time: use Go distribution zoneinfo if system copy not found

Fixes #2964.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5656101

src/pkg/time/zoneinfo.go

@@ -4,7 +4,10 @@
 
 package time
 
-import "sync"
+import (
+	"sync"
+	"syscall"
+)
 
 // A Location maps time instants to the zone in use at that time.
 // Typically, the Location represents the collection of time offsets
@@ -168,10 +171,7 @@ func (l *Location) lookupOffset(offset int) (name string, isDST bool, ok bool) {
 // NOTE(rsc): Eventually we will need to accept the POSIX TZ environment
 // syntax too, but I don't feel like implementing it today.
 
-// NOTE(rsc): Using the IANA names below means ensuring we have access
-// to the database.  Probably we will ship the files in $GOROOT/lib/zoneinfo/
-// and only look there if there are no system files available (such as on Windows).
-// The files total 200 kB.
+var zoneinfo, _ = syscall.Getenv("ZONEINFO")
 
 // LoadLocation returns the Location with the given name.
 //
@@ -180,6 +180,12 @@ func (l *Location) lookupOffset(offset int) (name string, isDST bool, ok bool) {
 //
 // Otherwise, the name is taken to be a location name corresponding to a file
 // in the IANA Time Zone database, such as "America/New_York".
+//
+// The time zone database needed by LoadLocation may not be
+// present on all systems, especially non-Unix systems.
+// LoadLocation looks in the directory named by the ZONEINFO environment
+// variable, if any, then looks in known installation locations on Unix systems,
+// and finally looks in $GOROOT/lib/time/zoneinfo.
 func LoadLocation(name string) (*Location, error) {
 	if name == "" || name == "UTC" {
 		return UTC, nil
@@ -187,5 +193,11 @@ func LoadLocation(name string) (*Location, error) {
 	if name == "Local" {
 		return Local, nil
 	}
+	if zoneinfo != "" {
+		if z, err := loadZoneFile(zoneinfo + "/" + name); err == nil {
+			z.name = name
+			return z, nil
+		}
+	}
 	return loadLocation(name)
 }

src/pkg/time/zoneinfo_plan9.go

@@ -51,7 +51,7 @@ func fields(s string) []string {
 	return a
 }
 
-func loadZoneData(s string) (l *Location, err error) {
+func loadZoneDataPlan9(s string) (l *Location, err error) {
 	f := fields(s)
 	if len(f) < 4 {
 		if len(f) == 2 && f[0] == "GMT" {
@@ -112,33 +112,32 @@ func loadZoneData(s string) (l *Location, err error) {
 	return l, nil
 }
 
-func loadZoneFile(name string) (*Location, error) {
+func loadZoneFilePlan9(name string) (*Location, error) {
 	b, err := readFile(name)
 	if err != nil {
 		return nil, err
 	}
-	return loadZoneData(string(b))
+	return loadZoneDataPlan9(string(b))
 }
 
 func initTestingZone() {
-	if z, err := loadZoneFile("/adm/timezone/US_Pacific"); err == nil {
-		localLoc = *z
-		return
+	z, err := loadLocation("America/Los_Angeles")
+	if err != nil {
+		panic("cannot load America/Los_Angeles for testing: " + err.Error())
 	}
-
-	// Fall back to UTC.
-	localLoc.name = "UTC"
+	z.name = "Local"
+	localLoc = *z
 }
 
 func initLocal() {
 	t, ok := syscall.Getenv("timezone")
 	if ok {
-		if z, err := loadZoneData(t); err == nil {
+		if z, err := loadZoneDataPlan9(t); err == nil {
 			localLoc = *z
 			return
 		}
 	} else {
-		if z, err := loadZoneFile("/adm/timezone/local"); err == nil {
+		if z, err := loadZoneFilePlan9("/adm/timezone/local"); err == nil {
 			localLoc = *z
 			localLoc.name = "Local"
 			return
@@ -150,7 +149,8 @@ func initLocal() {
 }
 
 func loadLocation(name string) (*Location, error) {
-	if z, err := loadZoneFile("/adm/timezone/" + name); err == nil {
+	if z, err := loadZoneFile(runtime.GOROOT() + "/lib/time/zoneinfo/" + name); err == nil {
+		z.name = name
 		return z, nil
 	}
 	return nil, errors.New("unknown time zone " + name)

