CoreFoundation/CFTimeZone.c

/*
 * Copyright (c) 2008-2009 Brent Fulgham <bfulgham@gmail.org>.  All rights reserved.
 * Copyright (c) 2009 David M. Cotter <me@davevcotter.com>.  All rights reserved.
 *
 * This source code is a modified version of the CoreFoundation sources released by Apple Inc. under
 * the terms of the APSL version 2.0 (see below).
 *
 * For information about changes from the original Apple source release can be found by reviewing the
 * source control system for the project at https://sourceforge.net/svn/?group_id=246198.
 *
 * The original license information is as follows:
 * 
 * Copyright (c) 2008 Apple Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*	CFTimeZone.c
	Copyright 1998-2002, Apple, Inc. All rights reserved.
	Responsibility: Christopher Kane
*/

#include <CoreFoundation/CFTimeZone.h>
#include <CoreFoundation/CFPropertyList.h>
#include "CFPriv.h"
#include "CFInternal.h"
#include <math.h>
#include <limits.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unicode/ucal.h>
#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_LINUX
#include <dirent.h>
#include <unistd.h>
#include <sys/fcntl.h>
#include <tzfile.h>
#elif DEPLOYMENT_TARGET_WINDOWS
#include <windows.h>
#include <winreg.h>
#include <time.h>
#include <tchar.h>
#endif

#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_LINUX
#define TZZONELINK	TZDEFAULT
#define TZZONEINFO	TZDIR "/"
#elif DEPLOYMENT_TARGET_WINDOWS
#define TZZONEINFO	"SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones"
#endif

CONST_STRING_DECL(kCFTimeZoneSystemTimeZoneDidChangeNotification, "kCFTimeZoneSystemTimeZoneDidChangeNotification")

static CFTimeZoneRef __CFTimeZoneSystem = NULL;
static CFTimeZoneRef __CFTimeZoneDefault = NULL;
static CFDictionaryRef __CFTimeZoneAbbreviationDict = NULL;
static CFSpinLock_t __CFTimeZoneAbbreviationLock = CFSpinLockInit;
static CFMutableDictionaryRef __CFTimeZoneCompatibilityMappingDict = NULL;
static CFSpinLock_t __CFTimeZoneCompatibilityMappingLock = CFSpinLockInit;
static CFArrayRef __CFKnownTimeZoneList = NULL;
static CFMutableDictionaryRef __CFTimeZoneCache = NULL;
static CFSpinLock_t __CFTimeZoneGlobalLock = CFSpinLockInit;

CF_INLINE void __CFTimeZoneLockGlobal(void) {
    __CFSpinLock(&__CFTimeZoneGlobalLock);
}

CF_INLINE void __CFTimeZoneUnlockGlobal(void) {
    __CFSpinUnlock(&__CFTimeZoneGlobalLock);
}

CF_INLINE void __CFTimeZoneLockAbbreviations(void) {
    __CFSpinLock(&__CFTimeZoneAbbreviationLock);
}

CF_INLINE void __CFTimeZoneUnlockAbbreviations(void) {
    __CFSpinUnlock(&__CFTimeZoneAbbreviationLock);
}

CF_INLINE void __CFTimeZoneLockCompatibilityMapping(void) {
    __CFSpinLock(&__CFTimeZoneCompatibilityMappingLock);
}

CF_INLINE void __CFTimeZoneUnlockCompatibilityMapping(void) {
    __CFSpinUnlock(&__CFTimeZoneCompatibilityMappingLock);
}

/* This function should be used for WIN32 instead of
 * __CFCopyRecursiveDirectoryList function.
 * It takes TimeZone names from the registry
 * (Aleksey Dukhnyakov)
 */
#if DEPLOYMENT_TARGET_WINDOWS
static CFMutableArrayRef __CFCopyWindowsTimeZoneList() {
    CFMutableArrayRef result = NULL;
    HKEY hkResult;
    TCHAR lpName[MAX_PATH+1];
    DWORD dwIndex, retCode;

    if (RegOpenKey(HKEY_LOCAL_MACHINE,_T(TZZONEINFO),&hkResult) !=
        ERROR_SUCCESS )
        return NULL;

    result = CFArrayCreateMutable(kCFAllocatorDefault, 0, &kCFTypeArrayCallBacks);

    for (dwIndex=0; (retCode = RegEnumKey(hkResult,dwIndex,lpName,MAX_PATH)) != ERROR_NO_MORE_ITEMS ; dwIndex++) {

        if (retCode != ERROR_SUCCESS) {
            RegCloseKey(hkResult);
            CFRelease(result);
            return NULL;
        }
        else {
#if defined(UNICODE)
		    CFStringRef string = CFStringCreateWithBytes(kCFAllocatorDefault, (UInt8*)lpName, (CFIndex)_tcslen(lpName), kCFStringEncodingUnicode, false);
#else
		    CFStringRef string = CFStringCreateWithBytes(kCFAllocatorDefault, (UInt8*)lpName, (CFIndex)_tcslen(lpName), CFStringGetSystemEncoding(), false);
#endif
		    CFArrayAppendValue(result, string);
		    CFRelease(string);
        }
    }

    RegCloseKey(hkResult);
    return result;
}
#endif

#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_WINDOWS || DEPLOYMENT_TARGET_LINUX
static CFMutableArrayRef __CFCopyRecursiveDirectoryList() {
    CFMutableArrayRef result = CFArrayCreateMutable(kCFAllocatorSystemDefault, 0, &kCFTypeArrayCallBacks);
#if !DEPLOYMENT_TARGET_WINDOWS
    int fd = open(TZDIR "/zone.tab", O_RDONLY);
    for (; 0 <= fd;) {
        uint8_t buffer[4096];
        ssize_t len = read(fd, buffer, sizeof(buffer));
        if (len <= 0) break;
	if (len < sizeof(buffer)) {
	    // assumes that partial read only occurs at the end of the file
	    buffer[len] = '\n';
	    len++;
	}
        const uint8_t *bytes = buffer;
        for (;;) {
	    const uint8_t *nextl = (const uint8_t*)memchr(bytes, '\n', len);
	    if (!nextl) break;
	    nextl++;
	    if ('#' == *bytes) {
		len -= (nextl - bytes);
		bytes = nextl;
		continue;
	    }
	    const uint8_t *tab1 = (const uint8_t*)memchr(bytes, '\t', (nextl - bytes));
	    if (!tab1) {
		len -= (nextl - bytes);
		bytes = nextl;
		continue;
	    }
	    tab1++;
	    len -= (tab1 - bytes);
	    bytes = tab1; 
	    const uint8_t *tab2 = (const uint8_t*)memchr(bytes, '\t', (nextl - bytes));
	    if (!tab2) {
		len -= (nextl - bytes);
		bytes = nextl;
		continue;
	    }
	    tab2++;
	    len -= (tab2 - bytes);
	    bytes = tab2; 
	    const uint8_t *tab3 = (const uint8_t*)memchr(bytes, '\t', (nextl - bytes));
	    int nmlen = tab3 ? (tab3 - bytes) : (nextl - 1 - bytes);
	    CFStringRef string = CFStringCreateWithBytes(kCFAllocatorSystemDefault, bytes, nmlen, kCFStringEncodingUTF8, false);
	    CFArrayAppendValue(result, string);
	    CFRelease(string);
	    len -= (nextl - bytes);
	    bytes = nextl;
        }
        lseek(fd, -len, SEEK_CUR);
    }
    close(fd);
#endif
    return result;
}
#else
#error Unknown or unspecified DEPLOYMENT_TARGET
#endif

typedef struct _CFTZPeriod {
    int32_t startSec;
    CFStringRef abbrev;
    uint32_t info;
} CFTZPeriod;

struct __CFTimeZone {
    CFRuntimeBase _base;
    CFStringRef _name;		/* immutable */
    CFDataRef _data;		/* immutable */
    CFTZPeriod *_periods;	/* immutable */
    int32_t _periodCnt;		/* immutable */
};

