331 lines
16 KiB
C++
331 lines
16 KiB
C++
// © 2016 and later: Unicode, Inc. and others.
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// License & terms of use: http://www.unicode.org/copyright.html
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/*
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********************************************************************************
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* Copyright (C) 2005-2015, International Business Machines
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* Corporation and others. All Rights Reserved.
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********************************************************************************
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*
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* File WINTZ.CPP
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*
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********************************************************************************
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*/
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#include "unicode/utypes.h"
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#if U_PLATFORM_USES_ONLY_WIN32_API
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#include "wintz.h"
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#include "charstr.h"
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#include "cmemory.h"
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#include "cstring.h"
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#include "unicode/ures.h"
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#include "unicode/unistr.h"
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#include "uresimp.h"
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#ifndef WIN32_LEAN_AND_MEAN
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# define WIN32_LEAN_AND_MEAN
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#endif
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# define VC_EXTRALEAN
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# define NOUSER
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# define NOSERVICE
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# define NOIME
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# define NOMCX
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#include <windows.h>
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U_NAMESPACE_BEGIN
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// Note these constants and the struct are only used when dealing with the fallback path for RDP sessions.
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// This is the location of the time zones in the registry on Vista+ systems.
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// See: https://docs.microsoft.com/windows/win32/api/timezoneapi/ns-timezoneapi-dynamic_time_zone_information
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#define WINDOWS_TIMEZONES_REG_KEY_PATH L"SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones"
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// Max length for a registry key is 255. +1 for null.
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// See: https://docs.microsoft.com/windows/win32/sysinfo/registry-element-size-limits
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#define WINDOWS_MAX_REG_KEY_LENGTH 256
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#if U_PLATFORM_HAS_WINUWP_API == 0
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// This is the layout of the TZI binary value in the registry.
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// See: https://docs.microsoft.com/windows/win32/api/timezoneapi/ns-timezoneapi-time_zone_information
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typedef struct _REG_TZI_FORMAT {
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LONG Bias;
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LONG StandardBias;
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LONG DaylightBias;
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SYSTEMTIME StandardDate;
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SYSTEMTIME DaylightDate;
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} REG_TZI_FORMAT;
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#endif // U_PLATFORM_HAS_WINUWP_API
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/**
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* This is main Windows time zone detection function.
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*
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* It returns the Windows time zone converted to an ICU time zone as a heap-allocated buffer, or nullptr upon failure.
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*
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* We use the Win32 API GetDynamicTimeZoneInformation (which is available since Vista) to get the current time zone info,
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* as this API returns a non-localized time zone name which can be then mapped to an ICU time zone.
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*
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* However, in some RDP/terminal services situations, this struct isn't always fully complete, and the TimeZoneKeyName
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* field of the struct might be NULL. This can happen with some 3rd party RDP clients, and also when using older versions
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* of the RDP protocol, which don't send the newer TimeZoneKeyNamei information and only send the StandardName and DaylightName.
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*
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* Since these 3rd party clients and older RDP clients only send the pre-Vista time zone information to the server, this means that we
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* need to fallback on using the pre-Vista methods to determine the time zone. This unfortunately requires examining the registry directly
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* in order to try and determine the current time zone.
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*
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* Note that this can however still fail in some cases though if the client and server are using different languages, as the StandardName
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* that is sent by client is localized in the client's language. However, we must compare this to the names that are on the server, which
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* are localized in registry using the server's language. Despite that, this is the best we can do.
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*
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* Note: This fallback method won't work for the UWP version though, as we can't use the registry APIs in UWP.
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*
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* Once we have the current Windows time zone, then we can then map it to an ICU time zone ID (~ Olsen ID).
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*/
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U_CAPI const char* U_EXPORT2
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uprv_detectWindowsTimeZone()
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{
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// We first try to obtain the time zone directly by using the TimeZoneKeyName field of the DYNAMIC_TIME_ZONE_INFORMATION struct.
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DYNAMIC_TIME_ZONE_INFORMATION dynamicTZI;
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uprv_memset(&dynamicTZI, 0, sizeof(dynamicTZI));
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SYSTEMTIME systemTimeAllZero;
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uprv_memset(&systemTimeAllZero, 0, sizeof(systemTimeAllZero));
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if (GetDynamicTimeZoneInformation(&dynamicTZI) == TIME_ZONE_ID_INVALID) {
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return nullptr;
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}
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// If the DST setting has been turned off in the Control Panel, then return "Etc/GMT<offset>".
