Retro68/gcc/libgo/go/time/zoneinfo_android.go
Wolfgang Thaller 6fbf4226da gcc-9.1
2019-06-20 20:10:10 +02:00

81 lines
2.0 KiB
Go

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