time-util: refuse formatting/parsing times that we can't store

[elogind.git] / src / basic / time-util.h

diff --git a/src/basic/time-util.h b/src/basic/time-util.h
index 4485d7eb0e3236e69c964497a5d5f0d28fa1ee87..2ea7e8b511173c461fe7d3523e442d1356530d0d 100644 (file)
--- a/src/basic/time-util.h
+++ b/src/basic/time-util.h
@@ -203,3 +203,14 @@ static inline usec_t usec_sub(usec_t timestamp, int64_t delta) {
 
         return timestamp - delta;
 }
+
+#if SIZEOF_TIME_T == 8
+/* The last second we can format is 31. Dec 9999, 1s before midnight, because otherwise we'd enter 5 digit year
+ * territory. However, since we want to stay away from this in all timezones we take one day off. */
+#define USEC_TIMESTAMP_FORMATTABLE_MAX ((usec_t) 253402214399000000)
+#elif SIZEOF_TIME_T == 4
+/* With a 32bit time_t we can't go beyond 2038... */
+#define USEC_TIMESTAMP_FORMATTABLE_MAX ((usec_t) 2147483647000000)
+#else
+#error "Yuck, time_t is neither 4 not 8 bytes wide?"
+#endif