lib-storage: Fail if two namespaces try to wrongly share the same LISTINDEX

If they have different mailboxes-path, they can't be sharing the same
mailbox list index. The previous behavior caused Dovecot to silently
overwrite the list index whenever each of the namespaces were accessed,
resulting in bad performance.

diff --git a/src/lib-storage/mail-namespace.c b/src/lib-storage/mail-namespace.c
index 26bc961c4239f429c1d8326dbc7a47a587749b15..40ac3b0595af86828196d34e5e5f1492eb22c1c7 100644 (file)
--- a/src/lib-storage/mail-namespace.c
+++ b/src/lib-storage/mail-namespace.c
@@ -258,6 +258,56 @@ namespace_set_alias_for(struct mail_namespace *ns,
        return 0;
 }
 
+static bool get_listindex_path(struct mail_namespace *ns, const char **path_r)
+{
+       const char *root;
+
+       if (ns->list->set.list_index_fname[0] == '\0' ||
+           !mailbox_list_get_root_path(ns->list,
+                                       MAILBOX_LIST_PATH_TYPE_LIST_INDEX,
+                                       &root))
+               return FALSE;
+
+       *path_r = t_strconcat(root, "/", ns->list->set.list_index_fname, NULL);
+       return TRUE;
+}
+
+static bool
+namespace_has_duplicate_listindex(struct mail_namespace *ns,
+                                 const char **error_r)
+{
+       struct mail_namespace *ns2;
+       const char *ns_list_index_path, *ns_mailboxes_root;
+       const char *ns2_list_index_path, *ns2_mailboxes_root;
+
+       if (!ns->mail_set->mailbox_list_index) {
+               /* mailbox list indexes not in use */
+               return FALSE;
+       }
+
+       if (!get_listindex_path(ns, &ns_list_index_path) ||
+           !mailbox_list_get_root_path(ns->list, MAILBOX_LIST_PATH_TYPE_MAILBOX,
+                                       &ns_mailboxes_root))
+               return FALSE;
+
+       for (ns2 = ns->next; ns2 != NULL; ns2 = ns2->next) {
+               if (!get_listindex_path(ns2, &ns2_list_index_path) ||
+                   !mailbox_list_get_root_path(ns2->list, MAILBOX_LIST_PATH_TYPE_MAILBOX,
+                                               &ns2_mailboxes_root))
+                       continue;
+
+               if (strcmp(ns_list_index_path, ns2_list_index_path) == 0 &&
+                   strcmp(ns_mailboxes_root, ns2_mailboxes_root) != 0) {
+                       *error_r = t_strdup_printf(
+                               "Namespaces '%s' and '%s' have different mailboxes paths, but duplicate LISTINDEX path. "
+                               "Add a unique LISTINDEX=<fname>",
+                               ns->prefix, ns2->prefix);
+                       return TRUE;
+               }
+       }
+       return FALSE;
+}
+
 static bool
 namespaces_check(struct mail_namespace *namespaces, const char **error_r)
 {
@@ -287,6 +337,8 @@ namespaces_check(struct mail_namespace *namespaces, const char **error_r)
                }
                if (namespace_set_alias_for(ns, namespaces, error_r) < 0)
                        return FALSE;
+               if (namespace_has_duplicate_listindex(ns, error_r))
+                       return FALSE;
 
                if (*ns->prefix != '\0' &&
                    (ns->flags & (NAMESPACE_FLAG_LIST_PREFIX |