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// Copyright 2022 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.
package time
import "errors"
// RFC 3339 is the most commonly used format.
//
// It is implicitly used by the Time.(Marshal|Unmarshal)(Text|JSON) methods.
// Also, according to analysis on https://go.dev/issue/52746,
// RFC 3339 accounts for 57% of all explicitly specified time formats,
// with the second most popular format only being used 8% of the time.
// The overwhelming use of RFC 3339 compared to all other formats justifies
// the addition of logic to optimize formatting and parsing.
func (t Time) appendFormatRFC3339(b []byte, nanos bool) []byte {
_, offset, abs := t.locabs()
// Format date.
year, month, day, _ := absDate(abs, true)
b = appendInt(b, year, 4)
b = append(b, '-')
b = appendInt(b, int(month), 2)
b = append(b, '-')
b = appendInt(b, day, 2)
b = append(b, 'T')
// Format time.
hour, min, sec := absClock(abs)
b = appendInt(b, hour, 2)
b = append(b, ':')
b = appendInt(b, min, 2)
b = append(b, ':')
b = appendInt(b, sec, 2)
if nanos {
std := stdFracSecond(stdFracSecond9, 9, '.')
b = appendNano(b, t.Nanosecond(), std)
}
if offset == 0 {
return append(b, 'Z')
}
// Format zone.
zone := offset / 60 // convert to minutes
if zone < 0 {
b = append(b, '-')
zone = -zone
} else {
b = append(b, '+')
}
b = appendInt(b, zone/60, 2)
b = append(b, ':')
b = appendInt(b, zone%60, 2)
return b
}
func (t Time) appendStrictRFC3339(b []byte) ([]byte, error) {
n0 := len(b)
b = t.appendFormatRFC3339(b, true)
// Not all valid Go timestamps can be serialized as valid RFC 3339.
// Explicitly check for these edge cases.
// See https://go.dev/issue/4556 and https://go.dev/issue/54580.
num2 := func(b []byte) byte { return 10*(b[0]-'0') + (b[1] - '0') }
switch {
case b[n0+len("9999")] != '-': // year must be exactly 4 digits wide
return b, errors.New("year outside of range [0,9999]")
case b[len(b)-1] != 'Z':
c := b[len(b)-len("Z07:00")]
if ('0' <= c && c <= '9') || num2(b[len(b)-len("07:00"):]) >= 24 {
return b, errors.New("timezone hour outside of range [0,23]")
}
}
return b, nil
}
func parseRFC3339[bytes []byte | string](s bytes, local *Location) (Time, bool) {
// parseUint parses s as an unsigned decimal integer and
// verifies that it is within some range.
// If it is invalid or out-of-range,
// it sets ok to false and returns the min value.
ok := true
parseUint := func(s bytes, min, max int) (x int) {
for _, c := range []byte(s) {
if c < '0' || '9' < c {
ok = false
return min
}
x = x*10 + int(c) - '0'
}
if x < min || max < x {
ok = false
return min
}
return x
}
// Parse the date and time.
if len(s) < len("2006-01-02T15:04:05") {
return Time{}, false
}
year := parseUint(s[0:4], 0, 9999) // e.g., 2006
month := parseUint(s[5:7], 1, 12) // e.g., 01
day := parseUint(s[8:10], 1, daysIn(Month(month), year)) // e.g., 02
hour := parseUint(s[11:13], 0, 23) // e.g., 15
min := parseUint(s[14:16], 0, 59) // e.g., 04
sec := parseUint(s[17:19], 0, 59) // e.g., 05
if !ok || !(s[4] == '-' && s[7] == '-' && s[10] == 'T' && s[13] == ':' && s[16] == ':') {
return Time{}, false
}
s = s[19:]
// Parse the fractional second.
var nsec int
if len(s) >= 2 && s[0] == '.' && isDigit(s, 1) {
n := 2
for ; n < len(s) && isDigit(s, n); n++ {
}
nsec, _, _ = parseNanoseconds(s, n)
s = s[n:]
}
// Parse the time zone.
t := Date(year, Month(month), day, hour, min, sec, nsec, UTC)
if len(s) != 1 || s[0] != 'Z' {
if len(s) != len("-07:00") {
return Time{}, false
}
hr := parseUint(s[1:3], 0, 23) // e.g., 07
mm := parseUint(s[4:6], 0, 59) // e.g., 00
if !ok || !((s[0] == '-' || s[0] == '+') && s[3] == ':') {
return Time{}, false
}
zoneOffset := (hr*60 + mm) * 60
if s[0] == '-' {
zoneOffset *= -1
}
t.addSec(-int64(zoneOffset))
// Use local zone with the given offset if possible.
if _, offset, _, _, _ := local.lookup(t.unixSec()); offset == zoneOffset {
t.setLoc(local)
} else {
t.setLoc(FixedZone("", zoneOffset))
}
}
return t, true
}
func parseStrictRFC3339(b []byte) (Time, error) {
t, ok := parseRFC3339(b, Local)
if !ok {
t, err := Parse(RFC3339, string(b))
if err != nil {
return Time{}, err
}
// The parse template syntax cannot correctly validate RFC 3339.
// Explicitly check for cases that Parse is unable to validate for.
// See https://go.dev/issue/54580.
num2 := func(b []byte) byte { return 10*(b[0]-'0') + (b[1] - '0') }
switch {
// TODO(https://go.dev/issue/54580): Strict parsing is disabled for now.
// Enable this again with a GODEBUG opt-out.
case true:
return t, nil
case b[len("2006-01-02T")+1] == ':': // hour must be two digits
return Time{}, &ParseError{RFC3339, string(b), "15", string(b[len("2006-01-02T"):][:1]), ""}
case b[len("2006-01-02T15:04:05")] == ',': // sub-second separator must be a period
return Time{}, &ParseError{RFC3339, string(b), ".", ",", ""}
case b[len(b)-1] != 'Z':
switch {
case num2(b[len(b)-len("07:00"):]) >= 24: // timezone hour must be in range
return Time{}, &ParseError{RFC3339, string(b), "Z07:00", string(b[len(b)-len("Z07:00"):]), ": timezone hour out of range"}
case num2(b[len(b)-len("00"):]) >= 60: // timezone minute must be in range
return Time{}, &ParseError{RFC3339, string(b), "Z07:00", string(b[len(b)-len("Z07:00"):]), ": timezone minute out of range"}
}
default: // unknown error; should not occur
return Time{}, &ParseError{RFC3339, string(b), RFC3339, string(b), ""}
}
}
return t, nil
}
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