/* startSec is the whole integer seconds from a CFAbsoluteTime, giving dates
 * between 1933 and 2069; info outside these years is discarded on read-in */
/* Bits 31-18 of the info are unused */
/* Bit 17 of the info is used for the is-DST state */
/* Bit 16 of the info is used for the sign of the offset (1 == negative) */
/* Bits 15-0 of the info are used for abs(offset) in seconds from GMT */

CF_INLINE void __CFTZPeriodInit(CFTZPeriod *period, int32_t startTime, CFStringRef abbrev, int32_t offset, Boolean isDST) {
    period->startSec = startTime;
    period->abbrev = abbrev ? (CFStringRef)CFRetain(abbrev) : NULL;
    __CFBitfieldSetValue(period->info, 15, 0, abs(offset));
    __CFBitfieldSetValue(period->info, 16, 16, (offset < 0 ? 1 : 0));
    __CFBitfieldSetValue(period->info, 17, 17, (isDST ? 1 : 0));
}

CF_INLINE int32_t __CFTZPeriodStartSeconds(const CFTZPeriod *period) {
    return period->startSec;
}

CF_INLINE CFStringRef __CFTZPeriodAbbreviation(const CFTZPeriod *period) {
    return period->abbrev;
}

CF_INLINE int32_t __CFTZPeriodGMTOffset(const CFTZPeriod *period) {
    int32_t v = __CFBitfieldGetValue(period->info, 15, 0);
    if (__CFBitfieldGetValue(period->info, 16, 16)) v = -v;
    return v;
}

CF_INLINE Boolean __CFTZPeriodIsDST(const CFTZPeriod *period) {
    return (Boolean)__CFBitfieldGetValue(period->info, 17, 17);
}

static CFComparisonResult __CFCompareTZPeriods(const void *val1, const void *val2, void *context) {
    CFTZPeriod *tzp1 = (CFTZPeriod *)val1;
    CFTZPeriod *tzp2 = (CFTZPeriod *)val2;
    // we treat equal as less than, as the code which uses the
    // result of the bsearch doesn't expect exact matches
    // (they're pretty rare, so no point in over-coding for them)
    if (__CFTZPeriodStartSeconds(tzp1) <= __CFTZPeriodStartSeconds(tzp2)) return kCFCompareLessThan;
    return kCFCompareGreaterThan;
}

static CFIndex __CFBSearchTZPeriods(CFTimeZoneRef tz, CFAbsoluteTime at) {
    CFTZPeriod elem;
    __CFTZPeriodInit(&elem, (int32_t)floor(at), NULL, 0, false);
    CFIndex idx = CFBSearch(&elem, sizeof(CFTZPeriod), tz->_periods, tz->_periodCnt, __CFCompareTZPeriods, NULL);
    if (tz->_periodCnt <= idx) {
	idx = tz->_periodCnt;
    } else if (0 == idx) {
	idx = 1;
    }
    return idx - 1;
}


CF_INLINE int32_t __CFDetzcode(const unsigned char *bufp) {
    int32_t result = (bufp[0] & 0x80) ? ~0L : 0L;
    result = (result << 8) | (bufp[0] & 0xff);
    result = (result << 8) | (bufp[1] & 0xff);
    result = (result << 8) | (bufp[2] & 0xff);
    result = (result << 8) | (bufp[3] & 0xff);
    return result;
}

CF_INLINE void __CFEntzcode(int32_t value, unsigned char *bufp) {
    bufp[0] = (value >> 24) & 0xff;
    bufp[1] = (value >> 16) & 0xff;
    bufp[2] = (value >> 8) & 0xff;
    bufp[3] = (value >> 0) & 0xff;
}

#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_LINUX
static Boolean __CFParseTimeZoneData(CFAllocatorRef allocator, CFDataRef data, CFTZPeriod **tzpp, CFIndex *cntp) {
    int32_t len, timecnt, typecnt, charcnt, idx, cnt;
    const uint8_t *p, *timep, *typep, *ttisp, *charp;
    CFStringRef *abbrs;
    Boolean result = true;

    p = CFDataGetBytePtr(data);
    len = CFDataGetLength(data);
    if (len < (int32_t)sizeof(struct tzhead)) {
	return false;
    }
    
    if (!(p[0] == 'T' && p[1] == 'Z' && p[2] == 'i' && p[3] == 'f')) return false;  /* Don't parse without TZif at head of file */
   
    p += 20 + 4 + 4 + 4;	/* skip reserved, ttisgmtcnt, ttisstdcnt, leapcnt */
    timecnt = __CFDetzcode(p);
    p += 4;
    typecnt = __CFDetzcode(p);
    p += 4;
    charcnt = __CFDetzcode(p);
    p += 4;
    if (typecnt <= 0 || timecnt < 0 || charcnt < 0) {
	return false;
    }
    if (1024 < timecnt || 32 < typecnt || 128 < charcnt) {
	// reject excessive timezones to avoid arithmetic overflows for
	// security reasons and to reject potentially corrupt files
	return false;
    }
    if (len - (int32_t)sizeof(struct tzhead) < (4 + 1) * timecnt + (4 + 1 + 1) * typecnt + charcnt) {
	return false;
    }
    timep = p;
    typep = timep + 4 * timecnt;
    ttisp = typep + timecnt;
    charp = ttisp + (4 + 1 + 1) * typecnt;
    cnt = (0 < timecnt) ? timecnt : 1;
    *tzpp = (CFTZPeriod*)CFAllocatorAllocate(allocator, cnt * sizeof(CFTZPeriod), 0);
    if (__CFOASafe) __CFSetLastAllocationEventName(*tzpp, "CFTimeZone (store)");
    memset(*tzpp, 0, cnt * sizeof(CFTZPeriod));
    abbrs = (CFStringRef*)CFAllocatorAllocate(allocator, (charcnt + 1) * sizeof(CFStringRef), 0);
    if (__CFOASafe) __CFSetLastAllocationEventName(abbrs, "CFTimeZone (temp)");
    for (idx = 0; idx < charcnt + 1; idx++) {
	abbrs[idx] = NULL;
    }
    for (idx = 0; idx < cnt; idx++) {
	CFAbsoluteTime at;
	int32_t itime, offset;
	uint8_t type, dst, abbridx;

