time: enable Location loading from user provided timezone data

The return values of the LoadLocation are inherently dependent
on the runtime environment. Add LoadLocationFromTZData, whose
results depend only on the timezone data provided as arguments.

Fixes #20629

Change-Id: I43b181f4c05c219be3ec57327540263b7cb3b2aa
Reviewed-on: https://go-review.googlesource.com/68890
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/time/export_test.go b/src/time/export_test.go
index 4c08ab13afc27276d76d9b08c268683eb686d1fa..ae24ceb99abd580c7d1512b7ad8a96b47bf471db 100644 (file)
--- a/src/time/export_test.go
+++ b/src/time/export_test.go
@@ -34,4 +34,5 @@ var (
        GetMono                = (*Time).mono
        ErrLocation            = errLocation
        ReadFile               = readFile
+       LoadTzinfo             = loadTzinfo
 )

diff --git a/src/time/internal_test.go b/src/time/internal_test.go
index 07ebe5e03d7e2f56597ebf0ceb9b7d8009da18db..76d55241241dacc50bea742dff4da65ef6cc637c 100644 (file)
--- a/src/time/internal_test.go
+++ b/src/time/internal_test.go
@@ -18,11 +18,11 @@ func initTestingZone() {
        localLoc = *z
 }
 
-var origZoneSources = zoneSources
+var OrigZoneSources = zoneSources
 
 func forceZipFileForTesting(zipOnly bool) {
-       zoneSources = make([]string, len(origZoneSources))
-       copy(zoneSources, origZoneSources)
+       zoneSources = make([]string, len(OrigZoneSources))
+       copy(zoneSources, OrigZoneSources)
        if zipOnly {
                zoneSources = zoneSources[len(zoneSources)-1:]
        }

diff --git a/src/time/zoneinfo.go b/src/time/zoneinfo.go
index 4424b4410687760b193f56d073f57d93d7bce473..96ff8d39708f5948473029387eee867e7c9eb703 100644 (file)
--- a/src/time/zoneinfo.go
+++ b/src/time/zoneinfo.go
@@ -294,7 +294,7 @@ func LoadLocation(name string) (*Location, error) {
        })
        if *zoneinfo != "" {
                if zoneData, err := loadTzinfoFromDirOrZip(*zoneinfo, name); err == nil {
-                       if z, err := newLocationFromTzinfo(name, zoneData); err == nil {
+                       if z, err := LoadLocationFromTZData(name, zoneData); err == nil {
                                return z, nil
                        }
                }

diff --git a/src/time/zoneinfo_read.go b/src/time/zoneinfo_read.go
index 6fdcc1a2a8628cabb401345273aa508c09cba0d2..839b37aac4e4d31a1aff8967ee261ac9c5284bc6 100644 (file)
--- a/src/time/zoneinfo_read.go
+++ b/src/time/zoneinfo_read.go
@@ -79,11 +79,12 @@ func byteString(p []byte) string {
 
 var badData = errors.New("malformed time zone information")
 
-// 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 := dataIO{Tzinfo, false}
+// LoadLocationFromTZData returns a Location with the given name
+// initialized from the IANA Time Zone database-formatted data.
+// The data should be in the format of a standard IANA time zone file
+// (for example, the content of /etc/localtime on Unix systems).
+func LoadLocationFromTZData(name string, data []byte) (*Location, error) {
+       d := dataIO{data, false}
 
        // 4-byte magic "TZif"
        if magic := d.read(4); string(magic) != "TZif" {
@@ -390,7 +391,7 @@ 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 {
+                       if z, err = LoadLocationFromTZData(name, zoneData); err == nil {
                                return z, nil
                        }
                }

diff --git a/src/time/zoneinfo_test.go b/src/time/zoneinfo_test.go
index 452262f2caf499eae3b3ec3a327377925a8e101b..b9455db025a8b317d20e853d0472f304eb1fc81e 100644 (file)
--- a/src/time/zoneinfo_test.go
+++ b/src/time/zoneinfo_test.go
@@ -7,6 +7,7 @@ package time_test
 import (
        "fmt"
        "os"
+       "reflect"
        "testing"
        "time"
 )
@@ -116,3 +117,27 @@ func TestLocationNames(t *testing.T) {
                t.Errorf(`invalid UTC location name: got %q want "UTC"`, time.UTC)
        }
 }
+
+func TestLoadLocationFromTzinfo(t *testing.T) {
+       time.ForceZipFileForTesting(true)
+       defer time.ForceZipFileForTesting(false)
+
+       const locationName = "Asia/Jerusalem"
+       reference, err := time.LoadLocation(locationName)
+       if err != nil {
+               t.Fatal(err)
+       }
+
+       tzinfo, err := time.LoadTzinfo(locationName, time.OrigZoneSources[len(time.OrigZoneSources)-1])
+       if err != nil {
+               t.Fatal(err)
+       }
+       sample, err := time.LoadLocationFromTZData(locationName, tzinfo)
+       if err != nil {
+               t.Fatal(err)
+       }
+
+       if !reflect.DeepEqual(reference, sample) {
+               t.Errorf("return values of LoadLocationFromTZData and LoadLocation don't match")
+       }
+}