sing-box/option/time_unit.go

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Go
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2023-12-01 05:24:12 +00:00
package option
import (
"errors"
"time"
)
// Copyright 2010 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.
const durationDay = 24 * time.Hour
var unitMap = map[string]uint64{
"ns": uint64(time.Nanosecond),
"us": uint64(time.Microsecond),
"µs": uint64(time.Microsecond), // U+00B5 = micro symbol
"μs": uint64(time.Microsecond), // U+03BC = Greek letter mu
"ms": uint64(time.Millisecond),
"s": uint64(time.Second),
"m": uint64(time.Minute),
"h": uint64(time.Hour),
"d": uint64(durationDay),
}
// ParseDuration parses a duration string.
// A duration string is a possibly signed sequence of
// decimal numbers, each with optional fraction and a unit suffix,
// such as "300ms", "-1.5h" or "2h45m".
// Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".
func ParseDuration(s string) (Duration, error) {
// [-+]?([0-9]*(\.[0-9]*)?[a-z]+)+
orig := s
var d uint64
neg := false
// Consume [-+]?
if s != "" {
c := s[0]
if c == '-' || c == '+' {
neg = c == '-'
s = s[1:]
}
}
// Special case: if all that is left is "0", this is zero.
if s == "0" {
return 0, nil
}
if s == "" {
return 0, errors.New("time: invalid duration " + quote(orig))
}
for s != "" {
var (
v, f uint64 // integers before, after decimal point
scale float64 = 1 // value = v + f/scale
)
var err error
// The next character must be [0-9.]
if !(s[0] == '.' || '0' <= s[0] && s[0] <= '9') {
return 0, errors.New("time: invalid duration " + quote(orig))
}
// Consume [0-9]*
pl := len(s)
v, s, err = leadingInt(s)
if err != nil {
return 0, errors.New("time: invalid duration " + quote(orig))
}
pre := pl != len(s) // whether we consumed anything before a period
// Consume (\.[0-9]*)?
post := false
if s != "" && s[0] == '.' {
s = s[1:]
pl := len(s)
f, scale, s = leadingFraction(s)
post = pl != len(s)
}
if !pre && !post {
// no digits (e.g. ".s" or "-.s")
return 0, errors.New("time: invalid duration " + quote(orig))
}
// Consume unit.
i := 0
for ; i < len(s); i++ {
c := s[i]
if c == '.' || '0' <= c && c <= '9' {
break
}
}
if i == 0 {
return 0, errors.New("time: missing unit in duration " + quote(orig))
}
u := s[:i]
s = s[i:]
unit, ok := unitMap[u]
if !ok {
return 0, errors.New("time: unknown unit " + quote(u) + " in duration " + quote(orig))
}
if v > 1<<63/unit {
// overflow
return 0, errors.New("time: invalid duration " + quote(orig))
}
v *= unit
if f > 0 {
// float64 is needed to be nanosecond accurate for fractions of hours.
// v >= 0 && (f*unit/scale) <= 3.6e+12 (ns/h, h is the largest unit)
v += uint64(float64(f) * (float64(unit) / scale))
if v > 1<<63 {
// overflow
return 0, errors.New("time: invalid duration " + quote(orig))
}
}
d += v
if d > 1<<63 {
return 0, errors.New("time: invalid duration " + quote(orig))
}
}
if neg {
return -Duration(d), nil
}
if d > 1<<63-1 {
return 0, errors.New("time: invalid duration " + quote(orig))
}
return Duration(d), nil
}
var errLeadingInt = errors.New("time: bad [0-9]*") // never printed
// leadingInt consumes the leading [0-9]* from s.
func leadingInt[bytes []byte | string](s bytes) (x uint64, rem bytes, err error) {
i := 0
for ; i < len(s); i++ {
c := s[i]
if c < '0' || c > '9' {
break
}
if x > 1<<63/10 {
// overflow
return 0, rem, errLeadingInt
}
x = x*10 + uint64(c) - '0'
if x > 1<<63 {
// overflow
return 0, rem, errLeadingInt
}
}
return x, s[i:], nil
}
// leadingFraction consumes the leading [0-9]* from s.
// It is used only for fractions, so does not return an error on overflow,
// it just stops accumulating precision.
func leadingFraction(s string) (x uint64, scale float64, rem string) {
i := 0
scale = 1
overflow := false
for ; i < len(s); i++ {
c := s[i]
if c < '0' || c > '9' {
break
}
if overflow {
continue
}
if x > (1<<63-1)/10 {
// It's possible for overflow to give a positive number, so take care.
overflow = true
continue
}
y := x*10 + uint64(c) - '0'
if y > 1<<63 {
overflow = true
continue
}
x = y
scale *= 10
}
return x, scale, s[i:]
}
// These are borrowed from unicode/utf8 and strconv and replicate behavior in
// that package, since we can't take a dependency on either.
const (
lowerhex = "0123456789abcdef"
runeSelf = 0x80
runeError = '\uFFFD'
)
func quote(s string) string {
buf := make([]byte, 1, len(s)+2) // slice will be at least len(s) + quotes
buf[0] = '"'
for i, c := range s {
if c >= runeSelf || c < ' ' {
// This means you are asking us to parse a time.Duration or
// time.Location with unprintable or non-ASCII characters in it.
// We don't expect to hit this case very often. We could try to
// reproduce strconv.Quote's behavior with full fidelity but
// given how rarely we expect to hit these edge cases, speed and
// conciseness are better.
var width int
if c == runeError {
width = 1
if i+2 < len(s) && s[i:i+3] == string(runeError) {
width = 3
}
} else {
width = len(string(c))
}
for j := 0; j < width; j++ {
buf = append(buf, `\x`...)
buf = append(buf, lowerhex[s[i+j]>>4])
buf = append(buf, lowerhex[s[i+j]&0xF])
}
} else {
if c == '"' || c == '\\' {
buf = append(buf, '\\')
}
buf = append(buf, string(c)...)
}
}
buf = append(buf, '"')
return string(buf)
}