syncthing/vendor/github.com/BurntSushi/toml/encode.go

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cmd/stdiscosrv: New discovery server (fixes #4618) This is a new revision of the discovery server. Relevant changes and non-changes: - Protocol towards clients is unchanged. - Recommended large scale design is still to be deployed nehind nginx (I tested, and it's still a lot faster at terminating TLS). - Database backend is leveldb again, only. It scales enough, is easy to setup, and we don't need any backend to take care of. - Server supports replication. This is a simple TCP channel - protect it with a firewall when deploying over the internet. (We deploy this within the same datacenter, and with firewall.) Any incoming client announces are sent over the replication channel(s) to other peer discosrvs. Incoming replication changes are applied to the database as if they came from clients, but without the TLS/certificate overhead. - Metrics are exposed using the prometheus library, when enabled. - The database values and replication protocol is protobuf, because JSON was quite CPU intensive when I tried that and benchmarked it. - The "Retry-After" value for failed lookups gets slowly increased from a default of 120 seconds, by 5 seconds for each failed lookup, independently by each discosrv. This lowers the query load over time for clients that are never seen. The Retry-After maxes out at 3600 after a couple of weeks of this increase. The number of failed lookups is stored in the database, now and then (avoiding making each lookup a database put). All in all this means clients can be pointed towards a cluster using just multiple A / AAAA records to gain both load sharing and redundancy (if one is down, clients will talk to the remaining ones). GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4648
2018-01-14 08:52:31 +00:00
package toml
import (
"bufio"
"errors"
"fmt"
"io"
"reflect"
"sort"
"strconv"
"strings"
"time"
)
type tomlEncodeError struct{ error }
var (
errArrayMixedElementTypes = errors.New(
"toml: cannot encode array with mixed element types")
errArrayNilElement = errors.New(
"toml: cannot encode array with nil element")
errNonString = errors.New(
"toml: cannot encode a map with non-string key type")
errAnonNonStruct = errors.New(
"toml: cannot encode an anonymous field that is not a struct")
errArrayNoTable = errors.New(
"toml: TOML array element cannot contain a table")
errNoKey = errors.New(
"toml: top-level values must be Go maps or structs")
errAnything = errors.New("") // used in testing
)
var quotedReplacer = strings.NewReplacer(
"\t", "\\t",
"\n", "\\n",
"\r", "\\r",
"\"", "\\\"",
"\\", "\\\\",
)
// Encoder controls the encoding of Go values to a TOML document to some
// io.Writer.
//
// The indentation level can be controlled with the Indent field.
type Encoder struct {
// A single indentation level. By default it is two spaces.
Indent string
// hasWritten is whether we have written any output to w yet.
hasWritten bool
w *bufio.Writer
}
// NewEncoder returns a TOML encoder that encodes Go values to the io.Writer
// given. By default, a single indentation level is 2 spaces.
func NewEncoder(w io.Writer) *Encoder {
return &Encoder{
w: bufio.NewWriter(w),
Indent: " ",
}
}
// Encode writes a TOML representation of the Go value to the underlying
// io.Writer. If the value given cannot be encoded to a valid TOML document,
// then an error is returned.
//
// The mapping between Go values and TOML values should be precisely the same
// as for the Decode* functions. Similarly, the TextMarshaler interface is
// supported by encoding the resulting bytes as strings. (If you want to write
// arbitrary binary data then you will need to use something like base64 since
// TOML does not have any binary types.)
//
// When encoding TOML hashes (i.e., Go maps or structs), keys without any
// sub-hashes are encoded first.
//
// If a Go map is encoded, then its keys are sorted alphabetically for
// deterministic output. More control over this behavior may be provided if
// there is demand for it.
//
// Encoding Go values without a corresponding TOML representation---like map
// types with non-string keys---will cause an error to be returned. Similarly
// for mixed arrays/slices, arrays/slices with nil elements, embedded
// non-struct types and nested slices containing maps or structs.
// (e.g., [][]map[string]string is not allowed but []map[string]string is OK
// and so is []map[string][]string.)
func (enc *Encoder) Encode(v interface{}) error {
rv := eindirect(reflect.ValueOf(v))
if err := enc.safeEncode(Key([]string{}), rv); err != nil {
return err
}
return enc.w.Flush()
}
func (enc *Encoder) safeEncode(key Key, rv reflect.Value) (err error) {
defer func() {
if r := recover(); r != nil {
if terr, ok := r.(tomlEncodeError); ok {
err = terr.error
return
}
panic(r)
}
}()
enc.encode(key, rv)
return nil
}
func (enc *Encoder) encode(key Key, rv reflect.Value) {
// Special case. Time needs to be in ISO8601 format.
