libgo/go/time/zoneinfo_windows.go

   1 // Copyright 2009 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package time
   6
   7 import (
   8         "errors"
   9         "internal/syscall/windows/registry"
  10         "runtime"
  11         "syscall"
  12 )
  13
  14 // TODO(rsc): Fall back to copy of zoneinfo files.
  15
  16 // BUG(brainman,rsc): On Windows, the operating system does not provide complete
  17 // time zone information.
  18 // The implementation assumes that this year's rules for daylight savings
  19 // time apply to all previous and future years as well.
  20
  21 // matchZoneKey checks if stdname and dstname match the corresponding key
  22 // values "MUI_Std" and MUI_Dlt" or "Std" and "Dlt" (the latter down-level
  23 // from Vista) in the kname key stored under the open registry key zones.
  24 func matchZoneKey(zones registry.Key, kname string, stdname, dstname string) (matched bool, err2 error) {
  25         k, err := registry.OpenKey(zones, kname, registry.READ)
  26         if err != nil {
  27                 return false, err
  28         }
  29         defer k.Close()
  30
  31         var std, dlt string
  32         if err = registry.LoadRegLoadMUIString(); err == nil {
  33                 // Try MUI_Std and MUI_Dlt first, fallback to Std and Dlt if *any* error occurs
  34                 std, err = k.GetMUIStringValue("MUI_Std")
  35                 if err == nil {
  36                         dlt, err = k.GetMUIStringValue("MUI_Dlt")
  37                 }
  38         }
  39         if err != nil { // Fallback to Std and Dlt
  40                 if std, _, err = k.GetStringValue("Std"); err != nil {
  41                         return false, err
  42                 }
  43                 if dlt, _, err = k.GetStringValue("Dlt"); err != nil {
  44                         return false, err
  45                 }
  46         }
  47
  48         if std != stdname {
  49                 return false, nil
  50         }
  51         if dlt != dstname && dstname != stdname {
  52                 return false, nil
  53         }
  54         return true, nil
  55 }
  56
  57 // toEnglishName searches the registry for an English name of a time zone
  58 // whose zone names are stdname and dstname and returns the English name.
  59 func toEnglishName(stdname, dstname string) (string, error) {
  60         k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones`, registry.ENUMERATE_SUB_KEYS|registry.QUERY_VALUE)
  61         if err != nil {
  62                 return "", err
  63         }
  64         defer k.Close()
  65
  66         names, err := k.ReadSubKeyNames(-1)
  67         if err != nil {
  68                 return "", err
  69         }
  70         for _, name := range names {
  71                 matched, err := matchZoneKey(k, name, stdname, dstname)
  72                 if err == nil && matched {
  73                         return name, nil
  74                 }
  75         }
  76         return "", errors.New(`English name for time zone "` + stdname + `" not found in registry`)
  77 }
  78
  79 // extractCAPS extracts capital letters from description desc.
  80 func extractCAPS(desc string) string {
  81         var short []rune
  82         for _, c := range desc {
  83                 if 'A' <= c && c <= 'Z' {
  84                         short = append(short, c)
  85                 }
  86         }
  87         return string(short)
  88 }
  89
  90 // abbrev returns the abbreviations to use for the given zone z.
  91 func abbrev(z *syscall.Timezoneinformation) (std, dst string) {
  92         stdName := syscall.UTF16ToString(z.StandardName[:])
  93         a, ok := abbrs[stdName]
  94         if !ok {
  95                 dstName := syscall.UTF16ToString(z.DaylightName[:])
  96                 // Perhaps stdName is not English. Try to convert it.
  97                 englishName, err := toEnglishName(stdName, dstName)
  98                 if err == nil {
  99                         a, ok = abbrs[englishName]
 100                         if ok {
 101                                 return a.std, a.dst
 102                         }
 103                 }
 104                 // fallback to using capital letters
 105                 return extractCAPS(stdName), extractCAPS(dstName)
 106         }
 107         return a.std, a.dst
 108 }
 109
 110 // pseudoUnix returns the pseudo-Unix time (seconds since Jan 1 1970 *LOCAL TIME*)
 111 // denoted by the system date+time d in the given year.
 112 // It is up to the caller to convert this local time into a UTC-based time.
 113 func pseudoUnix(year int, d *syscall.Systemtime) int64 {
 114         // Windows specifies daylight savings information in "day in month" format:
 115         // d.Month is month number (1-12)
 116         // d.DayOfWeek is appropriate weekday (Sunday=0 to Saturday=6)
 117         // d.Day is week within the month (1 to 5, where 5 is last week of the month)
 118         // d.Hour, d.Minute and d.Second are absolute time
 119         day := 1
 120         t := Date(year, Month(d.Month), day, int(d.Hour), int(d.Minute), int(d.Second), 0, UTC)
 121         i := int(d.DayOfWeek) - int(t.Weekday())
 122         if i < 0 {
 123                 i += 7
 124         }
 125         day += i
 126         if week := int(d.Day) - 1; week < 4 {
 127                 day += week * 7
 128         } else {
 129                 // "Last" instance of the day.
