diff options
| -rw-r--r-- | rlp/decode.go | 168 | ||||
| -rw-r--r-- | rlp/decode_test.go | 95 | ||||
| -rw-r--r-- | rlp/doc.go | 121 | ||||
| -rw-r--r-- | rlp/encode.go | 127 | ||||
| -rw-r--r-- | rlp/encode_test.go | 75 | ||||
| -rw-r--r-- | rlp/encoder_example_test.go | 12 | ||||
| -rw-r--r-- | rlp/typecache.go | 62 |
7 files changed, 416 insertions, 244 deletions
diff --git a/rlp/decode.go b/rlp/decode.go index 4f29f2fb0..524395915 100644 --- a/rlp/decode.go +++ b/rlp/decode.go @@ -55,81 +55,23 @@ var ( } ) -// Decoder is implemented by types that require custom RLP -// decoding rules or need to decode into private fields. +// Decoder is implemented by types that require custom RLP decoding rules or need to decode +// into private fields. // -// The DecodeRLP method should read one value from the given -// Stream. It is not forbidden to read less or more, but it might -// be confusing. +// The DecodeRLP method should read one value from the given Stream. It is not forbidden to +// read less or more, but it might be confusing. type Decoder interface { DecodeRLP(*Stream) error } -// Decode parses RLP-encoded data from r and stores the result in the -// value pointed to by val. Val must be a non-nil pointer. If r does -// not implement ByteReader, Decode will do its own buffering. +// Decode parses RLP-encoded data from r and stores the result in the value pointed to by +// val. Please see package-level documentation for the decoding rules. Val must be a +// non-nil pointer. // -// Decode uses the following type-dependent decoding rules: +// If r does not implement ByteReader, Decode will do its own buffering. // -// If the type implements the Decoder interface, decode calls -// DecodeRLP. -// -// To decode into a pointer, Decode will decode into the value pointed -// to. If the pointer is nil, a new value of the pointer's element -// type is allocated. If the pointer is non-nil, the existing value -// will be reused. -// -// To decode into a struct, Decode expects the input to be an RLP -// list. The decoded elements of the list are assigned to each public -// field in the order given by the struct's definition. The input list -// must contain an element for each decoded field. Decode returns an -// error if there are too few or too many elements. -// -// The decoding of struct fields honours certain struct tags, "tail", -// "nil" and "-". -// -// The "-" tag ignores fields. -// -// For an explanation of "tail", see the example. -// -// The "nil" tag applies to pointer-typed fields and changes the decoding -// rules for the field such that input values of size zero decode as a nil -// pointer. This tag can be useful when decoding recursive types. -// -// type StructWithEmptyOK struct { -// Foo *[20]byte `rlp:"nil"` -// } -// -// To decode into a slice, the input must be a list and the resulting -// slice will contain the input elements in order. For byte slices, -// the input must be an RLP string. Array types decode similarly, with -// the additional restriction that the number of input elements (or -// bytes) must match the array's length. -// -// To decode into a Go string, the input must be an RLP string. The -// input bytes are taken as-is and will not necessarily be valid UTF-8. -// -// To decode into an unsigned integer type, the input must also be an RLP -// string. The bytes are interpreted as a big endian representation of -// the integer. If the RLP string is larger than the bit size of the -// type, Decode will return an error. Decode also supports *big.Int. -// There is no size limit for big integers. -// -// To decode into a boolean, the input must contain an unsigned integer -// of value zero (false) or one (true). -// -// To decode into an interface value, Decode stores one of these -// in the value: -// -// []interface{}, for RLP lists -// []byte, for RLP strings -// -// Non-empty interface types are not supported, nor are signed integers, -// floating point numbers, maps, channels and functions. -// -// Note that Decode does not set an input limit for all readers -// and may be vulnerable to panics cause by huge value sizes. If -// you need an input limit, use +// Note that Decode does not set an input limit for all readers and may be vulnerable to +// panics cause