DataDog and StatsD Metrics Support

* Added support for DataDog and StatsD monitoring
* Added documentation

vendor/github.com/go-logfmt/logfmt/LICENSE

@@ -0,0 +1,22 @@
+The MIT License (MIT)
+
+Copyright (c) 2015 go-logfmt
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+

vendor/github.com/go-logfmt/logfmt/decode.go

@@ -0,0 +1,237 @@
+package logfmt
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"unicode/utf8"
+)
+
+// A Decoder reads and decodes logfmt records from an input stream.
+type Decoder struct {
+	pos     int
+	key     []byte
+	value   []byte
+	lineNum int
+	s       *bufio.Scanner
+	err     error
+}
+
+// NewDecoder returns a new decoder that reads from r.
+//
+// The decoder introduces its own buffering and may read data from r beyond
+// the logfmt records requested.
+func NewDecoder(r io.Reader) *Decoder {
+	dec := &Decoder{
+		s: bufio.NewScanner(r),
+	}
+	return dec
+}
+
+// ScanRecord advances the Decoder to the next record, which can then be
+// parsed with the ScanKeyval method. It returns false when decoding stops,
+// either by reaching the end of the input or an error. After ScanRecord
+// returns false, the Err method will return any error that occurred during
+// decoding, except that if it was io.EOF, Err will return nil.
+func (dec *Decoder) ScanRecord() bool {
+	if dec.err != nil {
+		return false
+	}
+	if !dec.s.Scan() {
+		dec.err = dec.s.Err()
+		return false
+	}
+	dec.lineNum++
+	dec.pos = 0
+	return true
+}
+
+// ScanKeyval advances the Decoder to the next key/value pair of the current
+// record, which can then be retrieved with the Key and Value methods. It
+// returns false when decoding stops, either by reaching the end of the
+// current record or an error.
+func (dec *Decoder) ScanKeyval() bool {
+	dec.key, dec.value = nil, nil
+	if dec.err != nil {
+		return false
+	}
+
+	line := dec.s.Bytes()
+
+	// garbage
+	for p, c := range line[dec.pos:] {
+		if c > ' ' {
+			dec.pos += p
+			goto key
+		}
+	}
+	dec.pos = len(line)
+	return false
+
+key:
+	const invalidKeyError = "invalid key"
+
+	start, multibyte := dec.pos, false
+	for p, c := range line[dec.pos:] {
+		switch {
+		case c == '=':
+			dec.pos += p
+			if dec.pos > start {
+				dec.key = line[start:dec.pos]
+				if multibyte && bytes.IndexRune(dec.key, utf8.RuneError) != -1 {
+					dec.syntaxError(invalidKeyError)
+					return false
+				}
+			}
+			if dec.key == nil {
+				dec.unexpectedByte(c)
+				return false
+			}
+			goto equal
+		case c == '"':
+			dec.pos += p
+			dec.unexpectedByte(c)
+			return false
+		case c <= ' ':
+			dec.pos += p
+			if dec.pos > start {
+				dec.key = line[start:dec.pos]
+				if multibyte && bytes.IndexRune(dec.key, utf8.RuneError) != -1 {
+					dec.syntaxError(invalidKeyError)
+					return false
+				}
+			}
+			return true
