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, 2 insertions, 0 deletions

diff --git a/include/libnftables/rule.h b/include/libnftables/rule.h
index a501d2d..cdbd8d2 100644
--- a/include/libnftables/rule.h
+++ b/include/libnftables/rule.h
@@ -1,6 +1,7 @@
 #ifndef _RULE_H_
 #define _RULE_H_
 
+#include <stdio.h>
 #include <stdint.h>
 #include <stdbool.h>
 
@@ -58,6 +59,7 @@ enum nft_rule_parse_type {
 
 int nft_rule_parse(struct nft_rule *r, enum nft_rule_parse_type type, const char *data);
 int nft_rule_snprintf(char *buf, size_t size, struct nft_rule *t, uint32_t type, uint32_t flags);
+int nft_rule_fprintf(FILE *fp, struct nft_rule *r, uint32_t type, uint32_t flags);
 
 struct nlmsghdr *nft_rule_nlmsg_build_hdr(char *buf, uint16_t cmd, uint16_t family, uint16_t type, uint32_t seq);
 int nft_rule_nlmsg_parse(const struct nlmsghdr *nlh, struct nft_rule *t);