by huge value sizes. If you need an input limit, use // // NewStream(r, limit).Decode(val) func Decode(r io.Reader, val interface{}) error { @@ -140,9 +82,8 @@ func Decode(r io.Reader, val interface{}) error { return stream.Decode(val) } -// DecodeBytes parses RLP data from b into val. -// Please see the documentation of Decode for the decoding rules. -// The input must contain exactly one value and no trailing data. +// DecodeBytes parses RLP data from b into val. Please see package-level documentation for +// the decoding rules. The input must contain exactly one value and no trailing data. func DecodeBytes(b []byte, val interface{}) error { r := bytes.NewReader(b) @@ -211,14 +152,15 @@ func makeDecoder(typ reflect.Type, tags tags) (dec decoder, err error) { switch { case typ == rawValueType: return decodeRawValue, nil - case typ.Implements(decoderInterface): return decodeDecoder, nil - case kind != reflect.Ptr && reflect.PtrTo(typ).Implements(decoderInterface): - return decodeDecoderNoPtr, nil case typ.AssignableTo(reflect.PtrTo(bigInt)): return decodeBigInt, nil case typ.AssignableTo(bigInt): return decodeBigIntNoPtr, nil + case kind == reflect.Ptr: + return makePtrDecoder(typ, tags) + case reflect.PtrTo(typ).Implements(decoderInterface): + return decodeDecoder, nil case isUint(kind): return decodeUint, nil case kind == reflect.Bool: @@ -229,11 +171,6 @@ func makeDecoder(typ reflect.Type, tags tags) (dec decoder, err error) { return makeListDecoder(typ, tags) case kind == reflect.Struct: return makeStructDecoder(typ) - case kind == reflect.Ptr: - if tags.nilOK { - return makeOptionalPtrDecoder(typ) - } - return makePtrDecoder(typ) case kind == reflect.Interface: return decodeInterface, nil default: @@ -448,6 +385,11 @@ func makeStructDecoder(typ reflect.Type) (decoder, error) { if err != nil { return nil, err } + for _, f := range fields { + if f.info.decoderErr != nil { + return nil, structFieldError{typ, f.index, f.info.decoderErr} + } + } dec := func(s *Stream, val reflect.Value) (err error) { if _, err := s.List(); err != nil { return wrapStreamError(err, typ) @@ -465,15 +407,22 @@ func makeStructDecoder(typ reflect.Type) (decoder, error) { return dec, nil } -// makePtrDecoder creates a decoder that decodes into -// the pointer's element type. -func makePtrDecoder(typ reflect.Type) (decoder, error) { +// makePtrDecoder creates a decoder that decodes into the pointer's element type. +func makePtrDecoder(typ reflect.Type, tag tags) (decoder, error) { etype := typ.Elem() etypeinfo := cachedTypeInfo1(etype, tags{}) - if etypeinfo.decoderErr != nil { + switch { + case etypeinfo.decoderErr != nil: return nil, etypeinfo.decoderErr + case !tag.nilOK: + return makeSimplePtrDecoder(etype, etypeinfo), nil + default: + return makeNilPtrDecoder(etype, etypeinfo, tag.nilKind), nil } - dec := func(s *Stream, val reflect.Value) (err error) { +} + +func makeSimplePtrDecoder(etype reflect.Type, etypeinfo *typeinfo) decoder { + return func(s *Stream, val reflect.Value) (err error) { newval := val if val.IsNil() { newval = reflect.New(etype) @@ -483,30 +432,35 @@ func makePtrDecoder(typ reflect.Type) (decoder, error) { } return err } - return dec, nil } -// makeOptionalPtrDecoder creates a decoder that decodes empty values -// as nil. Non-empty values are decoded into a value of the element type, -// just like makePtrDecoder does. +// makeNilPtrDecoder creates a decoder that decodes empty values as nil. Non-empty +// values are decoded into a value of the element type, just like makePtrDecoder does. // // This decoder is used for pointer-typed struct fields with struct tag "nil". -func makeOptionalPtrDecoder(typ reflect.Type) (decoder, error) { - etype := typ.Elem() - etypeinfo := cachedTypeInfo1(etype, tags{}) - if etypeinfo.decoderErr != nil { - return nil, etypeinfo.decoderErr - } - dec := func(s *Stream, val reflect.Value) (err error) { +func makeNilPtrDecoder(etype reflect.Type, etypeinfo *typeinfo, nilKind Kind) decoder { + typ := reflect.PtrTo(etype) + nilPtr := reflect.Zero(typ) + return func(s *Stream, val reflect.Value) (err error) { kind, size, err := s.Kind() - if err != nil || size == 0 && kind != Byte { + if err != nil { + val.Set(nilPtr) + return wrapStreamError(err, typ) + } + // Handle