plugeth-utils/restricted/rlp/encbuffer.go

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2023-04-05 04:25:21 +00:00
// Copyright 2022 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 (
"encoding/binary"
"io"
"math/big"
// "reflect"
"sync"
"github.com/holiman/uint256"
)
type encBuffer struct {
str []byte // string data, contains everything except list headers
lheads []listhead // all list headers
lhsize int // sum of sizes of all encoded list headers
sizebuf [9]byte // auxiliary buffer for uint encoding
}
// The global encBuffer pool.
var encBufferPool = sync.Pool{
New: func() interface{} { return new(encBuffer) },
}
func getEncBuffer() *encBuffer {
buf := encBufferPool.Get().(*encBuffer)
buf.reset()
return buf
}
func (buf *encBuffer) reset() {
buf.lhsize = 0
buf.str = buf.str[:0]
buf.lheads = buf.lheads[:0]
}
// size returns the length of the encoded data.
func (buf *encBuffer) size() int {
return len(buf.str) + buf.lhsize
}
// makeBytes creates the encoder output.
func (w *encBuffer) makeBytes() []byte {
out := make([]byte, w.size())
w.copyTo(out)
return out
}
func (w *encBuffer) copyTo(dst []byte) {
strpos := 0
pos := 0
for _, head := range w.lheads {
// write string data before header
n := copy(dst[pos:], w.str[strpos:head.offset])
pos += n
strpos += n
// write the header
enc := head.encode(dst[pos:])
pos += len(enc)
}
// copy string data after the last list header
copy(dst[pos:], w.str[strpos:])
}
// writeTo writes the encoder output to w.
func (buf *encBuffer) writeTo(w io.Writer) (err error) {
strpos := 0
for _, head := range buf.lheads {
// write string data before header
if head.offset-strpos > 0 {
n, err := w.Write(buf.str[strpos:head.offset])
strpos += n
if err != nil {
return err
}
}
// write the header
enc := head.encode(buf.sizebuf[:])
if _, err = w.Write(enc); err != nil {
return err
}
}
if strpos < len(buf.str) {
// write string data after the last list header
_, err = w.Write(buf.str[strpos:])
}
return err
}
// Write implements io.Writer and appends b directly to the output.
func (buf *encBuffer) Write(b []byte) (int, error) {
buf.str = append(buf.str, b...)
return len(b), nil
}
// writeBool writes b as the integer 0 (false) or 1 (true).
func (buf *encBuffer) writeBool(b bool) {
if b {
buf.str = append(buf.str, 0x01)
} else {
buf.str = append(buf.str, 0x80)
}
}
func (buf *encBuffer) writeUint64(i uint64) {
if i == 0 {
buf.str = append(buf.str, 0x80)
} else if i < 128 {
// fits single byte
buf.str = append(buf.str, byte(i))
} else {
s := putint(buf.sizebuf[1:], i)
buf.sizebuf[0] = 0x80 + byte(s)
buf.str = append(buf.str, buf.sizebuf[:s+1]...)
}
}
func (buf *encBuffer) writeBytes(b []byte) {
if len(b) == 1 && b[0] <= 0x7F {
// fits single byte, no string header
buf.str = append(buf.str, b[0])
} else {
buf.encodeStringHeader(len(b))
buf.str = append(buf.str, b...)
}
}
func (buf *encBuffer) writeString(s string) {
buf.writeBytes([]byte(s))
}
// // wordBytes is the number of bytes in a big.Word
// const wordBytes = (32 << (uint64(^big.Word(0)) >> 63)) / 8
// writeBigInt writes i as an integer.
func (w *encBuffer) writeBigInt(i *big.Int) {
bitlen := i.BitLen()
if bitlen <= 64 {
w.writeUint64(i.Uint64())
return
}
// Integer is larger than 64 bits, encode from i.Bits().