// Special case. If we can marshal the type to text, then we used that.
// Basically, this prevents the encoder for handling these types as
// generic structs (or whatever the underlying type of a TextMarshaler is).
switch rv.Interface().(type) {
case time.Time, TextMarshaler:
enc.keyEqElement(key, rv)
return
}
k := rv.Kind()
switch k {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32,
reflect.Int64,
reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32,
reflect.Uint64,
reflect.Float32, reflect.Float64, reflect.String, reflect.Bool:
enc.keyEqElement(key, rv)
case reflect.Array, reflect.Slice:
if typeEqual(tomlArrayHash, tomlTypeOfGo(rv)) {
enc.eArrayOfTables(key, rv)
} else {
enc.keyEqElement(key, rv)
}
case reflect.Interface:
if rv.IsNil() {
return
}
enc.encode(key, rv.Elem())
case reflect.Map:
if rv.IsNil() {
return
}
enc.eTable(key, rv)
case reflect.Ptr:
if rv.IsNil() {
return
}
enc.encode(key, rv.Elem())
case reflect.Struct:
enc.eTable(key, rv)
default:
panic(e("unsupported type for key '%s': %s", key, k))
}
}
// eElement encodes any value that can be an array element (primitives and
// arrays).
func (enc *Encoder) eElement(rv reflect.Value) {
switch v := rv.Interface().(type) {
case time.Time:
// Special case time.Time as a primitive. Has to come before
// TextMarshaler below because time.Time implements
// encoding.TextMarshaler, but we need to always use UTC.
enc.wf(v.UTC().Format("2006-01-02T15:04:05Z"))
return
case TextMarshaler:
// Special case. Use text marshaler if it's available for this value.
if s, err := v.MarshalText(); err != nil {
encPanic(err)
} else {
enc.writeQuoted(string(s))
}
return
}
switch rv.Kind() {
case reflect.Bool:
enc.wf(strconv.FormatBool(rv.Bool()))
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32,
reflect.Int64:
enc.wf(strconv.FormatInt(rv.Int(), 10))
case reflect.Uint, reflect.Uint8, reflect.Uint16,
reflect.Uint32, reflect.Uint64:
enc.wf(strconv.FormatUint(rv.Uint(), 10))
case reflect.Float32:
enc.wf(floatAddDecimal(strconv.FormatFloat(rv.Float(), 'f', -1, 32)))
case reflect.Float64:
enc.wf(floatAddDecimal(strconv.FormatFloat(rv.Float(), 'f', -1, 64)))
case reflect.Array, reflect.Slice:
enc.eArrayOrSliceElement(rv)
case reflect.Interface:
enc.eElement(rv.Elem())
case reflect.String:
enc.writeQuoted(rv.String())
default:
panic(e("unexpected primitive type: %s", rv.Kind()))
}
}
// By the TOML spec, all floats must have a decimal with at least one
// number on either side.
func floatAddDecimal(fstr string) string {
if !strings.Contains(fstr, ".") {
return fstr + ".0"
}
return fstr
}
func (enc *Encoder) writeQuoted(s string) {
enc.wf("\"%s\"", quotedReplacer.Replace(s))
}
func (enc *Encoder) eArrayOrSliceElement(rv reflect.Value) {
length := rv.Len()
enc.wf("[")
for i := 0; i < length; i++ {
elem := rv.Index(i)
enc.eElement(elem)
if i != length-1 {
enc.wf(", ")
}
}
enc.wf("]")
}
func (enc *Encoder) eArrayOfTables(key Key, rv reflect.Value) {
if len(key) == 0 {
encPanic(errNoKey)
}
for i := 0; i < rv.Len(); i++ {
trv := rv.Index(i)
if isNil(trv) {
continue
}
panicIfInvalidKey(key)
enc.newline()
enc.wf("%s[[%s]]", enc.indentStr(key), key.maybeQuotedAll())
enc.newline()
enc.eMapOrStruct(key, trv)
}
}
func (enc *Encoder) eTable(key Key, rv reflect.Value) {
panicIfInvalidKey(key)
if len(key) == 1 {
// Output an extra newline between top-level tables.
