150 lines
2.8 KiB
Go
150 lines
2.8 KiB
Go
package logfmt
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import (
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"strconv"
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"unicode"
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"unicode/utf16"
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"unicode/utf8"
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)
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// Taken from Go's encoding/json
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// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// getu4 decodes \uXXXX from the beginning of s, returning the hex value,
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// or it returns -1.
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func getu4(s []byte) rune {
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if len(s) < 6 || s[0] != '\\' || s[1] != 'u' {
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return -1
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}
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r, err := strconv.ParseUint(string(s[2:6]), 16, 64)
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if err != nil {
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return -1
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}
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return rune(r)
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}
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// unquote converts a quoted JSON string literal s into an actual string t.
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// The rules are different than for Go, so cannot use strconv.Unquote.
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func unquote(s []byte) (t string, ok bool) {
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s, ok = unquoteBytes(s)
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t = string(s)
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return
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}
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func unquoteBytes(s []byte) (t []byte, ok bool) {
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if len(s) < 2 || s[0] != '"' || s[len(s)-1] != '"' {
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return
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}
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s = s[1 : len(s)-1]
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// Check for unusual characters. If there are none,
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// then no unquoting is needed, so return a slice of the
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// original bytes.
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r := 0
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for r < len(s) {
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c := s[r]
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if c == '\\' || c == '"' || c < ' ' {
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break
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}
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if c < utf8.RuneSelf {
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r++
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continue
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}
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rr, size := utf8.DecodeRune(s[r:])
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if rr == utf8.RuneError && size == 1 {
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break
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}
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r += size
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}
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if r == len(s) {
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return s, true
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}
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b := make([]byte, len(s)+2*utf8.UTFMax)
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w := copy(b, s[0:r])
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for r < len(s) {
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// Out of room? Can only happen if s is full of
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// malformed UTF-8 and we're replacing each
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// byte with RuneError.
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if w >= len(b)-2*utf8.UTFMax {
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nb := make([]byte, (len(b)+utf8.UTFMax)*2)
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copy(nb, b[0:w])
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b = nb
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}
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switch c := s[r]; {
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case c == '\\':
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r++
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if r >= len(s) {
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return
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}
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switch s[r] {
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default:
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return
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case '"', '\\', '/', '\'':
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b[w] = s[r]
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r++
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w++
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case 'b':
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b[w] = '\b'
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r++
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w++
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case 'f':
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b[w] = '\f'
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r++
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w++
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case 'n':
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b[w] = '\n'
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r++
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w++
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case 'r':
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b[w] = '\r'
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r++
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w++
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case 't':
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b[w] = '\t'
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r++
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w++
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case 'u':
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r--
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rr := getu4(s[r:])
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if rr < 0 {
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return
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}
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r += 6
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if utf16.IsSurrogate(rr) {
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rr1 := getu4(s[r:])
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if dec := utf16.DecodeRune(rr, rr1); dec != unicode.ReplacementChar {
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// A valid pair; consume.
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r += 6
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w += utf8.EncodeRune(b[w:], dec)
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break
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}
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// Invalid surrogate; fall back to replacement rune.
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rr = unicode.ReplacementChar
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}
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w += utf8.EncodeRune(b[w:], rr)
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}
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// Quote, control characters are invalid.
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case c == '"', c < ' ':
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return
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// ASCII
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case c < utf8.RuneSelf:
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b[w] = c
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r++
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w++
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// Coerce to well-formed UTF-8.
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default:
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rr, size := utf8.DecodeRune(s[r:])
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r += size
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w += utf8.EncodeRune(b[w:], rr)
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}
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}
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return b[0:w], true
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}
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