20 // Sum of bytes used to Decode values.
25 func (d *Decoder) Decode(v interface{}) (err error) {
27 if e := recover(); e != nil {
28 if _, ok := e.(runtime.Error); ok {
35 pv := reflect.ValueOf(v)
36 if pv.Kind() != reflect.Ptr || pv.IsNil() {
37 return &UnmarshalInvalidArgError{reflect.TypeOf(v)}
40 ok, err := d.parseValue(pv.Elem())
45 d.throwSyntaxError(d.Offset-1, errors.New("unexpected 'e'"))
50 func checkForUnexpectedEOF(err error, offset int64) {
54 What: io.ErrUnexpectedEOF,
59 func (d *Decoder) readByte() byte {
60 b, err := d.r.ReadByte()
62 checkForUnexpectedEOF(err, d.Offset)
70 // reads data writing it to 'd.buf' until 'sep' byte is encountered, 'sep' byte
71 // is consumed, but not included into the 'd.buf'
72 func (d *Decoder) readUntil(sep byte) {
82 func checkForIntParseError(err error, offset int64) {
91 func (d *Decoder) throwSyntaxError(offset int64, err error) {
98 // called when 'i' was consumed
99 func (d *Decoder) parseInt(v reflect.Value) {
100 start := d.Offset - 1
102 if d.buf.Len() == 0 {
105 What: errors.New("empty integer value"),
112 case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
113 n, err := strconv.ParseInt(s, 10, 64)
114 checkForIntParseError(err, start)
116 if v.OverflowInt(n) {
117 panic(&UnmarshalTypeError{
118 Value: "integer " + s,
123 case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
124 n, err := strconv.ParseUint(s, 10, 64)
125 checkForIntParseError(err, start)
127 if v.OverflowUint(n) {
128 panic(&UnmarshalTypeError{
129 Value: "integer " + s,
137 panic(&UnmarshalTypeError{
138 Value: "integer " + s,
145 func (d *Decoder) parseString(v reflect.Value) error {
146 start := d.Offset - 1
148 // read the string length first
150 length, err := strconv.ParseInt(d.buf.String(), 10, 64)
151 checkForIntParseError(err, start)
154 n, err := io.CopyN(&d.buf, d.r, length)
157 checkForUnexpectedEOF(err, d.Offset)
160 What: errors.New("unexpected I/O error: " + err.Error()),
166 v.SetString(d.buf.String())
168 if v.Type().Elem().Kind() != reflect.Uint8 {
169 panic(&UnmarshalTypeError{
174 sl := make([]byte, len(d.buf.Bytes()))
175 copy(sl, d.buf.Bytes())
176 v.Set(reflect.ValueOf(sl))
178 return &UnmarshalTypeError{
188 // Info for parsing a dict value.
189 type dictField struct {
190 Value reflect.Value // Storage for the parsed value.
191 // True if field value should be parsed into Value. If false, the value
192 // should be parsed and discarded.
194 Set func() // Call this after parsing into Value.
195 IgnoreUnmarshalTypeError bool
198 // Returns specifics for parsing a dict field value.
199 func getDictField(dict reflect.Value, key string) dictField {
200 // get valuev as a map value or as a struct field
203 value := reflect.New(dict.Type().Elem()).Elem()
208 // Assigns the value into the map.
209 dict.SetMapIndex(reflect.ValueOf(key), value)
213 sf, ok := getStructFieldForKey(dict.Type(), key)
217 if sf.PkgPath != "" {
218 panic(&UnmarshalFieldError{
225 Value: dict.FieldByIndex(sf.Index),
228 IgnoreUnmarshalTypeError: getTag(sf.Tag).IgnoreUnmarshalTypeError(),
235 func getStructFieldForKey(struct_ reflect.Type, key string) (f reflect.StructField, ok bool) {
236 for i, n := 0, struct_.NumField(); i < n; i++ {
238 tag := f.Tag.Get("bencode")
246 if parseTag(tag).Key() == key {
256 if strings.EqualFold(f.Name, key) {
264 func (d *Decoder) parseDict(v reflect.Value) error {
268 if t.Key().Kind() != reflect.String {
269 panic(&UnmarshalTypeError{
275 v.Set(reflect.MakeMap(t))
279 panic(&UnmarshalTypeError{
285 // so, at this point 'd' byte was consumed, let's just read key/value
289 keyValue := reflect.ValueOf(&keyStr).Elem()
290 ok, err := d.parseValue(keyValue)
292 return fmt.Errorf("error parsing dict key: %s", err)
298 df := getDictField(v, keyStr)
300 // now we need to actually parse it
302 // log.Printf("parsing ok struct field for key %q", keyStr)
303 ok, err = d.parseValue(df.Value)
305 // Discard the value, there's nowhere to put it.