	at = (CFAbsoluteTime)(__CFDetzcode(timep) + 0.0) - kCFAbsoluteTimeIntervalSince1970;
	if (0 == timecnt) itime = INT_MIN;
	else if (at < (CFAbsoluteTime)INT_MIN) itime = INT_MIN;
	else if ((CFAbsoluteTime)INT_MAX < at) itime = INT_MAX;
	else itime = (int32_t)at;
	timep += 4;	/* harmless if 0 == timecnt */
	type = (0 < timecnt) ? (uint8_t)*typep++ : 0;
	if (typecnt <= type) {
	    result = false;
	    break;
	}
	offset = __CFDetzcode(ttisp + 6 * type);
	dst = (uint8_t)*(ttisp + 6 * type + 4);
	if (0 != dst && 1 != dst) {
	    result = false;
	    break;
	}
	abbridx = (uint8_t)*(ttisp + 6 * type + 5);
	if (charcnt < abbridx) {
	    result = false;
	    break;
	}
	if (NULL == abbrs[abbridx]) {
	    abbrs[abbridx] = CFStringCreateWithCString(allocator, (char *)&charp[abbridx], kCFStringEncodingASCII);
	}
	__CFTZPeriodInit(*tzpp + idx, itime, abbrs[abbridx], offset, (dst ? true : false));
    }
    for (idx = 0; idx < charcnt + 1; idx++) {
	if (NULL != abbrs[idx]) {
	    CFRelease(abbrs[idx]);
	}
    }
    CFAllocatorDeallocate(allocator, abbrs);
    if (result) {
	// dump all but the last INT_MIN and the first INT_MAX
	for (idx = 0; idx < cnt; idx++) {
	    if (((*tzpp + idx)->startSec == INT_MIN) && (idx + 1 < cnt) && (((*tzpp + idx + 1)->startSec == INT_MIN))) {
		if (NULL != (*tzpp + idx)->abbrev) CFRelease((*tzpp + idx)->abbrev);
		cnt--;
		memmove((*tzpp + idx), (*tzpp + idx + 1), sizeof(CFTZPeriod) * (cnt - idx));
		idx--;
	    }
	}
	// Don't combine these loops!  Watch the idx decrementing...
	for (idx = 0; idx < cnt; idx++) {
	    if (((*tzpp + idx)->startSec == INT_MAX) && (0 < idx) && (((*tzpp + idx - 1)->startSec == INT_MAX))) {
		if (NULL != (*tzpp + idx)->abbrev) CFRelease((*tzpp + idx)->abbrev);
		cnt--;
		memmove((*tzpp + idx), (*tzpp + idx + 1), sizeof(CFTZPeriod) * (cnt - idx));
		idx--;
	    }
	}
	CFQSortArray(*tzpp, cnt, sizeof(CFTZPeriod), __CFCompareTZPeriods, NULL);
	// if the first period is in DST and there is more than one period, drop it
	if (1 < cnt && __CFTZPeriodIsDST(*tzpp + 0)) {
	    if (NULL != (*tzpp + 0)->abbrev) CFRelease((*tzpp + 0)->abbrev);
	    cnt--;
	    memmove((*tzpp + 0), (*tzpp + 0 + 1), sizeof(CFTZPeriod) * (cnt - 0));
	}
	*cntp = cnt;
    } else {
	CFAllocatorDeallocate(allocator, *tzpp);
	*tzpp = NULL;
    }
    return result;
}
#elif DEPLOYMENT_TARGET_WINDOWS || 0
static Boolean __CFParseTimeZoneData(CFAllocatorRef allocator, CFDataRef data, CFTZPeriod **tzpp, CFIndex *cntp) {
/* We use Win32 function to find TimeZone
 * (Aleksey Dukhnyakov)
 */
    *tzpp = (CFTZPeriod *)CFAllocatorAllocate(allocator, sizeof(CFTZPeriod), 0);
    memset(*tzpp, 0, sizeof(CFTZPeriod));
    __CFTZPeriodInit(*tzpp, 0, NULL, 0, false);
    *cntp = 1;
    return TRUE;
}
#else
#error Unknown or unspecified DEPLOYMENT_TARGET
#endif

static Boolean __CFTimeZoneEqual(CFTypeRef cf1, CFTypeRef cf2) {
    CFTimeZoneRef tz1 = (CFTimeZoneRef)cf1;
    CFTimeZoneRef tz2 = (CFTimeZoneRef)cf2;
    if (!CFEqual(CFTimeZoneGetName(tz1), CFTimeZoneGetName(tz2))) return false;
    if (!CFEqual(CFTimeZoneGetData(tz1), CFTimeZoneGetData(tz2))) return false;
    return true;
}

static CFHashCode __CFTimeZoneHash(CFTypeRef cf) {
    CFTimeZoneRef tz = (CFTimeZoneRef)cf;
    return CFHash(CFTimeZoneGetName(tz));
}

static CFStringRef __CFTimeZoneCopyDescription(CFTypeRef cf) {
    CFTimeZoneRef tz = (CFTimeZoneRef)cf;
    CFStringRef result, abbrev;
    CFAbsoluteTime at;
    at = CFAbsoluteTimeGetCurrent();
    abbrev = CFTimeZoneCopyAbbreviation(tz, at);
    result = CFStringCreateWithFormat(kCFAllocatorSystemDefault, NULL, CFSTR("<CFTimeZone %p [%p]>{name = %@; abbreviation = %@; GMT offset = %g; is DST = %s}"), cf, CFGetAllocator(tz), tz->_name, abbrev, CFTimeZoneGetSecondsFromGMT(tz, at), CFTimeZoneIsDaylightSavingTime(tz, at) ? "true" : "false");
    CFRelease(abbrev);
    return result;
}

static void __CFTimeZoneDeallocate(CFTypeRef cf) {
    CFTimeZoneRef tz = (CFTimeZoneRef)cf;
    CFAllocatorRef allocator = CFGetAllocator(tz);
    CFIndex idx;
    if (tz->_name) CFRelease(tz->_name);
    if (tz->_data) CFRelease(tz->_data);
    for (idx = 0; idx < tz->_periodCnt; idx++) {
	if (NULL != tz->_periods[idx].abbrev) CFRelease(tz->_periods[idx].abbrev);
    }
    if (NULL != tz->_periods) CFAllocatorDeallocate(allocator, tz->_periods);
}

static CFTypeID __kCFTimeZoneTypeID = _kCFRuntimeNotATypeID;

static const CFRuntimeClass __CFTimeZoneClass = {
    0,
    "CFTimeZone",
    NULL,	// init
    NULL,	// copy
    __CFTimeZoneDeallocate,
    __CFTimeZoneEqual,
    __CFTimeZoneHash,
    NULL,	//
    __CFTimeZoneCopyDescription
};

__private_extern__ void __CFTimeZoneInitialize(void) {
    __kCFTimeZoneTypeID = _CFRuntimeRegisterClass(&__CFTimeZoneClass);
}

CFTypeID CFTimeZoneGetTypeID(void) {
    return __kCFTimeZoneTypeID;
}


#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_LINUX
static CFTimeZoneRef __CFTimeZoneCreateSystem(void) {
    CFTimeZoneRef result = NULL;

    char *tzenv;
    int ret;
    char linkbuf[CFMaxPathSize];

    tzenv = getenv("TZFILE");
    if (NULL != tzenv) {
	CFStringRef name = CFStringCreateWithBytes(kCFAllocatorSystemDefault, (uint8_t *)tzenv, strlen(tzenv), kCFStringEncodingUTF8, false);
	result = CFTimeZoneCreateWithName(kCFAllocatorSystemDefault, name, false);
	CFRelease(name);
	if (result) return result;
    }
    tzenv = getenv("TZ");
    if (NULL != tzenv) {
	CFStringRef name = CFStringCreateWithBytes(kCFAllocatorSystemDefault, (uint8_t *)tzenv, strlen(tzenv), kCFStringEncodingUTF8, false);
	result = CFTimeZoneCreateWithName(kCFAllocatorSystemDefault, name, true);
	CFRelease(name);
	if (result) return result;
    }
    ret = readlink(TZZONELINK, linkbuf, sizeof(linkbuf));
    if (0 < ret) {
	CFStringRef name;
	linkbuf[ret] = '\0';
	if (strncmp(linkbuf, TZZONEINFO, sizeof(TZZONEINFO) - 1) == 0) {
	    name = CFStringCreateWithBytes(kCFAllocatorSystemDefault, (uint8_t *)linkbuf + sizeof(TZZONEINFO) - 1, strlen(linkbuf) - sizeof(TZZONEINFO) + 1, kCFStringEncodingUTF8, false);
	} else {
	    name = CFStringCreateWithBytes(kCFAllocatorSystemDefault, (uint8_t *)linkbuf, strlen(linkbuf), kCFStringEncodingUTF8, false);
	}
	result = CFTimeZoneCreateWithName(kCFAllocatorSystemDefault, name, false);
	CFRelease(name);
	if (result) return result;
    }
    return CFTimeZoneCreateWithTimeIntervalFromGMT(kCFAllocatorSystemDefault, 0.0);
}
#elif DEPLOYMENT_TARGET_WINDOWS || 0
static CFTimeZoneRef __CFTimeZoneCreateSystem(void) {
    CFTimeZoneRef result = NULL;
/* The GetTimeZoneInformation function retrieves the current
 * time-zone parameters for Win32
 * (Aleksey Dukhnyakov)
 */
    CFDataRef data;
    TIME_ZONE_INFORMATION tz;
    DWORD dw_result;
    dw_result=GetTimeZoneInformation(&tz);