// The minimal byte length is bitlen rounded up to the next
// multiple of 8, divided by 8.
length := ((bitlen + 7) & -8) >> 3
w.encodeStringHeader(length)
w.str = append(w.str, make([]byte, length)...)
index := length
buf := w.str[len(w.str)-length:]
for _, d := range i.Bits() {
for j := 0; j < wordBytes && index > 0; j++ {
index--
buf[index] = byte(d)
d >>= 8
}
}
}
// writeUint256 writes z as an integer.
func (w *encBuffer) writeUint256(z *uint256.Int) {
bitlen := z.BitLen()
if bitlen <= 64 {
w.writeUint64(z.Uint64())
return
}
nBytes := byte((bitlen + 7) / 8)
var b [33]byte
binary.BigEndian.PutUint64(b[1:9], z[3])
binary.BigEndian.PutUint64(b[9:17], z[2])
binary.BigEndian.PutUint64(b[17:25], z[1])
binary.BigEndian.PutUint64(b[25:33], z[0])
b[32-nBytes] = 0x80 + nBytes
w.str = append(w.str, b[32-nBytes:]...)
}
// list adds a new list header to the header stack. It returns the index of the header.
// Call listEnd with this index after encoding the content of the list.
func (buf *encBuffer) list() int {
buf.lheads = append(buf.lheads, listhead{offset: len(buf.str), size: buf.lhsize})
return len(buf.lheads) - 1
}
func (buf *encBuffer) listEnd(index int) {
lh := &buf.lheads[index]
lh.size = buf.size() - lh.offset - lh.size
if lh.size < 56 {
buf.lhsize++ // length encoded into kind tag
} else {
buf.lhsize += 1 + intsize(uint64(lh.size))
}
}
// func (buf *encBuffer) encode(val interface{}) error {
// rval := reflect.ValueOf(val)
// writer, err := cachedWriter(rval.Type())
// if err != nil {
// return err
// }
// return writer(rval, buf)
// }
func (buf *encBuffer) encodeStringHeader(size int) {
if size < 56 {
buf.str = append(buf.str, 0x80+byte(size))
} else {
sizesize := putint(buf.sizebuf[1:], uint64(size))
buf.sizebuf[0] = 0xB7 + byte(sizesize)
buf.str = append(buf.str, buf.sizebuf[:sizesize+1]...)
}
}
// // encReader is the io.Reader returned by EncodeToReader.
// // It releases its encbuf at EOF.
// type encReader struct {
// buf *encBuffer // the buffer we're reading from. this is nil when we're at EOF.
// lhpos int // index of list header that we're reading
// strpos int // current position in string buffer
// piece []byte // next piece to be read
// }
// func (r *encReader) Read(b []byte) (n int, err error) {
// for {
// if r.piece = r.next(); r.piece == nil {
// // Put the encode buffer back into the pool at EOF when it
// // is first encountered. Subsequent calls still return EOF
// // as the error but the buffer is no longer valid.
// if r.buf != nil {
// encBufferPool.Put(r.buf)
// r.buf = nil
// }
// return n, io.EOF
// }
// nn := copy(b[n:], r.piece)
// n += nn
// if nn < len(r.piece) {
// // piece didn't fit, see you next time.
// r.piece = r.piece[nn:]
// return n, nil
// }
// r.piece = nil
// }
// }
// // next returns the next piece of data to be read.
// // it returns nil at EOF.
// func (r *encReader) next() []byte {
// switch {
// case r.buf == nil:
// return nil
// case r.piece != nil:
// // There is still data available for reading.
// return r.piece
// case r.lhpos < len(r.buf.lheads):
// // We're before the last list header.
// head := r.buf.lheads[r.lhpos]
// sizebefore := head.offset - r.strpos
// if sizebefore > 0 {
// // String data before header.
// p := r.buf.str[r.strpos:head.offset]
// r.strpos += sizebefore
// return p
// }
// r.lhpos++
// return head.encode(r.buf.sizebuf[:])
// case r.strpos < len(r.buf.str):
// // String data at the end, after all list headers.