src/pkg/time/zoneinfo_read.go

@@ -0,0 +1,203 @@
+// Copyright 2009 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 "zoneinfo" time zone file.
+// This is a fairly standard file format used on OS X, Linux, BSD, Sun, and others.
+// See tzfile(5), http://en.wikipedia.org/wiki/Zoneinfo,
+// and ftp://munnari.oz.au/pub/oldtz/
+
+package time
+
+import "errors"
+
+const (
+	headerSize = 4 + 16 + 4*7
+)
+
+// Simple I/O interface to binary blob of data.
+type data struct {
+	p     []byte
+	error bool
+}
+
+func (d *data) read(n int) []byte {
+	if len(d.p) < n {
+		d.p = nil
+		d.error = true
+		return nil
+	}
+	p := d.p[0:n]
+	d.p = d.p[n:]
+	return p
+}
+
+func (d *data) big4() (n uint32, ok bool) {
+	p := d.read(4)
+	if len(p) < 4 {
+		d.error = true
+		return 0, false
+	}
+	return uint32(p[0])<<24 | uint32(p[1])<<16 | uint32(p[2])<<8 | uint32(p[3]), true
+}
+
+func (d *data) byte() (n byte, ok bool) {
+	p := d.read(1)
+	if len(p) < 1 {
+		d.error = true
+		return 0, false
+	}
+	return p[0], true
+}
+
+// Make a string by stopping at the first NUL
+func byteString(p []byte) string {
+	for i := 0; i < len(p); i++ {
+		if p[i] == 0 {
+			return string(p[0:i])
+		}
+	}
+	return string(p)
+}
+
+var badData = errors.New("malformed time zone information")
+
+func loadZoneData(bytes []byte) (l *Location, err error) {
+	d := data{bytes, false}
+
+	// 4-byte magic "TZif"
+	if magic := d.read(4); string(magic) != "TZif" {
+		return nil, badData
+	}
+
+	// 1-byte version, then 15 bytes of padding
+	var p []byte
+	if p = d.read(16); len(p) != 16 || p[0] != 0 && p[0] != '2' {
+		return nil, badData
+	}
+
+	// six big-endian 32-bit integers:
+	//	number of UTC/local indicators
+	//	number of standard/wall indicators
+	//	number of leap seconds
+	//	number of transition times
+	//	number of local time zones
+	//	number of characters of time zone abbrev strings
+	const (
+		NUTCLocal = iota
+		NStdWall
+		NLeap
+		NTime
+		NZone
+		NChar
+	)
+	var n [6]int
+	for i := 0; i < 6; i++ {
+		nn, ok := d.big4()
+		if !ok {
+			return nil, badData
+		}
+		n[i] = int(nn)
+	}
+
+	// Transition times.
+	txtimes := data{d.read(n[NTime] * 4), false}
+
+	// Time zone indices for transition times.
+	txzones := d.read(n[NTime])
+
+	// Zone info structures
+	zonedata := data{d.read(n[NZone] * 6), false}
+
+	// Time zone abbreviations.
+	abbrev := d.read(n[NChar])
+
+	// Leap-second time pairs
+	d.read(n[NLeap] * 8)
+
+	// Whether tx times associated with local time types
+	// are specified as standard time or wall time.
+	isstd := d.read(n[NStdWall])
+
+	// Whether tx times associated with local time types
+	// are specified as UTC or local time.
+	isutc := d.read(n[NUTCLocal])
+
+	if d.error { // ran out of data
+		return nil, badData
+	}
+
+	// If version == 2, the entire file repeats, this time using
+	// 8-byte ints for txtimes and leap seconds.
+	// We won't need those until 2106.
+
+	// Now we can build up a useful data structure.
+	// First the zone information.
+	//	utcoff[4] isdst[1] nameindex[1]
+	zone := make([]zone, n[NZone])
+	for i := range zone {
+		var ok bool
+		var n uint32
+		if n, ok = zonedata.big4(); !ok {
+			return nil, badData
+		}
+		zone[i].offset = int(n)
+		var b byte
+		if b, ok = zonedata.byte(); !ok {
+			return nil, badData
+		}
+		zone[i].isDST = b != 0
+		if b, ok = zonedata.byte(); !ok || int(b) >= len(abbrev) {
+			return nil, badData
+		}
+		zone[i].name = byteString(abbrev[b:])
+	}
+
+	// Now the transition time info.
+	tx := make([]zoneTrans, n[NTime])
+	for i := range tx {
+		var ok bool
+		var n uint32
+		if n, ok = txtimes.big4(); !ok {
+			return nil, badData
+		}
+		tx[i].when = int64(int32(n))
+		if int(txzones[i]) >= len(zone) {
+			return nil, badData
+		}
+		tx[i].index = txzones[i]
+		if i < len(isstd) {
+			tx[i].isstd = isstd[i] != 0
+		}
+		if i < len(isutc) {
+			tx[i].isutc = isutc[i] != 0
+		}
+	}
+
+	// Commited to succeed.
+	l = &Location{zone: zone, tx: tx}
+
+	// Fill in the cache with information about right now,
+	// since that will be the most common lookup.
+	sec, _ := now()
+	for i := range tx {
+		if tx[i].when <= sec && (i+1 == len(tx) || sec < tx[i+1].when) {
+			l.cacheStart = tx[i].when
+			l.cacheEnd = 1<<63 - 1
+			if i+1 < len(tx) {
+				l.cacheEnd = tx[i+1].when
+			}
+			l.cacheZone = &l.zone[tx[i].index]
+		}
+	}
+
+	return l, nil
+}
+
+func loadZoneFile(name string) (l *Location, err error) {
+	buf, err := readFile(name)
+	if err != nil {
+		return
+	}
+	return loadZoneData(buf)
+}

