[PATCH xtables-nft 3/6] xtables: add and use nft_build_cache

[Florian Westphal]

Will be used with the "generation id" infrastructure.
When we're told that the commit failed because someone else made
changes, we can use this to re-initialize the cache and then
revalidate the transaction list (e.g. to detect that we now have
to flush the user-defined chain 'foo' that we wanted to create, but
was added just now by someone else).

Signed-off-by: Florian Westphal <f...@strlen.de>
---
 iptables/nft.c             | 28 +++++++++++++++++++++++-----
 iptables/nft.h             |  2 ++
 iptables/xtables-restore.c |  5 +----
 3 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/iptables/nft.c b/iptables/nft.c
index 1cef7a13c90d..4c9ce1a29383 100644
--- a/iptables/nft.c
+++ b/iptables/nft.c
@@ -1486,6 +1486,28 @@ static int fetch_rule_cache(struct nft_handle *h)
        return 0;
 }
 
+static void __nft_build_cache(struct nft_handle *h)
+{
+       fetch_chain_cache(h);
+       fetch_rule_cache(h);
+       h->have_cache = true;
+}
+
+
+void nft_build_cache(struct nft_handle *h)
+{
+       if (!h->have_cache)
+               __nft_build_cache(h);
+}
+
+void nft_rebuild_cache(struct nft_handle *h)
+{
+       if (!h->have_cache)
+               flush_chain_cache(h, NULL);
+
+       __nft_build_cache(h);
+}
+
 struct nftnl_chain_list *nft_chain_list_get(struct nft_handle *h,
                                            const char *table)
 {
@@ -1495,11 +1517,7 @@ struct nftnl_chain_list *nft_chain_list_get(struct 
nft_handle *h,
        if (!t)
                return NULL;
 
-       if (!h->have_cache) {
-               fetch_chain_cache(h);
-               fetch_rule_cache(h);
-               h->have_cache = true;
-       }
+       nft_build_cache(h);
 
        return h->table[t->type].chain_cache;
 }
diff --git a/iptables/nft.h b/iptables/nft.h
index d428287b46ff..97c28b356a46 100644
--- a/iptables/nft.h
+++ b/iptables/nft.h
@@ -63,6 +63,8 @@ int mnl_talk(struct nft_handle *h, struct nlmsghdr *nlh,
             void *data);
 int nft_init(struct nft_handle *h, const struct builtin_table *t);
 void nft_fini(struct nft_handle *h);
+void nft_build_cache(struct nft_handle *h);
+void nft_rebuild_cache(struct nft_handle *h);
 
 /*
  * Operations with tables.
diff --git a/iptables/xtables-restore.c b/iptables/xtables-restore.c
index b12ab6a60b3a..a6a331d39868 100644
--- a/iptables/xtables-restore.c
+++ b/iptables/xtables-restore.c
@@ -145,10 +145,7 @@ void xtables_restore_parse(struct nft_handle *h,
                        if (p->tablename && (strcmp(p->tablename, table) != 0))
                                continue;
 
-                       /* Fixme: Needed to init chain cache.
-                        * Should create explicit function to do this.
-                        */
-                       nft_chain_list_get(h, table);
+                       nft_build_cache(h);
 
                        if (h->noflush == 0) {
                                DEBUGP("Cleaning all chains of table '%s'\n",
-- 
2.21.0