fix format warnings
Enable format security, and fix the warning caused by printing
with string for format.
diff --git a/Makefile b/Makefile
index 543d9e8..9dbb29f 100644
--- a/Makefile
+++ b/Makefile
@@ -31,7 +31,7 @@
DEFINES += -D_GNU_SOURCE
CCOPTS = -O2
WFLAGS := -Wall -Wstrict-prototypes -Wmissing-prototypes
-WFLAGS += -Wmissing-declarations -Wold-style-definition
+WFLAGS += -Wmissing-declarations -Wold-style-definition -Wformat=2
CFLAGS = $(WFLAGS) $(CCOPTS) -I../include $(DEFINES)
YACCFLAGS = -d -t -v
diff --git a/ip/ipaddress.c b/ip/ipaddress.c
index ce5e762..76f4782 100644
--- a/ip/ipaddress.c
+++ b/ip/ipaddress.c
@@ -357,7 +357,7 @@
fprintf(fp, " TX errors: aborted fifo window heartbeat");
if (carrier_changes)
fprintf(fp, " transns");
- fprintf(fp, _SL_);
+ fprintf(fp, "%s", _SL_);
fprintf(fp, " %-7"PRIu64" %-7"PRIu64" %-7"PRIu64" %-8"PRIu64"",
(uint64_t)s->tx_aborted_errors,
(uint64_t)s->tx_fifo_errors,
@@ -406,7 +406,7 @@
fprintf(fp, " TX errors: aborted fifo window heartbeat");
if (carrier_changes)
fprintf(fp, " transns");
- fprintf(fp, _SL_);
+ fprintf(fp, "%s", _SL_);
fprintf(fp, " %-7u %-7u %-7u %-8u",
s->tx_aborted_errors,
s->tx_fifo_errors,