// p := r.buf.str[r.strpos:]
// r.strpos = len(r.buf.str)
// return p
// default:
// return nil
// }
// }
func encBufferFromWriter(w io.Writer) *encBuffer {
switch w := w.(type) {
case EncoderBuffer:
return w.buf
case *EncoderBuffer:
return w.buf
case *encBuffer:
return w
default:
return nil
}
}
// EncoderBuffer is a buffer for incremental encoding.
//
// The zero value is NOT ready for use. To get a usable buffer,
// create it using NewEncoderBuffer or call Reset.
type EncoderBuffer struct {
buf *encBuffer
dst io.Writer
ownBuffer bool
}
// NewEncoderBuffer creates an encoder buffer.
func NewEncoderBuffer(dst io.Writer) EncoderBuffer {
var w EncoderBuffer
w.Reset(dst)
return w
}
// Reset truncates the buffer and sets the output destination.
func (w *EncoderBuffer) Reset(dst io.Writer) {
if w.buf != nil && !w.ownBuffer {
panic("can't Reset derived EncoderBuffer")
}
// If the destination writer has an *encBuffer, use it.
// Note that w.ownBuffer is left false here.
if dst != nil {
if outer := encBufferFromWriter(dst); outer != nil {
*w = EncoderBuffer{outer, nil, false}
return
}
}
// Get a fresh buffer.
if w.buf == nil {
w.buf = encBufferPool.Get().(*encBuffer)
w.ownBuffer = true
}
w.buf.reset()
w.dst = dst
}
// Flush writes encoded RLP data to the output writer. This can only be called once.
// If you want to re-use the buffer after Flush, you must call Reset.
func (w *EncoderBuffer) Flush() error {
var err error
if w.dst != nil {
err = w.buf.writeTo(w.dst)
}
// Release the internal buffer.
if w.ownBuffer {
encBufferPool.Put(w.buf)
}
*w = EncoderBuffer{}
return err
}
// ToBytes returns the encoded bytes.
func (w *EncoderBuffer) ToBytes() []byte {
return w.buf.makeBytes()
}
// AppendToBytes appends the encoded bytes to dst.
func (w *EncoderBuffer) AppendToBytes(dst []byte) []byte {
size := w.buf.size()
out := append(dst, make([]byte, size)...)
w.buf.copyTo(out[len(dst):])
return out
}
// Write appends b directly to the encoder output.
func (w EncoderBuffer) Write(b []byte) (int, error) {
return w.buf.Write(b)
}
// WriteBool writes b as the integer 0 (false) or 1 (true).
func (w EncoderBuffer) WriteBool(b bool) {
w.buf.writeBool(b)
}
// WriteUint64 encodes an unsigned integer.
func (w EncoderBuffer) WriteUint64(i uint64) {
w.buf.writeUint64(i)
}
// WriteBigInt encodes a big.Int as an RLP string.
// Note: Unlike with Encode, the sign of i is ignored.
func (w EncoderBuffer) WriteBigInt(i *big.Int) {
w.buf.writeBigInt(i)
}
// WriteUint256 encodes uint256.Int as an RLP string.
func (w EncoderBuffer) WriteUint256(i *uint256.Int) {
w.buf.writeUint256(i)
}
// WriteBytes encodes b as an RLP string.
func (w EncoderBuffer) WriteBytes(b []byte) {
w.buf.writeBytes(b)
}
// WriteString encodes s as an RLP string.
func (w EncoderBuffer) WriteString(s string) {
w.buf.writeString(s)
}
// List starts a list. It returns an internal index. Call EndList with
// this index after encoding the content to finish the list.
func (w EncoderBuffer) List() int {
return w.buf.list()
}
// ListEnd finishes the given list.
func (w EncoderBuffer) ListEnd(index int) {
w.buf.listEnd(index)
}