[libnftnl PATCH] common: events: be more strict when placing the \0 character

[Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>]

Previous to this patch, the code path can potentially print an empty
buffer with the \0 at the end of the buffer.

Be more strict and place the \0 character in the first position if the
buffer is empty.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
---
 src/common.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/common.c b/src/common.c
index 1b600f1..c81a1d8 100644
--- a/src/common.c
+++ b/src/common.c
@@ -114,9 +114,10 @@ int nft_event_header_snprintf(char *buf, size_t size, uint32_t type,
 int nft_event_header_fprintf(FILE *fp, uint32_t type, uint32_t flags)
 {
 	char buf[64]; /* enough for the maximum string length above */
+	int ret;
 
-	nft_event_header_snprintf(buf, sizeof(buf), type, flags);
-	buf[sizeof(buf) - 1] = '\0';
+	ret = nft_event_header_snprintf(buf, sizeof(buf), type, flags);
+	buf[ret] = '\0';
 
 	return fprintf(fp, "%s", buf);
 }
@@ -140,9 +141,10 @@ int nft_event_footer_snprintf(char *buf, size_t size, uint32_t type,
 int nft_event_footer_fprintf(FILE *fp, uint32_t type, uint32_t flags)
 {
 	char buf[32]; /* enough for the maximum string length above */
+	int ret;
 
-	nft_event_footer_snprintf(buf, sizeof(buf), type, flags);
-	buf[sizeof(buf) - 1] = '\0';
+	ret = nft_event_footer_snprintf(buf, sizeof(buf), type, flags);
+	buf[ret] = '\0';
 
 	return fprintf(fp, "%s", buf);
 }