+		case c >= utf8.RuneSelf:
+			multibyte = true
+		}
+	}
+	dec.pos = len(line)
+	if dec.pos > start {
+		dec.key = line[start:dec.pos]
+		if multibyte && bytes.IndexRune(dec.key, utf8.RuneError) != -1 {
+			dec.syntaxError(invalidKeyError)
+			return false
+		}
+	}
+	return true
+
+equal:
+	dec.pos++
+	if dec.pos >= len(line) {
+		return true
+	}
+	switch c := line[dec.pos]; {
+	case c <= ' ':
+		return true
+	case c == '"':
+		goto qvalue
+	}
+
+	// value
+	start = dec.pos
+	for p, c := range line[dec.pos:] {
+		switch {
+		case c == '=' || c == '"':
+			dec.pos += p
+			dec.unexpectedByte(c)
+			return false
+		case c <= ' ':
+			dec.pos += p
+			if dec.pos > start {
+				dec.value = line[start:dec.pos]
+			}
+			return true
+		}
+	}
+	dec.pos = len(line)
+	if dec.pos > start {
+		dec.value = line[start:dec.pos]
+	}
+	return true
+
+qvalue:
+	const (
+		untermQuote  = "unterminated quoted value"
+		invalidQuote = "invalid quoted value"
+	)
+
+	hasEsc, esc := false, false
+	start = dec.pos
+	for p, c := range line[dec.pos+1:] {
+		switch {
+		case esc:
+			esc = false
+		case c == '\\':
+			hasEsc, esc = true, true
+		case c == '"':
+			dec.pos += p + 2
+			if hasEsc {
+				v, ok := unquoteBytes(line[start:dec.pos])
+				if !ok {
+					dec.syntaxError(invalidQuote)
+					return false
+				}
+				dec.value = v
+			} else {
+				start++
+				end := dec.pos - 1
+				if end > start {
+					dec.value = line[start:end]
+				}
+			}
+			return true
+		}
+	}
+	dec.pos = len(line)
+	dec.syntaxError(untermQuote)
+	return false
+}
+
+// Key returns the most recent key found by a call to ScanKeyval. The returned
+// slice may point to internal buffers and is only valid until the next call
+// to ScanRecord.  It does no allocation.
+func (dec *Decoder) Key() []byte {
+	return dec.key
+}
+
+// Value returns the most recent value found by a call to ScanKeyval. The
+// returned slice may point to internal buffers and is only valid until the
+// next call to ScanRecord.  It does no allocation when the value has no
+// escape sequences.
+func (dec *Decoder) Value() []byte {
+	return dec.value
+}
+
+// Err returns the first non-EOF error that was encountered by the Scanner.
+func (dec *Decoder) Err() error {
+	return dec.err
+}
+
+func (dec *Decoder) syntaxError(msg string) {
+	dec.err = &SyntaxError{
+		Msg:  msg,
+		Line: dec.lineNum,
+		Pos:  dec.pos + 1,
+	}
+}
+
+func (dec *Decoder) unexpectedByte(c byte) {
+	dec.err = &SyntaxError{
+		Msg:  fmt.Sprintf("unexpected %q", c),
+		Line: dec.lineNum,
+		Pos:  dec.pos + 1,
+	}
+}
+
+// A SyntaxError represents a syntax error in the logfmt input stream.
+type SyntaxError struct {
+	Msg  string
+	Line int
+	Pos  int
+}
+
+func (e *SyntaxError) Error() string {
+	return fmt.Sprintf("logfmt syntax error at pos %d on line %d: %s", e.Pos, e.Line, e.Msg)
+}

