plugeth/rlp/encode.go
Martin Holst Swende ee301c750b
all: fix docstrings
2022-10-04 09:18:02 +02:00

475 lines
12 KiB
Go

// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package rlp
import (
"errors"
"fmt"
"io"
"math/big"
"reflect"
"github.com/ethereum/go-ethereum/rlp/internal/rlpstruct"
)
var (
// Common encoded values.
// These are useful when implementing EncodeRLP.
// EmptyString is the encoding of an empty string.
EmptyString = []byte{0x80}
// EmptyList is the encoding of an empty list.
EmptyList = []byte{0xC0}
)
var ErrNegativeBigInt = errors.New("rlp: cannot encode negative big.Int")
// Encoder is implemented by types that require custom
// encoding rules or want to encode private fields.
type Encoder interface {
// EncodeRLP should write the RLP encoding of its receiver to w.
// If the implementation is a pointer method, it may also be
// called for nil pointers.
//
// Implementations should generate valid RLP. The data written is
// not verified at the moment, but a future version might. It is
// recommended to write only a single value but writing multiple
// values or no value at all is also permitted.
EncodeRLP(io.Writer) error
}
// Encode writes the RLP encoding of val to w. Note that Encode may
// perform many small writes in some cases. Consider making w
// buffered.
//
// Please see package-level documentation of encoding rules.
func Encode(w io.Writer, val interface{}) error {
// Optimization: reuse *encBuffer when called by EncodeRLP.
if buf := encBufferFromWriter(w); buf != nil {
return buf.encode(val)
}
buf := getEncBuffer()
defer encBufferPool.Put(buf)
if err := buf.encode(val); err != nil {
return err
}
return buf.writeTo(w)
}
// EncodeToBytes returns the RLP encoding of val.
// Please see package-level documentation for the encoding rules.
func EncodeToBytes(val interface{}) ([]byte, error) {
buf := getEncBuffer()
defer encBufferPool.Put(buf)
if err := buf.encode(val); err != nil {
return nil, err
}
return buf.makeBytes(), nil
}
// EncodeToReader returns a reader from which the RLP encoding of val
// can be read. The returned size is the total size of the encoded
// data.
//
// Please see the documentation of Encode for the encoding rules.
func EncodeToReader(val interface{}) (size int, r io.Reader, err error) {
buf := getEncBuffer()
if err := buf.encode(val); err != nil {
encBufferPool.Put(buf)
return 0, nil, err
}
// Note: can't put the reader back into the pool here
// because it is held by encReader. The reader puts it
// back when it has been fully consumed.
return buf.size(), &encReader{buf: buf}, nil
}
type listhead struct {
offset int // index of this header in string data
size int // total size of encoded data (including list headers)
}
// encode writes head to the given buffer, which must be at least
// 9 bytes long. It returns the encoded bytes.
func (head *listhead) encode(buf []byte) []byte {
return buf[:puthead(buf, 0xC0, 0xF7, uint64(head.size))]
}
// headsize returns the size of a list or string header
// for a value of the given size.
func headsize(size uint64) int {
if size < 56 {
return 1
}
return 1 + intsize(size)
}
// puthead writes a list or string header to buf.
// buf must be at least 9 bytes long.
func puthead(buf []byte, smalltag, largetag byte, size uint64) int {
if size < 56 {
buf[0] = smalltag + byte(size)
return 1
}
sizesize := putint(buf[1:], size)
buf[0] = largetag + byte(sizesize)
return sizesize + 1
}
var encoderInterface = reflect.TypeOf(new(Encoder)).Elem()
// makeWriter creates a writer function for the given type.
