2 files changed, 21 insertions, 30 deletions

diff --git a/time64.c b/time64.c
index 6c75c482cf..dfd5776e3a 100644
--- a/time64.c
+++ b/time64.c
@@ -289,28 +289,6 @@ static void S_copy_little_tm_to_big_TM(const struct tm *src, struct TM *dest) {
 #endif
 }
 
-
-#ifndef HAS_GMTIME_R
-/* Simulate gmtime_r() to the best of our ability */
-static struct tm * S_gmtime_r(const time_t *clock, struct tm *result) {
-#ifdef __VMS
-    dTHX;    /* the following is defined as Perl_my_localtime(aTHX_ ...) */
-#endif
-    const struct tm * const static_result = gmtime(clock);
-
-    assert(result != NULL);
-
-    if( static_result == NULL ) {
-        memset(result, 0, sizeof(*result));
-        return NULL;
-    }
-    else {
-        memcpy(result, static_result, sizeof(*result));
-        return result;
-    }
-}
-#endif
-
 struct TM *Perl_gmtime64_r (const Time64_T *in_time, struct TM *p)
 {
     int v_tm_sec, v_tm_min, v_tm_hour, v_tm_mon, v_tm_wday;
@@ -319,6 +297,7 @@ struct TM *Perl_gmtime64_r (const Time64_T *in_time, struct TM *p)
     Time64_T m;
     Time64_T time = *in_time;
     Year year = 70;
+    dTHX;
 
     assert(p != NULL);
 
@@ -326,9 +305,27 @@ struct TM *Perl_gmtime64_r (const Time64_T *in_time, struct TM *p)
     if( SHOULD_USE_SYSTEM_GMTIME(*in_time) ) {
         time_t safe_time = (time_t)*in_time;
         struct tm safe_date;
-        GMTIME_R(&safe_time, &safe_date);
+        struct tm * result;
+
+        /* reentr.h will automatically replace this with a call to gmtime_r()
+         * when appropriate */
+        result = gmtime(&safe_time);
+
+        assert(result != NULL);
+
+#if defined(HAS_GMTIME_R) && defined(USE_REENTRANT_API)
+
+        PERL_UNUSED_VAR(safe_date);
+#else
+        /* Here, no gmtime_r() and is a threaded perl where the result can be
+         * overwritten by a call in another thread.  Copy to a safe place,
+         * hopefully before another gmtime can jump in and trash this
+         * result. */
+        memcpy(&safe_date, result, sizeof(safe_date));
+        result = &safe_date;
+#endif
 
-        S_copy_little_tm_to_big_TM(&safe_date, p);
+        S_copy_little_tm_to_big_TM(result, p);
         assert(S_check_tm(p));
 
         return p;
diff --git a/time64.h b/time64.h
index 4da148b9aa..b86e771602 100644
--- a/time64.h
+++ b/time64.h
@@ -53,10 +53,4 @@ struct TM64 {
 struct TM *Perl_gmtime64_r    (const Time64_T *, struct TM *);
 struct TM *Perl_localtime64_r (const Time64_T *, struct TM *);
 
-/* Not everyone has gmtime_r(), provide a replacement */
-#ifdef HAS_GMTIME_R
-#    define GMTIME_R(clock, result)    gmtime_r(clock, result)
-#else
-#    define GMTIME_R(clock, result)    S_gmtime_r(clock, result)
-#endif
 #endif