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//
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// Note: This logic is based on how the Control Panel itself determines if DST is 'off' on Windows.
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// The code is somewhat convoluted; in a sort of pseudo-code it looks like this:
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//
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// IF (GetDynamicTimeZoneInformation != TIME_ZONE_ID_INVALID) && (DynamicDaylightTimeDisabled != 0) &&
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// (StandardDate == DaylightDate) &&
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// (
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// (TimeZoneKeyName != Empty && StandardDate == 0) ||
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// (TimeZoneKeyName == Empty && StandardDate != 0)
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// )
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// THEN
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// DST setting is "Disabled".
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//
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if (dynamicTZI.DynamicDaylightTimeDisabled != 0 &&
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uprv_memcmp(&dynamicTZI.StandardDate, &dynamicTZI.DaylightDate, sizeof(dynamicTZI.StandardDate)) == 0 &&
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((dynamicTZI.TimeZoneKeyName[0] != L'\0' && uprv_memcmp(&dynamicTZI.StandardDate, &systemTimeAllZero, sizeof(systemTimeAllZero)) == 0) ||
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(dynamicTZI.TimeZoneKeyName[0] == L'\0' && uprv_memcmp(&dynamicTZI.StandardDate, &systemTimeAllZero, sizeof(systemTimeAllZero)) != 0)))
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{
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LONG utcOffsetMins = dynamicTZI.Bias;
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if (utcOffsetMins == 0) {
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return uprv_strdup("Etc/UTC");
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}
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// No way to support when DST is turned off and the offset in minutes is not a multiple of 60.
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if (utcOffsetMins % 60 == 0) {
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char gmtOffsetTz[11] = {}; // "Etc/GMT+dd" is 11-char long with a terminal null.
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// Important note on the sign convention for zones:
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//
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// From https://en.wikipedia.org/wiki/Tz_database#Area
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// "In order to conform with the POSIX style, those zone names beginning with "Etc/GMT" have their sign reversed
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// from the standard ISO 8601 convention. In the "Etc" area, zones west of GMT have a positive sign and those
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// east have a negative sign in their name (e.g "Etc/GMT-14" is 14 hours ahead of GMT)."
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//
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// Regarding the POSIX style, from https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html
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// "The offset specifies the time value you must add to the local time to get a Coordinated Universal Time value."
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//
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// However, the Bias value in DYNAMIC_TIME_ZONE_INFORMATION *already* follows the POSIX convention.
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//
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// From https://docs.microsoft.com/en-us/windows/win32/api/timezoneapi/ns-timezoneapi-dynamic_time_zone_information
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// "The bias is the difference, in minutes, between Coordinated Universal Time (UTC) and
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// local time. All translations between UTC and local time are based on the following formula:
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// UTC = local time + bias"
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//
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// For example, a time zone that is 3 hours ahead of UTC (UTC+03:00) would have a Bias value of -180, and the
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// corresponding time zone ID would be "Etc/GMT-3". (So there is no need to negate utcOffsetMins below.)
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int ret = snprintf(gmtOffsetTz, UPRV_LENGTHOF(gmtOffsetTz), "Etc/GMT%+ld", utcOffsetMins / 60);
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if (ret > 0 && ret < UPRV_LENGTHOF(gmtOffsetTz)) {
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return uprv_strdup(gmtOffsetTz);
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}
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}
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}
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// If DST is NOT disabled, but the TimeZoneKeyName field of the struct is NULL, then we may be dealing with a
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// RDP/terminal services session where the 'Time Zone Redirection' feature is enabled. However, either the RDP
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// client sent the server incomplete info (some 3rd party RDP clients only send the StandardName and DaylightName,
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// but do not send the important TimeZoneKeyName), or if the RDP server has not appropriately populated the struct correctly.
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//
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// In this case we unfortunately have no choice but to fallback to using the pre-Vista method of determining the
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// time zone, which requires examining the registry directly.
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//
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// Note that this can however still fail though if the client and server are using different languages, as the StandardName
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// that is sent by client is *localized* in the client's language. However, we must compare this to the names that are
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// on the server, which are *localized* in registry using the server's language.
