157 lines
3.1 KiB
Go
157 lines
3.1 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Parse Plan 9 timezone(2) files.
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package time
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import (
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"errors"
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"runtime"
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"syscall"
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)
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func isSpace(r rune) bool {
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return r == ' ' || r == '\t' || r == '\n'
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}
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// Copied from strings to avoid a dependency.
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func fields(s string) []string {
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// First count the fields.
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n := 0
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inField := false
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for _, rune := range s {
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wasInField := inField
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inField = !isSpace(rune)
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if inField && !wasInField {
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n++
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}
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}
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// Now create them.
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a := make([]string, n)
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na := 0
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fieldStart := -1 // Set to -1 when looking for start of field.
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for i, rune := range s {
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if isSpace(rune) {
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if fieldStart >= 0 {
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a[na] = s[fieldStart:i]
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na++
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fieldStart = -1
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}
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} else if fieldStart == -1 {
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fieldStart = i
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}
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}
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if fieldStart >= 0 { // Last field might end at EOF.
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a[na] = s[fieldStart:]
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}
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return a
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}
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func loadZoneDataPlan9(s string) (l *Location, err error) {
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f := fields(s)
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if len(f) < 4 {
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if len(f) == 2 && f[0] == "GMT" {
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return UTC, nil
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}
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return nil, badData
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}
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var zones [2]zone
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// standard timezone offset
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o, err := atoi(f[1])
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if err != nil {
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return nil, badData
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}
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zones[0] = zone{name: f[0], offset: o, isDST: false}
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// alternate timezone offset
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o, err = atoi(f[3])
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if err != nil {
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return nil, badData
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}
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zones[1] = zone{name: f[2], offset: o, isDST: true}
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// transition time pairs
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var tx []zoneTrans
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f = f[4:]
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for i := 0; i < len(f); i++ {
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zi := 0
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if i%2 == 0 {
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zi = 1
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}
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t, err := atoi(f[i])
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if err != nil {
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return nil, badData
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}
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t -= zones[0].offset
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tx = append(tx, zoneTrans{when: int64(t), index: uint8(zi)})
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}
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// Committed to succeed.
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l = &Location{zone: zones[:], tx: tx}
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// Fill in the cache with information about right now,
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// since that will be the most common lookup.
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sec, _ := now()
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for i := range tx {
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if tx[i].when <= sec && (i+1 == len(tx) || sec < tx[i+1].when) {
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l.cacheStart = tx[i].when
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l.cacheEnd = 1<<63 - 1
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if i+1 < len(tx) {
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l.cacheEnd = tx[i+1].when
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}
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l.cacheZone = &l.zone[tx[i].index]
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}
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}
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return l, nil
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}
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func loadZoneFilePlan9(name string) (*Location, error) {
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b, err := readFile(name)
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if err != nil {
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return nil, err
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}
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return loadZoneDataPlan9(string(b))
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}
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func initTestingZone() {
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z, err := loadLocation("America/Los_Angeles")
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if err != nil {
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panic("cannot load America/Los_Angeles for testing: " + err.Error())
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}
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z.name = "Local"
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localLoc = *z
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}
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func initLocal() {
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t, ok := syscall.Getenv("timezone")
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if ok {
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if z, err := loadZoneDataPlan9(t); err == nil {
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localLoc = *z
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return
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}
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} else {
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if z, err := loadZoneFilePlan9("/adm/timezone/local"); err == nil {
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localLoc = *z
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localLoc.name = "Local"
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return
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}
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}
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// Fall back to UTC.
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localLoc.name = "UTC"
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}
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func loadLocation(name string) (*Location, error) {
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if z, err := loadZoneFile(runtime.GOROOT()+"/lib/time/zoneinfo.zip", name); err == nil {
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z.name = name
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return z, nil
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}
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return nil, errors.New("unknown time zone " + name)
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}
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