    if ( dw_result == TIME_ZONE_ID_STANDARD ||
            dw_result == TIME_ZONE_ID_DAYLIGHT ) {
        CFStringRef name = CFStringCreateWithCharacters(kCFAllocatorSystemDefault, (const UniChar *)tz.StandardName, (CFIndex)wcslen(tz.StandardName));
        data = CFDataCreate(kCFAllocatorSystemDefault, (UInt8 *)&tz, sizeof(tz));
        result = CFTimeZoneCreate(kCFAllocatorSystemDefault, name, data);
        CFRelease(name);
        CFRelease(data);
        if (result) return result;
    }
    return CFTimeZoneCreateWithTimeIntervalFromGMT(kCFAllocatorSystemDefault, 0.0);
}
#else
#error Unknown or unspecified DEPLOYMENT_TARGET
#endif

CFTimeZoneRef CFTimeZoneCopySystem(void) {
    CFTimeZoneRef tz;
    __CFTimeZoneLockGlobal();
    if (NULL == __CFTimeZoneSystem) {
	__CFTimeZoneUnlockGlobal();
	tz = __CFTimeZoneCreateSystem();
	__CFTimeZoneLockGlobal();
	if (NULL == __CFTimeZoneSystem) {
	    __CFTimeZoneSystem = tz;
	} else {
	    if (tz) CFRelease(tz);
	}
    }
    tz = __CFTimeZoneSystem ? (CFTimeZoneRef)CFRetain(__CFTimeZoneSystem) : NULL;
    __CFTimeZoneUnlockGlobal();
    return tz;
}

static CFIndex __noteCount = 0;

void CFTimeZoneResetSystem(void) {
    __CFTimeZoneLockGlobal();
    if (__CFTimeZoneDefault == __CFTimeZoneSystem) {
	if (__CFTimeZoneDefault) CFRelease(__CFTimeZoneDefault);
	__CFTimeZoneDefault = NULL;
    }
    CFTimeZoneRef tz = __CFTimeZoneSystem;
    __CFTimeZoneSystem = NULL;
    __CFTimeZoneUnlockGlobal();
    if (tz) CFRelease(tz);
}

CFIndex _CFTimeZoneGetNoteCount(void) {
    return __noteCount;
}

CFTimeZoneRef CFTimeZoneCopyDefault(void) {
    CFTimeZoneRef tz;
    __CFTimeZoneLockGlobal();
    if (NULL == __CFTimeZoneDefault) {
	__CFTimeZoneUnlockGlobal();
	tz = CFTimeZoneCopySystem();
	__CFTimeZoneLockGlobal();
	if (NULL == __CFTimeZoneDefault) {
	    __CFTimeZoneDefault = tz;
	} else {
	    if (tz) CFRelease(tz);
	}
    }
    tz = __CFTimeZoneDefault ? (CFTimeZoneRef)CFRetain(__CFTimeZoneDefault) : NULL;
    __CFTimeZoneUnlockGlobal();
    return tz;
}

void CFTimeZoneSetDefault(CFTimeZoneRef tz) {
    if (tz) __CFGenericValidateType(tz, CFTimeZoneGetTypeID());
    __CFTimeZoneLockGlobal();
    if (tz != __CFTimeZoneDefault) {
	if (tz) CFRetain(tz);
	if (__CFTimeZoneDefault) CFRelease(__CFTimeZoneDefault);
	__CFTimeZoneDefault = tz;
    }
    __CFTimeZoneUnlockGlobal();
}

static CFDictionaryRef __CFTimeZoneCopyCompatibilityDictionary(void);

CFArrayRef CFTimeZoneCopyKnownNames(void) {
    CFArrayRef tzs;
    __CFTimeZoneLockGlobal();
    if (NULL == __CFKnownTimeZoneList) {
	CFMutableArrayRef list;
/* TimeZone information locate in the registry for Win32
 * (Aleksey Dukhnyakov)
 */
#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_LINUX
        list = __CFCopyRecursiveDirectoryList();
#elif DEPLOYMENT_TARGET_WINDOWS
        list = __CFCopyWindowsTimeZoneList();
#else
#error Unknown or unspecified DEPLOYMENT_TARGET
#endif
	// Remove undesirable ancient cruft
	CFDictionaryRef dict = __CFTimeZoneCopyCompatibilityDictionary();
	CFIndex idx;
	for (idx = CFArrayGetCount(list); idx--; ) {
	    CFStringRef item = (CFStringRef)CFArrayGetValueAtIndex(list, idx);
	    if (CFDictionaryContainsKey(dict, item)) {
		CFArrayRemoveValueAtIndex(list, idx);
	    }
	}
	__CFKnownTimeZoneList = CFArrayCreateCopy(kCFAllocatorSystemDefault, list);
	CFRelease(list);
    }
    tzs = __CFKnownTimeZoneList ? (CFArrayRef)CFRetain(__CFKnownTimeZoneList) : NULL;
    __CFTimeZoneUnlockGlobal();
    return tzs;
}