empty values as a nil pointer. + if kind != Byte && size == 0 { + if kind != nilKind { + return &decodeError{ + msg: fmt.Sprintf("wrong kind of empty value (got %v, want %v)", kind, nilKind), + typ: typ, + } + } // rearm s.Kind. This is important because the input // position must advance to the next value even though // we don't read anything. s.kind = -1 - // set the pointer to nil. - val.Set(reflect.Zero(typ)) - return err + val.Set(nilPtr) + return nil } newval := val if val.IsNil() { @@ -517,7 +471,6 @@ func makeOptionalPtrDecoder(typ reflect.Type) (decoder, error) { } return err } - return dec, nil } var ifsliceType = reflect.TypeOf([]interface{}{}) @@ -546,21 +499,8 @@ func decodeInterface(s *Stream, val reflect.Value) error { return nil } -// This decoder is used for non-pointer values of types -// that implement the Decoder interface using a pointer receiver. -func decodeDecoderNoPtr(s *Stream, val reflect.Value) error { - return val.Addr().Interface().(Decoder).DecodeRLP(s) -} - func decodeDecoder(s *Stream, val reflect.Value) error { - // Decoder instances are not handled using the pointer rule if the type - // implements Decoder with pointer receiver (i.e. always) - // because it might handle empty values specially. - // We need to allocate one here in this case, like makePtrDecoder does. - if val.Kind() == reflect.Ptr && val.IsNil() { - val.Set(reflect.New(val.Type().Elem())) - } - return val.Interface().(Decoder).DecodeRLP(s) + return val.Addr().Interface().(Decoder).DecodeRLP(s) } // Kind represents the kind of value contained in an RLP stream. diff --git a/rlp/decode_test.go b/rlp/decode_test.go index fa57182c9..634d1cf3b 100644 --- a/rlp/decode_test.go +++ b/rlp/decode_test.go @@ -327,6 +327,10 @@ type recstruct struct { Child *recstruct `rlp:"nil"` } +type invalidNilTag struct { + X []byte `rlp:"nil"` +} + type invalidTail1 struct { A uint `rlp:"tail"` B string @@ -353,6 +357,18 @@ type tailPrivateFields struct { x, y bool } +type nilListUint struct { + X *uint `rlp:"nilList"` +} + +type nilStringSlice struct { + X *[]uint `rlp:"nilString"` +} + +type intField struct { + X int +} + var ( veryBigInt = big.NewInt(0).Add( big.NewInt(0).Lsh(big.NewInt(0xFFFFFFFFFFFFFF), 16), @@ -485,20 +501,20 @@ var decodeTests = []decodeTest{ error: "rlp: expected input string or byte for uint, decoding into (rlp.recstruct).Child.I", }, { - input: "C0", - ptr: new(invalidTail1), - error: "rlp: invalid struct tag \"tail\" for rlp.invalidTail1.A (must be on last field)", - }, - { - input: "C0", - ptr: new(invalidTail2), - error: "rlp: invalid struct tag \"tail\" for rlp.invalidTail2.B (field type is not slice)", + input: "C103", + ptr: new(intField), + error: "rlp: type int is not RLP-serializable (struct field rlp.intField.X)", }, { input: "C50102C20102", ptr: new(tailUint), error: "rlp: expected input string or byte for uint, decoding into (rlp.tailUint).Tail[1]", }, + { + input: "C0", + ptr: new(invalidNilTag), + error: `rlp: invalid struct tag "nil" for rlp.invalidNilTag.X (field is not a pointer)`, + }, // struct tag "tail" { @@ -521,6 +537,16 @@ var decodeTests = []decodeTest{ ptr: new(tailPrivateFields), value: tailPrivateFields{A: 1, Tail: []uint{2, 3}}, }, + { + input: "C0", + ptr: new(invalidTail1), + error: `rlp: invalid struct tag "tail" for rlp.invalidTail1.A (must be on last field)`, + }, + { + input: "C0", + ptr: new(invalidTail2), + error: `rlp: invalid struct tag "tail" for rlp.invalidTail2.B (field type is not slice)`, + }, // struct tag "-" { @@ -529,6 +555,43 @@ var decodeTests = []decodeTest{ value: hasIgnoredField{A: 1, C: 2}, }, + // struct tag "nilList" + { + input: "C180", + ptr: new(nilListUint), + error: "rlp: wrong kind of empty value (got String, want List) for *uint, decoding into (rlp.nilListUint).X", + }, + { + input: "C1C0", + ptr: new(nilListUint), + value: nilListUint{}, + }, + { + input: "C103", + ptr: new(nilListUint), + value: func() interface{} { + v := uint(3) + return nilListUint{X: &v} + }(), + }, + + // struct tag "nilString" + { + input: "C1C0", + ptr: new(nilStringSlice), + error: "rlp: wrong kind of empty value (got List, want String) for *[]uint, decoding into (rlp.nilStringSlice).X", + }, + { + input: "C180", + ptr: new(nilStringSlice), + value: