nft: Avoid pointless table/chain creation

Accept a chain name in nft_xt_builtin_init() to limit the base chain
creation to that specific chain only.

Introduce nft_xt_builtin_table_init() to create just the table for
situations where no builtin chains are needed but the command may still
succeed in an empty ruleset, particularly when creating a custom chain,
restoring base chains or adding a set for ebtables among match.

Introduce nft_xt_fake_builtin_chains(), a function to call after cache
has been populated to fill empty base chain slots. This keeps ruleset
listing output intact if some base chains do not exist (or even the
whole ruleset is completely empty).

Signed-off-by: Phil Sutter <phil@nwl.cc>

1 files changed, 1 insertions, 0 deletions

diff --git a/iptables/xtables-save.c b/iptables/xtables-save.c
index bf00b032..d7901c65 100644
--- a/iptables/xtables-save.c
+++ b/iptables/xtables-save.c
@@ -236,6 +236,7 @@ xtables_save_main(int family, int argc, char *argv[],
 
 	nft_cache_level_set(&h, NFT_CL_RULES, NULL);
 	nft_cache_build(&h);
+	nft_xt_fake_builtin_chains(&h, tablename, NULL);
 
 	ret = do_output(&h, tablename, &d);
 	nft_fini(&h);