#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_LINUX
/* The criteria here are sort of: coverage for the U.S. and Europe,
 * large cities, abbreviation uniqueness, and perhaps a few others.
 * But do not make the list too large with obscure information.
 */
static const char *__CFTimeZoneAbbreviationDefaults =
"<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
" <!DOCTYPE plist SYSTEM \"file://localhost/System/Library/DTDs/PropertyList.dtd\">"
" <plist version=\"1.0\">"
" <dict>"
"    <key>ADT</key>  <string>America/Halifax</string>"
"    <key>AKDT</key> <string>America/Juneau</string>"
"    <key>AKST</key> <string>America/Juneau</string>"
"    <key>ART</key>  <string>America/Argentina/Buenos_Aires</string>"
"    <key>AST</key>  <string>America/Halifax</string>"
"    <key>BDT</key>  <string>Asia/Dhaka</string>"
"    <key>BRST</key> <string>America/Sao_Paulo</string>"
"    <key>BRT</key>  <string>America/Sao_Paulo</string>"
"    <key>BST</key>  <string>Europe/London</string>"
"    <key>CAT</key>  <string>Africa/Harare</string>"
"    <key>CDT</key>  <string>America/Chicago</string>"
"    <key>CEST</key> <string>Europe/Paris</string>"
"    <key>CET</key>  <string>Europe/Paris</string>"
"    <key>CLST</key> <string>America/Santiago</string>"
"    <key>CLT</key>  <string>America/Santiago</string>"
"    <key>COT</key>  <string>America/Bogota</string>"
"    <key>CST</key>  <string>America/Chicago</string>"
"    <key>EAT</key>  <string>Africa/Addis_Ababa</string>"
"    <key>EDT</key>  <string>America/New_York</string>"
"    <key>EEST</key> <string>Europe/Istanbul</string>"
"    <key>EET</key>  <string>Europe/Istanbul</string>"
"    <key>EST</key>  <string>America/New_York</string>"
"    <key>GMT</key>  <string>GMT</string>"
"    <key>GST</key>  <string>Asia/Dubai</string>"
"    <key>HKT</key>  <string>Asia/Hong_Kong</string>"
"    <key>HST</key>  <string>Pacific/Honolulu</string>"
"    <key>ICT</key>  <string>Asia/Bangkok</string>"
"    <key>IRST</key> <string>Asia/Tehran</string>"
"    <key>IST</key>  <string>Asia/Calcutta</string>"
"    <key>JST</key>  <string>Asia/Tokyo</string>"
"    <key>KST</key>  <string>Asia/Seoul</string>"
"    <key>MDT</key>  <string>America/Denver</string>"
"    <key>MSD</key>  <string>Europe/Moscow</string>"
"    <key>MSK</key>  <string>Europe/Moscow</string>"
"    <key>MST</key>  <string>America/Denver</string>"
"    <key>NZDT</key> <string>Pacific/Auckland</string>"
"    <key>NZST</key> <string>Pacific/Auckland</string>"
"    <key>PDT</key>  <string>America/Los_Angeles</string>"
"    <key>PET</key>  <string>America/Lima</string>"
"    <key>PHT</key>  <string>Asia/Manila</string>"
"    <key>PKT</key>  <string>Asia/Karachi</string>"
"    <key>PST</key>  <string>America/Los_Angeles</string>"
"    <key>SGT</key>  <string>Asia/Singapore</string>"
"    <key>UTC</key>  <string>UTC</string>"
"    <key>WAT</key>  <string>Africa/Lagos</string>"
"    <key>WEST</key> <string>Europe/Lisbon</string>"
"    <key>WET</key>  <string>Europe/Lisbon</string>"
"    <key>WIT</key>  <string>Asia/Jakarta</string>"
" </dict>"
" </plist>";
#elif DEPLOYMENT_TARGET_WINDOWS || 0
static const char *__CFTimeZoneAbbreviationDefaults =
/* Mappings to time zones in Windows Registry are best-guess */
"<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
" <!DOCTYPE plist SYSTEM \"file://localhost/System/Library/DTDs/PropertyList.dtd\">"
" <plist version=\"1.0\">"
" <dict>"
"    <key>ADT</key>  <string>Atlantic Standard Time</string>"
"    <key>AKDT</key> <string>Alaskan Standard Time</string>"
"    <key>AKST</key> <string>Alaskan Standard Time</string>"
"    <key>ART</key>  <string>SA Eastern Standard Time</string>"
"    <key>AST</key>  <string>Atlantic Standard Time</string>"
"    <key>BDT</key>  <string>Central Asia Standard Time</string>"
"    <key>BRST</key> <string>SA Eastern Standard Time</string>"
"    <key>BRT</key>  <string>SA Eastern Standard Time</string>"
"    <key>BST</key>  <string>GMT Standard Time</string>"
"    <key>CAT</key>  <string>South Africa Standard Time</string>"
"    <key>CDT</key>  <string>Central Daylight Time</string>"
"    <key>CEST</key> <string>Central Europe Standard Time</string>"
"    <key>CET</key>  <string>Central Europe Standard Time</string>"
"    <key>CLST</key> <string>SA Western Standard Time</string>"
"    <key>CLT</key>  <string>SA Western Standard Time</string>"
"    <key>COT</key>  <string>Central Standard Time</string>"
"    <key>CST</key>  <string>Central Standard Time</string>"
"    <key>EAT</key>  <string>E. Africa Standard Time</string>"
"    <key>EDT</key>  <string>Eastern Daylight Time</string>"
"    <key>EEST</key> <string>E. Europe Standard Time</string>"
"    <key>EET</key>  <string>E. Europe Standard Time</string>"
"    <key>EST</key>  <string>Eastern Standard Time</string>"
"    <key>GMT</key>  <string>Greenwich Standard Time</string>"
"    <key>GST</key>  <string>Arabian Standard Time</string>"
"    <key>HKT</key>  <string>China Standard Time</string>"
"    <key>HST</key>  <string>Hawaiian Standard Time</string>"
"    <key>ICT</key>  <string>SE Asia Standard Time</string>"
"    <key>IRST</key> <string>Iran Standard Time</string>"
"    <key>IST</key>  <string>India Standard Time</string>"
"    <key>JST</key>  <string>Tokyo Standard Time</string>"
"    <key>KST</key>  <string>Korea Standard Time</string>"
"    <key>MDT</key>  <string>Mountain Daylight Time</string>"
"    <key>MSD</key>  <string>E. Europe Standard Time</string>"
"    <key>MSK</key>  <string>E. Europe Standard Time</string>"
"    <key>MST</key>  <string>Mountain Standard Time</string>"
"    <key>NZDT</key> <string>New Zealand Standard Time</string>"
"    <key>NZST</key> <string>New Zealand Standard Time</string>"
"    <key>PDT</key>  <string>Pacific Daylight Time</string>"
"    <key>PET</key>  <string>SA Pacific Standard Time</string>"
"    <key>PHT</key>  <string>Taipei Standard Time</string>"
"    <key>PKT</key>  <string>West Asia Standard Time</string>"
"    <key>PST</key>  <string>Pacific Standard Time</string>"
"    <key>SGT</key>  <string>Singapore Standard Time</string>"
"    <key>UTC</key>  <string>Greenwich Standard Time</string>"
"    <key>WAT</key>  <string>W. Central Africa Standard Time</string>"
"    <key>WEST</key> <string>W. Europe Standard Time</string>"
"    <key>WET</key>  <string>W. Europe Standard Time</string>"
"    <key>WIT</key>  <string>SE Asia Standard Time</string>"
" </dict>"
" </plist>";
#else
#error Unknown or unspecified DEPLOYMENT_TARGET
#endif

CFDictionaryRef CFTimeZoneCopyAbbreviationDictionary(void) {
    CFDictionaryRef dict;
    __CFTimeZoneLockAbbreviations();
    if (NULL == __CFTimeZoneAbbreviationDict) {
	CFDataRef data = CFDataCreate(kCFAllocatorSystemDefault, (uint8_t *)__CFTimeZoneAbbreviationDefaults, (CFIndex)strlen(__CFTimeZoneAbbreviationDefaults));
	__CFTimeZoneAbbreviationDict = (CFDictionaryRef)CFPropertyListCreateFromXMLData(kCFAllocatorSystemDefault, data, kCFPropertyListImmutable, NULL);
	CFRelease(data);
    }
    if (NULL == __CFTimeZoneAbbreviationDict) {
	__CFTimeZoneAbbreviationDict = CFDictionaryCreate(kCFAllocatorSystemDefault, NULL, NULL, 0, NULL, NULL);
    }
    dict = __CFTimeZoneAbbreviationDict ? (CFDictionaryRef)CFRetain(__CFTimeZoneAbbreviationDict) : NULL;
    __CFTimeZoneUnlockAbbreviations();
    return dict;
}

void CFTimeZoneSetAbbreviationDictionary(CFDictionaryRef dict) {
    __CFGenericValidateType(dict, CFDictionaryGetTypeID());
    __CFTimeZoneLockGlobal();
    if (dict != __CFTimeZoneAbbreviationDict) {
	if (dict) CFRetain(dict);
	if (__CFTimeZoneAbbreviationDict) {
	    CFIndex count, idx;
	    count = CFDictionaryGetCount(__CFTimeZoneAbbreviationDict);
	    CFTypeRef *keys = (CFTypeRef *)malloc(sizeof(CFTypeRef *) * count);
	    for (idx = 0; idx < count; idx++) {
		CFDictionaryRemoveValue(__CFTimeZoneCache, (CFStringRef)keys[idx]);
	    }
	    free(keys);
	    CFRelease(__CFTimeZoneAbbreviationDict);
	}
	__CFTimeZoneAbbreviationDict = dict;
    }
    __CFTimeZoneUnlockGlobal();
}