nilStringSlice{}, + }, + { + input: "C2C103", + ptr: new(nilStringSlice), + value: nilStringSlice{X: &[]uint{3}}, + }, + // RawValue {input: "01", ptr: new(RawValue), value: RawValue(unhex("01"))}, {input: "82FFFF", ptr: new(RawValue), value: RawValue(unhex("82FFFF"))}, @@ -672,6 +735,22 @@ func TestDecodeDecoder(t *testing.T) { } } +func TestDecodeDecoderNilPointer(t *testing.T) { + var s struct { + T1 *testDecoder `rlp:"nil"` + T2 *testDecoder + } + if err := Decode(bytes.NewReader(unhex("C2C002")), &s); err != nil { + t.Fatalf("Decode error: %v", err) + } + if s.T1 != nil { + t.Errorf("decoder T1 allocated for empty input (called: %v)", s.T1.called) + } + if s.T2 == nil || !s.T2.called { + t.Errorf("decoder T2 not allocated/called") + } +} + type byteDecoder byte func (bd *byteDecoder) DecodeRLP(s *Stream) error { diff --git a/rlp/doc.go b/rlp/doc.go index b3a81fe23..7e6ee8520 100644 --- a/rlp/doc.go +++ b/rlp/doc.go @@ -17,17 +17,114 @@ /* Package rlp implements the RLP serialization format. -The purpose of RLP (Recursive Linear Prefix) is to encode arbitrarily -nested arrays of binary data, and RLP is the main encoding method used -to serialize objects in Ethereum. The only purpose of RLP is to encode -structure; encoding specific atomic data types (eg. strings, ints, -floats) is left up to higher-order protocols; in Ethereum integers -must be represented in big endian binary form with no leading zeroes -(thus making the integer value zero equivalent to the empty byte -array). - -RLP values are distinguished by a type tag. The type tag precedes the -value in the input stream and defines the size and kind of the bytes -that follow. +The purpose of RLP (Recursive Linear Prefix) is to encode arbitrarily nested arrays of +binary data, and RLP is the main encoding method used to serialize objects in Ethereum. +The only purpose of RLP is to encode structure; encoding specific atomic data types (eg. +strings, ints, floats) is left up to higher-order protocols. In Ethereum integers must be +represented in big endian binary form with no leading zeroes (thus making the integer +value zero equivalent to the empty string). + +RLP values are distinguished by a type tag. The type tag precedes the value in the input +stream and defines the size and kind of the bytes that follow. + + +Encoding Rules + +Package rlp uses reflection and encodes RLP based on the Go type of the value. + +If the type implements the Encoder interface, Encode calls EncodeRLP. It does not +call EncodeRLP on nil pointer values. + +To encode a pointer, the value being pointed to is encoded. A nil pointer to a struct +type, slice or array always encodes as an empty RLP list unless the slice or array has +elememt type byte. A nil pointer to any other value encodes as the empty string. + +Struct values are encoded as an RLP list of all their encoded public fields. Recursive +struct types are supported. + +To encode slices and arrays, the elements are encoded as an RLP list of the value's +elements. Note that arrays and slices with element type uint8 or byte are always encoded +as an RLP string. + +A Go string is encoded as an RLP string. + +An unsigned integer value is encoded as an RLP string. Zero always encodes as an empty RLP +string. big.Int values are treated as integers. Signed integers (int, int8, int16, ...) +are not supported and will return an error when encoding. + +Boolean values are encoded as the unsigned integers zero (false) and one (true). + +An interface value encodes as the value contained in the interface. + +Floating point numbers, maps, channels and functions are not supported. + + +Decoding Rules + +Decoding uses the following type-dependent rules: + +If the type implements the Decoder interface, DecodeRLP is called. + +To decode into a pointer, the value will be decoded as the element type of the pointer. If +the pointer is nil, a new value of the pointer's element type is allocated. If the pointer +is non-nil, the existing value will be reused. Note that package rlp never leaves a +pointer-type struct field as nil unless one of the "nil" struct tags is present. + +To decode into a struct, decoding expects the input to be an RLP list. The decoded +elements of the list are assigned to each public