From 8333927737bf4e2daa5146cbc17b4a830c5da0c7 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max.kellermann@gmail.com>
Date: Mon, 3 Jan 2022 15:43:15 +0100
Subject: [PATCH] time/Zone: add native Windows implementation
---
src/time/Zone.cxx | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)
diff --git a/src/time/Zone.cxx b/src/time/Zone.cxx
index 9165a10d0..534657436 100644
--- a/src/time/Zone.cxx
+++ b/src/time/Zone.cxx
@@ -32,19 +32,35 @@
#include "Zone.hxx"
+#ifdef _WIN32
+#include <profileapi.h>
+#include <sysinfoapi.h>
+#include <timezoneapi.h>
+#else
#include <time.h>
+#endif
int
GetTimeZoneOffset() noexcept
{
- time_t t = 1234567890;
#ifdef _WIN32
- struct tm *p = gmtime(&t);
+ TIME_ZONE_INFORMATION TimeZoneInformation;
+ DWORD tzi = GetTimeZoneInformation(&TimeZoneInformation);
+
+ int offset = -TimeZoneInformation.Bias * 60;
+ if (tzi == TIME_ZONE_ID_STANDARD)
+ offset -= TimeZoneInformation.StandardBias * 60;
+
+ if (tzi == TIME_ZONE_ID_DAYLIGHT)
+ offset -= TimeZoneInformation.DaylightBias * 60;
+
+ return offset;
#else
+ time_t t = 1234567890;
struct tm tm;
tm.tm_isdst = 0;
struct tm *p = &tm;
gmtime_r(&t, p);
-#endif
return t - mktime(p);
+#endif
}