vendor/github.com/go-logfmt/logfmt/doc.go

@@ -0,0 +1,6 @@
+// Package logfmt implements utilities to marshal and unmarshal data in the
+// logfmt format. The logfmt format records key/value pairs in a way that
+// balances readability for humans and simplicity of computer parsing. It is
+// most commonly used as a more human friendly alternative to JSON for
+// structured logging.
+package logfmt

vendor/github.com/go-logfmt/logfmt/encode.go

@@ -0,0 +1,321 @@
+package logfmt
+
+import (
+	"bytes"
+	"encoding"
+	"errors"
+	"fmt"
+	"io"
+	"reflect"
+	"strings"
+	"unicode/utf8"
+)
+
+// MarshalKeyvals returns the logfmt encoding of keyvals, a variadic sequence
+// of alternating keys and values.
+func MarshalKeyvals(keyvals ...interface{}) ([]byte, error) {
+	buf := &bytes.Buffer{}
+	if err := NewEncoder(buf).EncodeKeyvals(keyvals...); err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
+// An Encoder writes logfmt data to an output stream.
+type Encoder struct {
+	w       io.Writer
+	scratch bytes.Buffer
+	needSep bool
+}
+
+// NewEncoder returns a new encoder that writes to w.
+func NewEncoder(w io.Writer) *Encoder {
+	return &Encoder{
+		w: w,
+	}
+}
+
+var (
+	space   = []byte(" ")
+	equals  = []byte("=")
+	newline = []byte("\n")
+	null    = []byte("null")
+)
+
+// EncodeKeyval writes the logfmt encoding of key and value to the stream. A
+// single space is written before the second and subsequent keys in a record.
+// Nothing is written if a non-nil error is returned.
+func (enc *Encoder) EncodeKeyval(key, value interface{}) error {
+	enc.scratch.Reset()
+	if enc.needSep {
+		if _, err := enc.scratch.Write(space); err != nil {
+			return err
+		}
+	}
+	if err := writeKey(&enc.scratch, key); err != nil {
+		return err
+	}
+	if _, err := enc.scratch.Write(equals); err != nil {
+		return err
+	}
+	if err := writeValue(&enc.scratch, value); err != nil {
+		return err
+	}
+	_, err := enc.w.Write(enc.scratch.Bytes())
+	enc.needSep = true
+	return err
+}
+
+// EncodeKeyvals writes the logfmt encoding of keyvals to the stream. Keyvals
+// is a variadic sequence of alternating keys and values. Keys of unsupported
+// type are skipped along with their corresponding value. Values of
+// unsupported type or that cause a MarshalerError are replaced by their error
+// but do not cause EncodeKeyvals to return an error. If a non-nil error is
+// returned some key/value pairs may not have be written.
+func (enc *Encoder) EncodeKeyvals(keyvals ...interface{}) error {
+	if len(keyvals) == 0 {
+		return nil
+	}
+	if len(keyvals)%2 == 1 {
+		keyvals = append(keyvals, nil)
+	}
+	for i := 0; i < len(keyvals); i += 2 {
+		k, v := keyvals[i], keyvals[i+1]
+		err := enc.EncodeKeyval(k, v)
+		if err == ErrUnsupportedKeyType {
+			continue
+		}
+		if _, ok := err.(*MarshalerError); ok || err == ErrUnsupportedValueType {
+			v = err
+			err = enc.EncodeKeyval(k, v)
+		}
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// MarshalerError represents an error encountered while marshaling a value.
+type MarshalerError struct {
+	Type reflect.Type
+	Err  error
+}
+
+func (e *MarshalerError) Error() string {
+	return "error marshaling value of type " + e.Type.String() + ": " + e.Err.Error()
+}
+
+// ErrNilKey is returned by Marshal functions and Encoder methods if a key is
+// a nil interface or pointer value.
+var ErrNilKey = errors.New("nil key")
+
+// ErrInvalidKey is returned by Marshal functions and Encoder methods if a key
+// contains an invalid character.
+var ErrInvalidKey = errors.New("invalid key")
+
+// ErrUnsupportedKeyType is returned by Encoder methods if a key has an
+// unsupported type.
+var ErrUnsupportedKeyType = errors.New("unsupported key type")
+
+// ErrUnsupportedValueType is returned by Encoder methods if a value has an
+// unsupported type.
+var ErrUnsupportedValueType = errors.New("unsupported value type")
+
+func writeKey(w io.Writer, key interface{}) error {
+	if key == nil {
+		return ErrNilKey
+	}
+
+	switch k := key.(type) {
+	case string:
+		return writeStringKey(w, k)
+	case []byte:
+		if k == nil {
+			return ErrNilKey
+		}
+		return writeBytesKey(w, k)
+	case encoding.TextMarshaler:
+		kb, err := safeMarshal(k)
+		if err != nil {
+			return err
+		}
+		if kb == nil {
