neoneo-go/pkg/vm/stackitem/serialization.go
Roman Khimov 5a9efcc654 stackitem: rework error handling
Return good named errors everywhere, export appropriate constants, make
errors.Is() work.
2021-07-07 00:18:00 +03:00

227 lines
5.4 KiB
Go

package stackitem
import (
"errors"
"fmt"
"math/big"
"github.com/nspcc-dev/neo-go/pkg/encoding/bigint"
"github.com/nspcc-dev/neo-go/pkg/io"
)
// ErrRecursive is returned on attempts to serialize some recursive stack item
// (like array including an item with reference to the same array).
var ErrRecursive = errors.New("recursive item")
// ErrUnserializable is returned on attempt to serialize some item that can't
// be serialized (like Interop item or Pointer).
var ErrUnserializable = errors.New("unserializable")
// serContext is an internal serialization context.
type serContext struct {
*io.BinWriter
buf *io.BufBinWriter
allowInvalid bool
seen map[Item]bool
}
// Serialize encodes given Item into the byte slice.
func Serialize(item Item) ([]byte, error) {
w := io.NewBufBinWriter()
sc := serContext{
BinWriter: w.BinWriter,
buf: w,
allowInvalid: false,
seen: make(map[Item]bool),
}
sc.serialize(item)
if w.Err != nil {
return nil, w.Err
}
return w.Bytes(), nil
}
// EncodeBinary encodes given Item into the given BinWriter. It's
// similar to io.Serializable's EncodeBinary, but works with Item
// interface.
func EncodeBinary(item Item, w *io.BinWriter) {
sc := serContext{
BinWriter: w,
allowInvalid: false,
seen: make(map[Item]bool),
}
sc.serialize(item)
}
// EncodeBinaryProtected encodes given Item into the given BinWriter. It's
// similar to EncodeBinary but allows to encode interop items (only type,
// value is lost) and doesn't return any errors in w, instead if error
// (like recursive array) is encountered it just writes special InvalidT
// type of element to w.
func EncodeBinaryProtected(item Item, w *io.BinWriter) {
bw := io.NewBufBinWriter()
sc := serContext{
BinWriter: bw.BinWriter,
buf: bw,
allowInvalid: true,
seen: make(map[Item]bool),
}
sc.serialize(item)
if bw.Err != nil {
w.WriteBytes([]byte{byte(InvalidT)})
return
}
w.WriteBytes(bw.Bytes())
}
func (w *serContext) serialize(item Item) {
if w.Err != nil {
return
}
if w.seen[item] {
w.Err = ErrRecursive
return
}
switch t := item.(type) {
case *ByteArray:
w.WriteBytes([]byte{byte(ByteArrayT)})
w.WriteVarBytes(t.Value().([]byte))
case *Buffer:
w.WriteBytes([]byte{byte(BufferT)})
w.WriteVarBytes(t.Value().([]byte))
case *Bool:
w.WriteBytes([]byte{byte(BooleanT)})
w.WriteBool(t.Value().(bool))
case *BigInteger:
w.WriteBytes([]byte{byte(IntegerT)})
w.WriteVarBytes(bigint.ToBytes(t.Value().(*big.Int)))
case *Interop:
if w.allowInvalid {
w.WriteBytes([]byte{byte(InteropT)})
} else {
w.Err = fmt.Errorf("%w: Interop", ErrUnserializable)
}
case *Array, *Struct:
w.seen[item] = true
_, isArray := t.(*Array)
if isArray {
w.WriteBytes([]byte{byte(ArrayT)})
} else {
w.WriteBytes([]byte{byte(StructT)})
}
arr := t.Value().([]Item)
w.WriteVarUint(uint64(len(arr)))
for i := range arr {
w.serialize(arr[i])
}
delete(w.seen, item)
case *Map:
w.seen[item] = true
w.WriteBytes([]byte{byte(MapT)})
w.WriteVarUint(uint64(len(t.Value().([]MapElement))))
for i := range t.Value().([]MapElement) {
w.serialize(t.Value().([]MapElement)[i].Key)
w.serialize(t.Value().([]MapElement)[i].Value)
}
delete(w.seen, item)
case Null:
w.WriteB(byte(AnyT))
case nil:
if w.allowInvalid {
w.WriteBytes([]byte{byte(InvalidT)})
} else {
w.Err = fmt.Errorf("%w: nil", ErrUnserializable)
}
}
if w.Err == nil && w.buf != nil && w.buf.Len() > MaxSize {
w.Err = errTooBigSize
}
}
// Deserialize decodes Item from the given byte slice.
func Deserialize(data []byte) (Item, error) {
r := io.NewBinReaderFromBuf(data)
item := DecodeBinary(r)
if r.Err != nil {
return nil, r.Err
}
return item, nil
}
// DecodeBinary decodes previously serialized Item from the given
// reader. It's similar to the io.Serializable's DecodeBinary(), but implemented
// as a function because Item itself is an interface. Caveat: always check
// reader's error value before using the returned Item.
func DecodeBinary(r *io.BinReader) Item {
return decodeBinary(r, false)
}
// DecodeBinaryProtected is similar to DecodeBinary but allows Interop and
// Invalid values to be present (making it symmetric to EncodeBinaryProtected).
func DecodeBinaryProtected(r *io.BinReader) Item {
return decodeBinary(r, true)
}
func decodeBinary(r *io.BinReader, allowInvalid bool) Item {
var t = Type(r.ReadB())
if r.Err != nil {
return nil
}
switch t {
case ByteArrayT, BufferT:
data := r.ReadVarBytes(MaxSize)
if t == ByteArrayT {
return NewByteArray(data)
}
return NewBuffer(data)
case BooleanT:
var b = r.ReadBool()
return NewBool(b)
case IntegerT:
data := r.ReadVarBytes(bigint.MaxBytesLen)
num := bigint.FromBytes(data)
return NewBigInteger(num)
case ArrayT, StructT:
size := int(r.ReadVarUint())
arr := make([]Item, size)
for i := 0; i < size; i++ {
arr[i] = DecodeBinary(r)
}
if t == ArrayT {
return NewArray(arr)
}
return NewStruct(arr)
case MapT:
size := int(r.ReadVarUint())
m := NewMap()
for i := 0; i < size; i++ {
key := DecodeBinary(r)
value := DecodeBinary(r)
if r.Err != nil {
break
}
m.Add(key, value)
}
return m
case AnyT:
return Null{}
case InteropT:
if allowInvalid {
return NewInterop(nil)
}
fallthrough
default:
if t == InvalidT && allowInvalid {
return nil
}
r.Err = fmt.Errorf("%w: %v", ErrInvalidType, t)
return nil
}
}