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Diffstat (limited to '')
| -rw-r--r-- | js/src/vm/DateTime.cpp | 784 |
1 files changed, 784 insertions, 0 deletions
diff --git a/js/src/vm/DateTime.cpp b/js/src/vm/DateTime.cpp new file mode 100644 index 0000000000..a587c912b3 --- /dev/null +++ b/js/src/vm/DateTime.cpp @@ -0,0 +1,784 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- + * vim: set ts=8 sts=2 et sw=2 tw=80: + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include "vm/DateTime.h" + +#include "mozilla/ScopeExit.h" +#include "mozilla/TextUtils.h" +#include "mozilla/Unused.h" + +#include <algorithm> +#include <cstdlib> +#include <cstring> +#include <iterator> +#include <time.h> + +#if !defined(XP_WIN) +# include <limits.h> +# include <unistd.h> +#endif /* !defined(XP_WIN) */ + +#include "js/Date.h" +#include "js/GCAPI.h" +#include "threading/ExclusiveData.h" + +#if JS_HAS_INTL_API && !MOZ_SYSTEM_ICU +# include "unicode/basictz.h" +# include "unicode/locid.h" +# include "unicode/timezone.h" +# include "unicode/unistr.h" +#endif /* JS_HAS_INTL_API && !MOZ_SYSTEM_ICU */ + +#include "util/Text.h" +#include "vm/MutexIDs.h" + +static bool ComputeLocalTime(time_t local, struct tm* ptm) { +#if defined(_WIN32) + return localtime_s(ptm, &local) == 0; +#elif defined(HAVE_LOCALTIME_R) + return localtime_r(&local, ptm); +#else + struct tm* otm = localtime(&local); + if (!otm) { + return false; + } + *ptm = *otm; + return true; +#endif +} + +static bool ComputeUTCTime(time_t t, struct tm* ptm) { +#if defined(_WIN32) + return gmtime_s(ptm, &t) == 0; +#elif defined(HAVE_GMTIME_R) + return gmtime_r(&t, ptm); +#else + struct tm* otm = gmtime(&t); + if (!otm) { + return false; + } + *ptm = *otm; + return true; +#endif +} + +/* + * Compute the offset in seconds from the current UTC time to the current local + * standard time (i.e. not including any offset due to DST). + * + * Examples: + * + * Suppose we are in California, USA on January 1, 2013 at 04:00 PST (UTC-8, no + * DST in effect), corresponding to 12:00 UTC. This function would then return + * -8 * SecondsPerHour, or -28800. + * + * Or suppose we are in Berlin, Germany on July 1, 2013 at 17:00 CEST (UTC+2, + * DST in effect), corresponding to 15:00 UTC. This function would then return + * +1 * SecondsPerHour, or +3600. + */ +static int32_t UTCToLocalStandardOffsetSeconds() { + using js::SecondsPerDay; + using js::SecondsPerHour; + using js::SecondsPerMinute; + + // Get the current time. + time_t currentMaybeWithDST = time(nullptr); + if (currentMaybeWithDST == time_t(-1)) { + return 0; + } + + // Break down the current time into its (locally-valued, maybe with DST) + // components. + struct tm local; + if (!ComputeLocalTime(currentMaybeWithDST, &local)) { + return 0; + } + + // Compute a |time_t| corresponding to |local| interpreted without DST. + time_t currentNoDST; + if (local.tm_isdst == 0) { + // If |local| wasn't DST, we can use the same time. + currentNoDST = currentMaybeWithDST; + } else { + // If |local| respected DST, we need a time broken down into components + // ignoring DST. Turn off DST in the broken-down time. Create a fresh + // copy of |local|, because mktime() will reset tm_isdst = 1 and will + // adjust tm_hour and tm_hour accordingly. + struct tm localNoDST = local; + localNoDST.tm_isdst = 0; + + // Compute a |time_t t| corresponding to the broken-down time with DST + // off. This has boundary-condition issues (for about the duration of + // a DST offset) near the time a location moves to a different time + // zone. But 1) errors will be transient; 2) locations rarely change + // time zone; and 3) in