1 files changed, 124 insertions, 0 deletions
diff --git a/intl/icu/source/common/wintz.cpp b/intl/icu/source/common/wintz.cpp
new file mode 100644
index 0000000000..115512e704
--- /dev/null
+++ b/intl/icu/source/common/wintz.cpp
@@ -0,0 +1,124 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+********************************************************************************
+*   Copyright (C) 2005-2015, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+********************************************************************************
+*
+* File WINTZ.CPP
+*
+********************************************************************************
+*/
+
+#include "unicode/utypes.h"
+
+#if U_PLATFORM_USES_ONLY_WIN32_API
+
+#include "wintz.h"
+#include "cmemory.h"
+#include "cstring.h"
+
+#include "unicode/ures.h"
+#include "unicode/ustring.h"
+#include "uresimp.h"
+
+#ifndef WIN32_LEAN_AND_MEAN
+#   define WIN32_LEAN_AND_MEAN
+#endif
+#   define VC_EXTRALEAN
+#   define NOUSER
+#   define NOSERVICE
+#   define NOIME
+#   define NOMCX
+#include <windows.h>
+
+U_NAMESPACE_BEGIN
+
+// The max size of TimeZoneKeyName is 128, defined in DYNAMIC_TIME_ZONE_INFORMATION
+#define MAX_TIMEZONE_ID_LENGTH 128
+
+/**
+* Main Windows time zone detection function.
+* Returns the Windows time zone converted to an ICU time zone as a heap-allocated buffer, or nullptr upon failure.
+* Note: We use the Win32 API GetDynamicTimeZoneInformation to get the current time zone info.
+* This API returns a non-localized time zone name, which we can then map to an ICU time zone name.
+*/
+U_INTERNAL const char* U_EXPORT2
+uprv_detectWindowsTimeZone()
+{
+    UErrorCode status = U_ZERO_ERROR;
+    char* icuid = nullptr;
+    char dynamicTZKeyName[MAX_TIMEZONE_ID_LENGTH];
+    char tmpid[MAX_TIMEZONE_ID_LENGTH];
+    int32_t len;
+    int id = GEOID_NOT_AVAILABLE;
+    int errorCode;
+    wchar_t ISOcodeW[3] = {}; /* 2 letter ISO code in UTF-16 */
+    char ISOcode[3] = {}; /* 2 letter ISO code in UTF-8 */
+
+    DYNAMIC_TIME_ZONE_INFORMATION dynamicTZI;
+    uprv_memset(&dynamicTZI, 0, sizeof(dynamicTZI));
+    uprv_memset(dynamicTZKeyName, 0, sizeof(dynamicTZKeyName));
+    uprv_memset(tmpid, 0, sizeof(tmpid));
+
+    /* Obtain TIME_ZONE_INFORMATION from the API and get the non-localized time zone name. */
+    if (TIME_ZONE_ID_INVALID == GetDynamicTimeZoneInformation(&dynamicTZI)) {
+        return nullptr;
+    }
+
+    id = GetUserGeoID(GEOCLASS_NATION);
+    errorCode = GetGeoInfoW(id, GEO_ISO2, ISOcodeW, 3, 0);
+
+    // convert from wchar_t* (UTF-16 on Windows) to char* (UTF-8).
+    u_strToUTF8(ISOcode, UPRV_LENGTHOF(ISOcode), nullptr,
+        reinterpret_cast<const UChar*>(ISOcodeW), UPRV_LENGTHOF(ISOcodeW), &status);
+
+    LocalUResourceBundlePointer bundle(ures_openDirect(nullptr, "windowsZones", &status));
+    ures_getByKey(bundle.getAlias(), "mapTimezones", bundle.getAlias(), &status);
+
+    // convert from wchar_t* (UTF-16 on Windows) to char* (UTF-8).
+    u_strToUTF8(dynamicTZKeyName, UPRV_LENGTHOF(dynamicTZKeyName), nullptr,
+        reinterpret_cast<const UChar*>(dynamicTZI.TimeZoneKeyName), -1, &status);
+
+    if (U_FAILURE(status)) {
+        return nullptr;
+    }
+
+    if (dynamicTZI.TimeZoneKeyName[0] != 0) {
+        StackUResourceBundle winTZ;
+        ures_getByKey(bundle.getAlias(), dynamicTZKeyName, winTZ.getAlias(), &status);
+
+        if (U_SUCCESS(status)) {
+            const UChar* icuTZ = nullptr;
+            if (errorCode != 0) {
+                icuTZ = ures_getStringByKey(winTZ.getAlias(), ISOcode, &len, &status);
+            }
+            if (errorCode == 0 || icuTZ == nullptr) {
+                /* fallback to default "001" and reset status */
+                status = U_ZERO_ERROR;
+                icuTZ = ures_getStringByKey(winTZ.getAlias(), "001", &len, &status);
+            }
+
+            if (U_SUCCESS(status)) {
+                int index = 0;
+
+                while (!(*icuTZ == '\0' || *icuTZ == ' ')) {
+                    // time zone IDs only contain ASCII invariant characters.
+                    tmpid[index++] = (char)(*icuTZ++);
+                }
+                tmpid[index] = '\0';
+            }
+        }
+    }
+
+    // Copy the timezone ID to icuid to be returned.
+    if (tmpid[0] != 0) {
+        icuid = uprv_strdup(tmpid);
+    }
+
+    return icuid;
+}
+
+U_NAMESPACE_END
+#endif /* U_PLATFORM_USES_ONLY_WIN32_API  */