field in the order given by the struct's +definition. The input list must contain an element for each decoded field. Decoding +returns an error if there are too few or too many elements for the struct. + +To decode into a slice, the input must be a list and the resulting slice will contain the +input elements in order. For byte slices, the input must be an RLP string. Array types +decode similarly, with the additional restriction that the number of input elements (or +bytes) must match the array's defined length. + +To decode into a Go string, the input must be an RLP string. The input bytes are taken +as-is and will not necessarily be valid UTF-8. + +To decode into an unsigned integer type, the input must also be an RLP string. The bytes +are interpreted as a big endian representation of the integer. If the RLP string is larger +than the bit size of the type, decoding will return an error. Decode also supports +*big.Int. There is no size limit for big integers. + +To decode into a boolean, the input must contain an unsigned integer of value zero (false) +or one (true). + +To decode into an interface value, one of these types is stored in the value: + + []interface{}, for RLP lists + []byte, for RLP strings + +Non-empty interface types are not supported when decoding. +Signed integers, floating point numbers, maps, channels and functions cannot be decoded into. + + +Struct Tags + +Package rlp honours certain struct tags: "-", "tail", "nil", "nilList" and "nilString". + +The "-" tag ignores fields. + +The "tail" tag, which may only be used on the last exported struct field, allows slurping +up any excess list elements into a slice. See examples for more details. + +The "nil" tag applies to pointer-typed fields and changes the decoding rules for the field +such that input values of size zero decode as a nil pointer. This tag can be useful when +decoding recursive types. + + type StructWithOptionalFoo struct { + Foo *[20]byte `rlp:"nil"` + } + +RLP supports two kinds of empty values: empty lists and empty strings. When using the +"nil" tag, the kind of empty value allowed for a type is chosen automatically. A struct +field whose Go type is a pointer to an unsigned integer, string, boolean or byte +array/slice expects an empty RLP string. Any other pointer field type encodes/decodes as +an empty RLP list. + +The choice of null value can be made explicit with the "nilList" and "nilString" struct +tags. Using these tags encodes/decodes a Go nil pointer value as the kind of empty +RLP value defined by the tag. */ package rlp diff --git a/rlp/encode.go b/rlp/encode.go index f255c38a9..9c9e8d706 100644 --- a/rlp/encode.go +++ b/rlp/encode.go @@ -49,36 +49,7 @@ type Encoder interface { // perform many small writes in some cases. Consider making w // buffered. // -// Encode uses the following type-dependent encoding rules: -// -// If the type implements the Encoder interface, Encode calls -// EncodeRLP. This is true even for nil pointers, please see the -// documentation for Encoder. -// -// To encode a pointer, the value being pointed to is encoded. For nil -// pointers, Encode will encode the zero value of the type. A nil -// pointer to a struct type always encodes as an empty RLP list. -// A nil pointer to an array encodes as an empty list (or empty string -// if the array has element type byte). -// -// Struct values are encoded as an RLP list of all their encoded -// public fields. Recursive struct types are supported. -// -// To encode slices and arrays, the elements are encoded as an RLP -// list of the value's elements. Note that arrays and slices with -// element type uint8 or byte are always encoded as an RLP string. -// -// A Go string is encoded as an RLP string. -// -// An unsigned integer value is encoded as an RLP string. Zero always -// encodes as an empty RLP string. Encode also supports *big.Int. -// -// Boolean values are encoded as unsigned integers zero (false) and one (true). -// -// An interface value encodes as the value contained in the interface. -// -// Signed integers are not supported, nor are floating point numbers, maps, -// channels and functions. +// Please see package-level documentation of encoding rules. func Encode(w io.Writer, val interface{}) error { if outer, ok := w.