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serialize big ints without a tag

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This commit is contained in:
whyrusleeping 2019-09-25 13:52:28 -07:00
parent 78fa12d2b9
commit 5f31544faa
1 changed files with 28 additions and 27 deletions
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55
chain/types/bigint.go
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@ -7,9 +7,9 @@ import (
"math/big"
"github.com/filecoin-project/go-lotus/build"
cbor "github.com/ipfs/go-ipld-cbor"
"github.com/polydawn/refmt/obj/atlas"
cbg "github.com/whyrusleeping/cbor-gen"
"golang.org/x/xerrors"
)
@ -123,24 +123,21 @@ func (bi *BigInt) MarshalCBOR(w io.Writer) error {
return zero.MarshalCBOR(w)
}
tag := uint64(2)
if bi.Sign() < 0 {
tag = 3
var enc []byte
switch {
case bi.Sign() == 0:
case bi.Sign() > 0:
enc = append([]byte{0}, bi.Bytes()...)
case bi.Sign() < 0:
enc = append([]byte{1}, bi.Bytes()...)
}
header := cbg.CborEncodeMajorType(cbg.MajTag, tag)
header := cbg.CborEncodeMajorType(cbg.MajByteString, uint64(len(enc)))
if _, err := w.Write(header); err != nil {
return err
}
b := bi.Bytes()
header = cbg.CborEncodeMajorType(cbg.MajByteString, uint64(len(b)))
if _, err := w.Write(header); err != nil {
return err
}
if _, err := w.Write(b); err != nil {
if _, err := w.Write(enc); err != nil {
return err
}
@ -153,19 +150,13 @@ func (bi *BigInt) UnmarshalCBOR(br io.Reader) error {
return err
}
if maj != cbg.MajTag && extra != 2 && extra != 3 {
return fmt.Errorf("cbor input for big int was not a tagged big int")
}
minus := extra & 1
maj, extra, err = cbg.CborReadHeader(br)
if err != nil {
return err
}
if maj != cbg.MajByteString {
return fmt.Errorf("cbor input for big int was not a tagged byte string")
return fmt.Errorf("cbor input for fil big int was not a byte string")
}
if extra == 0 {
bi.Int = big.NewInt(0)
return nil
}
if extra > BigIntMaxSerializedLen {
@ -177,8 +168,18 @@ func (bi *BigInt) UnmarshalCBOR(br io.Reader) error {
return err
}
bi.Int = big.NewInt(0).SetBytes(buf)
if minus > 0 {
var negative bool
switch buf[0] {
case 0:
negative = false
case 1:
negative = true
default:
return fmt.Errorf("big int prefix should be either 0 or 1, got %d", buf[0])
}
bi.Int = big.NewInt(0).SetBytes(buf[1:])
if negative {
bi.Int.Neg(bi.Int)
}