src/time/zoneinfo_windows.go - go - Git at Google

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package time

 import (
 	"errors"
 	"internal/syscall/windows/registry"
 	"syscall"
 )

 var platformZoneSources []string // none: Windows uses system calls instead

 // TODO(rsc): Fall back to copy of zoneinfo files.

 // BUG(brainman,rsc): On Windows, the operating system does not provide complete
 // time zone information.
 // The implementation assumes that this year's rules for daylight savings
 // time apply to all previous and future years as well.

 // matchZoneKey checks if stdname and dstname match the corresponding key
 // values "MUI_Std" and MUI_Dlt" or "Std" and "Dlt" (the latter down-level
 // from Vista) in the kname key stored under the open registry key zones.
 func matchZoneKey(zones registry.Key, kname string, stdname, dstname string) (matched bool, err2 error) {
 	k, err := registry.OpenKey(zones, kname, registry.READ)
 	if err != nil {
 		return false, err
 	}
 	defer k.Close()

 	var std, dlt string
 	if err = registry.LoadRegLoadMUIString(); err == nil {
 		// Try MUI_Std and MUI_Dlt first, fallback to Std and Dlt if *any* error occurs
 		std, err = k.GetMUIStringValue("MUI_Std")
 		if err == nil {
 			dlt, err = k.GetMUIStringValue("MUI_Dlt")
 		}
 	}
 	if err != nil { // Fallback to Std and Dlt
 		if std, _, err = k.GetStringValue("Std"); err != nil {
 			return false, err
 		}
 		if dlt, _, err = k.GetStringValue("Dlt"); err != nil {
 			return false, err
 		}
 	}

 	if std != stdname {
 		return false, nil
 	}
 	if dlt != dstname && dstname != stdname {
 		return false, nil
 	}
 	return true, nil
 }

 // toEnglishName searches the registry for an English name of a time zone
 // whose zone names are stdname and dstname and returns the English name.
 func toEnglishName(stdname, dstname string) (string, error) {
 	k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones`, registry.ENUMERATE_SUB_KEYS|registry.QUERY_VALUE)
 	if err != nil {
 		return "", err
 	}
 	defer k.Close()

 	names, err := k.ReadSubKeyNames()
 	if err != nil {
 		return "", err
 	}
 	for _, name := range names {
 		matched, err := matchZoneKey(k, name, stdname, dstname)
 		if err == nil && matched {
 			return name, nil
 		}
 	}
 	return "", errors.New(`English name for time zone "` + stdname + `" not found in registry`)
 }

 // extractCAPS extracts capital letters from description desc.
 func extractCAPS(desc string) string {
 	var short []rune
 	for _, c := range desc {
 		if 'A' <= c && c <= 'Z' {
 			short = append(short, c)
 		}
 	}
 	return string(short)
 }

 // abbrev returns the abbreviations to use for the given zone z.
 func abbrev(z *syscall.Timezoneinformation) (std, dst string) {
 	stdName := syscall.UTF16ToString(z.StandardName[:])
 	a, ok := abbrs[stdName]
 	if !ok {
 		dstName := syscall.UTF16ToString(z.DaylightName[:])
 		// Perhaps stdName is not English. Try to convert it.
 		englishName, err := toEnglishName(stdName, dstName)
 		if err == nil {
 			a, ok = abbrs[englishName]
 			if ok {
 				return a.std, a.dst
 			}
 		}
 		// fallback to using capital letters
 		return extractCAPS(stdName), extractCAPS(dstName)
 	}
 	return a.std, a.dst
 }

 // pseudoUnix returns the pseudo-Unix time (seconds since Jan 1 1970 *LOCAL TIME*)
 // denoted by the system date+time d in the given year.
 // It is up to the caller to convert this local time into a UTC-based time.
 func pseudoUnix(year int, d *syscall.Systemtime) int64 {
 	// Windows specifies daylight savings information in "day in month" format:
 	// d.Month is month number (1-12)
 	// d.DayOfWeek is appropriate weekday (Sunday=0 to Saturday=6)
 	// d.Day is week within the month (1 to 5, where 5 is last week of the month)
 	// d.Hour, d.Minute and d.Second are absolute time
 	day := 1
 	t := Date(year, Month(d.Month), day, int(d.Hour), int(d.Minute), int(d.Second), 0, UTC)
 	i := int(d.DayOfWeek) - int(t.Weekday())
 	if i < 0 {
 		i += 7
 	}
 	day += i
 	if week := int(d.Day) - 1; week < 4 {
 		day += week * 7
 	} else {
 		// "Last" instance of the day.
 		day += 4 * 7
 		if day > daysIn(Month(d.Month), year) {
 			day -= 7
 		}
 	}
 	return t.sec() + int64(day-1)*secondsPerDay + internalToUnix
 }

