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time: fix timezone lookup logic for non-DST zones

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This change fixes time.LoadLocationFromTZData and time.Location.lookup logic if the given time is after the last transition and the extend string doesn't have the DST rule.

Fixes #58682

Change-Id: Ie34a6d658d14c2b33098b29ab83c041ef0d34266
GitHub-Last-Rev: f6681eb44c
GitHub-Pull-Request: golang/go#58684
Reviewed-on: https://go-review.googlesource.com/c/go/+/471020
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
This commit is contained in:
Geon Kim 2023-03-11 00:57:57 +00:00 committed by Gopher Robot
parent e671fe0c3e
commit 90dde5dec1
4 changed files with 24 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
src/time/time_test.go
View File

@ -1860,16 +1860,26 @@ func TestZoneBounds(t *testing.T) {
5: {Date(1991, September, 14, 17, 0, 0, 0, loc), boundTwo, boundThree},
6: {Date(1991, September, 15, 0, 50, 0, 0, loc), boundTwo, boundThree},
// The ZoneBounds of a "Asia/Shanghai" after the last transition (Standard Time)
7: {boundThree, boundThree, Time{}},
8: {Date(1991, December, 15, 1, 50, 0, 0, loc), boundThree, Time{}},
9: {Date(1992, April, 13, 17, 50, 0, 0, loc), boundThree, Time{}},
10: {Date(1992, April, 13, 18, 0, 0, 0, loc), boundThree, Time{}},
11: {Date(1992, April, 14, 1, 50, 0, 0, loc), boundThree, Time{}},
12: {Date(1992, September, 14, 16, 50, 0, 0, loc), boundThree, Time{}},
13: {Date(1992, September, 14, 17, 0, 0, 0, loc), boundThree, Time{}},
14: {Date(1992, September, 15, 0, 50, 0, 0, loc), boundThree, Time{}},
// The ZoneBounds of a local time would return two local Time.
// Note: We preloaded "America/Los_Angeles" as time.Local for testing
7: {makeLocalTime(0), makeLocalTime(-5756400), makeLocalTime(9972000)},
8: {makeLocalTime(1221681866), makeLocalTime(1205056800), makeLocalTime(1225616400)},
9: {makeLocalTime(2152173599), makeLocalTime(2145916800), makeLocalTime(2152173600)},
10: {makeLocalTime(2152173600), makeLocalTime(2152173600), makeLocalTime(2172733200)},
11: {makeLocalTime(2152173601), makeLocalTime(2152173600), makeLocalTime(2172733200)},
12: {makeLocalTime(2159200800), makeLocalTime(2152173600), makeLocalTime(2172733200)},
13: {makeLocalTime(2172733199), makeLocalTime(2152173600), makeLocalTime(2172733200)},
14: {makeLocalTime(2172733200), makeLocalTime(2172733200), makeLocalTime(2177452800)},
15: {makeLocalTime(0), makeLocalTime(-5756400), makeLocalTime(9972000)},
16: {makeLocalTime(1221681866), makeLocalTime(1205056800), makeLocalTime(1225616400)},
17: {makeLocalTime(2152173599), makeLocalTime(2145916800), makeLocalTime(2152173600)},
18: {makeLocalTime(2152173600), makeLocalTime(2152173600), makeLocalTime(2172733200)},
19: {makeLocalTime(2152173601), makeLocalTime(2152173600), makeLocalTime(2172733200)},
20: {makeLocalTime(2159200800), makeLocalTime(2152173600), makeLocalTime(2172733200)},
21: {makeLocalTime(2172733199), makeLocalTime(2152173600), makeLocalTime(2172733200)},
22: {makeLocalTime(2172733200), makeLocalTime(2172733200), makeLocalTime(2177452800)},
}
for i, tt := range realTests {
start, end := tt.giveTime.ZoneBounds()

8
src/time/zoneinfo.go
View File

@ -203,7 +203,7 @@ func (l *Location) lookup(sec int64) (name string, offset int, start, end int64,
// If we're at the end of the known zone transitions,
// try the extend string.
if lo == len(tx)-1 && l.extend != "" {
if ename, eoffset, estart, eend, eisDST, ok := tzset(l.extend, end, sec); ok {
if ename, eoffset, estart, eend, eisDST, ok := tzset(l.extend, start, sec); ok {
return ename, eoffset, estart, eend, eisDST
}
}
@ -264,12 +264,12 @@ func (l *Location) firstZoneUsed() bool {
}
// tzset takes a timezone string like the one found in the TZ environment
// variable, the end of the last time zone transition expressed as seconds
// variable, the time of the last time zone transition expressed as seconds
// since January 1, 1970 00:00:00 UTC, and a time expressed the same way.
// We call this a tzset string since in C the function tzset reads TZ.
// The return values are as for lookup, plus ok which reports whether the
// parse succeeded.
func tzset(s string, initEnd, sec int64) (name string, offset int, start, end int64, isDST, ok bool) {
func tzset(s string, lastTxSec, sec int64) (name string, offset int, start, end int64, isDST, ok bool) {
var (
stdName, dstName string
stdOffset, dstOffset int
@ -290,7 +290,7 @@ func tzset(s string, initEnd, sec int64) (name string, offset int, start, end in
if len(s) == 0 || s[0] == ',' {
// No daylight savings time.
return stdName, stdOffset, initEnd, omega, false, true
return stdName, stdOffset, lastTxSec, omega, false, true
}
dstName, s, ok = tzsetName(s)

2
src/time/zoneinfo_read.go
View File

@ -329,7 +329,7 @@ func LoadLocationFromTZData(name string, data []byte) (*Location, error) {
} else if l.extend != "" {
// If we're at the end of the known zone transitions,
// try the extend string.
if name, offset, estart, eend, isDST, ok := tzset(l.extend, l.cacheEnd, sec); ok {
if name, offset, estart, eend, isDST, ok := tzset(l.extend, l.cacheStart, sec); ok {
l.cacheStart = estart
l.cacheEnd = eend
// Find the zone that is returned by tzset to avoid allocation if possible.

1
src/time/zoneinfo_test.go
View File

@ -271,6 +271,7 @@ func TestTzset(t *testing.T) {
{"PST8PDT,M3.2.0,M11.1.0", 0, 2172733199, "PDT", -7 * 60 * 60, 2152173600, 2172733200, true, true},
{"PST8PDT,M3.2.0,M11.1.0", 0, 2172733200, "PST", -8 * 60 * 60, 2172733200, 2177452800, false, true},
{"PST8PDT,M3.2.0,M11.1.0", 0, 2172733201, "PST", -8 * 60 * 60, 2172733200, 2177452800, false, true},
{"KST-9", 592333200, 1677246697, "KST", 9 * 60 * 60, 592333200, 1<<63 - 1, false, true},
} {
name, off, start, end, isDST, ok := time.Tzset(test.inStr, test.inEnd, test.inSec)
if name != test.name || off != test.off || start != test.start || end != test.end || isDST != test.isDST || ok != test.ok {