gkm: Fix some format-truncation warningsnielsdg/fix-snprintf-truncation-warning

When enabling fatal warnings (like in our CI), the
`-Werror=format-truncation=` flag is complaining about us using
`snprintf()` in a way that can theoretically truncate its arguments,
even though this will not happen in practice, unless people are still
running gnome-keyring in the year 100000.

Solve the warning by doing a dumb check that aborts if `snprintf`
returns an error

1 files changed, 7 insertions, 3 deletions

diff --git a/pkcs11/gkm/gkm-attributes.c b/pkcs11/gkm/gkm-attributes.c
index dfdd08f3..69320ffb 100644
--- a/pkcs11/gkm/gkm-attributes.c
+++ b/pkcs11/gkm/gkm-attributes.c
@@ -28,6 +28,7 @@
 
 #include <stdarg.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 
@@ -216,15 +217,18 @@ gkm_attribute_set_date (CK_ATTRIBUTE_PTR attr, time_t time)
 		g_return_val_if_reached (CKR_GENERAL_ERROR);
 
 	g_assert (sizeof (date.year) == 4);
-	snprintf ((char*)buf, 5, "%04d", 1900 + tm.tm_year);
+	if (G_UNLIKELY (snprintf ((char*)buf, 5, "%04d", 1900 + tm.tm_year) < 0))
+		abort ();
 	memcpy (date.year, buf, 4);
 
 	g_assert (sizeof (date.month) == 2);
-	snprintf ((char*)buf, 3, "%02d", tm.tm_mon + 1);
+	if (G_UNLIKELY (snprintf ((char*)buf, 3, "%02d", tm.tm_mon + 1) < 0))
+		abort ();
 	memcpy (date.month, buf, 2);
 
 	g_assert (sizeof (date.day) == 2);
-	snprintf ((char*)buf, 3, "%02d", tm.tm_mday);
+	if (G_UNLIKELY (snprintf ((char*)buf, 3, "%02d", tm.tm_mday) < 0))
+		abort ();
 	memcpy (date.day, buf, 2);
 
 	return gkm_attribute_set_data (attr, &date, sizeof (date));