 func initLocalFromTZI(i *syscall.Timezoneinformation) {
 	l := &localLoc

 	l.name = "Local"

 	nzone := 1
 	if i.StandardDate.Month > 0 {
 		nzone++
 	}
 	l.zone = make([]zone, nzone)

 	stdname, dstname := abbrev(i)

 	std := &l.zone[0]
 	std.name = stdname
 	if nzone == 1 {
 		// No daylight savings.
 		std.offset = -int(i.Bias) * 60
 		l.cacheStart = alpha
 		l.cacheEnd = omega
 		l.cacheZone = std
 		l.tx = make([]zoneTrans, 1)
 		l.tx[0].when = l.cacheStart
 		l.tx[0].index = 0
 		return
 	}

 	// StandardBias must be ignored if StandardDate is not set,
 	// so this computation is delayed until after the nzone==1
 	// return above.
 	std.offset = -int(i.Bias+i.StandardBias) * 60

 	dst := &l.zone[1]
 	dst.name = dstname
 	dst.offset = -int(i.Bias+i.DaylightBias) * 60
 	dst.isDST = true

 	// Arrange so that d0 is first transition date, d1 second,
 	// i0 is index of zone after first transition, i1 second.
 	d0 := &i.StandardDate
 	d1 := &i.DaylightDate
 	i0 := 0
 	i1 := 1
 	if d0.Month > d1.Month {
 		d0, d1 = d1, d0
 		i0, i1 = i1, i0
 	}

 	// 2 tx per year, 100 years on each side of this year
 	l.tx = make([]zoneTrans, 400)

 	t := Now().UTC()
 	year := t.Year()
 	txi := 0
 	for y := year - 100; y < year+100; y++ {
 		tx := &l.tx[txi]
 		tx.when = pseudoUnix(y, d0) - int64(l.zone[i1].offset)
 		tx.index = uint8(i0)
 		txi++

 		tx = &l.tx[txi]
 		tx.when = pseudoUnix(y, d1) - int64(l.zone[i0].offset)
 		tx.index = uint8(i1)
 		txi++
 	}
 }

 var usPacific = syscall.Timezoneinformation{
 	Bias: 8 * 60,
 	StandardName: [32]uint16{
 		'P', 'a', 'c', 'i', 'f', 'i', 'c', ' ', 'S', 't', 'a', 'n', 'd', 'a', 'r', 'd', ' ', 'T', 'i', 'm', 'e',
 	},
 	StandardDate: syscall.Systemtime{Month: 11, Day: 1, Hour: 2},
 	DaylightName: [32]uint16{
 		'P', 'a', 'c', 'i', 'f', 'i', 'c', ' ', 'D', 'a', 'y', 'l', 'i', 'g', 'h', 't', ' ', 'T', 'i', 'm', 'e',
 	},
 	DaylightDate: syscall.Systemtime{Month: 3, Day: 2, Hour: 2},
 	DaylightBias: -60,
 }

 var aus = syscall.Timezoneinformation{
 	Bias: -10 * 60,
 	StandardName: [32]uint16{
 		'A', 'U', 'S', ' ', 'E', 'a', 's', 't', 'e', 'r', 'n', ' ', 'S', 't', 'a', 'n', 'd', 'a', 'r', 'd', ' ', 'T', 'i', 'm', 'e',
 	},
 	StandardDate: syscall.Systemtime{Month: 4, Day: 1, Hour: 3},
 	DaylightName: [32]uint16{
 		'A', 'U', 'S', ' ', 'E', 'a', 's', 't', 'e', 'r', 'n', ' ', 'D', 'a', 'y', 'l', 'i', 'g', 'h', 't', ' ', 'T', 'i', 'm', 'e',
 	},
 	DaylightDate: syscall.Systemtime{Month: 10, Day: 1, Hour: 2},
 	DaylightBias: -60,
 }

 func initLocal() {
 	var i syscall.Timezoneinformation
 	if _, err := syscall.GetTimeZoneInformation(&i); err != nil {
 		localLoc.name = "UTC"
 		return
 	}
 	initLocalFromTZI(&i)
 }
	// Copyright 2009 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package time

	import (
	"errors"
	"internal/syscall/windows/registry"
	"syscall"
	)

	var platformZoneSources []string // none: Windows uses system calls instead

	// TODO(rsc): Fall back to copy of zoneinfo files.