CFTimeZoneRef CFTimeZoneCreate(CFAllocatorRef allocator, CFStringRef name, CFDataRef data) {
// assert:    (NULL != name && NULL != data);
    CFTimeZoneRef memory;
    uint32_t size;
    CFTZPeriod *tzp = NULL;
    CFIndex idx, cnt = 0;

    if (allocator == NULL) allocator = __CFGetDefaultAllocator();
    __CFGenericValidateType(allocator, CFAllocatorGetTypeID());
    __CFGenericValidateType(name, CFStringGetTypeID());
    __CFGenericValidateType(data, CFDataGetTypeID());
    __CFTimeZoneLockGlobal();
    if (NULL != __CFTimeZoneCache && CFDictionaryGetValueIfPresent(__CFTimeZoneCache, name, (const void **)&memory)) {
	__CFTimeZoneUnlockGlobal();
	return (CFTimeZoneRef)CFRetain(memory);
    }
    if (!__CFParseTimeZoneData(allocator, data, &tzp, &cnt)) {
	__CFTimeZoneUnlockGlobal();
	return NULL;
    }
    size = sizeof(struct __CFTimeZone) - sizeof(CFRuntimeBase);
    memory = (CFTimeZoneRef)_CFRuntimeCreateInstance(allocator, CFTimeZoneGetTypeID(), size, NULL);
    if (NULL == memory) {
	__CFTimeZoneUnlockGlobal();
	for (idx = 0; idx < cnt; idx++) {
	    if (NULL != tzp[idx].abbrev) CFRelease(tzp[idx].abbrev);
	}
	if (NULL != tzp) CFAllocatorDeallocate(allocator, tzp);
        return NULL;
    }
    ((struct __CFTimeZone *)memory)->_name = (CFStringRef)CFStringCreateCopy(allocator, name);
    ((struct __CFTimeZone *)memory)->_data = CFDataCreateCopy(allocator, data);
    ((struct __CFTimeZone *)memory)->_periods = tzp;
    ((struct __CFTimeZone *)memory)->_periodCnt = cnt;
    if (NULL == __CFTimeZoneCache) {
	__CFTimeZoneCache = CFDictionaryCreateMutable(kCFAllocatorSystemDefault, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
    }
    CFDictionaryAddValue(__CFTimeZoneCache, ((struct __CFTimeZone *)memory)->_name, memory);
    __CFTimeZoneUnlockGlobal();
    return memory;
}

#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_LINUX
static CFTimeZoneRef __CFTimeZoneCreateFixed(CFAllocatorRef allocator, int32_t seconds, CFStringRef name, int isDST) {
    CFTimeZoneRef result;
    CFDataRef data;
    int32_t nameLen = CFStringGetLength(name);
    unsigned char dataBytes[52 + nameLen + 1];
    memset(dataBytes, 0, sizeof(dataBytes));
    
    // Put in correct magic bytes for timezone structures
    dataBytes[0] = 'T';
    dataBytes[1] = 'Z';
    dataBytes[2] = 'i';
    dataBytes[3] = 'f';
    
    __CFEntzcode(1, dataBytes + 20);
    __CFEntzcode(1, dataBytes + 24);
    __CFEntzcode(1, dataBytes + 36);
    __CFEntzcode(nameLen + 1, dataBytes + 40);
    __CFEntzcode(seconds, dataBytes + 44);
    dataBytes[48] = isDST ? 1 : 0;
    CFStringGetCString(name, (char *)dataBytes + 50, nameLen + 1, kCFStringEncodingASCII);
    data = CFDataCreate(allocator, dataBytes, 52 + nameLen + 1);
    result = CFTimeZoneCreate(allocator, name, data);
    CFRelease(data);
    return result;
}
#elif DEPLOYMENT_TARGET_WINDOWS || 0
static CFTimeZoneRef __CFTimeZoneCreateFixed(CFAllocatorRef allocator, int32_t seconds, CFStringRef name, int isDST) {
/* CFTimeZoneRef->_data will contain TIME_ZONE_INFORMATION structure
 * to find current timezone
 * (Aleksey Dukhnyakov)
 */
    CFTimeZoneRef result;
    TIME_ZONE_INFORMATION tzi;
    CFDataRef data;
    CFIndex length = CFStringGetLength(name);

    memset(&tzi,0,sizeof(tzi));
    tzi.Bias=(long)(-seconds/60);
    CFStringGetCharacters(name, CFRangeMake(0, length < 31 ? length : 31 ), (UniChar *)tzi.StandardName);
    data = CFDataCreate(allocator,(UInt8 *)&tzi, sizeof(tzi));
    result = CFTimeZoneCreate(allocator, name, data);
    CFRelease(data);
    return result;
}
#else
#error Unknown or unspecified DEPLOYMENT_TARGET
#endif

// rounds offset to nearest minute
CFTimeZoneRef CFTimeZoneCreateWithTimeIntervalFromGMT(CFAllocatorRef allocator, CFTimeInterval ti) {
    CFTimeZoneRef result;
    CFStringRef name;
    int32_t seconds, minute, hour;
    if (allocator == NULL) allocator = __CFGetDefaultAllocator();
    __CFGenericValidateType(allocator, CFAllocatorGetTypeID());
    if (ti < -18.0 * 3600 || 18.0 * 3600 < ti) return NULL;
    ti = (ti < 0.0) ? ceil((ti / 60.0) - 0.5) * 60.0 : floor((ti / 60.0) + 0.5) * 60.0;
    seconds = (int32_t)ti;
    hour = (ti < 0) ? (-seconds / 3600) : (seconds / 3600);
    seconds -= ((ti < 0) ? -hour : hour) * 3600;
    minute = (ti < 0) ? (-seconds / 60) : (seconds / 60);
    if (fabs(ti) < 1.0) {
	name = (CFStringRef)CFRetain(CFSTR("GMT"));
    } else {
	name = CFStringCreateWithFormat(allocator, NULL, CFSTR("GMT%c%02d%02d"), (ti < 0.0 ? '-' : '+'), hour, minute);
    }
    result = __CFTimeZoneCreateFixed(allocator, (int32_t)ti, name, 0);
    CFRelease(name);
    return result;
}

CFTimeZoneRef CFTimeZoneCreateWithName(CFAllocatorRef allocator, CFStringRef name, Boolean tryAbbrev) {
    CFTimeZoneRef result = NULL;
    CFStringRef tzName = NULL;
    CFDataRef data = NULL;

    if (allocator == NULL) allocator = __CFGetDefaultAllocator();
    __CFGenericValidateType(allocator, CFAllocatorGetTypeID());
    __CFGenericValidateType(name, CFStringGetTypeID());
    if (CFEqual(CFSTR(""), name)) {
	// empty string is not a time zone name, just abort now,
	// following stuff will fail anyway
	return NULL;
    }
    __CFTimeZoneLockGlobal();
    if (NULL != __CFTimeZoneCache && CFDictionaryGetValueIfPresent(__CFTimeZoneCache, name, (const void **)&result)) {
	__CFTimeZoneUnlockGlobal();
	return (CFTimeZoneRef)CFRetain(result);
    }
    __CFTimeZoneUnlockGlobal();
#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_LINUX
    CFURLRef baseURL, tempURL;
    void *bytes;
    CFIndex length;