the absence of an API that provides the time + // zone offset directly, this may be the best we can do. + currentNoDST = mktime(&localNoDST); + if (currentNoDST == time_t(-1)) { + return 0; + } + } + + // Break down the time corresponding to the no-DST |local| into UTC-based + // components. + struct tm utc; + if (!ComputeUTCTime(currentNoDST, &utc)) { + return 0; + } + + // Finally, compare the seconds-based components of the local non-DST + // representation and the UTC representation to determine the actual + // difference. + int utc_secs = utc.tm_hour * SecondsPerHour + utc.tm_min * SecondsPerMinute; + int local_secs = + local.tm_hour * SecondsPerHour + local.tm_min * SecondsPerMinute; + + // Same-day? Just subtract the seconds counts. + if (utc.tm_mday == local.tm_mday) { + return local_secs - utc_secs; + } + + // If we have more UTC seconds, move local seconds into the UTC seconds' + // frame of reference and then subtract. + if (utc_secs > local_secs) { + return (SecondsPerDay + local_secs) - utc_secs; + } + + // Otherwise we have more local seconds, so move the UTC seconds into the + // local seconds' frame of reference and then subtract. + return local_secs - (utc_secs + SecondsPerDay); +} + +void js::DateTimeInfo::internalResetTimeZone(ResetTimeZoneMode mode) { + // Nothing to do when an update request is already enqueued. + if (timeZoneStatus_ == TimeZoneStatus::NeedsUpdate) { + return; + } + + // Mark the state as needing an update, but defer the actual update until it's + // actually needed to delay any system calls to the last possible moment. This + // is beneficial when this method is called during start-up, because it avoids + // main-thread I/O blocking the process. + if (mode == ResetTimeZoneMode::ResetEvenIfOffsetUnchanged) { + timeZoneStatus_ = TimeZoneStatus::NeedsUpdate; + } else { + timeZoneStatus_ = TimeZoneStatus::UpdateIfChanged; + } +} + +void js::DateTimeInfo::updateTimeZone() { + MOZ_ASSERT(timeZoneStatus_ != TimeZoneStatus::Valid); + + bool updateIfChanged = timeZoneStatus_ == TimeZoneStatus::UpdateIfChanged; + + timeZoneStatus_ = TimeZoneStatus::Valid; + + /* + * The difference between local standard time and UTC will never change for + * a given time zone. + */ + int32_t newOffset = UTCToLocalStandardOffsetSeconds(); + + if (updateIfChanged && newOffset == utcToLocalStandardOffsetSeconds_) { + return; + } + + utcToLocalStandardOffsetSeconds_ = newOffset; + + dstRange_.reset(); + +#if JS_HAS_INTL_API && !MOZ_SYSTEM_ICU + utcRange_.reset(); + localRange_.reset(); + + { + // Tell the analysis the |pFree| function pointer called by uprv_free + // cannot GC. + JS::AutoSuppressGCAnalysis nogc; + + timeZone_ = nullptr; + } + + standardName_ = nullptr; + daylightSavingsName_ = nullptr; +#endif /* JS_HAS_INTL_API && !MOZ_SYSTEM_ICU */ + + // Propagate the time zone change to ICU, too. + { + // Tell the analysis calling into ICU cannot GC. + JS::AutoSuppressGCAnalysis nogc; + + internalResyncICUDefaultTimeZone(); + } +} + +js::DateTimeInfo::DateTimeInfo() { + // Set the time zone status into the invalid state, so we compute the actual + // defaults on first access. We don't yet want to initialize neither <ctime> + // nor ICU's time zone classes, because that may cause I/O operations slowing + // down the JS engine initialization, which we're currently in the middle of. + timeZoneStatus_ = TimeZoneStatus::NeedsUpdate; +} + +js::DateTimeInfo::~DateTimeInfo() = default; + +int64_t js::DateTimeInfo::toClampedSeconds(int64_t milliseconds) { + int64_t seconds = milliseconds / msPerSecond; + if (seconds > MaxTimeT) { + seconds = MaxTimeT; + } else if (seconds < MinTimeT) { + /* Go ahead a day to make localtime work (does not work with 0). */ + seconds = SecondsPerDay; + } + return seconds; +} + +int32_t js::DateTimeInfo::computeDSTOffsetMilliseconds(int64_t utcSeconds) { + MOZ_ASSERT(utcSeconds >= MinTimeT); + MOZ_ASSERT(utcSeconds <= MaxTimeT); + +#if JS_HAS_INTL_API && !MOZ_SYSTEM_ICU + UDate date = UDate(utcSeconds * msPerSecond); + constexpr bool dateIsLocalTime = false; + int32_t rawOffset, dstOffset; + UErrorCode status = U_ZERO_ERROR; + + timeZone()->getOffset(date, dateIsLocalTime, rawOffset, dstOffset, status); + if (U_FAILURE(status)) { + return 0; + } + + return dstOffset; +#else + struct tm tm; + if (!ComputeLocalTime(static_cast<time_t>(utcSeconds), &tm)) { + return 0; + } + + // NB: The offset isn't computed correctly when the standard local offset + // at |utcSeconds| is different from |utcToLocalStandardOffsetSeconds|. + int32_t dayoff = + int32_t((utcSeconds + utcToLocalStandardOffsetSeconds_) % SecondsPerDay); + int32_t tmoff = tm.tm_sec + (tm.tm_min * SecondsPerMinute) + + (tm.tm_hour * SecondsPerHour); + + int32_t diff = tmoff - dayoff; + + if (diff < 0) { + diff += SecondsPerDay; + } else if (uint32_t(diff) >= SecondsPerDay) { + diff -= SecondsPerDay; + } + + return diff * msPerSecond; +#endif /* JS_HAS_INTL_API && !MOZ_SYSTEM_ICU */ +} + +int32_t js::DateTimeInfo::internalGetDSTOffsetMilliseconds( + int64_t utcMilliseconds) { + int64_t utcSeconds = toClampedSeconds(utcMilliseconds); + return getOrComputeValue(dstRange_, utcSeconds, + &DateTimeInfo::computeDSTOffsetMilliseconds); +} + +int32_t js::DateTimeInfo::getOrComputeValue(RangeCache& range, int64_t seconds, + ComputeFn compute) { + range.sanityCheck(); + + auto checkSanity = + mozilla::MakeScopeExit([&range]() { range.sanityCheck(); }); + + // NB: Be aware of the initial range values when making changes to this + // code: the first call to this method, with those initial range + // values, must result in a cache miss. + MOZ_ASSERT(seconds != INT64_MIN); + + if (range.startSeconds <= seconds && seconds <= range.endSeconds) { + return range.offsetMilliseconds; + } + + if (range.oldStartSeconds <= seconds && seconds <= range.oldEndSeconds) { + return range.oldOffsetMilliseconds; + } + + range.oldOffsetMilliseconds = range.offsetMilliseconds; + range.oldStartSeconds = range.startSeconds; + range.oldEndSeconds = range.endSeconds; + + if (range.startSeconds <= seconds) { + int64_t newEndSeconds = + std::min({range.endSeconds + RangeExpansionAmount, MaxTimeT}); + if (newEndSeconds >= seconds) { + int32_t endOffsetMilliseconds = (this->*compute)(newEndSeconds); + if (endOffsetMilliseconds == range.offsetMilliseconds) { + range.endSeconds = newEndSeconds; + return range.offsetMilliseconds; + } + + range.offsetMilliseconds = (this->*compute)(seconds); + if (range.offsetMilliseconds == endOffsetMilliseconds) { + range.startSeconds = seconds; + range.endSeconds = newEndSeconds; + } else { + range.endSeconds = seconds; + } + return range.offsetMilliseconds; + } + + range.offsetMilliseconds = (this->*compute)(seconds); + range.startSeconds = range.endSeconds = seconds; + return range.offsetMilliseconds; + } + + int64_t newStartSeconds = + std::max<int64_t>({range.startSeconds - RangeExpansionAmount, MinTimeT}); + if (newStartSeconds <= seconds) { + int32_t startOffsetMilliseconds = (this->*compute)(newStartSeconds); + if (startOffsetMilliseconds == range.offsetMilliseconds) { + range.startSeconds = newStartSeconds; + return range.offsetMilliseconds; + } + + range.offsetMilliseconds = (this->*compute)(seconds); + if (range.offsetMilliseconds == startOffsetMilliseconds) { + range.startSeconds = newStartSeconds; + range.endSeconds = seconds; + } else { + range.startSeconds = seconds; + } + return range.offsetMilliseconds; + } + + range.startSeconds = range.endSeconds = seconds; + range.offsetMilliseconds = (this->*compute)(seconds); + return range.offsetMilliseconds; +} + +void js::DateTimeInfo::RangeCache::reset() { + // The initial range values are carefully chosen to result in a cache miss + // on first use given the range of possible values. Be careful to keep + // these values and the caching algorithm in sync! + offsetMilliseconds = 0; + startSeconds = endSeconds = INT64_MIN; + oldOffsetMilliseconds = 0; + oldStartSeconds = oldEndSeconds = INT64_MIN; + + sanityCheck(); +} + +void js::DateTimeInfo::RangeCache::sanityCheck() { + auto assertRange = [](int64_t start, int64_t end) { + MOZ_ASSERT(start <= end); + MOZ_ASSERT_IF(start == INT64_MIN, end == INT64_MIN); + MOZ_ASSERT_IF(end == INT64_MIN, start == INT64_MIN); + MOZ_ASSERT_IF(start != INT64_MIN, start >= MinTimeT && end >= MinTimeT); + MOZ_ASSERT_IF(start != INT64_MIN, start <= MaxTimeT && end <= MaxTimeT); + }; + + assertRange(startSeconds, endSeconds); + assertRange(oldStartSeconds, oldEndSeconds); +} + +#if JS_HAS_INTL_API && !MOZ_SYSTEM_ICU +int32_t js::DateTimeInfo::computeUTCOffsetMilliseconds(int64_t localSeconds) { + MOZ_ASSERT(localSeconds >= MinTimeT); + MOZ_ASSERT(localSeconds <= MaxTimeT); + + UDate date = UDate(localSeconds * msPerSecond); + + // ES2019 draft rev 0ceb728a1adbffe42b26972a6541fd7f398b1557 + // + // 20.3.1.7 LocalTZA + // + // If |localSeconds| represents either a skipped (at a positive time zone + // transition) or repeated (at a negative time zone transition) locale + // time, it must be interpreted as a time value before the transition. + constexpr int32_t skippedTime = icu::BasicTimeZone::kFormer; + constexpr int32_t repeatedTime = icu::BasicTimeZone::kFormer; + + int32_t rawOffset, dstOffset; + UErrorCode status = U_ZERO_ERROR; + + // All ICU TimeZone classes derive from BasicTimeZone, so we can safely + // perform the static_cast. + // Once <https://unicode-org.atlassian.net/browse/ICU-13705> is fixed we + // can remove this extra cast. + auto* basicTz = static_cast<icu::BasicTimeZone*>(timeZone()); + basicTz->getOffsetFromLocal(date, skippedTime, repeatedTime, rawOffset, + dstOffset, status); + if (U_FAILURE(status)) { + return 0; + } + + return rawOffset + dstOffset; +} + +int32_t js::DateTimeInfo::computeLocalOffsetMilliseconds(int64_t utcSeconds) { + MOZ_ASSERT(utcSeconds >= MinTimeT); + MOZ_ASSERT(utcSeconds <= MaxTimeT); + + UDate date = UDate(utcSeconds * msPerSecond); + constexpr bool dateIsLocalTime = false; + int32_t rawOffset, dstOffset; + UErrorCode status = U_ZERO_ERROR; + + timeZone()->getOffset(date, dateIsLocalTime, rawOffset, dstOffset, status); + if (U_FAILURE(status)) { + return 0; + } + + return rawOffset + dstOffset; +} + +int32_t js::DateTimeInfo::internalGetOffsetMilliseconds(int64_t milliseconds, + TimeZoneOffset offset) { + int64_t seconds = toClampedSeconds(milliseconds); + return offset == TimeZoneOffset::UTC + ? getOrComputeValue(localRange_, seconds, + &DateTimeInfo::computeLocalOffsetMilliseconds) + : getOrComputeValue(utcRange_, seconds, + &DateTimeInfo::computeUTCOffsetMilliseconds); +} + +bool js::DateTimeInfo::internalTimeZoneDisplayName(char16_t* buf, size_t buflen, + int64_t utcMilliseconds, + const char* locale) { + MOZ_ASSERT(buf != nullptr); + MOZ_ASSERT(buflen > 0); + MOZ_ASSERT(locale != nullptr); + + // Clear any previously cached names when the default locale changed. + if (!locale_ || std::strcmp(locale_.get(), locale) != 