(*encbuf); ok { // Encode was called by some type's EncodeRLP. @@ -95,7 +66,7 @@ func Encode(w io.Writer, val interface{}) error { } // EncodeToBytes returns the RLP encoding of val. -// Please see the documentation of Encode for the encoding rules. +// Please see package-level documentation for the encoding rules. func EncodeToBytes(val interface{}) ([]byte, error) { eb := encbufPool.Get().(*encbuf) defer encbufPool.Put(eb) @@ -349,16 +320,14 @@ func makeWriter(typ reflect.Type, ts tags) (writer, error) { switch { case typ == rawValueType: return writeRawValue, nil - case typ.Implements(encoderInterface): - return writeEncoder, nil - case kind != reflect.Ptr && reflect.PtrTo(typ).Implements(encoderInterface): - return writeEncoderNoPtr, nil - case kind == reflect.Interface: - return writeInterface, nil case typ.AssignableTo(reflect.PtrTo(bigInt)): return writeBigIntPtr, nil case typ.AssignableTo(bigInt): return writeBigIntNoPtr, nil + case kind == reflect.Ptr: + return makePtrWriter(typ, ts) + case reflect.PtrTo(typ).Implements(encoderInterface): + return makeEncoderWriter(typ), nil case isUint(kind): return writeUint, nil case kind == reflect.Bool: @@ -373,8 +342,8 @@ func makeWriter(typ reflect.Type, ts tags) (writer, error) { return makeSliceWriter(typ, ts) case kind == reflect.Struct: return makeStructWriter(typ) - case kind == reflect.Ptr: - return makePtrWriter(typ) + case kind == reflect.Interface: + return writeInterface, nil default: return nil, fmt.Errorf("rlp: type %v is not RLP-serializable", typ) } @@ -470,26 +439,6 @@ func writeString(val reflect.Value, w *encbuf) error { return nil } -func writeEncoder(val reflect.Value, w *encbuf) error { - return val.Interface().(Encoder).EncodeRLP(w) -} - -// writeEncoderNoPtr handles non-pointer values that implement Encoder -// with a pointer receiver. -func writeEncoderNoPtr(val reflect.Value, w *encbuf) error { - if !val.CanAddr() { - // We can't get the address. It would be possible to make the - // value addressable by creating a shallow copy, but this - // creates other problems so we're not doing it (yet). - // - // package json simply doesn't call MarshalJSON for cases like - // this, but encodes the value as if it didn't implement the - // interface. We don't want to handle it that way. - return fmt.Errorf("rlp: game over: unadressable value of type %v, EncodeRLP is pointer method", val.Type()) - } - return val.Addr().Interface().(Encoder).EncodeRLP(w) -} - func writeInterface(val reflect.Value, w *encbuf) error { if val.IsNil() { // Write empty list. This is consistent with the previous RLP @@ -531,6 +480,11 @@ func makeStructWriter(typ reflect.Type) (writer, error) { if err != nil { return nil, err } + for _, f := range fields { + if f.info.writerErr != nil { + return nil, structFieldError{typ, f.index, f.info.writerErr} + } + } writer := func(val reflect.Value, w *encbuf) error { lh := w.list() for _, f := range fields { @@ -544,44 +498,51 @@ func makeStructWriter(typ reflect.Type) (writer, error) { return writer, nil } -func makePtrWriter(typ reflect.Type) (writer, error) { +func makePtrWriter(typ reflect.Type, ts tags) (writer, error) { etypeinfo := cachedTypeInfo1(typ.Elem(), tags{}) if etypeinfo.writerErr != nil { return nil, etypeinfo.writerErr } - - // determine nil pointer handler - var nilfunc func(*encbuf) error - kind := typ.Elem().Kind() - switch { - case kind == reflect.Array && isByte(typ.Elem().Elem()): - nilfunc = func(w *encbuf) error { - w.str = append(w.str, 0x80) - return nil - } - case kind == reflect.Struct || kind == reflect.Array: - nilfunc = func(w *encbuf) error { - // encoding the zero value of a struct/array could trigger - // infinite recursion, avoid that. - w.listEnd(w.list()) - return nil - } - default: - zero := reflect.Zero(typ.Elem()) - nilfunc = func(w *encbuf) error { - return etypeinfo.writer(zero, w) - } + // Determine how to encode nil pointers. + var nilKind Kind + if ts.nilOK { + nilKind = ts.nilKind // use struct tag if provided + } else { + nilKind = defaultNilKind(typ.Elem()) } writer := func(val reflect.Value, w *encbuf) error { if val.IsNil() { - return nilfunc(w) + if nilKind == String { + w.str = append(w.str, 0x80) + } else { + w.listEnd(w.list()) + } + return nil } return etypeinfo.writer(val.Elem(), w) } return writer, nil } +func makeEncoderWriter(typ reflect.Type) writer { + if typ.Implements(encoderInterface) { + return func(val reflect.Value, w *encbuf) error { + return val.Interface().