acl: Empty negative rights list should be the same as NULL negative rights list.

There may be other places where this should be fixed, but this at least
fixes errors with dsync where "-user" entry without any rights was attempted
to be synced in dovecot-acl (although such entry shouldn't really have
existed in the first place).

diff --git a/src/plugins/acl/acl-api.c b/src/plugins/acl/acl-api.c
index fd266558921552c77b8867d8bcb1500ec6be5cde..e447a01e646167d7c6f670e7d53646893b31fa6d 100644 (file)
--- a/src/plugins/acl/acl-api.c
+++ b/src/plugins/acl/acl-api.c
@@ -363,7 +363,7 @@ const char *acl_rights_export(const struct acl_rights *rights)
 
        if (rights->rights != NULL)
                str_append(str, t_strarray_join(rights->rights, " "));
-       if (rights->neg_rights != NULL) {
+       if (rights->neg_rights != NULL && rights->neg_rights[0] != NULL) {
                if (str_len(str) > 0)
                        str_append_c(str, ' ');
                str_append_c(str, '-');