	// BUG(brainman,rsc): On Windows, the operating system does not provide complete
	// time zone information.
	// The implementation assumes that this year's rules for daylight savings
	// time apply to all previous and future years as well.

	// matchZoneKey checks if stdname and dstname match the corresponding key
	// values "MUI_Std" and MUI_Dlt" or "Std" and "Dlt" (the latter down-level
	// from Vista) in the kname key stored under the open registry key zones.
	func matchZoneKey(zones registry.Key, kname string, stdname, dstname string) (matched bool, err2 error) {
	k, err := registry.OpenKey(zones, kname, registry.READ)
	if err != nil {
	return false, err
	}
	defer k.Close()

	var std, dlt string
	if err = registry.LoadRegLoadMUIString(); err == nil {
	// Try MUI_Std and MUI_Dlt first, fallback to Std and Dlt if any error occurs
	std, err = k.GetMUIStringValue("MUI_Std")
	if err == nil {
	dlt, err = k.GetMUIStringValue("MUI_Dlt")
	}
	}
	if err != nil { // Fallback to Std and Dlt
	if std, _, err = k.GetStringValue("Std"); err != nil {
	return false, err
	}
	if dlt, _, err = k.GetStringValue("Dlt"); err != nil {
	return false, err
	}
	}

	if std != stdname {
	return false, nil
	}
	if dlt != dstname && dstname != stdname {
	return false, nil
	}
	return true, nil
	}

	// toEnglishName searches the registry for an English name of a time zone
	// whose zone names are stdname and dstname and returns the English name.
	func toEnglishName(stdname, dstname string) (string, error) {
	k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones`, registry.ENUMERATE_SUB_KEYS\|registry.QUERY_VALUE)
	if err != nil {
	return "", err
	}
	defer k.Close()

	names, err := k.ReadSubKeyNames()
	if err != nil {
	return "", err
	}
	for _, name := range names {
	matched, err := matchZoneKey(k, name, stdname, dstname)
	if err == nil && matched {
	return name, nil
	}
	}
	return "", errors.New(`English name for time zone "` + stdname + `" not found in registry`)
	}

	// extractCAPS extracts capital letters from description desc.
	func extractCAPS(desc string) string {
	var short []rune
	for _, c := range desc {
	if 'A' <= c && c <= 'Z' {
	short = append(short, c)
	}
	}
	return string(short)
	}

	// abbrev returns the abbreviations to use for the given zone z.
	func abbrev(z *syscall.Timezoneinformation) (std, dst string) {
	stdName := syscall.UTF16ToString(z.StandardName[:])
	a, ok := abbrs[stdName]
	if !ok {
	dstName := syscall.UTF16ToString(z.DaylightName[:])
	// Perhaps stdName is not English. Try to convert it.
	englishName, err := toEnglishName(stdName, dstName)
	if err == nil {
	a, ok = abbrs[englishName]
	if ok {
	return a.std, a.dst
	}
	}
	// fallback to using capital letters
	return extractCAPS(stdName), extractCAPS(dstName)
	}
	return a.std, a.dst
	}

	// pseudoUnix returns the pseudo-Unix time (seconds since Jan 1 1970 LOCAL TIME)
	// denoted by the system date+time d in the given year.
	// It is up to the caller to convert this local time into a UTC-based time.
	func pseudoUnix(year int, d *syscall.Systemtime) int64 {
	// Windows specifies daylight savings information in "day in month" format:
	// d.Month is month number (1-12)
	// d.DayOfWeek is appropriate weekday (Sunday=0 to Saturday=6)
	// d.Day is week within the month (1 to 5, where 5 is last week of the month)
	// d.Hour, d.Minute and d.Second are absolute time
	day := 1
	t := Date(year, Month(d.Month), day, int(d.Hour), int(d.Minute), int(d.Second), 0, UTC)
	i := int(d.DayOfWeek) - int(t.Weekday())
	if i < 0 {
	i += 7
	}
	day += i
	if week := int(d.Day) - 1; week < 4 {
	day += week * 7
	} else {
	// "Last" instance of the day.
	day += 4 * 7
	if day > daysIn(Month(d.Month), year) {
	day -= 7
	}
	}
	return t.sec() + int64(day-1)*secondsPerDay + internalToUnix
	}