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//
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// One other note is that this fallback method doesn't work for the UWP version, as we can't use the registry APIs.
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// windowsTimeZoneName will point at timezoneSubKeyName if we had to fallback to using the registry, and we found a match.
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WCHAR timezoneSubKeyName[WINDOWS_MAX_REG_KEY_LENGTH];
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WCHAR *windowsTimeZoneName = dynamicTZI.TimeZoneKeyName;
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if (dynamicTZI.TimeZoneKeyName[0] == 0) {
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// We can't use the registry APIs in the UWP version.
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#if U_PLATFORM_HAS_WINUWP_API == 1
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(void)timezoneSubKeyName; // suppress unused variable warnings.
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return nullptr;
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#else
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// Open the path to the time zones in the Windows registry.
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LONG ret;
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HKEY hKeyAllTimeZones = nullptr;
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ret = RegOpenKeyExW(HKEY_LOCAL_MACHINE, WINDOWS_TIMEZONES_REG_KEY_PATH, 0, KEY_READ,
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reinterpret_cast<PHKEY>(&hKeyAllTimeZones));
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if (ret != ERROR_SUCCESS) {
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// If we can't open the key, then we can't do much, so fail.
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return nullptr;
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}
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// Read the number of subkeys under the time zone registry path.
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DWORD numTimeZoneSubKeys;
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ret = RegQueryInfoKeyW(hKeyAllTimeZones, nullptr, nullptr, nullptr, &numTimeZoneSubKeys,
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nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr);
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if (ret != ERROR_SUCCESS) {
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RegCloseKey(hKeyAllTimeZones);
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return nullptr;
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}
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// Examine each of the subkeys to try and find a match for the localized standard name ("Std").
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//
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// Note: The name of the time zone subkey itself is not localized, but the "Std" name is localized. This means
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// that we could fail to find a match if the RDP client and RDP server are using different languages, but unfortunately
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// there isn't much we can do about it.
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HKEY hKeyTimeZoneSubKey = nullptr;
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ULONG registryValueType;
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WCHAR registryStandardName[WINDOWS_MAX_REG_KEY_LENGTH];
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for (DWORD i = 0; i < numTimeZoneSubKeys; i++) {
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// Note: RegEnumKeyExW wants the size of the buffer in characters.
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DWORD size = UPRV_LENGTHOF(timezoneSubKeyName);
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ret = RegEnumKeyExW(hKeyAllTimeZones, i, timezoneSubKeyName, &size, nullptr, nullptr, nullptr, nullptr);
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if (ret != ERROR_SUCCESS) {
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RegCloseKey(hKeyAllTimeZones);
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return nullptr;
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}
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ret = RegOpenKeyExW(hKeyAllTimeZones, timezoneSubKeyName, 0, KEY_READ,
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reinterpret_cast<PHKEY>(&hKeyTimeZoneSubKey));
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if (ret != ERROR_SUCCESS) {
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RegCloseKey(hKeyAllTimeZones);
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return nullptr;
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}
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// Note: RegQueryValueExW wants the size of the buffer in bytes.
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size = sizeof(registryStandardName);
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ret = RegQueryValueExW(hKeyTimeZoneSubKey, L"Std", nullptr, ®istryValueType,
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reinterpret_cast<LPBYTE>(registryStandardName), &size);
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if (ret != ERROR_SUCCESS || registryValueType != REG_SZ) {
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RegCloseKey(hKeyTimeZoneSubKey);
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RegCloseKey(hKeyAllTimeZones);
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return nullptr;
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}
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// Note: wcscmp does an ordinal (byte) comparison.
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if (wcscmp(reinterpret_cast<WCHAR *>(registryStandardName), dynamicTZI.StandardName) == 0) {
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// Since we are comparing the *localized* time zone name, it's possible that some languages might use
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// the same string for more than one time zone. Thus we need to examine the TZI data in the registry to
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// compare the GMT offset (the bias), and the DST transition dates, to ensure it's the same time zone
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// as the currently reported one.
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REG_TZI_FORMAT registryTziValue;
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uprv_memset(®istryTziValue, 0, sizeof(registryTziValue));
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// Note: RegQueryValueExW wants the size of the buffer in bytes.