// (The newline isn't written if nothing else has been written though.)
enc.newline()
}
if len(key) > 0 {
enc.wf("%s[%s]", enc.indentStr(key), key.maybeQuotedAll())
enc.newline()
}
enc.eMapOrStruct(key, rv)
}
func (enc *Encoder) eMapOrStruct(key Key, rv reflect.Value) {
switch rv := eindirect(rv); rv.Kind() {
case reflect.Map:
enc.eMap(key, rv)
case reflect.Struct:
enc.eStruct(key, rv)
default:
panic("eTable: unhandled reflect.Value Kind: " + rv.Kind().String())
}
}
func (enc *Encoder) eMap(key Key, rv reflect.Value) {
rt := rv.Type()
if rt.Key().Kind() != reflect.String {
encPanic(errNonString)
}
// Sort keys so that we have deterministic output. And write keys directly
// underneath this key first, before writing sub-structs or sub-maps.
var mapKeysDirect, mapKeysSub []string
for _, mapKey := range rv.MapKeys() {
k := mapKey.String()
if typeIsHash(tomlTypeOfGo(rv.MapIndex(mapKey))) {
mapKeysSub = append(mapKeysSub, k)
} else {
mapKeysDirect = append(mapKeysDirect, k)
}
}
var writeMapKeys = func(mapKeys []string) {
sort.Strings(mapKeys)
for _, mapKey := range mapKeys {
mrv := rv.MapIndex(reflect.ValueOf(mapKey))
if isNil(mrv) {
// Don't write anything for nil fields.
continue
}
enc.encode(key.add(mapKey), mrv)
}
}
writeMapKeys(mapKeysDirect)
writeMapKeys(mapKeysSub)
}
func (enc *Encoder) eStruct(key Key, rv reflect.Value) {
// Write keys for fields directly under this key first, because if we write
// a field that creates a new table, then all keys under it will be in that
// table (not the one we're writing here).
rt := rv.Type()
var fieldsDirect, fieldsSub [][]int
var addFields func(rt reflect.Type, rv reflect.Value, start []int)
addFields = func(rt reflect.Type, rv reflect.Value, start []int) {
for i := 0; i < rt.NumField(); i++ {
f := rt.Field(i)
// skip unexported fields
if f.PkgPath != "" && !f.Anonymous {
continue
}
frv := rv.Field(i)
if f.Anonymous {
t := f.Type
switch t.Kind() {
case reflect.Struct:
// Treat anonymous struct fields with
// tag names as though they are not
// anonymous, like encoding/json does.
if getOptions(f.Tag).name == "" {
addFields(t, frv, f.Index)
continue
}
case reflect.Ptr:
if t.Elem().Kind() == reflect.Struct &&
getOptions(f.Tag).name == "" {
if !frv.IsNil() {
addFields(t.Elem(), frv.Elem(), f.Index)
}
continue
}
// Fall through to the normal field encoding logic below
// for non-struct anonymous fields.
}
}
if typeIsHash(tomlTypeOfGo(frv)) {
fieldsSub = append(fieldsSub, append(start, f.Index...))
} else {
fieldsDirect = append(fieldsDirect, append(start, f.Index...))
}
}
}
addFields(rt, rv, nil)
var writeFields = func(fields [][]int) {
for _, fieldIndex := range fields {
sft := rt.FieldByIndex(fieldIndex)
sf := rv.FieldByIndex(fieldIndex)
if isNil(sf) {
// Don't write anything for nil fields.
continue
}
opts := getOptions(sft.Tag)
if opts.skip {
continue
}
keyName := sft.Name
if opts.name != "" {
keyName = opts.name
}
if opts.omitempty && isEmpty(sf) {
continue
}
if opts.omitzero && isZero(sf) {
continue
}
enc.encode(key.add(keyName), sf)
}
}
writeFields(fieldsDirect)
writeFields(fieldsSub)
}
// tomlTypeName returns the TOML type name of the Go value's type. It is
// used to determine whether the types of array elements are mixed (which is
// forbidden). If the Go value is nil, then it is illegal for it to be an array
// element, and valueIsNil is returned as true.
