time: reduce OS dependent timezone related code

Loading and testing timezones is currently implemented using several,
partly redundant, OS specific data structures and functions. This
change merges most of that code into OS independent implementations.

Change-Id: Iae2877c5f48d1e4a9de9ce55d0530d52e24cf96e
Reviewed-on: https://go-review.googlesource.com/64391
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/time/export_android_test.go

@@ -5,8 +5,8 @@
 package time
 
 func ForceAndroidTzdataForTest(tzdata bool) {
-	tzdataPaths = origTzdataPaths
+	forceZipFileForTesting(false)
 	if tzdata {
-		tzdataPaths = tzdataPaths[:1]
+		zoneSources = zoneSources[:len(zoneSources)-1]
 	}
 }

src/time/export_windows_test.go

@@ -4,9 +4,14 @@
 
 package time
 
-func ForceAusForTesting() {
+func ForceAusFromTZIForTesting() {
 	ResetLocalOnceForTest()
-	localOnce.Do(initAusTestingZone)
+	localOnce.Do(func() { initLocalFromTZI(&aus) })
+}
+
+func ForceUSPacificFromTZIForTesting() {
+	ResetLocalOnceForTest()
+	localOnce.Do(func() { initLocalFromTZI(&usPacific) })
 }
 
 func ToEnglishName(stdname, dstname string) (string, error) {

src/time/internal_test.go

@@ -9,6 +9,25 @@ func init() {
 	ForceUSPacificForTesting()
 }
 
+func initTestingZone() {
+	z, err := loadLocation("America/Los_Angeles", zoneSources[len(zoneSources)-1:])
+	if err != nil {
+		panic("cannot load America/Los_Angeles for testing: " + err.Error())
+	}
+	z.name = "Local"
+	localLoc = *z
+}
+
+var origZoneSources = zoneSources
+
+func forceZipFileForTesting(zipOnly bool) {
+	zoneSources = make([]string, len(origZoneSources))
+	copy(zoneSources, origZoneSources)
+	if zipOnly {
+		zoneSources = zoneSources[len(zoneSources)-1:]
+	}
+}
+
 var Interrupt = interrupt
 var DaysIn = daysIn
 

src/time/sys_unix.go

@@ -78,5 +78,3 @@ func preadn(fd uintptr, buf []byte, off int) error {
 	}
 	return nil
 }
-
-func isNotExist(err error) bool { return err == syscall.ENOENT }

src/time/zoneinfo.go

@@ -292,13 +292,14 @@ func LoadLocation(name string) (*Location, error) {
 		env, _ := syscall.Getenv("ZONEINFO")
 		zoneinfo = &env
 	})
-	if zoneinfo != nil && *zoneinfo != "" {
-		if z, err := loadZoneFile(*zoneinfo, name); err == nil {
-			z.name = name
-			return z, nil
+	if *zoneinfo != "" {
+		if zoneData, err := loadTzinfoFromDirOrZip(*zoneinfo, name); err == nil {
+			if z, err := newLocationFromTzinfo(name, zoneData); err == nil {
+				return z, nil
+			}
 		}
 	}
-	return loadLocation(name)
+	return loadLocation(name, zoneSources)
 }
 
 // containsDotDot reports whether s contains "..".

src/time/zoneinfo_android.go

@@ -13,62 +13,22 @@ import (
 	"runtime"
 )
 
-var tzdataPaths = []string{
+var zoneSources = []string{
 	"/system/usr/share/zoneinfo/tzdata",
 	"/data/misc/zoneinfo/current/tzdata",
 	runtime.GOROOT() + "/lib/time/zoneinfo.zip",
 }
 
-var origTzdataPaths = tzdataPaths
-
-func forceZipFileForTesting(zipOnly bool) {
-	tzdataPaths = make([]string, len(origTzdataPaths))
-	copy(tzdataPaths, origTzdataPaths)
-	if zipOnly {
-		for i := 0; i < len(tzdataPaths)-1; i++ {
-			tzdataPaths[i] = "/XXXNOEXIST"
-		}
-	}
-}
-
-func initTestingZone() {
-	z, err := loadLocation("America/Los_Angeles")
-	if err != nil {
-		panic("cannot load America/Los_Angeles for testing: " + err.Error())
-	}
-	z.name = "Local"
-	localLoc = *z
-}
-
 func initLocal() {
 	// TODO(elias.naur): getprop persist.sys.timezone
 	localLoc = *UTC
 }
 