0) { + locale_ = DuplicateString(locale); + if (!locale_) { + return false; + } + + standardName_.reset(); + daylightSavingsName_.reset(); + } + + bool daylightSavings = internalGetDSTOffsetMilliseconds(utcMilliseconds) != 0; + + JS::UniqueTwoByteChars& cachedName = + daylightSavings ? daylightSavingsName_ : standardName_; + if (!cachedName) { + // Retrieve the display name for the given locale. + icu::UnicodeString displayName; + timeZone()->getDisplayName(daylightSavings, icu::TimeZone::LONG, + icu::Locale(locale), displayName); + + size_t capacity = displayName.length() + 1; // Null-terminate. + JS::UniqueTwoByteChars displayNameChars(js_pod_malloc<char16_t>(capacity)); + if (!displayNameChars) { + return false; + } + + // Copy the display name. This operation always succeeds because the + // destination buffer is large enough to hold the complete string. + UErrorCode status = U_ZERO_ERROR; + displayName.extract(displayNameChars.get(), capacity, status); + MOZ_ASSERT(U_SUCCESS(status)); + MOZ_ASSERT(displayNameChars[capacity - 1] == '\0'); + + cachedName = std::move(displayNameChars); + } + + // Return an empty string if the display name doesn't fit into the buffer. + size_t length = js_strlen(cachedName.get()); + if (length < buflen) { + std::copy(cachedName.get(), cachedName.get() + length, buf); + } else { + length = 0; + } + + buf[length] = '\0'; + return true; +} + +icu::TimeZone* js::DateTimeInfo::timeZone() { + if (!timeZone_) { + timeZone_.reset(icu::TimeZone::createDefault()); + MOZ_ASSERT(timeZone_); + } + + return timeZone_.get(); +} +#endif /* JS_HAS_INTL_API && !MOZ_SYSTEM_ICU */ + +/* static */ js::ExclusiveData<js::DateTimeInfo>* js::DateTimeInfo::instance; + +bool js::InitDateTimeState() { + MOZ_ASSERT(!DateTimeInfo::instance, "we should be initializing only once"); + + DateTimeInfo::instance = + js_new<ExclusiveData<DateTimeInfo>>(mutexid::DateTimeInfoMutex); + return !!DateTimeInfo::instance; +} + +/* static */ +void js::FinishDateTimeState() { + js_delete(DateTimeInfo::instance); + DateTimeInfo::instance = nullptr; +} + +void js::ResetTimeZoneInternal(ResetTimeZoneMode mode) { + js::DateTimeInfo::resetTimeZone(mode); +} + +JS_PUBLIC_API void JS::ResetTimeZone() { + js::ResetTimeZoneInternal(js::ResetTimeZoneMode::ResetEvenIfOffsetUnchanged); +} + +#if defined(XP_WIN) +static bool IsOlsonCompatibleWindowsTimeZoneId(const char* tz) { + // ICU ignores the TZ environment variable on Windows and instead directly + // invokes Win API functions to retrieve the current time zone. But since + // we're still using the POSIX-derived localtime_s() function on Windows + // and localtime_s() does return a time zone adjusted value based on the + // TZ environment variable, we need to manually adjust the default ICU + // time zone if TZ is set. + // + // Windows supports the following format for TZ: tzn[+|-]hh[:mm[:ss]][dzn] + // where "tzn" is the time zone name for standard time, the time zone + // offset is positive for time zones west of GMT, and "dzn" is the + // optional time zone name when daylight savings are observed. Daylight + // savings are always based on the U.S. daylight saving rules, that means + // for example it's not possible to use "TZ=CET-1CEST" to select the IANA + // time zone "CET". + // + // When comparing this restricted format for TZ to all IANA time zone + // names, the following time zones are in the intersection of what's + // supported by Windows and is also a valid IANA time zone identifier. + // + // Even though the time zone offset is marked as mandatory on MSDN, it + // appears it defaults to zero when omitted. This in turn means