[ulogd2 PATCH 25/26] output: JSON: optimize appending of newline to output.

[Jeremy Sowden <jeremy@azazel.net>]

We have `buflen` available.  We can remove `strncat` and assign the characters
directly, without traversing the whole buffer.

Correct `buflen` type and fix leak if `realloc` fails.

Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
---
 output/ulogd_output_JSON.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/output/ulogd_output_JSON.c b/output/ulogd_output_JSON.c
index 6c61eb144135..c15c9f239441 100644
--- a/output/ulogd_output_JSON.c
+++ b/output/ulogd_output_JSON.c
@@ -275,8 +275,8 @@ static int json_interp(struct ulogd_pluginstance *upi)
 {
 	struct json_priv *opi = (struct json_priv *) &upi->private;
 	unsigned int i;
-	char *buf;
-	int buflen;
+	char *buf, *tmp;
+	size_t buflen;
 	json_t *msg;
 
 	msg = json_object();
@@ -337,8 +337,6 @@ static int json_interp(struct ulogd_pluginstance *upi)
 		json_object_set_new(msg, "dvc", json_string(dvc));
 	}
 
-
-
 	for (i = 0; i < upi->input.num_keys; i++) {
 		struct ulogd_key *key = upi->input.keys[i].u.source;
 		char *field_name;
@@ -391,7 +389,6 @@ static int json_interp(struct ulogd_pluginstance *upi)
 		}
 	}
 
-
 	buf = json_dumps(msg, 0);
 	json_decref(msg);
 	if (buf == NULL) {
@@ -399,13 +396,15 @@ static int json_interp(struct ulogd_pluginstance *upi)
 		return ULOGD_IRET_ERR;
 	}
 	buflen = strlen(buf);
-	buf = realloc(buf, sizeof(char)*(buflen+2));
-	if (buf == NULL) {
+	tmp = realloc(buf, buflen + sizeof("\n"));
+	if (tmp == NULL) {
+		free(buf);
 		ulogd_log(ULOGD_ERROR, "Could not create message\n");
 		return ULOGD_IRET_ERR;
 	}
-	strncat(buf, "\n", 1);
-	buflen++;
+	buf = tmp;
+	buf[buflen++] = '\n';
+	buf[buflen]   = '\0';
 
 	if (opi->mode == JSON_MODE_FILE)
 		return json_interp_file(upi, buf);
-- 
2.33.0