-func loadLocation(name string) (*Location, error) {
-	var firstErr error
-	for _, path := range tzdataPaths {
-		var z *Location
-		var err error
-		if len(path) > 4 && path[len(path)-4:] == ".zip" {
-			z, err = loadZoneZip(path, name)
-		} else {
-			z, err = loadTzdataFile(path, name)
-		}
-		if err == nil {
-			z.name = name
-			return z, nil
-		} else if firstErr == nil && !isNotExist(err) {
-			firstErr = err
-		}
-	}
-	if firstErr != nil {
-		return nil, firstErr
-	}
-	return nil, errors.New("unknown time zone " + name)
+func init() {
+	loadTzinfoFromTzdata = androidLoadTzinfoFromTzdata
 }
 
-func loadTzdataFile(file, name string) (*Location, error) {
+func androidLoadTzinfoFromTzdata(file, name string) ([]byte, error) {
 	const (
 		headersize = 12 + 3*4
 		namesize   = 40
@@ -113,7 +73,7 @@ func loadTzdataFile(file, name string) (*Location, error) {
 		if err := preadn(fd, buf, int(off+dataOff)); err != nil {
 			return nil, errors.New("corrupt tzdata file " + file)
 		}
-		return loadZoneData(buf)
+		return buf, nil
 	}
 	return nil, errors.New("cannot find " + name + " in tzdata file " + file)
 }

src/time/zoneinfo_ios.go

@@ -9,43 +9,23 @@ package time
 
 import "syscall"
 
-var zoneFile string
+var zoneSources = []string{
+	getZipParent() + "/zoneinfo.zip",
+}
 
-func init() {
+func getZipParent() string {
 	wd, err := syscall.Getwd()
 	if err != nil {
-		return
+		return "/XXXNOEXIST"
 	}
 
 	// The working directory at initialization is the root of the
 	// app bundle: "/private/.../bundlename.app". That's where we
 	// keep zoneinfo.zip.
-	zoneFile = wd + "/zoneinfo.zip"
-}
-
-func forceZipFileForTesting(zipOnly bool) {
-	// On iOS we only have the zip file.
-}
-
-func initTestingZone() {
-	z, err := loadZoneFile(zoneFile, "America/Los_Angeles")
-	if err != nil {
-		panic("cannot load America/Los_Angeles for testing: " + err.Error())
-	}
-	z.name = "Local"
-	localLoc = *z
+	return wd
 }
 
 func initLocal() {
 	// TODO(crawshaw): [NSTimeZone localTimeZone]
 	localLoc = *UTC
 }
-
-func loadLocation(name string) (*Location, error) {
-	z, err := loadZoneFile(zoneFile, name)
-	if err != nil {
-		return nil, err
-	}
-	z.name = name
-	return z, nil
-}

src/time/zoneinfo_plan9.go

@@ -11,6 +11,10 @@ import (
 	"syscall"
 )
 
+var zoneSources = []string{
+	runtime.GOROOT() + "/lib/time/zoneinfo.zip",
+}
+
 func isSpace(r rune) bool {
 	return r == ' ' || r == '\t' || r == '\n'
 }
@@ -118,15 +122,6 @@ func loadZoneFilePlan9(name string) (*Location, error) {
 	return loadZoneDataPlan9(string(b))
 }
 
-func initTestingZone() {
-	z, err := loadLocation("America/Los_Angeles")
-	if err != nil {
-		panic("cannot load America/Los_Angeles for testing: " + err.Error())
-	}
-	z.name = "Local"
-	localLoc = *z
-}
-
 func initLocal() {
 	t, ok := syscall.Getenv("timezone")
 	if ok {
@@ -145,16 +140,3 @@ func initLocal() {
 	// Fall back to UTC.
 	localLoc.name = "UTC"
 }
-
-func loadLocation(name string) (*Location, error) {
-	z, err := loadZoneFile(runtime.GOROOT()+"/lib/time/zoneinfo.zip", name)
-	if err != nil {
-		return nil, err
-	}
-	z.name = name
-	return z, nil
-}
-
-func forceZipFileForTesting(zipOnly bool) {
-	// We only use the zip file anyway.
-}

src/time/zoneinfo_read.go

@@ -9,7 +9,10 @@
 
 package time
 
-import "errors"
+import (
+	"errors"
+	"syscall"
+)
 