	func initLocalFromTZI(i *syscall.Timezoneinformation) {
	l := &localLoc

	l.name = "Local"

	nzone := 1
	if i.StandardDate.Month > 0 {
	nzone++
	}
	l.zone = make([]zone, nzone)

	stdname, dstname := abbrev(i)

	std := &l.zone[0]
	std.name = stdname
	if nzone == 1 {
	// No daylight savings.
	std.offset = -int(i.Bias) * 60
	l.cacheStart = alpha
	l.cacheEnd = omega
	l.cacheZone = std
	l.tx = make([]zoneTrans, 1)
	l.tx[0].when = l.cacheStart
	l.tx[0].index = 0
	return
	}

	// StandardBias must be ignored if StandardDate is not set,
	// so this computation is delayed until after the nzone==1
	// return above.
	std.offset = -int(i.Bias+i.StandardBias) * 60

	dst := &l.zone[1]
	dst.name = dstname
	dst.offset = -int(i.Bias+i.DaylightBias) * 60
	dst.isDST = true

	// Arrange so that d0 is first transition date, d1 second,
	// i0 is index of zone after first transition, i1 second.
	d0 := &i.StandardDate
	d1 := &i.DaylightDate
	i0 := 0
	i1 := 1
	if d0.Month > d1.Month {
	d0, d1 = d1, d0
	i0, i1 = i1, i0
	}

	// 2 tx per year, 100 years on each side of this year
	l.tx = make([]zoneTrans, 400)

	t := Now().UTC()
	year := t.Year()
	txi := 0
	for y := year - 100; y < year+100; y++ {
	tx := &l.tx[txi]
	tx.when = pseudoUnix(y, d0) - int64(l.zone[i1].offset)
	tx.index = uint8(i0)
	txi++

	tx = &l.tx[txi]
	tx.when = pseudoUnix(y, d1) - int64(l.zone[i0].offset)
	tx.index = uint8(i1)
	txi++
	}
	}

	var usPacific = syscall.Timezoneinformation{
	Bias: 8 * 60,
	StandardName: [32]uint16{
	'P', 'a', 'c', 'i', 'f', 'i', 'c', ' ', 'S', 't', 'a', 'n', 'd', 'a', 'r', 'd', ' ', 'T', 'i', 'm', 'e',
	},
	StandardDate: syscall.Systemtime{Month: 11, Day: 1, Hour: 2},
	DaylightName: [32]uint16{
	'P', 'a', 'c', 'i', 'f', 'i', 'c', ' ', 'D', 'a', 'y', 'l', 'i', 'g', 'h', 't', ' ', 'T', 'i', 'm', 'e',
	},
	DaylightDate: syscall.Systemtime{Month: 3, Day: 2, Hour: 2},
	DaylightBias: -60,
	}

	var aus = syscall.Timezoneinformation{
	Bias: -10 * 60,
	StandardName: [32]uint16{
	'A', 'U', 'S', ' ', 'E', 'a', 's', 't', 'e', 'r', 'n', ' ', 'S', 't', 'a', 'n', 'd', 'a', 'r', 'd', ' ', 'T', 'i', 'm', 'e',
	},
	StandardDate: syscall.Systemtime{Month: 4, Day: 1, Hour: 3},
	DaylightName: [32]uint16{
	'A', 'U', 'S', ' ', 'E', 'a', 's', 't', 'e', 'r', 'n', ' ', 'D', 'a', 'y', 'l', 'i', 'g', 'h', 't', ' ', 'T', 'i', 'm', 'e',
	},
	DaylightDate: syscall.Systemtime{Month: 10, Day: 1, Hour: 2},
	DaylightBias: -60,
	}

	func initLocal() {
	var i syscall.Timezoneinformation
	if _, err := syscall.GetTimeZoneInformation(&i); err != nil {
	localLoc.name = "UTC"
	return
	}
	initLocalFromTZI(&i)
	}