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DWORD timezoneTziValueSize = sizeof(registryTziValue);
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ret = RegQueryValueExW(hKeyTimeZoneSubKey, L"TZI", nullptr, ®istryValueType,
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reinterpret_cast<LPBYTE>(®istryTziValue), &timezoneTziValueSize);
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if (ret == ERROR_SUCCESS) {
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if ((dynamicTZI.Bias == registryTziValue.Bias) &&
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(memcmp((const void *)&dynamicTZI.StandardDate, (const void *)®istryTziValue.StandardDate, sizeof(SYSTEMTIME)) == 0) &&
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(memcmp((const void *)&dynamicTZI.DaylightDate, (const void *)®istryTziValue.DaylightDate, sizeof(SYSTEMTIME)) == 0))
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{
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// We found a matching time zone.
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windowsTimeZoneName = timezoneSubKeyName;
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break;
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}
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}
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}
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RegCloseKey(hKeyTimeZoneSubKey);
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hKeyTimeZoneSubKey = nullptr;
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}
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if (hKeyTimeZoneSubKey != nullptr) {
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RegCloseKey(hKeyTimeZoneSubKey);
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}
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if (hKeyAllTimeZones != nullptr) {
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RegCloseKey(hKeyAllTimeZones);
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}
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#endif // U_PLATFORM_HAS_WINUWP_API
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}
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CharString winTZ;
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UErrorCode status = U_ZERO_ERROR;
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winTZ.appendInvariantChars(UnicodeString(TRUE, windowsTimeZoneName, -1), status);
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// Map Windows Timezone name (non-localized) to ICU timezone ID (~ Olson timezone id).
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StackUResourceBundle winTZBundle;
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ures_openDirectFillIn(winTZBundle.getAlias(), nullptr, "windowsZones", &status);
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ures_getByKey(winTZBundle.getAlias(), "mapTimezones", winTZBundle.getAlias(), &status);
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ures_getByKey(winTZBundle.getAlias(), winTZ.data(), winTZBundle.getAlias(), &status);
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if (U_FAILURE(status)) {
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return nullptr;
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}
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// Note: Since the ISO 3166 country/region codes are all invariant ASCII chars, we can
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// directly downcast from wchar_t to do the conversion.
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// We could call the A version of the GetGeoInfo API, but that would be slightly slower than calling the W API,
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// as the A version of the API will end up calling MultiByteToWideChar anyways internally.
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wchar_t regionCodeW[3] = {};
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char regionCode[3] = {}; // 2 letter ISO 3166 country/region code made entirely of invariant chars.
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int geoId = GetUserGeoID(GEOCLASS_NATION);
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int regionCodeLen = GetGeoInfoW(geoId, GEO_ISO2, regionCodeW, UPRV_LENGTHOF(regionCodeW), 0);
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const UChar *icuTZ16 = nullptr;
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int32_t tzListLen = 0;
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if (regionCodeLen != 0) {
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for (int i = 0; i < UPRV_LENGTHOF(regionCodeW); i++) {
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regionCode[i] = static_cast<char>(regionCodeW[i]);
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}
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icuTZ16 = ures_getStringByKey(winTZBundle.getAlias(), regionCode, &tzListLen, &status);
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}
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if (regionCodeLen == 0 || U_FAILURE(status)) {
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// fallback to default "001" (world)
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status = U_ZERO_ERROR;
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icuTZ16 = ures_getStringByKey(winTZBundle.getAlias(), "001", &tzListLen, &status);
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}
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// Note: We want the first entry in the string returned by ures_getStringByKey.
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// However this string can be a space delimited list of timezones:
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// Ex: "America/New_York America/Detroit America/Indiana/Petersburg ..."
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// We need to stop at the first space, so we pass tzLen (instead of tzListLen) to appendInvariantChars below.
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int32_t tzLen = 0;
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if (tzListLen > 0) {
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while (!(icuTZ16[tzLen] == u'\0' || icuTZ16[tzLen] == u' ')) {
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tzLen++;
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}
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}
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// Note: cloneData returns nullptr if the status is a failure, so this
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// will return nullptr if the above look-up fails.
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CharString icuTZStr;
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return icuTZStr.appendInvariantChars(icuTZ16, tzLen, status).cloneData(status);
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}
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U_NAMESPACE_END
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#endif /* U_PLATFORM_USES_ONLY_WIN32_API */
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