[nft PATCH v5 03/10] libnftables: Drop cache in error case

[Phil Sutter <phil@nwl.cc>]

If a transaction is rejected by the kernel (for instance due to a
semantic error), cache contents are potentially invalid. Release the
cache in that case to avoid the inconsistency.

The problem is easy to reproduce in an interactive session:

| nft> list ruleset
| table ip t {
| 	chain c {
| 	}
| }
| nft> flush ruleset; add rule ip t c accept
| Error: No such file or directory
| flush ruleset; add rule ip t c accept
|                            ^
| nft> list ruleset
| nft>

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 src/libnftables.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/libnftables.c b/src/libnftables.c
index d8de89ca509cd..e928ce476a90f 100644
--- a/src/libnftables.c
+++ b/src/libnftables.c
@@ -423,6 +423,8 @@ err:
 	    nft_output_json(&nft->output) &&
 	    nft_output_echo(&nft->output))
 		json_print_echo(nft);
+	if (rc)
+		cache_release(&nft->cache);
 	return rc;
 }
 
@@ -466,6 +468,8 @@ err:
 	    nft_output_json(&nft->output) &&
 	    nft_output_echo(&nft->output))
 		json_print_echo(nft);
+	if (rc)
+		cache_release(&nft->cache);
 	return rc;
 }
 
-- 
2.21.0