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 v.SetBytes(append([]byte(nil), d.buf.Bytes()...))
176 return &UnmarshalTypeError{
186 // Info for parsing a dict value.
187 type dictField struct {
188 Value reflect.Value // Storage for the parsed value.
189 // True if field value should be parsed into Value. If false, the value
190 // should be parsed and discarded.
192 Set func() // Call this after parsing into Value.
193 IgnoreUnmarshalTypeError bool
196 // Returns specifics for parsing a dict field value.
197 func getDictField(dict reflect.Value, key string) dictField {
198 // get valuev as a map value or as a struct field
201 value := reflect.New(dict.Type().Elem()).Elem()
206 // Assigns the value into the map.
207 dict.SetMapIndex(reflect.ValueOf(key), value)
211 sf, ok := getStructFieldForKey(dict.Type(), key)
215 if sf.PkgPath != "" {
216 panic(&UnmarshalFieldError{
223 Value: dict.FieldByIndex(sf.Index),
226 IgnoreUnmarshalTypeError: getTag(sf.Tag).IgnoreUnmarshalTypeError(),
233 func getStructFieldForKey(struct_ reflect.Type, key string) (f reflect.StructField, ok bool) {
234 for i, n := 0, struct_.NumField(); i < n; i++ {
236 tag := f.Tag.Get("bencode")
244 if parseTag(tag).Key() == key {
254 if strings.EqualFold(f.Name, key) {
262 func (d *Decoder) parseDict(v reflect.Value) error {
266 if t.Key().Kind() != reflect.String {
267 panic(&UnmarshalTypeError{
273 v.Set(reflect.MakeMap(t))
277 panic(&UnmarshalTypeError{
283 // so, at this point 'd' byte was consumed, let's just read key/value
287 keyValue := reflect.ValueOf(&keyStr).Elem()
288 ok, err := d.parseValue(keyValue)
290 return fmt.Errorf("error parsing dict key: %s", err)
296 df := getDictField(v, keyStr)
298 // now we need to actually parse it
300 // log.Printf("parsing ok struct field for key %q", keyStr)
301 ok, err = d.parseValue(df.Value)
303 // Discard the value, there's nowhere to put it.
305 if_, ok = d.parseValueInterface()
307 err = fmt.Errorf("error parsing value for key %q", keyStr)
311 if _, ok := err.(*UnmarshalTypeError); !ok || !df.IgnoreUnmarshalTypeError {
312 return fmt.Errorf("parsing value for key %q: %s", keyStr, err)
316 return fmt.Errorf("missing value for key %q", keyStr)
324 func (d *Decoder) parseList(v reflect.Value) error {
326 case reflect.Array, reflect.Slice:
328 panic(&UnmarshalTypeError{
336 if v.Kind() == reflect.Slice && i >= v.Len() {
337 v.Set(reflect.Append(v, reflect.Zero(v.Type().Elem())))
341 ok, err := d.parseValue(v.Index(i))
349 _, ok := d.parseValueInterface()
357 if v.Kind() == reflect.Array {
358 z := reflect.Zero(v.Type().Elem())
359 for n := v.Len(); i < n; i++ {
367 if i == 0 && v.Kind() == reflect.Slice {
368 v.Set(reflect.MakeSlice(v.Type(), 0, 0))
373 func (d *Decoder) readOneValue() bool {
374 b, err := d.r.ReadByte()
388 // read until there is nothing to read
389 for d.readOneValue() {
391 // consume 'e' as well
396 d.buf.WriteString("e")
398 if b >= '0' && b <= '9' {
399 start := d.buf.Len() - 1
401 length, err := strconv.ParseInt(d.buf.String()[start:], 10, 64)
402 checkForIntParseError(err, d.Offset-1)
404 d.buf.WriteString(":")
405 n, err := io.CopyN(&d.buf, d.r, length)
408 checkForUnexpectedEOF(err, d.Offset)
411 What: errors.New("unexpected I/O error: " + err.Error()),
417 d.raiseUnknownValueType(b, d.Offset-1)
424 func (d *Decoder) parseUnmarshaler(v reflect.Value) bool {
425 m, ok := v.Interface().(Unmarshaler)
427 // T doesn't work, try *T
428 if v.Kind() != reflect.Ptr && v.CanAddr() {
429 m, ok = v.Addr().Interface().(Unmarshaler)
435 if ok && (v.Kind() != reflect.Ptr || !v.IsNil()) {
436 if d.readOneValue() {
437 err := m.UnmarshalBencode(d.buf.Bytes())
440 panic(&UnmarshalerError{v.Type(), err})
450 // Returns true if there was a value and it's now stored in 'v', otherwise
451 // there was an end symbol ("e") and no value was stored.
452 func (d *Decoder) parseValue(v reflect.Value) (bool, error) {
453 // we support one level of indirection at the moment
454 if v.Kind() == reflect.Ptr {
455 // if the pointer is nil, allocate a new element of the type it
458 v.Set(reflect.New(v.Type().Elem()))
463 if d.parseUnmarshaler(v) {
467 // common case: interface{}
468 if v.Kind() == reflect.Interface && v.NumMethod() == 0 {
469 iface, _ := d.parseValueInterface()
470 v.Set(reflect.ValueOf(iface))
474 b, err := d.r.ReadByte()
484 return true, d.parseDict(v)
486 return true, d.parseList(v)
491 if b >= '0' && b <= '9' {
493 // append first digit of the length to the buffer
495 return true, d.parseString(v)
498 d.raiseUnknownValueType(b, d.Offset-1)
503 // An unknown bencode type character was encountered.
504 func (d *Decoder) raiseUnknownValueType(b byte, offset int64) {
507 What: fmt.Errorf("unknown value type %+q", b),
511 func (d *Decoder) parseValueInterface() (interface{}, bool) {
512 b, err := d.r.ReadByte()
522 return d.parseDictInterface(), true
524 return d.parseListInterface(), true
526 return d.parseIntInterface(), true
528 if b >= '0' && b <= '9' {
530 // append first digit of the length to the buffer
532 return d.parseStringInterface(), true
535 d.raiseUnknownValueType(b, d.Offset-1)
540 func (d *Decoder) parseIntInterface() (ret interface{}) {
541 start := d.Offset - 1
543 if d.buf.Len() == 0 {
546 What: errors.New("empty integer value"),
550 n, err := strconv.ParseInt(d.buf.String(), 10, 64)
551 if ne, ok := err.(*strconv.NumError); ok && ne.Err == strconv.ErrRange {
553 _, ok := i.SetString(d.buf.String(), 10)
557 What: errors.New("failed to parse integer"),
562 checkForIntParseError(err, start)
570 func (d *Decoder) parseStringInterface() interface{} {
571 start := d.Offset - 1
573 // read the string length first
575 length, err := strconv.ParseInt(d.buf.String(), 10, 64)
576 checkForIntParseError(err, start)
579 n, err := io.CopyN(&d.buf, d.r, length)
582 checkForUnexpectedEOF(err, d.Offset)
585 What: errors.New("unexpected I/O error: " + err.Error()),
594 func (d *Decoder) parseDictInterface() interface{} {
595 dict := make(map[string]interface{})
597 keyi, ok := d.parseValueInterface()
602 key, ok := keyi.(string)
606 What: errors.New("non-string key in a dict"),
610 valuei, ok := d.parseValueInterface()
620 func (d *Decoder) parseListInterface() interface{} {
621 var list []interface{}
623 valuei, ok := d.parseValueInterface()
628 list = append(list, valuei)
631 list = make([]interface{}, 0, 0)