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// +build darwin,386 darwin,amd64 dragonfly freebsd linux nacl netbsd openbsd solaris
6
7// Parse "zoneinfo" time zone file.
8// This is a fairly standard file format used on OS X, Linux, BSD, Sun, and others.
9// See tzfile(5), http://en.wikipedia.org/wiki/Zoneinfo,
10// and ftp://munnari.oz.au/pub/oldtz/
11
12package time
13
14import (
15	"errors"
16	"runtime"
17	"syscall"
18)
19
20func initTestingZone() {
21	syscall.Setenv("TZ", "America/Los_Angeles")
22	initLocal()
23}
24
25// Many systems use /usr/share/zoneinfo, Solaris 2 has
26// /usr/share/lib/zoneinfo, IRIX 6 has /usr/lib/locale/TZ.
27var zoneDirs = []string{
28	"/usr/share/zoneinfo/",
29	"/usr/share/lib/zoneinfo/",
30	"/usr/lib/locale/TZ/",
31	runtime.GOROOT() + "/lib/time/zoneinfo.zip",
32}
33
34var origZoneDirs = zoneDirs
35
36func forceZipFileForTesting(zipOnly bool) {
37	zoneDirs = make([]string, len(origZoneDirs))
38	copy(zoneDirs, origZoneDirs)
39	if zipOnly {
40		for i := 0; i < len(zoneDirs)-1; i++ {
41			zoneDirs[i] = "/XXXNOEXIST"
42		}
43	}
44}
45
46func initLocal() {
47	// consult $TZ to find the time zone to use.
48	// no $TZ means use the system default /etc/localtime.
49	// $TZ="" means use UTC.
50	// $TZ="foo" means use /usr/share/zoneinfo/foo.
51
52	tz, ok := syscall.Getenv("TZ")
53	switch {
54	case !ok:
55		z, err := loadZoneFile("", "/etc/localtime")
56		if err == nil {
57			localLoc = *z
58			localLoc.name = "Local"
59			return
60		}
61	case tz != "" && tz != "UTC":
62		if z, err := loadLocation(tz); err == nil {
63			localLoc = *z
64			return
65		}
66	}
67
68	// Fall back to UTC.
69	localLoc.name = "UTC"
70}
71
72func loadLocation(name string) (*Location, error) {
73	var firstErr error
74	for _, zoneDir := range zoneDirs {
75		if z, err := loadZoneFile(zoneDir, name); err == nil {
76			z.name = name
77			return z, nil
78		} else if firstErr == nil && !isNotExist(err) {
79			firstErr = err
80		}
81	}
82	if firstErr != nil {
83		return nil, firstErr
84	}
85	return nil, errors.New("unknown time zone " + name)
86}
87