lib-storage: Added struct mailbox.corrupted_mailbox_name

This allows backends that are adding lost mailboxes to mailbox list index to
indicate that they don't actually know the name of the mailbox, and the
mailbox list index should try to figure it out and rename the mailbox to its
proper name.

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

@@ -288,11 +288,19 @@ index_list_mailbox_create_selectable(struct mailbox *box,
 		return -1;
 
 	seq = mailbox_list_index_sync_name(sync_ctx, box->name, &node, &created);
+	if (box->corrupted_mailbox_name) {
+		/* an existing mailbox is being created with a "unknown" name.
+		   opening the mailbox will hopefully find its real name and
+		   rename it. */
+		node->flags |= MAILBOX_LIST_INDEX_FLAG_CORRUPTED_NAME;
+		mail_index_update_flags(sync_ctx->trans, seq, MODIFY_ADD,
+			MAILBOX_LIST_INDEX_FLAG_CORRUPTED_NAME);
+	}
 	if (!created &&
 	    (node->flags & (MAILBOX_LIST_INDEX_FLAG_NONEXISTENT |
 			    MAILBOX_LIST_INDEX_FLAG_NOSELECT)) == 0) {
 		/* already selectable */
-		(void)mailbox_list_index_sync_end(&sync_ctx, FALSE);
+		(void)mailbox_list_index_sync_end(&sync_ctx, TRUE);
 		return 0;
 	}
 
@@ -303,8 +311,10 @@ index_list_mailbox_create_selectable(struct mailbox *box,
 	i_assert(guid_128_is_empty(rec.guid));
 
 	/* make it selectable */
-	node->flags = 0;
-	mail_index_update_flags(sync_ctx->trans, seq, MODIFY_REPLACE, 0);
+	node->flags &= ~(MAILBOX_LIST_INDEX_FLAG_NONEXISTENT |
+			 MAILBOX_LIST_INDEX_FLAG_NOSELECT |
+			 MAILBOX_LIST_INDEX_FLAG_NOINFERIORS);
+	mail_index_update_flags(sync_ctx->trans, seq, MODIFY_REPLACE, node->flags);
 
 	memcpy(rec.guid, mailbox_guid, sizeof(rec.guid));
 	mail_index_update_ext(sync_ctx->trans, seq, ilist->ext_id, &rec, NULL);
@@ -460,6 +470,9 @@ static bool mailbox_has_corrupted_name(struct mailbox *box)
 {
 	struct mailbox_list_index_node *node;
 
+	if (box->corrupted_mailbox_name)
+		return TRUE;
+
 	node = mailbox_list_index_lookup(box->list, box->name);
 	return node != NULL &&
 		(node->flags & MAILBOX_LIST_INDEX_FLAG_CORRUPTED_NAME) != 0;

src/lib-storage/mail-storage-private.h

@@ -414,6 +414,9 @@ struct mailbox {
 	bool update_first_saved:1;
 	/* mailbox_verify_create_name() only checks for mailbox_verify_name() */
 	bool skip_create_name_restrictions:1;
+	/* Using LAYOUT=index and mailbox is being opened with a corrupted
+	   mailbox name. Try to revert to the previously known good name. */
+	bool corrupted_mailbox_name:1;
 };
 
 struct mail_vfuncs {