we can + // also allow the time zone identifiers "UCT", "UTC", and "GMT". + + static const char* const allowedIds[] = { + // From tzdata's "northamerica" file: + "EST5EDT", + "CST6CDT", + "MST7MDT", + "PST8PDT", + + // From tzdata's "backward" file: + "GMT+0", + "GMT-0", + "GMT0", + "UCT", + "UTC", + + // From tzdata's "etcetera" file: + "GMT", + }; + for (const auto& allowedId : allowedIds) { + if (std::strcmp(allowedId, tz) == 0) { + return true; + } + } + return false; +} +#elif JS_HAS_INTL_API && !MOZ_SYSTEM_ICU +static inline const char* TZContainsAbsolutePath(const char* tzVar) { + // A TZ environment variable may be an absolute path. The path + // format of TZ may begin with a colon. (ICU handles relative paths.) + if (tzVar[0] == ':' && tzVar[1] == '/') { + return tzVar + 1; + } + if (tzVar[0] == '/') { + return tzVar; + } + return nullptr; +} + +/** + * Reject the input if it doesn't match the time zone id pattern or legacy time + * zone names. + * + * See <https://github.com/eggert/tz/blob/master/theory.html>. + */ +static icu::UnicodeString MaybeTimeZoneId(const char* timeZone) { + size_t timeZoneLen = std::strlen(timeZone); + + for (size_t i = 0; i < timeZoneLen; i++) { + char c = timeZone[i]; + + // According to theory.html, '.' is allowed in time zone ids, but the + // accompanying zic.c file doesn't allow it. Assume the source file is + // correct and disallow '.' here, too. + if (mozilla::IsAsciiAlphanumeric(c) || c == '_' || c == '-' || c == '+') { + continue; + } + + // Reject leading, trailing, or consecutive '/' characters. + if (c == '/' && i > 0 && i + 1 < timeZoneLen && timeZone[i + 1] != '/') { + continue; + } + + return icu::UnicodeString(); + } + + return icu::UnicodeString(timeZone, timeZoneLen, US_INV); +} + +/** + * Given a presumptive path |tz| to a zoneinfo time zone file + * (e.g. /etc/localtime), attempt to compute the time zone encoded by that + * path by repeatedly resolving symlinks until a path containing "/zoneinfo/" + * followed by time zone looking components is found. If a symlink is broken, + * symlink-following recurs too deeply, non time zone looking components are + * encountered, or some other error is encountered, return the empty string. + * + * If a non-empty string is returned, it's only guaranteed to have certain + * syntactic validity. It might not actually *be* a time zone name. + */ +static icu::UnicodeString ReadTimeZoneLink(const char* tz) { + // The resolved link name can have different paths depending on the OS. + // Follow ICU and only search for "/zoneinfo/"; see $ICU/common/putil.cpp. + static constexpr char ZoneInfoPath[] = "/zoneinfo/"; + constexpr size_t ZoneInfoPathLength = js_strlen(ZoneInfoPath); + + // Stop following symlinks after a fixed depth, because some common time + // zones are stored in files whose name doesn't match an Olson time zone + // name. For example on Ubuntu, "/usr/share/zoneinfo/America/New_York" is a + // symlink to "/usr/share/zoneinfo/posixrules" and "posixrules" is not an + // Olson time zone name. + // Four hops should be a reasonable limit for most use cases. + constexpr uint32_t FollowDepthLimit = 4; + +# ifdef PATH_MAX + constexpr size_t PathMax = PATH_MAX; +# else + constexpr size_t PathMax = 4096; +# endif + static_assert(PathMax > 0, "PathMax should be larger than zero"); + + char linkName[PathMax]; + constexpr size_t linkNameLen = + std::size(linkName) - 1; // -1 to null-terminate. + + // Return if the TZ value is too large. + if (std::strlen(tz) > linkNameLen) { + return icu::UnicodeString(); + } + + std::strcpy(linkName, tz); + + char linkTarget[PathMax]; + constexpr size_t linkTargetLen = + std::size(linkTarget) - 1; // -1 to null-terminate. + + uint32_t depth = 0; + + // Search until we find "/zoneinfo/" in the link name. + const char* timeZoneWithZoneInfo; + while (!