src: add fprintf API functions

Now it's possible to print directly from libnftables to a file or
other stream. The caller must explicitly print the trailing '\n'
in this call.

The error reporting of fprintf (< 0) is respected. However, we have
already print some information in case that the default (plain text)
output is used, that output is mostly intended for debugging so it
should not be a problem.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/src/chain.c b/src/chain.c
index 6179f68..cdb398f 100644
--- a/src/chain.c
+++ b/src/chain.c
@@ -851,6 +851,19 @@ int nft_chain_snprintf(char *buf, size_t size, struct nft_chain *c,
 }
 EXPORT_SYMBOL(nft_chain_snprintf);
 
+static inline int nft_chain_do_snprintf(char *buf, size_t size, void *c,
+					uint32_t type, uint32_t flags)
+{
+	return nft_chain_snprintf(buf, size, c, type, flags);
+}
+
+int nft_chain_fprintf(FILE *fp, struct nft_chain *c, uint32_t type,
+		      uint32_t flags)
+{
+	return nft_fprintf(fp, c, type, flags, nft_chain_do_snprintf);
+}
+EXPORT_SYMBOL(nft_chain_fprintf);
+
 struct nft_chain_list {
 	struct list_head list;
 };