307 if_, ok = d.parseValueInterface()
309 err = fmt.Errorf("error parsing value for key %q", keyStr)
313 if _, ok := err.(*UnmarshalTypeError); !ok || !df.IgnoreUnmarshalTypeError {
314 return fmt.Errorf("parsing value for key %q: %s", keyStr, err)
318 return fmt.Errorf("missing value for key %q", keyStr)
326 func (d *Decoder) parseList(v reflect.Value) error {
328 case reflect.Array, reflect.Slice:
330 panic(&UnmarshalTypeError{
338 if v.Kind() == reflect.Slice && i >= v.Len() {
339 v.Set(reflect.Append(v, reflect.Zero(v.Type().Elem())))
343 ok, err := d.parseValue(v.Index(i))
351 _, ok := d.parseValueInterface()
359 if v.Kind() == reflect.Array {
360 z := reflect.Zero(v.Type().Elem())
361 for n := v.Len(); i < n; i++ {
369 if i == 0 && v.Kind() == reflect.Slice {
370 v.Set(reflect.MakeSlice(v.Type(), 0, 0))
375 func (d *Decoder) readOneValue() bool {
376 b, err := d.r.ReadByte()
390 // read until there is nothing to read
391 for d.readOneValue() {
393 // consume 'e' as well
398 d.buf.WriteString("e")
400 if b >= '0' && b <= '9' {
401 start := d.buf.Len() - 1
403 length, err := strconv.ParseInt(d.buf.String()[start:], 10, 64)
404 checkForIntParseError(err, d.Offset-1)
406 d.buf.WriteString(":")
407 n, err := io.CopyN(&d.buf, d.r, length)
410 checkForUnexpectedEOF(err, d.Offset)
413 What: errors.New("unexpected I/O error: " + err.Error()),
419 d.raiseUnknownValueType(b, d.Offset-1)
426 func (d *Decoder) parseUnmarshaler(v reflect.Value) bool {
427 m, ok := v.Interface().(Unmarshaler)
429 // T doesn't work, try *T
430 if v.Kind() != reflect.Ptr && v.CanAddr() {
431 m, ok = v.Addr().Interface().(Unmarshaler)
437 if ok && (v.Kind() != reflect.Ptr || !v.IsNil()) {
438 if d.readOneValue() {
439 err := m.UnmarshalBencode(d.buf.Bytes())
442 panic(&UnmarshalerError{v.Type(), err})
452 // Returns true if there was a value and it's now stored in 'v', otherwise
453 // there was an end symbol ("e") and no value was stored.
454 func (d *Decoder) parseValue(v reflect.Value) (bool, error) {
455 // we support one level of indirection at the moment
456 if v.Kind() == reflect.Ptr {
457 // if the pointer is nil, allocate a new element of the type it
460 v.Set(reflect.New(v.Type().Elem()))
465 if d.parseUnmarshaler(v) {
469 // common case: interface{}
470 if v.Kind() == reflect.Interface && v.NumMethod() == 0 {
471 iface, _ := d.parseValueInterface()
472 v.Set(reflect.ValueOf(iface))
476 b, err := d.r.ReadByte()
486 return true, d.parseDict(v)
488 return true, d.parseList(v)
493 if b >= '0' && b <= '9' {
495 // append first digit of the length to the buffer
497 return true, d.parseString(v)
500 d.raiseUnknownValueType(b, d.Offset-1)
505 // An unknown bencode type character was encountered.
506 func (d *Decoder) raiseUnknownValueType(b byte, offset int64) {
509 What: fmt.Errorf("unknown value type %+q", b),
513 func (d *Decoder) parseValueInterface() (interface{}, bool) {
514 b, err := d.r.ReadByte()
524 return d.parseDictInterface(), true
526 return d.parseListInterface(), true
528 return d.parseIntInterface(), true
530 if b >= '0' && b <= '9' {
532 // append first digit of the length to the buffer
534 return d.parseStringInterface(), true
537 d.raiseUnknownValueType(b, d.Offset-1)
542 func (d *Decoder) parseIntInterface() (ret interface{}) {
543 start := d.Offset - 1
545 if d.buf.Len() == 0 {
548 What: errors.New("empty integer value"),
552 n, err := strconv.ParseInt(d.buf.String(), 10, 64)
553 if ne, ok := err.(*strconv.NumError); ok && ne.Err == strconv.ErrRange {
555 _, ok := i.SetString(d.buf.String(), 10)
559 What: errors.New("failed to parse integer"),
564 checkForIntParseError(err, start)
572 func (d *Decoder) parseStringInterface() interface{} {
573 start := d.Offset - 1
575 // read the string length first
577 length, err := strconv.ParseInt(d.buf.String(), 10, 64)
578 checkForIntParseError(err, start)
581 n, err := io.CopyN(&d.buf, d.r, length)
584 checkForUnexpectedEOF(err, d.Offset)
587 What: errors.New("unexpected I/O error: " + err.Error()),
596 func (d *Decoder) parseDictInterface() interface{} {
597 dict := make(map[string]interface{})
599 keyi, ok := d.parseValueInterface()
604 key, ok := keyi.(string)
608 What: errors.New("non-string key in a dict"),
612 valuei, ok := d.parseValueInterface()
622 func (d *Decoder) parseListInterface() interface{} {
623 var list []interface{}
625 valuei, ok := d.parseValueInterface()
630 list = append(list, valuei)
633 list = make([]interface{}, 0, 0)