+			return ErrNilKey
+		}
+		return writeBytesKey(w, kb)
+	case fmt.Stringer:
+		ks, ok := safeString(k)
+		if !ok {
+			return ErrNilKey
+		}
+		return writeStringKey(w, ks)
+	default:
+		rkey := reflect.ValueOf(key)
+		switch rkey.Kind() {
+		case reflect.Array, reflect.Chan, reflect.Func, reflect.Map, reflect.Slice, reflect.Struct:
+			return ErrUnsupportedKeyType
+		case reflect.Ptr:
+			if rkey.IsNil() {
+				return ErrNilKey
+			}
+			return writeKey(w, rkey.Elem().Interface())
+		}
+		return writeStringKey(w, fmt.Sprint(k))
+	}
+}
+
+func invalidKeyRune(r rune) bool {
+	return r <= ' ' || r == '=' || r == '"' || r == utf8.RuneError
+}
+
+func invalidKeyString(key string) bool {
+	return len(key) == 0 || strings.IndexFunc(key, invalidKeyRune) != -1
+}
+
+func invalidKey(key []byte) bool {
+	return len(key) == 0 || bytes.IndexFunc(key, invalidKeyRune) != -1
+}
+
+func writeStringKey(w io.Writer, key string) error {
+	if invalidKeyString(key) {
+		return ErrInvalidKey
+	}
+	_, err := io.WriteString(w, key)
+	return err
+}
+
+func writeBytesKey(w io.Writer, key []byte) error {
+	if invalidKey(key) {
+		return ErrInvalidKey
+	}
+	_, err := w.Write(key)
+	return err
+}
+
+func writeValue(w io.Writer, value interface{}) error {
+	switch v := value.(type) {
+	case nil:
+		return writeBytesValue(w, null)
+	case string:
+		return writeStringValue(w, v, true)
+	case []byte:
+		return writeBytesValue(w, v)
+	case encoding.TextMarshaler:
+		vb, err := safeMarshal(v)
+		if err != nil {
+			return err
+		}
+		if vb == nil {
+			vb = null
+		}
+		return writeBytesValue(w, vb)
+	case error:
+		se, ok := safeError(v)
+		return writeStringValue(w, se, ok)
+	case fmt.Stringer:
+		ss, ok := safeString(v)
+		return writeStringValue(w, ss, ok)
+	default:
+		rvalue := reflect.ValueOf(value)
+		switch rvalue.Kind() {
+		case reflect.Array, reflect.Chan, reflect.Func, reflect.Map, reflect.Slice, reflect.Struct:
+			return ErrUnsupportedValueType
+		case reflect.Ptr:
+			if rvalue.IsNil() {
+				return writeBytesValue(w, null)
+			}
+			return writeValue(w, rvalue.Elem().Interface())
+		}
+		return writeStringValue(w, fmt.Sprint(v), true)
+	}
+}
+
+func needsQuotedValueRune(r rune) bool {
+	return r <= ' ' || r == '=' || r == '"' || r == utf8.RuneError
+}
+
+func writeStringValue(w io.Writer, value string, ok bool) error {
+	var err error
+	if ok && value == "null" {
+		_, err = io.WriteString(w, `"null"`)
+	} else if strings.IndexFunc(value, needsQuotedValueRune) != -1 {
+		_, err = writeQuotedString(w, value)
+	} else {
+		_, err = io.WriteString(w, value)
+	}
+	return err
+}
+
+func writeBytesValue(w io.Writer, value []byte) error {
+	var err error
+	if bytes.IndexFunc(value, needsQuotedValueRune) != -1 {
+		_, err = writeQuotedBytes(w, value)
+	} else {
+		_, err = w.Write(value)
+	}
+	return err
+}
+
+// EndRecord writes a newline character to the stream and resets the encoder
+// to the beginning of a new record.
+func (enc *Encoder) EndRecord() error {
+	_, err := enc.w.Write(newline)
+	if err == nil {
+		enc.needSep = false
+	}
+	return err
+}
+
+// Reset resets the encoder to the beginning of a new record.
+func (enc *Encoder) Reset() {
+	enc.needSep = false
+}
+
+func safeError(err error) (s string, ok bool) {
+	defer func() {
+		if panicVal := recover(); panicVal != nil {
+			if v := reflect.ValueOf(err); v.Kind() == reflect.Ptr && v.IsNil() {
+				s, ok = "null", false
+			} else {
+				panic(panicVal)
+			}
+		}
+	}()
+	s, ok = err.Error(), true
+	return
+}
+
+func safeString(str fmt.Stringer) (s string, ok bool) {
+	defer func() {
+		if panicVal := recover(); panicVal != nil {
+			if v := reflect.ValueOf(str); v.Kind() == reflect.Ptr && v.IsNil() {
+				s, ok = "null", false
+			} else {
+				panic(panicVal)
+			}
+		}
+	}()
+	s, ok = str.String(), true
+	return
+}
+
+func safeMarshal(tm encoding.TextMarshaler) (b []byte, err error) {
+	defer func() {
+		if panicVal := recover(); panicVal != nil {
+			if v := reflect.ValueOf(tm); v.Kind() == reflect.Ptr && v.IsNil() {
+				b, err = nil, nil
+			} else {
+				panic(panicVal)
+			}
+		}
+	}()
+	b, err = tm.MarshalText()
+	if err != nil {
+		return nil, &MarshalerError{
+			Type: reflect.TypeOf(tm),
+			Err:  err,
+		}
+	}
+	return
+}