func makeWriter(typ reflect.Type, ts rlpstruct.Tags) (writer, error) {
kind := typ.Kind()
switch {
case typ == rawValueType:
return writeRawValue, 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:
return writeBool, nil
case kind == reflect.String:
return writeString, nil
case kind == reflect.Slice && isByte(typ.Elem()):
return writeBytes, nil
case kind == reflect.Array && isByte(typ.Elem()):
return makeByteArrayWriter(typ), nil
case kind == reflect.Slice || kind == reflect.Array:
return makeSliceWriter(typ, ts)
case kind == reflect.Struct:
return makeStructWriter(typ)
case kind == reflect.Interface:
return writeInterface, nil
default:
return nil, fmt.Errorf("rlp: type %v is not RLP-serializable", typ)
}
}
func writeRawValue(val reflect.Value, w *encBuffer) error {
w.str = append(w.str, val.Bytes()...)
return nil
}
func writeUint(val reflect.Value, w *encBuffer) error {
w.writeUint64(val.Uint())
return nil
}
func writeBool(val reflect.Value, w *encBuffer) error {
w.writeBool(val.Bool())
return nil
}
func writeBigIntPtr(val reflect.Value, w *encBuffer) error {
ptr := val.Interface().(*big.Int)
if ptr == nil {
w.str = append(w.str, 0x80)
return nil
}
if ptr.Sign() == -1 {
return ErrNegativeBigInt
}
w.writeBigInt(ptr)
return nil
}
func writeBigIntNoPtr(val reflect.Value, w *encBuffer) error {
i := val.Interface().(big.Int)
if i.Sign() == -1 {
return ErrNegativeBigInt
}
w.writeBigInt(&i)
return nil
}
func writeBytes(val reflect.Value, w *encBuffer) error {
w.writeBytes(val.Bytes())
return nil
}
func makeByteArrayWriter(typ reflect.Type) writer {
switch typ.Len() {
case 0:
return writeLengthZeroByteArray
case 1:
return writeLengthOneByteArray
default:
length := typ.Len()
return func(val reflect.Value, w *encBuffer) error {
if !val.CanAddr() {
// Getting the byte slice of val requires it to be addressable. Make it
// addressable by copying.
copy := reflect.New(val.Type()).Elem()
copy.Set(val)
val = copy
}
slice := byteArrayBytes(val, length)
w.encodeStringHeader(len(slice))
w.str = append(w.str, slice...)
return nil
}
}
}
func writeLengthZeroByteArray(val reflect.Value, w *encBuffer) error {
w.str = append(w.str, 0x80)
return nil
}
func writeLengthOneByteArray(val reflect.Value, w *encBuffer) error {
b := byte(val.Index(0).Uint())
if b <= 0x7f {
w.str = append(w.str, b)
} else {
w.str = append(w.str, 0x81, b)
}
return nil
}
func writeString(val reflect.Value, w *encBuffer) error {
s := val.String()
if len(s) == 1 && s[0] <= 0x7f {
// fits single byte, no string header
w.str = append(w.str, s[0])
} else {
w.encodeStringHeader(len(s))
w.str = append(w.str, s...)
}
return nil
}
func writeInterface(val reflect.Value, w *encBuffer) error {
if val.IsNil() {
// Write empty list. This is consistent with the previous RLP
// encoder that we had and should therefore avoid any
// problems.
w.str = append(w.str, 0xC0)
return nil
}
eval := val.Elem()
writer, err := cachedWriter(eval.Type())
if err != nil {
return err
}
return writer(eval, w)
}
func makeSliceWriter(typ reflect.Type, ts rlpstruct.Tags) (writer, error) {
etypeinfo := theTC.infoWhileGenerating(typ.Elem(), rlpstruct.Tags{})
if etypeinfo.writerErr != nil {
return nil, etypeinfo.writerErr
}
var wfn writer
if ts.Tail {
// This is for struct tail slices.