    baseURL = CFURLCreateWithFileSystemPath(kCFAllocatorSystemDefault, CFSTR(TZZONEINFO), kCFURLPOSIXPathStyle, true);
    if (tryAbbrev) {
	CFDictionaryRef abbrevs = CFTimeZoneCopyAbbreviationDictionary();
	tzName = (CFStringRef)CFDictionaryGetValue(abbrevs, name);
	if (NULL != tzName) {
	    tempURL = CFURLCreateCopyAppendingPathComponent(kCFAllocatorSystemDefault, baseURL, tzName, false);
	    if (NULL != tempURL) {
		if (_CFReadBytesFromFile(kCFAllocatorSystemDefault, tempURL, &bytes, &length, 0)) {
		    data = CFDataCreateWithBytesNoCopy(kCFAllocatorSystemDefault, (const uint8_t*)bytes, length, kCFAllocatorSystemDefault);
		}
		CFRelease(tempURL);
	    }
	}
	CFRelease(abbrevs);
    }
    if (NULL == data) {
	CFDictionaryRef dict = __CFTimeZoneCopyCompatibilityDictionary();
	CFStringRef mapping = (CFStringRef)CFDictionaryGetValue(dict, name);
	if (mapping) {
	    name = mapping;
	} else if (CFStringHasPrefix(name, CFSTR(TZZONEINFO))) {
	    CFMutableStringRef unprefixed = CFStringCreateMutableCopy(kCFAllocatorSystemDefault, CFStringGetLength(name), name);
	    CFStringDelete(unprefixed, CFRangeMake(0, sizeof(TZZONEINFO)));
	    mapping = (CFStringRef)CFDictionaryGetValue(dict, unprefixed);
	    if (mapping) {
		name = mapping;
	    }
	    CFRelease(unprefixed);
	}
	CFRelease(dict);
	if (CFEqual(CFSTR(""), name)) {
	    return NULL;
	}
    }
    if (NULL == data) {
       tzName = name;
       tempURL = CFURLCreateCopyAppendingPathComponent(kCFAllocatorSystemDefault, baseURL, tzName, false);
       if (NULL != tempURL) {
           if (_CFReadBytesFromFile(kCFAllocatorSystemDefault, tempURL, &bytes, &length, 0)) {
               data = CFDataCreateWithBytesNoCopy(kCFAllocatorSystemDefault, (const uint8_t*)bytes, length, kCFAllocatorSystemDefault);
           }
           CFRelease(tempURL);
       }
    }
    CFRelease(baseURL);
    if (NULL != data) {
	result = CFTimeZoneCreate(allocator, tzName, data);
	if (name != tzName) {
	    CFStringRef nameCopy = (CFStringRef)CFStringCreateCopy(allocator, name);
	    __CFTimeZoneLockGlobal();
	    CFDictionaryAddValue(__CFTimeZoneCache, nameCopy, result);
	    __CFTimeZoneUnlockGlobal();
	    CFRelease(nameCopy);
	}
	CFRelease(data);
    }
    return result;
}
#elif DEPLOYMENT_TARGET_WINDOWS || 0
/* Reading GMT offset and daylight flag from the registry
 * for TimeZone name
 * (Aleksey Dukhnyakov)
 */
    {
        CFStringRef safeName = name;
        TIME_ZONE_INFORMATION tzi_system;

        DWORD zoneID = TIME_ZONE_ID_INVALID,
        dwSize_name1=sizeof(tzi_system.StandardName),
        dwSize_name2=sizeof(tzi_system.DaylightName);

        if (tryAbbrev) {
            CFDictionaryRef abbrevs = CFTimeZoneCopyAbbreviationDictionary();
            tzName = (CFStringRef)CFDictionaryGetValue(abbrevs, name);
            if (NULL == tzName) {
                CFRelease(abbrevs);
                return NULL;
            }
            name = tzName;
            CFRelease(abbrevs);
        }

/* CFTimeZoneRef->_data will contain TIME_ZONE_INFORMATION structure
 * to find current timezone
 * (Aleksey Dukhnyakov)
 */
       zoneID = GetTimeZoneInformation(&tzi_system);
       if (zoneID == TIME_ZONE_ID_INVALID) {
           return(NULL);
       }
       data = CFDataCreate(allocator,(UInt8 *)&tzi_system, sizeof(tzi_system));

       result = CFTimeZoneCreate(allocator, name, data);
        if (result) {
            if (tryAbbrev)
                result->_periods->abbrev = (CFStringRef)CFStringCreateCopy(allocator,safeName);
        }
        CFRelease(data);
    }
    return result;
}
#else
#error Unknown or unspecified DEPLOYMENT_TARGET
#endif

CFStringRef CFTimeZoneGetName(CFTimeZoneRef tz) {
    CF_OBJC_FUNCDISPATCH0(CFTimeZoneGetTypeID(), CFStringRef, tz, "name");
    __CFGenericValidateType(tz, CFTimeZoneGetTypeID());
    return tz->_name;
}

CFDataRef CFTimeZoneGetData(CFTimeZoneRef tz) {
    CF_OBJC_FUNCDISPATCH0(CFTimeZoneGetTypeID(), CFDataRef, tz, "data");
    __CFGenericValidateType(tz, CFTimeZoneGetTypeID());
    return tz->_data;
}

/* This function converts CFAbsoluteTime to (Win32) SYSTEMTIME
 * (Aleksey Dukhnyakov)
 */
#if DEPLOYMENT_TARGET_WINDOWS
BOOL __CFTimeZoneGetWin32SystemTime(SYSTEMTIME * sys_time, CFAbsoluteTime time)
{
    LONGLONG l;
    FILETIME * ftime=(FILETIME*)&l;

    /*  seconds between 1601 and 1970 : 11644473600,
     *  seconds between 1970 and 2001 : 978307200,
     *  FILETIME - number of 100-nanosecond intervals since January 1, 1601
     */
    l=(LONGLONG)(time+11644473600LL+978307200)*10000000;
    if (FileTimeToSystemTime(ftime,sys_time))
        return TRUE;
    else
        return FALSE;
}
#endif

CFTimeInterval _CFTimeZoneGetDSTOffset(CFTimeZoneRef tz, CFAbsoluteTime at) {
#if !DEPLOYMENT_TARGET_WINDOWS
    // #warning this does not work for non-CFTimeZoneRefs
    CFIndex idx;
    idx = __CFBSearchTZPeriods(tz, at);
    // idx 0 is never returned if it is in DST
    if (__CFTZPeriodIsDST(&(tz->_periods[idx]))) {
        return __CFTZPeriodGMTOffset(&(tz->_periods[idx])) - __CFTZPeriodGMTOffset(&(tz->_periods[idx - 1]));
    }
#endif
    return 0.0;
}

// returns 0.0 if there is no data for the next switch after 'at'
CFAbsoluteTime _CFTimeZoneGetNextDSTSwitch(CFTimeZoneRef tz, CFAbsoluteTime at) {
#if !DEPLOYMENT_TARGET_WINDOWS
// #warning this does not work for non-CFTimeZoneRefs
    CFIndex idx;
    idx = __CFBSearchTZPeriods(tz, at);
    if (tz->_periodCnt <= idx + 1) {
        return 0.0;
    }
    return (CFAbsoluteTime)__CFTZPeriodStartSeconds(&(tz->_periods[idx + 1]));
#endif
    return 0.0;
}

CFTimeInterval CFTimeZoneGetSecondsFromGMT(CFTimeZoneRef tz, CFAbsoluteTime at) {
#if !DEPLOYMENT_TARGET_WINDOWS
    CFIndex idx;
    CF_OBJC_FUNCDISPATCH1(CFTimeZoneGetTypeID(), CFTimeInterval, tz, "_secondsFromGMTForAbsoluteTime:", at);
    __CFGenericValidateType(tz, CFTimeZoneGetTypeID());
    idx = __CFBSearchTZPeriods(tz, at);
    return __CFTZPeriodGMTOffset(&(tz->_periods[idx]));
#else
/* To calculate seconds from GMT, calculate current timezone time and
 * subtract GMT timnezone time
 * (Aleksey Dukhnyakov)
 */
    TIME_ZONE_INFORMATION tzi;
    FILETIME ftime1,ftime2;
    SYSTEMTIME stime0,stime1,stime2;
    LONGLONG * l1= (LONGLONG*)&ftime1;
    LONGLONG * l2= (LONGLONG*)&ftime2;
    CFRange range={0,sizeof(TIME_ZONE_INFORMATION)};
    double result;

    CF_OBJC_FUNCDISPATCH1(__kCFTimeZoneTypeID, CFTimeInterval, tz, "_secondsFromGMTForAbsoluteTime:", at);