src/pkg/time/zoneinfo_unix.go

@@ -13,203 +13,17 @@ package time
 
 import (
 	"errors"
+	"runtime"
 	"syscall"
 )
 
-const (
-	headerSize = 4 + 16 + 4*7
-)
-
-// Simple I/O interface to binary blob of data.
-type data struct {
-	p     []byte
-	error bool
-}
-
-func (d *data) read(n int) []byte {
-	if len(d.p) < n {
-		d.p = nil
-		d.error = true
-		return nil
-	}
-	p := d.p[0:n]
-	d.p = d.p[n:]
-	return p
-}
-
-func (d *data) big4() (n uint32, ok bool) {
-	p := d.read(4)
-	if len(p) < 4 {
-		d.error = true
-		return 0, false
-	}
-	return uint32(p[0])<<24 | uint32(p[1])<<16 | uint32(p[2])<<8 | uint32(p[3]), true
-}
-
-func (d *data) byte() (n byte, ok bool) {
-	p := d.read(1)
-	if len(p) < 1 {
-		d.error = true
-		return 0, false
-	}
-	return p[0], true
-}
-
-// Make a string by stopping at the first NUL
-func byteString(p []byte) string {
-	for i := 0; i < len(p); i++ {
-		if p[i] == 0 {
-			return string(p[0:i])
-		}
-	}
-	return string(p)
-}
-
-var badData = errors.New("malformed time zone information")
-
-func loadZoneData(bytes []byte) (l *Location, err error) {
-	d := data{bytes, false}
-
-	// 4-byte magic "TZif"
-	if magic := d.read(4); string(magic) != "TZif" {
-		return nil, badData
-	}
-
-	// 1-byte version, then 15 bytes of padding
-	var p []byte
-	if p = d.read(16); len(p) != 16 || p[0] != 0 && p[0] != '2' {
-		return nil, badData
-	}
-
-	// six big-endian 32-bit integers:
-	//	number of UTC/local indicators
-	//	number of standard/wall indicators
-	//	number of leap seconds
-	//	number of transition times
-	//	number of local time zones
-	//	number of characters of time zone abbrev strings
-	const (
-		NUTCLocal = iota
-		NStdWall
-		NLeap
-		NTime
-		NZone
-		NChar
-	)
-	var n [6]int
-	for i := 0; i < 6; i++ {
-		nn, ok := d.big4()
-		if !ok {
-			return nil, badData
-		}
-		n[i] = int(nn)
-	}
-
-	// Transition times.
-	txtimes := data{d.read(n[NTime] * 4), false}
-
-	// Time zone indices for transition times.
-	txzones := d.read(n[NTime])
-
-	// Zone info structures
-	zonedata := data{d.read(n[NZone] * 6), false}
-
-	// Time zone abbreviations.
-	abbrev := d.read(n[NChar])
-
-	// Leap-second time pairs
-	d.read(n[NLeap] * 8)
-
-	// Whether tx times associated with local time types
-	// are specified as standard time or wall time.
-	isstd := d.read(n[NStdWall])
-
-	// Whether tx times associated with local time types
-	// are specified as UTC or local time.
-	isutc := d.read(n[NUTCLocal])
-
-	if d.error { // ran out of data
-		return nil, badData
-	}
-
-	// If version == 2, the entire file repeats, this time using