vendor/github.com/go-logfmt/logfmt/fuzz.go

@@ -0,0 +1,126 @@
+// +build gofuzz
+
+package logfmt
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"reflect"
+
+	kr "github.com/kr/logfmt"
+)
+
+// Fuzz checks reserialized data matches
+func Fuzz(data []byte) int {
+	parsed, err := parse(data)
+	if err != nil {
+		return 0
+	}
+	var w1 bytes.Buffer
+	if err = write(parsed, &w1); err != nil {
+		panic(err)
+	}
+	parsed, err = parse(w1.Bytes())
+	if err != nil {
+		panic(err)
+	}
+	var w2 bytes.Buffer
+	if err = write(parsed, &w2); err != nil {
+		panic(err)
+	}
+	if !bytes.Equal(w1.Bytes(), w2.Bytes()) {
+		panic(fmt.Sprintf("reserialized data does not match:\n%q\n%q\n", w1.Bytes(), w2.Bytes()))
+	}
+	return 1
+}
+
+// FuzzVsKR checks go-logfmt/logfmt against kr/logfmt
+func FuzzVsKR(data []byte) int {
+	parsed, err := parse(data)
+	parsedKR, errKR := parseKR(data)
+
+	// github.com/go-logfmt/logfmt is a stricter parser. It returns errors for
+	// more inputs than github.com/kr/logfmt. Ignore any inputs that have a
+	// stict error.
+	if err != nil {
+		return 0
+	}
+
+	// Fail if the more forgiving parser finds an error not found by the
+	// stricter parser.
+	if errKR != nil {
+		panic(fmt.Sprintf("unmatched error: %v", errKR))
+	}
+
+	if !reflect.DeepEqual(parsed, parsedKR) {
+		panic(fmt.Sprintf("parsers disagree:\n%+v\n%+v\n", parsed, parsedKR))
+	}
+	return 1
+}
+
+type kv struct {
+	k, v []byte
+}
+
+func parse(data []byte) ([][]kv, error) {
+	var got [][]kv
+	dec := NewDecoder(bytes.NewReader(data))
+	for dec.ScanRecord() {
+		var kvs []kv
+		for dec.ScanKeyval() {
+			kvs = append(kvs, kv{dec.Key(), dec.Value()})
+		}
+		got = append(got, kvs)
+	}
+	return got, dec.Err()
+}
+
+func parseKR(data []byte) ([][]kv, error) {
+	var (
+		s   = bufio.NewScanner(bytes.NewReader(data))
+		err error
+		h   saveHandler
+		got [][]kv
+	)
+	for err == nil && s.Scan() {
+		h.kvs = nil
+		err = kr.Unmarshal(s.Bytes(), &h)
+		got = append(got, h.kvs)
+	}
+	if err == nil {
+		err = s.Err()
+	}
+	return got, err
+}
+
+type saveHandler struct {
+	kvs []kv
+}
+
+func (h *saveHandler) HandleLogfmt(key, val []byte) error {
+	if len(key) == 0 {
+		key = nil
+	}
+	if len(val) == 0 {
+		val = nil
+	}
+	h.kvs = append(h.kvs, kv{key, val})
+	return nil
+}
+
+func write(recs [][]kv, w io.Writer) error {
+	enc := NewEncoder(w)
+	for _, rec := range recs {
+		for _, f := range rec {
+			if err := enc.EncodeKeyval(f.k, f.v); err != nil {
+				return err
+			}
+		}
+		if err := enc.EndRecord(); err != nil {
+			return err
+		}
+	}
+	return nil
+}