// w.list is not called for them.
wfn = func(val reflect.Value, w *encBuffer) error {
vlen := val.Len()
for i := 0; i < vlen; i++ {
if err := etypeinfo.writer(val.Index(i), w); err != nil {
return err
}
}
return nil
}
} else {
// This is for regular slices and arrays.
wfn = func(val reflect.Value, w *encBuffer) error {
vlen := val.Len()
if vlen == 0 {
w.str = append(w.str, 0xC0)
return nil
}
listOffset := w.list()
for i := 0; i < vlen; i++ {
if err := etypeinfo.writer(val.Index(i), w); err != nil {
return err
}
}
w.listEnd(listOffset)
return nil
}
}
return wfn, nil
}
func makeStructWriter(typ reflect.Type) (writer, error) {
fields, err := structFields(typ)
if err != nil {
return nil, err
}
for _, f := range fields {
if f.info.writerErr != nil {
return nil, structFieldError{typ, f.index, f.info.writerErr}
}
}
var writer writer
firstOptionalField := firstOptionalField(fields)
if firstOptionalField == len(fields) {
// This is the writer function for structs without any optional fields.
writer = func(val reflect.Value, w *encBuffer) error {
lh := w.list()
for _, f := range fields {
if err := f.info.writer(val.Field(f.index), w); err != nil {
return err
}
}
w.listEnd(lh)
return nil
}
} else {
// If there are any "optional" fields, the writer needs to perform additional
// checks to determine the output list length.
writer = func(val reflect.Value, w *encBuffer) error {
lastField := len(fields) - 1
for ; lastField >= firstOptionalField; lastField-- {
if !val.Field(fields[lastField].index).IsZero() {
break
}
}
lh := w.list()
for i := 0; i <= lastField; i++ {
if err := fields[i].info.writer(val.Field(fields[i].index), w); err != nil {
return err
}
}
w.listEnd(lh)
return nil
}
}
return writer, nil
}
func makePtrWriter(typ reflect.Type, ts rlpstruct.Tags) (writer, error) {
nilEncoding := byte(0xC0)
if typeNilKind(typ.Elem(), ts) == String {
nilEncoding = 0x80
}
etypeinfo := theTC.infoWhileGenerating(typ.Elem(), rlpstruct.Tags{})
if etypeinfo.writerErr != nil {
return nil, etypeinfo.writerErr
}
writer := func(val reflect.Value, w *encBuffer) error {
if ev := val.Elem(); ev.IsValid() {
return etypeinfo.writer(ev, w)
}
w.str = append(w.str, nilEncoding)
return nil
}
return writer, nil
}
func makeEncoderWriter(typ reflect.Type) writer {
if typ.Implements(encoderInterface) {
return func(val reflect.Value, w *encBuffer) error {
return val.Interface().(Encoder).EncodeRLP(w)
}
}
w := func(val reflect.Value, w *encBuffer) 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) {
switch {
case i < (1 << 8):
b[0] = byte(i)
return 1
case i < (1 << 16):
b[0] = byte(i >> 8)
b[1] = byte(i)
return 2
case i < (1 << 24):
b[0] = byte(i >> 16)
b[1] = byte(i >> 8)
b[2] = byte(i)
return 3
case i < (1 << 32):
b[0] = byte(i >> 24)
b[1] = byte(i >> 16)
b[2] = byte(i >> 8)
b[3] = byte(i)
return 4
case i < (1 << 40):
b[0] = byte(i >> 32)
b[1] = byte(i >> 24)
b[2] = byte(i >> 16)
b[3] = byte(i >> 8)
b[4] = byte(i)
return 5
case i < (1 << 48):
b[0] = byte(i >> 40)
b[1] = byte(i >> 32)
b[2] = byte(i >> 24)
b[3] = byte(i >> 16)
b[4] = byte(i >> 8)
b[5] = byte(i)
return 6
case i < (1 << 56):
b[0] = byte(i >> 48)
b[1] = byte(i >> 40)
b[2] = byte(i >> 32)
b[3] = byte(i >> 24)
b[4] = byte(i >> 16)
b[5] = byte(i >> 8)
b[6] = byte(i)
return 7
default:
b[0] = byte(i >> 56)
b[1] = byte(i >> 48)
b[2] = byte(i >> 40)
b[3] = byte(i >> 32)
b[4] = byte(i >> 24)
b[5] = byte(i >> 16)
b[6] = byte(i >> 8)
b[7] = byte(i)
return 8
}
}
// intsize computes the minimum number of bytes required to store i.
func intsize(i uint64) (size int) {
for size = 1; ; size++ {
if i >>= 8; i == 0 {
return size
}
}
}