attempted) {
+		/* unlock and resync the index */
+		mail_index_sync_rollback(&index_sync_ctx);
+		if (mailbox_list_index_handle_corruption(list) < 0)
+			return -1;
+		fix_attempted = TRUE;
+		goto retry;
+	}
 
 	sync_ctx = i_new(struct mailbox_list_index_sync_context, 1);
 	sync_ctx->list = list;

src/lib-storage/list/mailbox-list-index.c

@@ -413,6 +413,8 @@ int mailbox_list_index_parse(struct mailbox_list *list,
 		/* nothing changed */
 		return 0;
 	}
+	if ((hdr->flags & MAIL_INDEX_HDR_FLAG_FSCKD) != 0)
+		ilist->call_corruption_callback = TRUE;
 
 	mailbox_list_index_reset(ilist);
 	ilist->sync_log_file_seq = hdr->log_file_seq;
@@ -425,6 +427,7 @@ int mailbox_list_index_parse(struct mailbox_list *list,
 			mail_index_mark_corrupted(ilist->index);
 			return -1;
 		}
+		ilist->call_corruption_callback = TRUE;
 		ilist->corrupted_names_or_parents = TRUE;
 	}
 	if (mailbox_list_index_parse_records(ilist, view, &error) < 0) {
@@ -437,6 +440,7 @@ int mailbox_list_index_parse(struct mailbox_list *list,
 		}
 		/* FIXME: find any missing mailboxes, add them and write the
 		   index back. */
+		ilist->call_corruption_callback = TRUE;
 		ilist->corrupted_names_or_parents = TRUE;
 	}
 	return 0;
@@ -500,7 +504,8 @@ int mailbox_list_index_refresh_force(struct mailbox_list *list)
 		ret = mailbox_list_index_parse(list, view, FALSE);
 	}
 	mail_index_view_close(&view);
-	return ret;
+
+	return mailbox_list_index_handle_corruption(list);
 }
 
 static void mailbox_list_index_refresh_timeout(struct mailbox_list *list)
@@ -548,6 +553,51 @@ void mailbox_list_index_refresh_later(struct mailbox_list *list)
 	}
 }
 
+int mailbox_list_index_handle_corruption(struct mailbox_list *list)
+{
+	struct mailbox_list_index *ilist = INDEX_LIST_CONTEXT(list);
+	struct mail_storage *const *storagep;
+	int ret = 0;
+
+	if (!ilist->call_corruption_callback)
+		return 0;
+
+	/* make sure we don't recurse */
+	if (ilist->handling_corruption)
+		return 0;
+	ilist->handling_corruption = TRUE;
+
+	array_foreach(&list->ns->all_storages, storagep) {
+		if ((*storagep)->v.list_index_corrupted != NULL) {
+			if ((*storagep)->v.list_index_corrupted(*storagep) < 0)
+				ret = -1;
+			else {
+				/* FIXME: implement a generic handler that
+				   just lists mailbox directories in filesystem
+				   and adds the missing ones to the index. */
+			}
+		}
+	}
+	if (ret == 0)
+		ret = mailbox_list_index_set_uncorrupted(list);
+	ilist->handling_corruption = FALSE;
+	return ret;
+}
+
+int mailbox_list_index_set_uncorrupted(struct mailbox_list *list)
+{
+	struct mailbox_list_index *ilist = INDEX_LIST_CONTEXT(list);
+	struct mailbox_list_index_sync_context *sync_ctx;
+
+	ilist->call_corruption_callback = FALSE;
+
+	if (mailbox_list_index_sync_begin(list, &sync_ctx) < 0)
+		return -1;
+
+	mail_index_unset_fscked(sync_ctx->trans);
+	return mailbox_list_index_sync_end(&sync_ctx, TRUE);
+}
+
 static void mailbox_list_index_deinit(struct mailbox_list *list)
 {
 	struct mailbox_list_index *ilist = INDEX_LIST_CONTEXT(list);

src/lib-storage/list/mailbox-list-index.h

@@ -117,6 +117,8 @@ struct mailbox_list_index {
 	unsigned int has_backing_store:1;
 	unsigned int index_last_check_changed:1;
 	unsigned int corrupted_names_or_parents:1;
+	unsigned int handling_corruption:1;
+	unsigned int call_corruption_callback:1;
 };
 
 struct mailbox_list_index_iterate_context {
@@ -156,6 +158,8 @@ int mailbox_list_index_refresh(struct mailbox_list *list);
 /* Refresh the index regardless of when the last refresh was done. */
 int mailbox_list_index_refresh_force(struct mailbox_list *list);
 void mailbox_list_index_refresh_later(struct mailbox_list *list);
+int mailbox_list_index_handle_corruption(struct mailbox_list *list);
+int mailbox_list_index_set_uncorrupted(struct mailbox_list *list);
 
 struct mailbox_list_index_node *
 mailbox_list_index_node_find_sibling(struct mailbox_list_index_node *node,