Use time64 implementation by Michael G Schwern to extend allowed date/time range

The main benefit of this is to allow date/time values outside of the 32bit time_t
range which is very important on 32bit platforms. But there are also some other
issues that will be fixed with this, for example on macOS, mktime() will not work
for dates < 1902 despite time_t being 64bit.

In the same run this commit will also use a reentrant version of gmtime64_r that
should help in multithreaded scenarios.

Original code taken from: https://github.com/evalEmpire/y2038

1 files changed, 85 insertions, 0 deletions

diff --git a/src/time64.h b/src/time64.h
new file mode 100644
index 0000000..556e06f
--- /dev/null
+++ b/src/time64.h
@@ -0,0 +1,85 @@
+#ifndef TIME64_H
+#    define TIME64_H
+
+#include <time.h>
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+/* Set our custom types */
+typedef long long       Int64;
+typedef Int64           Time64_T;
+typedef Int64           Year;
+
+
+/* A copy of the tm struct but with a 64 bit year */
+struct TM64 {
+        int     tm_sec;
+        int     tm_min;
+        int     tm_hour;
+        int     tm_mday;
+        int     tm_mon;
+        Year    tm_year;
+        int     tm_wday;
+        int     tm_yday;
+        int     tm_isdst;
+
+#ifdef HAVE_TM_TM_GMTOFF
+        long    tm_gmtoff;
+#endif
+
+#ifdef HAVE_TM_TM_ZONE
+        char    *tm_zone;
+#endif
+};
+
+
+/* Decide which tm struct to use */
+#ifdef USE_TM64
+#define TM      TM64
+#else
+#define TM      tm
+#endif   
+
+
+/* Declare public functions */
+struct TM *gmtime64_r    (const Time64_T *, struct TM *);
+struct TM *localtime64_r (const Time64_T *, struct TM *);
+struct TM *gmtime64      (const Time64_T *);
+struct TM *localtime64   (const Time64_T *);
+
+char *asctime64          (const struct TM *);
+char *asctime64_r        (const struct TM *, char *);
+
+char *ctime64            (const Time64_T*);
+char *ctime64_r          (const Time64_T*, char*);
+
+Time64_T   timegm64      (const struct TM *);
+Time64_T   mktime64      (struct TM *);
+Time64_T   timelocal64   (struct TM *);
+
+
+/* Not everyone has gm/localtime_r(), provide a replacement */
+#ifdef HAVE_LOCALTIME_R
+#    define LOCALTIME_R(clock, result) localtime_r(clock, result)
+#else
+#    define LOCALTIME_R(clock, result) fake_localtime_r(clock, result)
+#endif
+#ifdef HAVE_GMTIME_R
+#    define GMTIME_R(clock, result)    gmtime_r(clock, result)
+#else
+#    define GMTIME_R(clock, result)    fake_gmtime_r(clock, result)
+#endif
+
+
+/* Use a different asctime format depending on how big the year is */
+#ifdef USE_TM64
+    #define TM64_ASCTIME_FORMAT "%.3s %.3s%3d %.2d:%.2d:%.2d %lld\n"
+#else
+    #define TM64_ASCTIME_FORMAT "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n"
+#endif
+
+void copy_tm_to_TM64(const struct tm *src, struct TM *dest);
+void copy_TM64_to_tm(const struct TM *src, struct tm *dest);
+
+#endif