(Encoder).EncodeRLP(w) + } + } + w := func(val reflect.Value, w *encbuf) error { + if !val.CanAddr() { + // package json simply doesn't call MarshalJSON for this case, but encodes the + // value as if it didn't implement the interface. We don't want to handle it that + // way. + return fmt.Errorf("rlp: unadressable value of type %v, EncodeRLP is pointer method", val.Type()) + } + return val.Addr().Interface().(Encoder).EncodeRLP(w) + } + return w +} + // putint writes i to the beginning of b in big endian byte // order, using the least number of bytes needed to represent i. func putint(b []byte, i uint64) (size int) { diff --git a/rlp/encode_test.go b/rlp/encode_test.go index 6e49b89a8..b4b9e5128 100644 --- a/rlp/encode_test.go +++ b/rlp/encode_test.go @@ -33,8 +33,9 @@ type testEncoder struct { func (e *testEncoder) EncodeRLP(w io.Writer) error { if e == nil { - w.Write([]byte{0, 0, 0, 0}) - } else if e.err != nil { + panic("EncodeRLP called on nil value") + } + if e.err != nil { return e.err } else { w.Write([]byte{0, 1, 0, 1, 0, 1, 0, 1, 0, 1}) @@ -42,6 +43,13 @@ func (e *testEncoder) EncodeRLP(w io.Writer) error { return nil } +type testEncoderValueMethod struct{} + +func (e testEncoderValueMethod) EncodeRLP(w io.Writer) error { + w.Write([]byte{0xFA, 0xFE, 0xF0}) + return nil +} + type byteEncoder byte func (e byteEncoder) EncodeRLP(w io.Writer) error { @@ -52,8 +60,8 @@ func (e byteEncoder) EncodeRLP(w io.Writer) error { type undecodableEncoder func() func (f undecodableEncoder) EncodeRLP(w io.Writer) error { - _, err := w.Write(EmptyList) - return err + w.Write([]byte{0xF5, 0xF5, 0xF5}) + return nil } type encodableReader struct { @@ -226,6 +234,7 @@ var encTests = []encTest{ {val: &tailRaw{A: 1, Tail: []RawValue{}}, output: "C101"}, {val: &tailRaw{A: 1, Tail: nil}, output: "C101"}, {val: &hasIgnoredField{A: 1, B: 2, C: 3}, output: "C20103"}, + {val: &intField{X: 3}, error: "rlp: type int is not RLP-serializable (struct field rlp.intField.X)"}, // nil {val: (*uint)(nil), output: "80"}, @@ -239,22 +248,66 @@ var encTests = []encTest{ {val: (*[]struct{ uint })(nil), output: "C0"}, {val: (*interface{})(nil), output: "C0"}, + // nil struct fields + { + val: struct { + X *[]byte + }{}, + output: "C180", + }, + { + val: struct { + X *[2]byte + }{}, + output: "C180", + }, + { + val: struct { + X *uint64 + }{}, + output: "C180", + }, + { + val: struct { + X *uint64 `rlp:"nilList"` + }{}, + output: "C1C0", + }, + { + val: struct { + X *[]uint64 + }{}, + output: "C1C0", + }, + { + val: struct { + X *[]uint64 `rlp:"nilString"` + }{}, + output: "C180", + }, + // interfaces {val: []io.Reader{reader}, output: "C3C20102"}, // the contained value is a struct // Encoder - {val: (*testEncoder)(nil), output: "00000000"}, + {val: (*testEncoder)(nil), output: "C0"}, {val: &testEncoder{}, output: "00010001000100010001"}, {val: &testEncoder{errors.New("test error")}, error: "test error"}, - // verify that the Encoder interface works for unsupported types like func(). - {val: undecodableEncoder(func() {}), output: "C0"}, - // verify that pointer method testEncoder.EncodeRLP is called for + {val: struct{ E testEncoderValueMethod }{}, output: "C3FAFEF0"}, + {val: struct{ E *testEncoderValueMethod }{}, output: "C1C0"}, + + // Verify that the Encoder interface works for unsupported types like func(). + {val: undecodableEncoder(func() {}), output: "F5F5F5"}, + + // Verify that pointer method testEncoder.EncodeRLP is called for // addressable non-pointer values. {val: &struct{ TE testEncoder }{testEncoder{}}, output: "CA00010001000100010001"}, {val: &struct{ TE testEncoder }{testEncoder{errors.New("test error")}}, error: "test error"}, - // verify the error for non-addressable non-pointer Encoder - {val: testEncoder{}, error: "rlp: game over: unadressable value of type rlp.testEncoder, EncodeRLP is pointer method"}, - // verify the special case for []byte + + // Verify the error for non-addressable non-pointer Encoder. + {val: testEncoder{}, error: "rlp: unadressable value of