gcc/libgo/go/time/zoneinfo_windows.go

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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"
"runtime"
"syscall"
"unsafe"
)
//go:generate go run genzabbrs.go -output zoneinfo_abbrs_windows.go
// 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.
// getKeyValue retrieves the string value kname associated with the open registry key kh.
func getKeyValue(kh syscall.Handle, kname string) (string, error) {
var buf [50]uint16 // buf needs to be large enough to fit zone descriptions
var typ uint32
n := uint32(len(buf) * 2) // RegQueryValueEx's signature expects array of bytes, not uint16
p, _ := syscall.UTF16PtrFromString(kname)
if err := syscall.RegQueryValueEx(kh, p, nil, &typ, (*byte)(unsafe.Pointer(&buf[0])), &n); err != nil {
return "", err
}
if typ != syscall.REG_SZ { // null terminated strings only
return "", errors.New("Key is not string")
}
return syscall.UTF16ToString(buf[:]), nil
}
// matchZoneKey checks if stdname and dstname match the corresponding "Std"
// and "Dlt" key values in the kname key stored under the open registry key zones.
func matchZoneKey(zones syscall.Handle, kname string, stdname, dstname string) (matched bool, err2 error) {
var h syscall.Handle
p, _ := syscall.UTF16PtrFromString(kname)
if err := syscall.RegOpenKeyEx(zones, p, 0, syscall.KEY_READ, &h); err != nil {
return false, err
}
defer syscall.RegCloseKey(h)
s, err := getKeyValue(h, "Std")
if err != nil {
return false, err
}
if s != stdname {
return false, nil
}
s, err = getKeyValue(h, "Dlt")
if err != nil {
return false, err
}
if s != 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) {
var zones syscall.Handle
p, _ := syscall.UTF16PtrFromString(`SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones`)
if err := syscall.RegOpenKeyEx(syscall.HKEY_LOCAL_MACHINE, p, 0, syscall.KEY_READ, &zones); err != nil {
return "", err
}
defer syscall.RegCloseKey(zones)
var count uint32
if err := syscall.RegQueryInfoKey(zones, nil, nil, nil, &count, nil, nil, nil, nil, nil, nil, nil); err != nil {
return "", err
}
var buf [50]uint16 // buf needs to be large enough to fit zone descriptions
for i := uint32(0); i < count; i++ {
n := uint32(len(buf))
if syscall.RegEnumKeyEx(zones, i, &buf[0], &n, nil, nil, nil, nil) != nil {
continue
}
kname := syscall.UTF16ToString(buf[:])
matched, err := matchZoneKey(zones, kname, stdname, dstname)
if err == nil && matched {
return kname, 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, rune(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
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 initTestingZone() {
initLocalFromTZI(&usPacific)
}
func initAusTestingZone() {
initLocalFromTZI(&aus)
}
func initLocal() {
var i syscall.Timezoneinformation
if _, err := syscall.GetTimeZoneInformation(&i); err != nil {
localLoc.name = "UTC"
return
}
initLocalFromTZI(&i)
}
func loadLocation(name string) (*Location, error) {
if z, err := loadZoneFile(runtime.GOROOT()+`\lib\time\zoneinfo.zip`, name); err == nil {
z.name = name
return z, nil
}
return nil, errors.New("unknown time zone " + name)
}
func forceZipFileForTesting(zipOnly bool) {
// We only use the zip file anyway.
}