-	// 8-byte ints for txtimes and leap seconds.
-	// We won't need those until 2106.
-
-	// Now we can build up a useful data structure.
-	// First the zone information.
-	//	utcoff[4] isdst[1] nameindex[1]
-	zone := make([]zone, n[NZone])
-	for i := range zone {
-		var ok bool
-		var n uint32
-		if n, ok = zonedata.big4(); !ok {
-			return nil, badData
-		}
-		zone[i].offset = int(n)
-		var b byte
-		if b, ok = zonedata.byte(); !ok {
-			return nil, badData
-		}
-		zone[i].isDST = b != 0
-		if b, ok = zonedata.byte(); !ok || int(b) >= len(abbrev) {
-			return nil, badData
-		}
-		zone[i].name = byteString(abbrev[b:])
-	}
-
-	// Now the transition time info.
-	tx := make([]zoneTrans, n[NTime])
-	for i := range tx {
-		var ok bool
-		var n uint32
-		if n, ok = txtimes.big4(); !ok {
-			return nil, badData
-		}
-		tx[i].when = int64(int32(n))
-		if int(txzones[i]) >= len(zone) {
-			return nil, badData
-		}
-		tx[i].index = txzones[i]
-		if i < len(isstd) {
-			tx[i].isstd = isstd[i] != 0
-		}
-		if i < len(isutc) {
-			tx[i].isutc = isutc[i] != 0
-		}
-	}
-
-	// Commited to succeed.
-	l = &Location{zone: zone, tx: tx}
-
-	// Fill in the cache with information about right now,
-	// since that will be the most common lookup.
-	sec, _ := now()
-	for i := range tx {
-		if tx[i].when <= sec && (i+1 == len(tx) || sec < tx[i+1].when) {
-			l.cacheStart = tx[i].when
-			l.cacheEnd = 1<<63 - 1
-			if i+1 < len(tx) {
-				l.cacheEnd = tx[i+1].when
-			}
-			l.cacheZone = &l.zone[tx[i].index]
-		}
-	}
-
-	return l, nil
-}
-
-func loadZoneFile(name string) (l *Location, err error) {
-	buf, err := readFile(name)
-	if err != nil {
-		return
-	}
-	return loadZoneData(buf)
-}
-
 func initTestingZone() {
-	syscall.Setenv("TZ", "America/Los_Angeles")
-	initLocal()
+	z, err := loadZoneFile(runtime.GOROOT() + "/lib/time/zoneinfo/" + "America/Los_Angeles")
+	if err != nil {
+		panic("cannot load America/Los_Angeles for testing: " + err.Error())
+	}
+	z.name = "Local"
+	localLoc = *z
 }
 
 // Many systems use /usr/share/zoneinfo, Solaris 2 has
@@ -218,6 +32,7 @@ var zoneDirs = []string{
 	"/usr/share/zoneinfo/",
 	"/usr/share/lib/zoneinfo/",
 	"/usr/lib/locale/TZ/",
+	runtime.GOROOT() + "/lib/time/zoneinfo/",
 }
 
 func initLocal() {

src/pkg/time/zoneinfo_windows.go

@@ -151,7 +151,10 @@ func initLocal() {
 	initLocalFromTZI(&i)
 }
 
-// TODO(rsc): Implement.
 func loadLocation(name string) (*Location, error) {
+	if z, err := loadZoneFile(runtime.GOROOT() + `\lib\time\zoneinfo\` + name); err == nil {
+		z.name = name
+		return z, nil
+	}
 	return nil, errors.New("unknown time zone " + name)
 }