From 22894ddef07cbe1a0f2277cec61e7b8a83614c7d Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Thu, 11 Jan 2024 12:07:19 +0100
Subject: [PATCH] degrib: use gmtime_r() or gmtime_s() when possible

---
 frmts/grib/degrib/degrib/clock.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/frmts/grib/degrib/degrib/clock.c b/frmts/grib/degrib/degrib/clock.c
index c7e0ba5887dc..5791787d2354 100644
--- a/frmts/grib/degrib/degrib/clock.c
+++ b/frmts/grib/degrib/degrib/clock.c
@@ -712,7 +712,6 @@ sChar Clock_GetTimeZone ()
 {
    struct tm l_time;
    time_t ansTime;
-   struct tm *gmTime;
    static int timeZone = 9999;
 
    if (timeZone == 9999) {
@@ -721,10 +720,21 @@ sChar Clock_GetTimeZone ()
       l_time.tm_year = 70;
       l_time.tm_mday = 2;
       ansTime = mktime (&l_time);
-      gmTime = gmtime (&ansTime);
-      timeZone = gmTime->tm_hour;
-      if (gmTime->tm_mday != 2) {
-         timeZone -= 24;
+#if HAVE_GMTIME_R
+      struct tm gmTime;
+      const struct tm *gmTimePtr = gmtime_r(&ansTime, &gmTime);
+#elif defined(_WIN32)
+      struct tm gmTime;
+      const struct tm *gmTimePtr = gmtime_s(&gmTime, &ansTime) == 0 ? &gmTime : NULL;
+#else
+      const struct tm *gmTimePtr = gmtime (&ansTime);
+#endif
+      if (gmTimePtr)
+      {
+          timeZone = gmTimePtr->tm_hour;
+          if (gmTimePtr->tm_mday != 2) {
+             timeZone -= 24;
+          }
       }
    }
    return timeZone;