 130                 day += 4 * 7
 131                 if day > daysIn(Month(d.Month), year) {
 132                         day -= 7
 133                 }
 134         }
 135         return t.sec + int64(day-1)*secondsPerDay + internalToUnix
 136 }
 137
 138 func initLocalFromTZI(i *syscall.Timezoneinformation) {
 139         l := &localLoc
 140
 141         l.name = "Local"
 142
 143         nzone := 1
 144         if i.StandardDate.Month > 0 {
 145                 nzone++
 146         }
 147         l.zone = make([]zone, nzone)
 148
 149         stdname, dstname := abbrev(i)
 150
 151         std := &l.zone[0]
 152         std.name = stdname
 153         if nzone == 1 {
 154                 // No daylight savings.
 155                 std.offset = -int(i.Bias) * 60
 156                 l.cacheStart = alpha
 157                 l.cacheEnd = omega
 158                 l.cacheZone = std
 159                 l.tx = make([]zoneTrans, 1)
 160                 l.tx[0].when = l.cacheStart
 161                 l.tx[0].index = 0
 162                 return
 163         }
 164
 165         // StandardBias must be ignored if StandardDate is not set,
 166         // so this computation is delayed until after the nzone==1
 167         // return above.
 168         std.offset = -int(i.Bias+i.StandardBias) * 60
 169
 170         dst := &l.zone[1]
 171         dst.name = dstname
 172         dst.offset = -int(i.Bias+i.DaylightBias) * 60
 173         dst.isDST = true
 174
 175         // Arrange so that d0 is first transition date, d1 second,
 176         // i0 is index of zone after first transition, i1 second.
 177         d0 := &i.StandardDate
 178         d1 := &i.DaylightDate
 179         i0 := 0
 180         i1 := 1
 181         if d0.Month > d1.Month {
 182                 d0, d1 = d1, d0
 183                 i0, i1 = i1, i0
 184         }
 185
 186         // 2 tx per year, 100 years on each side of this year
 187         l.tx = make([]zoneTrans, 400)
 188
 189         t := Now().UTC()
 190         year := t.Year()
 191         txi := 0
 192         for y := year - 100; y < year+100; y++ {
 193                 tx := &l.tx[txi]
 194                 tx.when = pseudoUnix(y, d0) - int64(l.zone[i1].offset)
 195                 tx.index = uint8(i0)
 196                 txi++
 197
 198                 tx = &l.tx[txi]
 199                 tx.when = pseudoUnix(y, d1) - int64(l.zone[i0].offset)
 200                 tx.index = uint8(i1)
 201                 txi++
 202         }
 203 }
 204
 205 var usPacific = syscall.Timezoneinformation{
 206         Bias: 8 * 60,
 207         StandardName: [32]uint16{
 208                 'P', 'a', 'c', 'i', 'f', 'i', 'c', ' ', 'S', 't', 'a', 'n', 'd', 'a', 'r', 'd', ' ', 'T', 'i', 'm', 'e',
 209         },
 210         StandardDate: syscall.Systemtime{Month: 11, Day: 1, Hour: 2},
 211         DaylightName: [32]uint16{
 212                 'P', 'a', 'c', 'i', 'f', 'i', 'c', ' ', 'D', 'a', 'y', 'l', 'i', 'g', 'h', 't', ' ', 'T', 'i', 'm', 'e',
 213         },
 214         DaylightDate: syscall.Systemtime{Month: 3, Day: 2, Hour: 2},
 215         DaylightBias: -60,
 216 }
 217
 218 var aus = syscall.Timezoneinformation{
 219         Bias: -10 * 60,
 220         StandardName: [32]uint16{
 221                 'A', 'U', 'S', ' ', 'E', 'a', 's', 't', 'e', 'r', 'n', ' ', 'S', 't', 'a', 'n', 'd', 'a', 'r', 'd', ' ', 'T', 'i', 'm', 'e',
 222         },
 223         StandardDate: syscall.Systemtime{Month: 4, Day: 1, Hour: 3},
 224         DaylightName: [32]uint16{
 225                 'A', 'U', 'S', ' ', 'E', 'a', 's', 't', 'e', 'r', 'n', ' ', 'D', 'a', 'y', 'l', 'i', 'g', 'h', 't', ' ', 'T', 'i', 'm', 'e',
 226         },
 227         DaylightDate: syscall.Systemtime{Month: 10, Day: 1, Hour: 2},
 228         DaylightBias: -60,
 229 }
 230
 231 func initTestingZone() {
 232         initLocalFromTZI(&usPacific)
 233 }
 234
 235 func initAusTestingZone() {
 236         initLocalFromTZI(&aus)
 237 }
 238
 239 func initLocal() {
 240         var i syscall.Timezoneinformation
 241         if _, err := syscall.GetTimeZoneInformation(&i); err != nil {
 242                 localLoc.name = "UTC"
 243                 return
 244         }
 245         initLocalFromTZI(&i)
 246 }
 247
 248 func loadLocation(name string) (*Location, error) {
 249         z, err := loadZoneFile(runtime.GOROOT()+`\lib\time\zoneinfo.zip`, name)
 250         if err != nil {
 251                 return nil, err
 252         }
 253         z.name = name
 254         return z, nil
 255 }
 256
 257 func forceZipFileForTesting(zipOnly bool) {
 258         // We only use the zip file anyway.
 259 }