// Returns the TOML type of a Go value. The type may be `nil`, which means
// no concrete TOML type could be found.
func tomlTypeOfGo(rv reflect.Value) tomlType {
if isNil(rv) || !rv.IsValid() {
return nil
}
switch rv.Kind() {
case reflect.Bool:
return tomlBool
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32,
reflect.Int64,
reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32,
reflect.Uint64:
return tomlInteger
case reflect.Float32, reflect.Float64:
return tomlFloat
case reflect.Array, reflect.Slice:
if typeEqual(tomlHash, tomlArrayType(rv)) {
return tomlArrayHash
}
return tomlArray
case reflect.Ptr, reflect.Interface:
return tomlTypeOfGo(rv.Elem())
case reflect.String:
return tomlString
case reflect.Map:
return tomlHash
case reflect.Struct:
switch rv.Interface().(type) {
case time.Time:
return tomlDatetime
case TextMarshaler:
return tomlString
default:
return tomlHash
}
default:
panic("unexpected reflect.Kind: " + rv.Kind().String())
}
}
// tomlArrayType returns the element type of a TOML array. The type returned
// may be nil if it cannot be determined (e.g., a nil slice or a zero length
// slize). This function may also panic if it finds a type that cannot be
// expressed in TOML (such as nil elements, heterogeneous arrays or directly
// nested arrays of tables).
func tomlArrayType(rv reflect.Value) tomlType {
if isNil(rv) || !rv.IsValid() || rv.Len() == 0 {
return nil
}
firstType := tomlTypeOfGo(rv.Index(0))
if firstType == nil {
encPanic(errArrayNilElement)
}
rvlen := rv.Len()
for i := 1; i < rvlen; i++ {
elem := rv.Index(i)
switch elemType := tomlTypeOfGo(elem); {
case elemType == nil:
encPanic(errArrayNilElement)
case !typeEqual(firstType, elemType):
encPanic(errArrayMixedElementTypes)
}
}
// If we have a nested array, then we must make sure that the nested
// array contains ONLY primitives.
// This checks arbitrarily nested arrays.
if typeEqual(firstType, tomlArray) || typeEqual(firstType, tomlArrayHash) {
nest := tomlArrayType(eindirect(rv.Index(0)))
if typeEqual(nest, tomlHash) || typeEqual(nest, tomlArrayHash) {
encPanic(errArrayNoTable)
}
}
return firstType
}
type tagOptions struct {
skip bool // "-"
name string
omitempty bool
omitzero bool
}
func getOptions(tag reflect.StructTag) tagOptions {
t := tag.Get("toml")
if t == "-" {
return tagOptions{skip: true}
}
var opts tagOptions
parts := strings.Split(t, ",")
opts.name = parts[0]
for _, s := range parts[1:] {
switch s {
case "omitempty":
opts.omitempty = true
case "omitzero":
opts.omitzero = true
}
}
return opts
}
func isZero(rv reflect.Value) bool {
switch rv.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return rv.Int() == 0
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
return rv.Uint() == 0
case reflect.Float32, reflect.Float64:
return rv.Float() == 0.0
}
return false
}
func isEmpty(rv reflect.Value) bool {
switch rv.Kind() {
case reflect.Array, reflect.Slice, reflect.Map, reflect.String:
return rv.Len() == 0
case reflect.Bool:
return !rv.Bool()
}
return false
}
func (enc *Encoder) newline() {
if enc.hasWritten {
enc.wf("\n")
}
}
func (enc *Encoder) keyEqElement(key Key, val reflect.Value) {
if len(key) == 0 {
encPanic(errNoKey)
}
panicIfInvalidKey(key)
enc.wf("%s%s = ", enc.indentStr(key), key.maybeQuoted(len(key)-1))
enc.eElement(val)
enc.newline()
}
func (enc *Encoder) wf(format string, v ...interface{}) {
if _, err := fmt.Fprintf(enc.w, format, v...); err != nil {
encPanic(err)
}
enc.hasWritten = true
}
func (enc *Encoder) indentStr(key Key) string {
return strings.Repeat(enc.Indent, len(key)-1)
}
func encPanic(err error) {
panic(tomlEncodeError{err})
}
func eindirect(v reflect.Value) reflect.Value {
switch v.Kind() {
case reflect.Ptr, reflect.Interface:
return eindirect(v.Elem())
default:
return v
}
}
func isNil(rv reflect.Value) bool {
switch rv.Kind() {
case reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
return rv.IsNil()
default:
return false
}
}
func panicIfInvalidKey(key Key) {
for _, k := range key {
if len(k) == 0 {
encPanic(e("Key '%s' is not a valid table name. Key names "+
"cannot be empty.", key.maybeQuotedAll()))
}
}
}
func isValidKeyName(s string) bool {
return len(s) != 0
}