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// 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" 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
// 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)
}
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