github.com/tidwall/go@v0.0.0-20170415222209-6694a6888b7d/src/time/zoneinfo_unix.go (about)

     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,!android 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  
    12  package time
    13  
    14  import (
    15  	"errors"
    16  	"runtime"
    17  	"syscall"
    18  )
    19  
    20  func initTestingZone() {
    21  	z, err := loadZoneFile(runtime.GOROOT()+"/lib/time/zoneinfo.zip", "America/Los_Angeles")
    22  	if err != nil {
    23  		panic("cannot load America/Los_Angeles for testing: " + err.Error())
    24  	}
    25  	z.name = "Local"
    26  	localLoc = *z
    27  }
    28  
    29  // Many systems use /usr/share/zoneinfo, Solaris 2 has
    30  // /usr/share/lib/zoneinfo, IRIX 6 has /usr/lib/locale/TZ.
    31  var zoneDirs = []string{
    32  	"/usr/share/zoneinfo/",
    33  	"/usr/share/lib/zoneinfo/",
    34  	"/usr/lib/locale/TZ/",
    35  	runtime.GOROOT() + "/lib/time/zoneinfo.zip",
    36  }
    37  
    38  var origZoneDirs = zoneDirs
    39  
    40  func forceZipFileForTesting(zipOnly bool) {
    41  	zoneDirs = make([]string, len(origZoneDirs))
    42  	copy(zoneDirs, origZoneDirs)
    43  	if zipOnly {
    44  		for i := 0; i < len(zoneDirs)-1; i++ {
    45  			zoneDirs[i] = "/XXXNOEXIST"
    46  		}
    47  	}
    48  }
    49  
    50  func initLocal() {
    51  	// consult $TZ to find the time zone to use.
    52  	// no $TZ means use the system default /etc/localtime.
    53  	// $TZ="" means use UTC.
    54  	// $TZ="foo" means use /usr/share/zoneinfo/foo.
    55  
    56  	tz, ok := syscall.Getenv("TZ")
    57  	switch {
    58  	case !ok:
    59  		z, err := loadZoneFile("", "/etc/localtime")
    60  		if err == nil {
    61  			localLoc = *z
    62  			localLoc.name = "Local"
    63  			return
    64  		}
    65  	case tz != "" && tz != "UTC":
    66  		if z, err := loadLocation(tz); err == nil {
    67  			localLoc = *z
    68  			return
    69  		}
    70  	}
    71  
    72  	// Fall back to UTC.
    73  	localLoc.name = "UTC"
    74  }
    75  
    76  func loadLocation(name string) (*Location, error) {
    77  	var firstErr error
    78  	for _, zoneDir := range zoneDirs {
    79  		if z, err := loadZoneFile(zoneDir, name); err == nil {
    80  			z.name = name
    81  			return z, nil
    82  		} else if firstErr == nil && !isNotExist(err) {
    83  			firstErr = err
    84  		}
    85  	}
    86  	if firstErr != nil {
    87  		return nil, firstErr
    88  	}
    89  	return nil, errors.New("unknown time zone " + name)
    90  }