diff mbox series

[ulogd2,v3,27/32] output: JSON: fix output of GMT offset

Message ID 20211124222444.2597311-41-jeremy@azazel.net
State Changes Requested
Delegated to: Pablo Neira
Headers show
Series Fixes for compiler warnings | expand

Commit Message

Jeremy Sowden Nov. 24, 2021, 10:24 p.m. UTC 
The compiler has two sets of complaints.  Firstly, `t->tm_gmtoffset` is
a `long int`, but it is being passed to `abs`, which leads to warnings
such as:

  ulogd_output_JSON.c:308:34: warning: absolute value function `abs` given an argument of type `long int` but has parameter of type `int` which may cause truncation of value

Secondly, it can't verify that the hour value derived from the offset
will in fact fit into `%02d`, thus:

  ulogd_output_JSON.c:306:37: warning: `%02d` directive output may be truncated writing between 2 and 6 bytes into a region of size 5

To remedy these, we now mod the offset by 86,400 and assign it to an `int`
before deriving the hour and minute values.

We also change the format-specifier for the hour value to `%+03d` which
causes a sign to be printed even if the value is positive, thus allowing
us not to specify the sign explicitly and to drop the `abs` call for the
hour value.

Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
---
 output/ulogd_output_JSON.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/output/ulogd_output_JSON.c b/output/ulogd_output_JSON.c
index 6edfa902efaf..f5c065dd062a 100644
--- a/output/ulogd_output_JSON.c
+++ b/output/ulogd_output_JSON.c
@@ -302,11 +302,12 @@  static int json_interp(struct ulogd_pluginstance *upi)
 			now = time(NULL);
 		t = localtime_r(&now, &result);
 		if (unlikely(*opi->cached_tz = '\0' || t->tm_gmtoff != opi->cached_gmtoff)) {
+			int gmtoff   = t->tm_gmtoff % 86400;
+			int gmtoff_h = gmtoff / 3600;
+			int gmtoff_m = abs(gmtoff) / 60 % 60;
+
 			snprintf(opi->cached_tz, sizeof(opi->cached_tz),
-				 "%c%02d%02d",
-				 t->tm_gmtoff > 0 ? '+' : '-',
-				 abs(t->tm_gmtoff) / 60 / 60,
-				 abs(t->tm_gmtoff) / 60 % 60);
+				 "%+03d%02d", gmtoff_h, gmtoff_m);
 		}
 
 		if (pp_is_valid(inp, opi->usec_idx)) {