    CFDataGetBytes(tz->_data,range,(UInt8*)&tzi);

    if (!__CFTimeZoneGetWin32SystemTime(&stime0,at) ||
        !SystemTimeToTzSpecificLocalTime(&tzi,&stime0,&stime1) ||
        !SystemTimeToFileTime(&stime1,&ftime1) )
    {
        CFAssert(0, __kCFLogAssertion, "Win32 system time/timezone failed !\n");
        return 0;
    }

    tzi.DaylightDate.wMonth=0;
    tzi.StandardDate.wMonth=0;
    tzi.StandardBias=0;
    tzi.DaylightBias=0;
    tzi.Bias=0;

	if ( !SystemTimeToTzSpecificLocalTime(&tzi,&stime0,&stime2) ||
            !SystemTimeToFileTime(&stime2,&ftime2))
    {
        CFAssert(0, __kCFLogAssertion, "Win32 system time/timezone failed !\n");
		return 0;
    }
    result=(double)((*l1-*l2)/10000000);
	return result;
#endif
}

CFStringRef CFTimeZoneCopyAbbreviation(CFTimeZoneRef tz, CFAbsoluteTime at) {
    CFStringRef result;
    CFIndex idx;
    CF_OBJC_FUNCDISPATCH1(CFTimeZoneGetTypeID(), CFStringRef, tz, "_abbreviationForAbsoluteTime:", at);
    __CFGenericValidateType(tz, CFTimeZoneGetTypeID());
    idx = __CFBSearchTZPeriods(tz, at);
    result = __CFTZPeriodAbbreviation(&(tz->_periods[idx]));
    return result ? (CFStringRef)CFRetain(result) : NULL;
}

Boolean CFTimeZoneIsDaylightSavingTime(CFTimeZoneRef tz, CFAbsoluteTime at) {
#if !DEPLOYMENT_TARGET_WINDOWS
    CFIndex idx;
    CF_OBJC_FUNCDISPATCH1(CFTimeZoneGetTypeID(), Boolean, tz, "_isDaylightSavingTimeForAbsoluteTime:", at);
    __CFGenericValidateType(tz, CFTimeZoneGetTypeID());
    idx = __CFBSearchTZPeriods(tz, at);
    return __CFTZPeriodIsDST(&(tz->_periods[idx]));
#else
/* Compare current timezone time and current timezone time without
 * transition to day light saving time
 * (Aleskey Dukhnyakov)
 */
    TIME_ZONE_INFORMATION tzi;
    SYSTEMTIME stime0,stime1,stime2;
    CFRange range={0,sizeof(TIME_ZONE_INFORMATION)};

    CF_OBJC_FUNCDISPATCH1(__kCFTimeZoneTypeID, Boolean, tz, "_isDaylightSavingTimeForAbsoluteTime:", at);

    CFDataGetBytes(tz->_data,range,(UInt8*)&tzi);

    if (!__CFTimeZoneGetWin32SystemTime(&stime0,at) ||
        !SystemTimeToTzSpecificLocalTime(&tzi,&stime0,&stime1)) {
        CFAssert(0, __kCFLogAssertion, "Win32 system time/timezone failed !\n");
        return FALSE;
    }

    tzi.DaylightDate.wMonth=0;
    tzi.StandardDate.wMonth=0;

	if ( !SystemTimeToTzSpecificLocalTime(&tzi,&stime0,&stime2)) {
        CFAssert(0, __kCFLogAssertion, "Win32 system time/timezone failed !\n");
		return FALSE;
    }

    if ( !memcmp(&stime1,&stime2,sizeof(stime1)) )
        return FALSE;

    return TRUE;
#endif
}

CFTimeInterval CFTimeZoneGetDaylightSavingTimeOffset(CFTimeZoneRef tz, CFAbsoluteTime at) {
    CF_OBJC_FUNCDISPATCH1(CFTimeZoneGetTypeID(), CFTimeInterval, tz, "_daylightSavingTimeOffsetForAbsoluteTime:", at);
    __CFGenericValidateType(tz, CFTimeZoneGetTypeID());
    CFIndex idx = __CFBSearchTZPeriods(tz, at);
    if (__CFTZPeriodIsDST(&(tz->_periods[idx]))) {
        CFTimeInterval offset = __CFTZPeriodGMTOffset(&(tz->_periods[idx]));
        if (idx + 1 < tz->_periodCnt) {
            return offset - __CFTZPeriodGMTOffset(&(tz->_periods[idx + 1]));
        } else if (0 < idx) {
            return offset - __CFTZPeriodGMTOffset(&(tz->_periods[idx - 1]));
        }
    }
    return 0.0;
}

CFAbsoluteTime CFTimeZoneGetNextDaylightSavingTimeTransition(CFTimeZoneRef tz, CFAbsoluteTime at) {
    CF_OBJC_FUNCDISPATCH1(CFTimeZoneGetTypeID(), CFTimeInterval, tz, "_nextDaylightSavingTimeTransitionAfterAbsoluteTime:", at);
    __CFGenericValidateType(tz, CFTimeZoneGetTypeID());
    CFIndex idx = __CFBSearchTZPeriods(tz, at);
    if (tz->_periodCnt <= idx + 1) {
        return 0.0;
    }
    return (CFAbsoluteTime)__CFTZPeriodStartSeconds(&(tz->_periods[idx + 1]));
}

enum {
	kCFTimeZoneNameStyleGeneric = 4,
	kCFTimeZoneNameStyleShortGeneric = 5
};

extern UCalendar *__CFCalendarCreateUCalendar(CFStringRef calendarID, CFStringRef localeID, CFTimeZoneRef tz);

#define BUFFER_SIZE 768

CFStringRef CFTimeZoneCopyLocalizedName(CFTimeZoneRef tz, CFTimeZoneNameStyle style, CFLocaleRef locale) {
    CF_OBJC_FUNCDISPATCH2(CFTimeZoneGetTypeID(), CFStringRef, tz, "localizedName:locale:", style, locale);
    __CFGenericValidateType(tz, CFTimeZoneGetTypeID());
    __CFGenericValidateType(locale, CFLocaleGetTypeID());


    CFStringRef localeID = CFLocaleGetIdentifier(locale);
    UCalendar *cal = __CFCalendarCreateUCalendar(NULL, localeID, tz);
    if (NULL == cal) {
        return NULL;
    }

    char buffer[BUFFER_SIZE];
    const char *cstr = CFStringGetCStringPtr(localeID, kCFStringEncodingASCII);
    if (NULL == cstr) {
        if (CFStringGetCString(localeID, buffer, BUFFER_SIZE, kCFStringEncodingASCII)) cstr = buffer;
    }
    if (NULL == cstr) {
        ucal_close(cal);
        return NULL;
    }

    UChar ubuffer[BUFFER_SIZE];
    UErrorCode status = U_ZERO_ERROR;
    int32_t cnt = ucal_getTimeZoneDisplayName(cal, (UCalendarDisplayNameType)style, cstr, ubuffer, BUFFER_SIZE, &status);
    ucal_close(cal);
    if (U_SUCCESS(status) && cnt <= BUFFER_SIZE) {
        return CFStringCreateWithCharacters(CFGetAllocator(tz), (const UniChar *)ubuffer, cnt);
    }
    return NULL;
}

static CFDictionaryRef __CFTimeZoneCopyCompatibilityDictionary(void) {
    CFDictionaryRef dict;
    __CFTimeZoneLockCompatibilityMapping();
    if (NULL == __CFTimeZoneCompatibilityMappingDict) {
	__CFTimeZoneCompatibilityMappingDict = CFDictionaryCreateMutable(kCFAllocatorSystemDefault, 112, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);

	// Empty string means delete/ignore these 
    }
    dict = __CFTimeZoneCompatibilityMappingDict ? (CFDictionaryRef)CFRetain(__CFTimeZoneCompatibilityMappingDict) : NULL;
    __CFTimeZoneUnlockCompatibilityMapping();
    return dict;
}

#undef TZZONEINFO
#undef TZZONELINK