(timeZoneWithZoneInfo = std::strstr(linkName, ZoneInfoPath))) { + // Return if the symlink nesting is too deep. + if (++depth > FollowDepthLimit) { + return icu::UnicodeString(); + } + + // Return on error or if the result was truncated. + ssize_t slen = readlink(linkName, linkTarget, linkTargetLen); + if (slen < 0 || size_t(slen) >= linkTargetLen) { + return icu::UnicodeString(); + } + + // Ensure linkTarget is null-terminated. (readlink may not necessarily + // null-terminate the string.) + size_t len = size_t(slen); + linkTarget[len] = '\0'; + + // If the target is absolute, continue with that. + if (linkTarget[0] == '/') { + std::strcpy(linkName, linkTarget); + continue; + } + + // If the target is relative, it must be resolved against either the + // directory the link was in, or against the current working directory. + char* separator = std::strrchr(linkName, '/'); + + // If the link name is just something like "foo", resolve linkTarget + // against the current working directory. + if (!separator) { + std::strcpy(linkName, linkTarget); + continue; + } + + // Remove everything after the final path separator in linkName. + separator[1] = '\0'; + + // Return if the concatenated path name is too large. + if (std::strlen(linkName) + len > linkNameLen) { + return icu::UnicodeString(); + } + + // Keep it simple and just concatenate the path names. + std::strcat(linkName, linkTarget); + } + + const char* timeZone = timeZoneWithZoneInfo + ZoneInfoPathLength; + return MaybeTimeZoneId(timeZone); +} +#endif /* JS_HAS_INTL_API && !MOZ_SYSTEM_ICU */ + +void js::ResyncICUDefaultTimeZone() { + js::DateTimeInfo::resyncICUDefaultTimeZone(); +} + +void js::DateTimeInfo::internalResyncICUDefaultTimeZone() { +#if JS_HAS_INTL_API && !MOZ_SYSTEM_ICU + if (const char* tz = std::getenv("TZ")) { + icu::UnicodeString tzid; + +# if defined(XP_WIN) + // If TZ is set and its value is valid under Windows' and IANA's time zone + // identifier rules, update the ICU default time zone to use this value. + if (IsOlsonCompatibleWindowsTimeZoneId(tz)) { + tzid.setTo(icu::UnicodeString(tz, -1, US_INV)); + } else { + // If |tz| isn't a supported time zone identifier, use the default Windows + // time zone for ICU. + // TODO: Handle invalid time zone identifiers (bug 342068). + } +# else + // The TZ environment variable allows both absolute and relative paths, + // optionally beginning with a colon (':'). (Relative paths, without the + // colon, are just Olson time zone names.) We need to handle absolute paths + // ourselves, including handling that they might be symlinks. + // <https://unicode-org.atlassian.net/browse/ICU-13694> + if (const char* tzlink = TZContainsAbsolutePath(tz)) { + tzid.setTo(ReadTimeZoneLink(tzlink)); + } + +# ifdef ANDROID + // ICU ignores the TZ environment variable on Android. If it doesn't contain + // an absolute path, try to parse it as a time zone name. + else { + tzid.setTo(MaybeTimeZoneId(tz)); + } +# endif +# endif /* defined(XP_WIN) */ + + if (!tzid.isEmpty()) { + mozilla::UniquePtr<icu::TimeZone> newTimeZone( + icu::TimeZone::createTimeZone(tzid)); + MOZ_ASSERT(newTimeZone); + if (*newTimeZone != icu::TimeZone::getUnknown()) { + // adoptDefault() takes ownership of the time zone. + icu::TimeZone::adoptDefault(newTimeZone.release()); + return; + } + } + } + + if (icu::TimeZone* defaultZone = icu::TimeZone::detectHostTimeZone()) { + icu::TimeZone::adoptDefault(defaultZone); + } +#endif +} |