 // maxFileSize is the max permitted size of files read by readFile.
 // As reference, the zoneinfo.zip distributed by Go is ~350 KB,
@@ -76,8 +79,11 @@ func byteString(p []byte) string {
 
 var badData = errors.New("malformed time zone information")
 
-func loadZoneData(bytes []byte) (l *Location, err error) {
-	d := data{bytes, false}
+// newLocationFromTzinfo returns the Location described by Tzinfo with the given name.
+// The expected format for Tzinfo is that of a timezone file as they are found in the
+// the IANA Time Zone database.
+func newLocationFromTzinfo(name string, Tzinfo []byte) (*Location, error) {
+	d := data{Tzinfo, false}
 
 	// 4-byte magic "TZif"
 	if magic := d.read(4); string(magic) != "TZif" {
@@ -195,7 +201,7 @@ func loadZoneData(bytes []byte) (l *Location, err error) {
 	}
 
 	// Committed to succeed.
-	l = &Location{zone: zone, tx: tx}
+	l := &Location{zone: zone, tx: tx, name: name}
 
 	// Fill in the cache with information about right now,
 	// since that will be the most common lookup.
@@ -214,18 +220,16 @@ func loadZoneData(bytes []byte) (l *Location, err error) {
 	return l, nil
 }
 
-func loadZoneFile(dir, name string) (l *Location, err error) {
+// loadTzinfoFromDirOrZip returns the contents of the file with the given name
+// in dir. dir can either be an uncompressed zip file, or a directory.
+func loadTzinfoFromDirOrZip(dir, name string) ([]byte, error) {
 	if len(dir) > 4 && dir[len(dir)-4:] == ".zip" {
-		return loadZoneZip(dir, name)
+		return loadTzinfoFromZip(dir, name)
 	}
 	if dir != "" {
 		name = dir + "/" + name
 	}
-	buf, err := readFile(name)
-	if err != nil {
-		return
-	}
-	return loadZoneData(buf)
+	return readFile(name)
 }
 
 // There are 500+ zoneinfo files. Rather than distribute them all
@@ -252,7 +256,9 @@ func get2(b []byte) int {
 	return int(b[0]) | int(b[1])<<8
 }
 
-func loadZoneZip(zipfile, name string) (l *Location, err error) {
+// loadTzinfoFromZip returns the contents of the file with the given name
+// in the given uncompressed zip file.
+func loadTzinfoFromZip(zipfile, name string) ([]byte, error) {
 	fd, err := open(zipfile)
 	if err != nil {
 		return nil, errors.New("open " + zipfile + ": " + err.Error())
@@ -354,8 +360,46 @@ func loadZoneZip(zipfile, name string) (l *Location, err error) {
 			return nil, errors.New("corrupt zip file " + zipfile)
 		}
 
-		return loadZoneData(buf)
+		return buf, nil
 	}
 
 	return nil, errors.New("cannot find " + name + " in zip file " + zipfile)
 }
+
+// loadTzinfoFromTzdata returns the time zone information of the time zone
+// with the given name, from a tzdata database file as they are typically
+// found on android.
+var loadTzinfoFromTzdata func(file, name string) ([]byte, error)
+
+// loadTzinfo returns the time zone information of the time zone
+// with the given name, from a given source. A source may be a
+// timezone database directory, tzdata database file or an uncompressed
+// zip file, containing the contents of such a directory.
+func loadTzinfo(name string, source string) ([]byte, error) {
+	if len(source) >= 6 && source[len(source)-6:] == "tzdata" {
+		return loadTzinfoFromTzdata(source, name)
+	}
+	return loadTzinfoFromDirOrZip(source, name)
+}
+
+// loadLocation returns the Location with the given name from one of
+// the specified sources. See loadTzinfo for a list of supported sources.
+// The first timezone data matching the given name that is successfully loaded
+// and parsed is returned as a Location.
+func loadLocation(name string, sources []string) (z *Location, firstErr error) {
+	for _, source := range sources {
+		var zoneData, err = loadTzinfo(name, source)
+		if err == nil {
+			if z, err = newLocationFromTzinfo(name, zoneData); err == nil {
+				return z, nil
+			}
+		}
+		if firstErr == nil && err != syscall.ENOENT {
+			firstErr = err
+		}
+	}
+	if firstErr != nil {
+		return nil, firstErr
+	}
+	return nil, errors.New("unknown time zone " + name)
+}

src/time/zoneinfo_unix.go

@@ -12,41 +12,19 @@
 package time
 
 import (
-	"errors"
 	"runtime"
 	"syscall"
 )
 
