// Copyright 2016 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 the "tzdata" packed timezone file used on Android.
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// The format is lifted from ZoneInfoDB.java and ZoneInfo.java in
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// java/libcore/util in the AOSP.
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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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var zoneSources = []string{
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"/system/usr/share/zoneinfo/tzdata",
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"/data/misc/zoneinfo/current/tzdata",
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runtime.GOROOT() + "/lib/time/zoneinfo.zip",
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}
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func initLocal() {
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// TODO(elias.naur): getprop persist.sys.timezone
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localLoc = *UTC
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}
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func init() {
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loadTzinfoFromTzdata = androidLoadTzinfoFromTzdata
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}
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func androidLoadTzinfoFromTzdata(file, name string) ([]byte, error) {
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const (
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headersize = 12 + 3*4
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namesize = 40
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entrysize = namesize + 3*4
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)
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if len(name) > namesize {
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return nil, errors.New(name + " is longer than the maximum zone name length (40 bytes)")
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}
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fd, err := open(file)
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if err != nil {
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return nil, err
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}
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defer closefd(fd)
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buf := make([]byte, headersize)
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if err := preadn(fd, buf, 0); err != nil {
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return nil, errors.New("corrupt tzdata file " + file)
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}
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d := dataIO{buf, false}
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if magic := d.read(6); string(magic) != "tzdata" {
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return nil, errors.New("corrupt tzdata file " + file)
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}
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d = dataIO{buf[12:], false}
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indexOff, _ := d.big4()
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dataOff, _ := d.big4()
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indexSize := dataOff - indexOff
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entrycount := indexSize / entrysize
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buf = make([]byte, indexSize)
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if err := preadn(fd, buf, int(indexOff)); err != nil {
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return nil, errors.New("corrupt tzdata file " + file)
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}
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for i := 0; i < int(entrycount); i++ {
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entry := buf[i*entrysize : (i+1)*entrysize]
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// len(name) <= namesize is checked at function entry
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if string(entry[:len(name)]) != name {
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continue
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}
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d := dataIO{entry[namesize:], false}
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off, _ := d.big4()
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size, _ := d.big4()
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buf := make([]byte, size)
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if err := preadn(fd, buf, int(off+dataOff)); err != nil {
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return nil, errors.New("corrupt tzdata file " + file)
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}
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return buf, nil
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}
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return nil, syscall.ENOENT
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}
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