vendor/github.com/go-logfmt/logfmt/jsonstring.go

@@ -0,0 +1,277 @@
+package logfmt
+
+import (
+	"bytes"
+	"io"
+	"strconv"
+	"sync"
+	"unicode"
+	"unicode/utf16"
+	"unicode/utf8"
+)
+
+// Taken from Go's encoding/json and modified for use here.
+
+// 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.
+
+var hex = "0123456789abcdef"
+
+var bufferPool = sync.Pool{
+	New: func() interface{} {
+		return &bytes.Buffer{}
+	},
+}
+
+func getBuffer() *bytes.Buffer {
+	return bufferPool.Get().(*bytes.Buffer)
+}
+
+func poolBuffer(buf *bytes.Buffer) {
+	buf.Reset()
+	bufferPool.Put(buf)
+}
+
+// NOTE: keep in sync with writeQuotedBytes below.
+func writeQuotedString(w io.Writer, s string) (int, error) {
+	buf := getBuffer()
+	buf.WriteByte('"')
+	start := 0
+	for i := 0; i < len(s); {
+		if b := s[i]; b < utf8.RuneSelf {
+			if 0x20 <= b && b != '\\' && b != '"' {
+				i++
+				continue
+			}
+			if start < i {
+				buf.WriteString(s[start:i])
+			}
+			switch b {
+			case '\\', '"':
+				buf.WriteByte('\\')
+				buf.WriteByte(b)
+			case '\n':
+				buf.WriteByte('\\')
+				buf.WriteByte('n')
+			case '\r':
+				buf.WriteByte('\\')
+				buf.WriteByte('r')
+			case '\t':
+				buf.WriteByte('\\')
+				buf.WriteByte('t')
+			default:
+				// This encodes bytes < 0x20 except for \n, \r, and \t.
+				buf.WriteString(`\u00`)
+				buf.WriteByte(hex[b>>4])
+				buf.WriteByte(hex[b&0xF])
+			}
+			i++
+			start = i
+			continue
+		}
+		c, size := utf8.DecodeRuneInString(s[i:])
+		if c == utf8.RuneError {
+			if start < i {
+				buf.WriteString(s[start:i])
+			}
+			buf.WriteString(`\ufffd`)
+			i += size
+			start = i
+			continue
+		}
+		i += size
+	}
+	if start < len(s) {
+		buf.WriteString(s[start:])
+	}
+	buf.WriteByte('"')
+	n, err := w.Write(buf.Bytes())
+	poolBuffer(buf)
+	return n, err
+}
+
+// NOTE: keep in sync with writeQuoteString above.
+func writeQuotedBytes(w io.Writer, s []byte) (int, error) {
+	buf := getBuffer()
+	buf.WriteByte('"')
+	start := 0
+	for i := 0; i < len(s); {
+		if b := s[i]; b < utf8.RuneSelf {
+			if 0x20 <= b && b != '\\' && b != '"' {
+				i++
+				continue
+			}
+			if start < i {
+				buf.Write(s[start:i])
+			}
+			switch b {
+			case '\\', '"':
+				buf.WriteByte('\\')
+				buf.WriteByte(b)
+			case '\n':
+				buf.WriteByte('\\')
+				buf.WriteByte('n')
+			case '\r':
+				buf.WriteByte('\\')
+				buf.WriteByte('r')
+			case '\t':
+				buf.WriteByte('\\')
+				buf.WriteByte('t')
+			default:
+				// This encodes bytes < 0x20 except for \n, \r, and \t.
+				buf.WriteString(`\u00`)
+				buf.WriteByte(hex[b>>4])
+				buf.WriteByte(hex[b&0xF])
+			}
+			i++
+			start = i
+			continue
+		}
+		c, size := utf8.DecodeRune(s[i:])
+		if c == utf8.RuneError {