-func initTestingZone() {
-	z, err := loadZoneFile(runtime.GOROOT()+"/lib/time/zoneinfo.zip", "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
 // /usr/share/lib/zoneinfo, IRIX 6 has /usr/lib/locale/TZ.
-var zoneDirs = []string{
+var zoneSources = []string{
 	"/usr/share/zoneinfo/",
 	"/usr/share/lib/zoneinfo/",
 	"/usr/lib/locale/TZ/",
 	runtime.GOROOT() + "/lib/time/zoneinfo.zip",
 }
 
-var origZoneDirs = zoneDirs
-
-func forceZipFileForTesting(zipOnly bool) {
-	zoneDirs = make([]string, len(origZoneDirs))
-	copy(zoneDirs, origZoneDirs)
-	if zipOnly {
-		for i := 0; i < len(zoneDirs)-1; i++ {
-			zoneDirs[i] = "/XXXNOEXIST"
-		}
-	}
-}
-
 func initLocal() {
 	// consult $TZ to find the time zone to use.
 	// no $TZ means use the system default /etc/localtime.
@@ -56,14 +34,14 @@ func initLocal() {
 	tz, ok := syscall.Getenv("TZ")
 	switch {
 	case !ok:
-		z, err := loadZoneFile("", "/etc/localtime")
+		z, err := loadLocation("localtime", []string{"/etc/"})
 		if err == nil {
 			localLoc = *z
 			localLoc.name = "Local"
 			return
 		}
 	case tz != "" && tz != "UTC":
-		if z, err := loadLocation(tz); err == nil {
+		if z, err := loadLocation(tz, zoneSources); err == nil {
 			localLoc = *z
 			return
 		}
@@ -72,19 +50,3 @@ func initLocal() {
 	// Fall back to UTC.
 	localLoc.name = "UTC"
 }
-
-func loadLocation(name string) (*Location, error) {
-	var firstErr error
-	for _, zoneDir := range zoneDirs {
-		if z, err := loadZoneFile(zoneDir, name); err == nil {
-			z.name = name
-			return z, nil
-		} else if firstErr == nil && !isNotExist(err) {
-			firstErr = err
-		}
-	}
-	if firstErr != nil {
-		return nil, firstErr
-	}
-	return nil, errors.New("unknown time zone " + name)
-}

src/time/zoneinfo_windows.go

@@ -11,6 +11,10 @@ import (
 	"syscall"
 )
 
+var zoneSources = []string{
+	runtime.GOROOT() + "/lib/time/zoneinfo.zip",
+}
+
 // TODO(rsc): Fall back to copy of zoneinfo files.
 
 // BUG(brainman,rsc): On Windows, the operating system does not provide complete
@@ -228,14 +232,6 @@ var aus = syscall.Timezoneinformation{
 	DaylightBias: -60,
 }
 
-func initTestingZone() {
-	initLocalFromTZI(&usPacific)
-}
-
-func initAusTestingZone() {
-	initLocalFromTZI(&aus)
-}
-
 func initLocal() {
 	var i syscall.Timezoneinformation
 	if _, err := syscall.GetTimeZoneInformation(&i); err != nil {
@@ -244,16 +240,3 @@ func initLocal() {
 	}
 	initLocalFromTZI(&i)
 }
-
-func loadLocation(name string) (*Location, error) {
-	z, err := loadZoneFile(runtime.GOROOT()+`\lib\time\zoneinfo.zip`, name)
-	if err != nil {
-		return nil, err
-	}
-	z.name = name
-	return z, nil
-}
-
-func forceZipFileForTesting(zipOnly bool) {
-	// We only use the zip file anyway.
-}

src/time/zoneinfo_windows_test.go

@@ -31,14 +31,14 @@ func testZoneAbbr(t *testing.T) {
 	}
 }
 
-func TestLocalZoneAbbr(t *testing.T) {
-	ResetLocalOnceForTest() // reset the Once to trigger the race
+func TestUSPacificZoneAbbr(t *testing.T) {
+	ForceUSPacificFromTZIForTesting() // reset the Once to trigger the race
 	defer ForceUSPacificForTesting()
 	testZoneAbbr(t)
 }
 
 func TestAusZoneAbbr(t *testing.T) {
-	ForceAusForTesting()
+	ForceAusFromTZIForTesting()
 	defer ForceUSPacificForTesting()
 	testZoneAbbr(t)
 }