type rlp.testEncoder, EncodeRLP is pointer method"}, + + // Verify Encoder takes precedence over []byte. {val: []byteEncoder{0, 1, 2, 3, 4}, output: "C5C0C0C0C0C0"}, } diff --git a/rlp/encoder_example_test.go b/rlp/encoder_example_test.go index 1cffa241c..42c1c5c89 100644 --- a/rlp/encoder_example_test.go +++ b/rlp/encoder_example_test.go @@ -28,15 +28,7 @@ type MyCoolType struct { // EncodeRLP writes x as RLP list [a, b] that omits the Name field. func (x *MyCoolType) EncodeRLP(w io.Writer) (err error) { - // Note: the receiver can be a nil pointer. This allows you to - // control the encoding of nil, but it also means that you have to - // check for a nil receiver. - if x == nil { - err = Encode(w, []uint{0, 0}) - } else { - err = Encode(w, []uint{x.a, x.b}) - } - return err + return Encode(w, []uint{x.a, x.b}) } func ExampleEncoder() { @@ -49,6 +41,6 @@ func ExampleEncoder() { fmt.Printf("%v → %X\n", t, bytes) // Output: - // <nil> → C28080 + // <nil> → C0 // &{foobar 5 6} → C20506 } diff --git a/rlp/typecache.go b/rlp/typecache.go index ab5ee3da7..e9a1e3f9e 100644 --- a/rlp/typecache.go +++ b/rlp/typecache.go @@ -35,22 +35,28 @@ type typeinfo struct { writerErr error // error from makeWriter } -// represents struct tags +// tags represents struct tags. type tags struct { // rlp:"nil" controls whether empty input results in a nil pointer. nilOK bool + + // This controls whether nil pointers are encoded/decoded as empty strings + // or empty lists. + nilKind Kind + // rlp:"tail" controls whether this field swallows additional list // elements. It can only be set for the last field, which must be // of slice type. tail bool + // rlp:"-" ignores fields. ignored bool } +// typekey is the key of a type in typeCache. It includes the struct tags because +// they might generate a different decoder. type typekey struct { reflect.Type - // the key must include the struct tags because they - // might generate a different decoder. tags } @@ -120,6 +126,25 @@ func structFields(typ reflect.Type) (fields []field, err error) { return fields, nil } +type structFieldError struct { + typ reflect.Type + field int + err error +} + +func (e structFieldError) Error() string { + return fmt.Sprintf("%v (struct field %v.%s)", e.err, e.typ, e.typ.Field(e.field).Name) +} + +type structTagError struct { + typ reflect.Type + field, tag, err string +} + +func (e structTagError) Error() string { + return fmt.Sprintf("rlp: invalid struct tag %q for %v.%s (%s)", e.tag, e.typ, e.field, e.err) +} + func parseStructTag(typ reflect.Type, fi, lastPublic int) (tags, error) { f := typ.Field(fi) var ts tags @@ -128,15 +153,26 @@ func parseStructTag(typ reflect.Type, fi, lastPublic int) (tags, error) { case "": case "-": ts.ignored = true - case "nil": + case "nil", "nilString", "nilList": ts.nilOK = true + if f.Type.Kind() != reflect.Ptr { + return ts, structTagError{typ, f.Name, t, "field is not a pointer"} + } + switch t { + case "nil": + ts.nilKind = defaultNilKind(f.Type.Elem()) + case "nilString": + ts.nilKind = String + case "nilList": + ts.nilKind = List + } case "tail": ts.tail = true if fi != lastPublic { - return ts, fmt.Errorf(`rlp: invalid struct tag "tail" for %v.%s (must be on last field)`, typ, f.Name) + return ts, structTagError{typ, f.Name, t, "must be on last field"} } if f.Type.Kind() != reflect.Slice { - return ts, fmt.Errorf(`rlp: invalid struct tag "tail" for %v.%s (field type is not slice)`, typ, f.Name) + return ts, structTagError{typ, f.Name, t, "field type is not slice"} } default: return ts, fmt.Errorf("rlp: unknown struct tag %q on %v.%s", t, typ, f.Name) @@ -160,6 +196,20 @@ func (i *typeinfo) generate(typ reflect.Type, tags tags) { i.writer, i.writerErr = makeWriter(typ, tags) } +// defaultNilKind determines whether a nil pointer to typ encodes/decodes +// as an empty string or empty list. +func defaultNilKind(typ reflect.Type) Kind { + k := typ.Kind() + if isUint(k) || k == reflect.String || k == reflect.Bool || isByteArray(typ) { + return String + } + return List +} + func isUint(k reflect.Kind) bool { return k >= reflect.Uint && k <= reflect.Uintptr } + +func isByteArray(typ reflect.Type) bool { + return (typ.Kind() == reflect.Slice || typ.Kind() == reflect.Array) && isByte(typ.Elem()) +} |