+			if start < i {
+				buf.Write(s[start:i])
+			}
+			buf.WriteString(`\ufffd`)
+			i += size
+			start = i
+			continue
+		}
+		i += size
+	}
+	if start < len(s) {
+		buf.Write(s[start:])
+	}
+	buf.WriteByte('"')
+	n, err := w.Write(buf.Bytes())
+	poolBuffer(buf)
+	return n, err
+}
+
+// getu4 decodes \uXXXX from the beginning of s, returning the hex value,
+// or it returns -1.
+func getu4(s []byte) rune {
+	if len(s) < 6 || s[0] != '\\' || s[1] != 'u' {
+		return -1
+	}
+	r, err := strconv.ParseUint(string(s[2:6]), 16, 64)
+	if err != nil {
+		return -1
+	}
+	return rune(r)
+}
+
+func unquoteBytes(s []byte) (t []byte, ok bool) {
+	if len(s) < 2 || s[0] != '"' || s[len(s)-1] != '"' {
+		return
+	}
+	s = s[1 : len(s)-1]
+
+	// Check for unusual characters. If there are none,
+	// then no unquoting is needed, so return a slice of the
+	// original bytes.
+	r := 0
+	for r < len(s) {
+		c := s[r]
+		if c == '\\' || c == '"' || c < ' ' {
+			break
+		}
+		if c < utf8.RuneSelf {
+			r++
+			continue
+		}
+		rr, size := utf8.DecodeRune(s[r:])
+		if rr == utf8.RuneError {
+			break
+		}
+		r += size
+	}
+	if r == len(s) {
+		return s, true
+	}
+
+	b := make([]byte, len(s)+2*utf8.UTFMax)
+	w := copy(b, s[0:r])
+	for r < len(s) {
+		// Out of room?  Can only happen if s is full of
+		// malformed UTF-8 and we're replacing each
+		// byte with RuneError.
+		if w >= len(b)-2*utf8.UTFMax {
+			nb := make([]byte, (len(b)+utf8.UTFMax)*2)
+			copy(nb, b[0:w])
+			b = nb
+		}
+		switch c := s[r]; {
+		case c == '\\':
+			r++
+			if r >= len(s) {
+				return
+			}
+			switch s[r] {
+			default:
+				return
+			case '"', '\\', '/', '\'':
+				b[w] = s[r]
+				r++
+				w++
+			case 'b':
+				b[w] = '\b'
+				r++
+				w++
+			case 'f':
+				b[w] = '\f'
+				r++
+				w++
+			case 'n':
+				b[w] = '\n'
+				r++
+				w++
+			case 'r':
+				b[w] = '\r'
+				r++
+				w++
+			case 't':
+				b[w] = '\t'
+				r++
+				w++
+			case 'u':
+				r--
+				rr := getu4(s[r:])
+				if rr < 0 {
+					return
+				}
+				r += 6
+				if utf16.IsSurrogate(rr) {
+					rr1 := getu4(s[r:])
+					if dec := utf16.DecodeRune(rr, rr1); dec != unicode.ReplacementChar {
+						// A valid pair; consume.
+						r += 6
+						w += utf8.EncodeRune(b[w:], dec)
+						break
+					}
+					// Invalid surrogate; fall back to replacement rune.
+					rr = unicode.ReplacementChar
+				}
+				w += utf8.EncodeRune(b[w:], rr)
+			}
+
+		// Quote, control characters are invalid.
+		case c == '"', c < ' ':
+			return
+
+		// ASCII
+		case c < utf8.RuneSelf:
+			b[w] = c
+			r++
+			w++
+
+		// Coerce to well-formed UTF-8.
+		default:
+			rr, size := utf8.DecodeRune(s[r:])
+			r += size
+			w += utf8.EncodeRune(b[w:], rr)
+		}
+	}
+	return b[0:w], true
+}