Initial commit: Go 1.23 release state

src/time/zoneinfo_plan9.go

@@ -0,0 +1,139 @@
+// Copyright 2011 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 Plan 9 timezone(2) files.
+
+package time
+
+import (
+	"syscall"
+)
+
+var platformZoneSources []string // none on Plan 9
+
+func isSpace(r rune) bool {
+	return r == ' ' || r == '\t' || r == '\n'
+}
+
+// Copied from strings to avoid a dependency.
+func fields(s string) []string {
+	// First count the fields.
+	n := 0
+	inField := false
+	for _, rune := range s {
+		wasInField := inField
+		inField = !isSpace(rune)
+		if inField && !wasInField {
+			n++
+		}
+	}
+
+	// Now create them.
+	a := make([]string, n)
+	na := 0
+	fieldStart := -1 // Set to -1 when looking for start of field.
+	for i, rune := range s {
+		if isSpace(rune) {
+			if fieldStart >= 0 {
+				a[na] = s[fieldStart:i]
+				na++
+				fieldStart = -1
+			}
+		} else if fieldStart == -1 {
+			fieldStart = i
+		}
+	}
+	if fieldStart >= 0 { // Last field might end at EOF.
+		a[na] = s[fieldStart:]
+	}
+	return a
+}
+
+func loadZoneDataPlan9(s string) (l *Location, err error) {
+	f := fields(s)
+	if len(f) < 4 {
+		if len(f) == 2 && f[0] == "GMT" {
+			return UTC, nil
+		}
+		return nil, errBadData
+	}
+
+	var zones [2]zone
+
+	// standard timezone offset
+	o, err := atoi(f[1])
+	if err != nil {
+		return nil, errBadData
+	}
+	zones[0] = zone{name: f[0], offset: o, isDST: false}
+
+	// alternate timezone offset
+	o, err = atoi(f[3])
+	if err != nil {
+		return nil, errBadData
+	}
+	zones[1] = zone{name: f[2], offset: o, isDST: true}
+
+	// transition time pairs
+	var tx []zoneTrans
+	f = f[4:]
+	for i := 0; i < len(f); i++ {
+		zi := 0
+		if i%2 == 0 {
+			zi = 1
+		}
+		t, err := atoi(f[i])
+		if err != nil {
+			return nil, errBadData
+		}
+		t -= zones[0].offset
+		tx = append(tx, zoneTrans{when: int64(t), index: uint8(zi)})
+	}
+
+	// Committed to succeed.
+	l = &Location{zone: zones[:], 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 = omega
+			if i+1 < len(tx) {
+				l.cacheEnd = tx[i+1].when
+			}
+			l.cacheZone = &l.zone[tx[i].index]
+		}
+	}
+
+	return l, nil
+}
+
+func loadZoneFilePlan9(name string) (*Location, error) {
+	b, err := readFile(name)
+	if err != nil {
+		return nil, err
+	}
+	return loadZoneDataPlan9(string(b))
+}
+
+func initLocal() {
+	t, ok := syscall.Getenv("timezone")
+	if ok {
+		if z, err := loadZoneDataPlan9(t); err == nil {
+			localLoc = *z
+			return
+		}
+	} else {
+		if z, err := loadZoneFilePlan9("/adm/timezone/local"); err == nil {
+			localLoc = *z
+			localLoc.name = "Local"
+			return
+		}
+	}
+
+	// Fall back to UTC.
+	localLoc.name = "UTC"
+}