diff options
Diffstat (limited to 'thirdparty/icu4c/common/wintz.cpp')
| -rw-r--r-- | thirdparty/icu4c/common/wintz.cpp | 214 |
1 files changed, 199 insertions, 15 deletions
diff --git a/thirdparty/icu4c/common/wintz.cpp b/thirdparty/icu4c/common/wintz.cpp index 3730232286..ebf31650c2 100644 --- a/thirdparty/icu4c/common/wintz.cpp +++ b/thirdparty/icu4c/common/wintz.cpp @@ -36,17 +36,58 @@ U_NAMESPACE_BEGIN +// Note these constants and the struct are only used when dealing with the fallback path for RDP sesssions. + +// This is the location of the time zones in the registry on Vista+ systems. +// See: https://docs.microsoft.com/windows/win32/api/timezoneapi/ns-timezoneapi-dynamic_time_zone_information +#define WINDOWS_TIMEZONES_REG_KEY_PATH L"SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones" + +// Max length for a registry key is 255. +1 for null. +// See: https://docs.microsoft.com/windows/win32/sysinfo/registry-element-size-limits +#define WINDOWS_MAX_REG_KEY_LENGTH 256 + +#if U_PLATFORM_HAS_WINUWP_API == 0 + +// This is the layout of the TZI binary value in the registry. +// See: https://docs.microsoft.com/windows/win32/api/timezoneapi/ns-timezoneapi-time_zone_information +typedef struct _REG_TZI_FORMAT { + LONG Bias; + LONG StandardBias; + LONG DaylightBias; + SYSTEMTIME StandardDate; + SYSTEMTIME DaylightDate; +} REG_TZI_FORMAT; + +#endif // U_PLATFORM_HAS_WINUWP_API + /** -* 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. +* This is main Windows time zone detection function. +* +* It 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 (available since Vista+) to get the current time zone info. -* This API returns a non-localized time zone name, which is mapped to an ICU time zone ID (~ Olsen ID). +* We use the Win32 API GetDynamicTimeZoneInformation (which is available since Vista) to get the current time zone info, +* as this API returns a non-localized time zone name which can be then mapped to an ICU time zone. +* +* However, in some RDP/terminal services situations, this struct isn't always fully complete, and the TimeZoneKeyName +* field of the struct might be NULL. This can happen with some 3rd party RDP clients, and also when using older versions +* of the RDP protocol, which don't send the newer TimeZoneKeyNamei information and only send the StandardName and DaylightName. +* +* Since these 3rd party clients and older RDP clients only send the pre-Vista time zone information to the server, this means that we +* need to fallback on using the pre-Vista methods to determine the time zone. This unfortunately requires examining the registry directly +* in order to try and determine the current time zone. +* +* Note that this can however still fail in some cases though if the client and server are using different languages, as the StandardName +* 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 +* are localized in registry using the server's language. Despite that, this is the best we can do. +* +* Note: This fallback method won't work for the UWP version though, as we can't use the registry APIs in UWP. +* +* Once we have the current Windows time zone, then we can then map it to an ICU time zone ID (~ Olsen ID). */ U_CAPI const char* U_EXPORT2 uprv_detectWindowsTimeZone() { - // Obtain the DYNAMIC_TIME_ZONE_INFORMATION info to get the non-localized time zone name. + // We first try to obtain the time zone directly by using the TimeZoneKeyName field of the DYNAMIC_TIME_ZONE_INFORMATION struct. DYNAMIC_TIME_ZONE_INFORMATION dynamicTZI; uprv_memset(&dynamicTZI, 0, sizeof(dynamicTZI)); SYSTEMTIME systemTimeAllZero; @@ -83,25 +124,157 @@ uprv_detectWindowsTimeZone() // No way to support when DST is turned off and the offset in minutes is not a multiple of 60. if (utcOffsetMins % 60 == 0) { char gmtOffsetTz[11] = {}; // "Etc/GMT+dd" is 11-char long with a terminal null. - // Note '-' before 'utcOffsetMin'. The timezone ID's sign convention - // is that a timezone ahead of UTC is Etc/GMT-<offset> and a timezone - // behind UTC is Etc/GMT+<offset>. - int ret = snprintf(gmtOffsetTz, UPRV_LENGTHOF(gmtOffsetTz), "Etc/GMT%+d", -utcOffsetMins / 60); + // Important note on the sign convention for zones: + // + // From https://en.wikipedia.org/wiki/Tz_database#Area + // "In order to conform with the POSIX style, those zone names beginning with "Etc/GMT" have their sign reversed + // from the standard ISO 8601 convention. In the "Etc" area, zones west of GMT have a positive sign and those + // east have a negative sign in their name (e.g "Etc/GMT-14" is 14 hours ahead of GMT)." + // + // Regarding the POSIX style, from https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html + // "The offset specifies the time value you must add to the local time to get a Coordinated Universal Time value." + // + // However, the Bias value in DYNAMIC_TIME_ZONE_INFORMATION *already* follows the POSIX convention. + // + // From https://docs.microsoft.com/en-us/windows/win32/api/timezoneapi/ns-timezoneapi-dynamic_time_zone_information + // "The bias is the difference, in minutes, between Coordinated Universal Time (UTC) and + // local time. All translations between UTC and local time are based on the following formula: + // UTC = local time + bias" + // + // For example, a time zone that is 3 hours ahead of UTC (UTC+03:00) would have a Bias value of -180, and the + // corresponding time zone ID would be "Etc/GMT-3". (So there is no need to negate utcOffsetMins below.) + int ret = snprintf(gmtOffsetTz, UPRV_LENGTHOF(gmtOffsetTz), "Etc/GMT%+ld", utcOffsetMins / 60); if (ret > 0 && ret < UPRV_LENGTHOF(gmtOffsetTz)) { return uprv_strdup(gmtOffsetTz); } } } - // If DST is NOT disabled, but we have an empty TimeZoneKeyName, then it is unclear - // what we should do as this should not happen. + // If DST is NOT disabled, but the TimeZoneKeyName field of the struct is NULL, then we may be dealing with a + // RDP/terminal services session where the 'Time Zone Redirection' feature is enabled. However, either the RDP + // client sent the server incomplete info (some 3rd party RDP clients only send the StandardName and DaylightName, + // but do not send the important TimeZoneKeyName), or if the RDP server has not appropriately populated the struct correctly. + // + // In this case we unfortunately have no choice but to fallback to using the pre-Vista method of determining the + // time zone, which requires examining the registry directly. + // + // Note that this can however still fail though if the client and server are using different languages, as the StandardName + // 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 are *localized* in registry using the server's language. + // + // One other note is that this fallback method doesn't work for the UWP version, as we can't use the registry APIs. + + // windowsTimeZoneName will point at timezoneSubKeyName if we had to fallback to using the registry, and we found a match. + WCHAR timezoneSubKeyName[WINDOWS_MAX_REG_KEY_LENGTH]; + WCHAR *windowsTimeZoneName = dynamicTZI.TimeZoneKeyName; + if (dynamicTZI.TimeZoneKeyName[0] == 0) { + +// We can't use the registry APIs in the UWP version. +#if U_PLATFORM_HAS_WINUWP_API == 1 + (void)timezoneSubKeyName; // suppress unused variable warnings. return nullptr; +#else + // Open the path to the time zones in the Windows registry. + LONG ret; + HKEY hKeyAllTimeZones = nullptr; + ret = RegOpenKeyExW(HKEY_LOCAL_MACHINE, WINDOWS_TIMEZONES_REG_KEY_PATH, 0, KEY_READ, + reinterpret_cast<PHKEY>(&hKeyAllTimeZones)); + + if (ret != ERROR_SUCCESS) { + // If we can't open the key, then we can't do much, so fail. + return nullptr; + } + + // Read the number of subkeys under the time zone registry path. + DWORD numTimeZoneSubKeys; + ret = RegQueryInfoKeyW(hKeyAllTimeZones, nullptr, nullptr, nullptr, &numTimeZoneSubKeys, + nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr); + + if (ret != ERROR_SUCCESS) { + RegCloseKey(hKeyAllTimeZones); + return nullptr; + } + + // Examine each of the subkeys to try and find a match for the localized standard name ("Std"). + // + // Note: The name of the time zone subkey itself is not localized, but the "Std" name is localized. This means + // that we could fail to find a match if the RDP client and RDP server are using different languages, but unfortunately + // there isn't much we can do about it. + HKEY hKeyTimeZoneSubKey = nullptr; + ULONG registryValueType; + WCHAR registryStandardName[WINDOWS_MAX_REG_KEY_LENGTH]; + + for (DWORD i = 0; i < numTimeZoneSubKeys; i++) { + // Note: RegEnumKeyExW wants the size of the buffer in characters. + DWORD size = UPRV_LENGTHOF(timezoneSubKeyName); + ret = RegEnumKeyExW(hKeyAllTimeZones, i, timezoneSubKeyName, &size, nullptr, nullptr, nullptr, nullptr); + + if (ret != ERROR_SUCCESS) { + RegCloseKey(hKeyAllTimeZones); + return nullptr; + } + + ret = RegOpenKeyExW(hKeyAllTimeZones, timezoneSubKeyName, 0, KEY_READ, + reinterpret_cast<PHKEY>(&hKeyTimeZoneSubKey)); + + if (ret != ERROR_SUCCESS) { + RegCloseKey(hKeyAllTimeZones); + return nullptr; + } + + // Note: RegQueryValueExW wants the size of the buffer in bytes. + size = sizeof(registryStandardName); + ret = RegQueryValueExW(hKeyTimeZoneSubKey, L"Std", nullptr, ®istryValueType, + reinterpret_cast<LPBYTE>(registryStandardName), &size); + + if (ret != ERROR_SUCCESS || registryValueType != REG_SZ) { + RegCloseKey(hKeyTimeZoneSubKey); + RegCloseKey(hKeyAllTimeZones); + return nullptr; + } + + // Note: wcscmp does an ordinal (byte) comparison. + if (wcscmp(reinterpret_cast<WCHAR *>(registryStandardName), dynamicTZI.StandardName) == 0) { + // Since we are comparing the *localized* time zone name, it's possible that some languages might use + // the same string for more than one time zone. Thus we need to examine the TZI data in the registry to + // compare the GMT offset (the bias), and the DST transition dates, to ensure it's the same time zone + // as the currently reported one. + REG_TZI_FORMAT registryTziValue; + uprv_memset(®istryTziValue, 0, sizeof(registryTziValue)); + + // Note: RegQueryValueExW wants the size of the buffer in bytes. + DWORD timezoneTziValueSize = sizeof(registryTziValue); + ret = RegQueryValueExW(hKeyTimeZoneSubKey, L"TZI", nullptr, ®istryValueType, + reinterpret_cast<LPBYTE>(®istryTziValue), &timezoneTziValueSize); + + if (ret == ERROR_SUCCESS) { + if ((dynamicTZI.Bias == registryTziValue.Bias) && + (memcmp((const void *)&dynamicTZI.StandardDate, (const void *)®istryTziValue.StandardDate, sizeof(SYSTEMTIME)) == 0) && + (memcmp((const void *)&dynamicTZI.DaylightDate, (const void *)®istryTziValue.DaylightDate, sizeof(SYSTEMTIME)) == 0)) + { + // We found a matching time zone. + windowsTimeZoneName = timezoneSubKeyName; + break; + } + } + } + RegCloseKey(hKeyTimeZoneSubKey); + hKeyTimeZoneSubKey = nullptr; + } + + if (hKeyTimeZoneSubKey != nullptr) { + RegCloseKey(hKeyTimeZoneSubKey); + } + if (hKeyAllTimeZones != nullptr) { + RegCloseKey(hKeyAllTimeZones); + } +#endif // U_PLATFORM_HAS_WINUWP_API } CharString winTZ; UErrorCode status = U_ZERO_ERROR; - winTZ.appendInvariantChars(UnicodeString(TRUE, dynamicTZI.TimeZoneKeyName, -1), status); + winTZ.appendInvariantChars(UnicodeString(TRUE, windowsTimeZoneName, -1), status); // Map Windows Timezone name (non-localized) to ICU timezone ID (~ Olson timezone id). StackUResourceBundle winTZBundle; @@ -123,18 +296,29 @@ uprv_detectWindowsTimeZone() int regionCodeLen = GetGeoInfoW(geoId, GEO_ISO2, regionCodeW, UPRV_LENGTHOF(regionCodeW), 0); const UChar *icuTZ16 = nullptr; - int32_t tzLen; + int32_t tzListLen = 0; if (regionCodeLen != 0) { for (int i = 0; i < UPRV_LENGTHOF(regionCodeW); i++) { regionCode[i] = static_cast<char>(regionCodeW[i]); } - icuTZ16 = ures_getStringByKey(winTZBundle.getAlias(), regionCode, &tzLen, &status); + icuTZ16 = ures_getStringByKey(winTZBundle.getAlias(), regionCode, &tzListLen, &status); } if (regionCodeLen == 0 || U_FAILURE(status)) { // fallback to default "001" (world) status = U_ZERO_ERROR; - icuTZ16 = ures_getStringByKey(winTZBundle.getAlias(), "001", &tzLen, &status); + icuTZ16 = ures_getStringByKey(winTZBundle.getAlias(), "001", &tzListLen, &status); + } + + // Note: We want the first entry in the string returned by ures_getStringByKey. + // However this string can be a space delimited list of timezones: + // Ex: "America/New_York America/Detroit America/Indiana/Petersburg ..." + // We need to stop at the first space, so we pass tzLen (instead of tzListLen) to appendInvariantChars below. + int32_t tzLen = 0; + if (tzListLen > 0) { + while (!(icuTZ16[tzLen] == u'\0' || icuTZ16[tzLen] == u' ')) { + tzLen++; + } } // Note: cloneData returns nullptr if the status is a failure, so this |