From 440fc1b96bf1b33a23af616e416b2483d51a34b2 Mon Sep 17 00:00:00 2001
From: Nathan Rajlich <n@n8.io>
Date: Sun, 24 Dec 2023 00:34:14 -0800
Subject: [PATCH] Fix `getTimezoneOffset()` when `tm_gmtoff` is not available
 (#224)

---
 quickjs.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/quickjs.c b/quickjs.c
index 7be7abb..4e4a5cd 100644
--- a/quickjs.c
+++ b/quickjs.c
@@ -60,6 +60,10 @@
 #define CONFIG_PRINTF_RNDN
 #endif
 
+#if defined(__NEWLIB__)
+#define NO_TM_GMTOFF
+#endif
+
 /* dump object free */
 //#define DUMP_FREE
 //#define DUMP_CLOSURE
@@ -40685,7 +40689,17 @@ static int getTimezoneOffset(int64_t time) {
     }
     ti = time;
     localtime_r(&ti, &tm);
+#ifdef NO_TM_GMTOFF
+    struct tm gmt;
+    gmtime_r(&ti, &gmt);
+
+    /* disable DST adjustment on the local tm struct */
+    tm.tm_isdst = 0;
+
+    return difftime(mktime(&gmt), mktime(&tm)) / 60;
+#else
     return -tm.tm_gmtoff / 60;
+#endif /* NO_TM_GMTOFF */
 #endif
 }