chain: Add fallback supplementBlock decoding

chain/db.go

@@ -37,6 +37,29 @@ func (sb *supplementedBlock) DecodeFrom(d *types.Decoder) {
 	}
 }
 
+func (sb *supplementedBlock) decodeOldSupplement(d *types.Decoder) {
+	if v := d.ReadUint8(); v != 2 {
+		d.SetErr(fmt.Errorf("incompatible version (%d)", v))
+	}
+	(*types.V2Block)(&sb.Block).DecodeFrom(d)
+	if d.ReadBool() {
+		sb.Supplement = new(consensus.V1BlockSupplement)
+		types.DecodeSliceFn(d, &sb.Supplement.Transactions, func(d *types.Decoder) (ts consensus.V1TransactionSupplement) {
+			types.DecodeSlice(d, &ts.SiacoinInputs)
+			types.DecodeSlice(d, &ts.SiafundInputs)
+			types.DecodeSlice(d, &ts.RevisedFileContracts)
+			var fces []types.FileContractElement
+			types.DecodeSlice(d, &fces)
+			ts.StorageProofs = make([]consensus.V1StorageProofSupplement, len(fces))
+			for i, fce := range fces {
+				ts.StorageProofs[i] = consensus.V1StorageProofSupplement{FileContract: fce}
+			}
+			return
+		})
+		types.DecodeSlice(d, &sb.Supplement.ExpiringFileContracts)
+	}
+}
+
 // helper type for decoding just the header information from a block
 type supplementedHeader struct {
 	ParentID  types.BlockID
@@ -306,8 +329,22 @@ func (db *DBStore) putState(cs consensus.State) {
 
 func (db *DBStore) getBlock(id types.BlockID) (b types.Block, bs *consensus.V1BlockSupplement, _ bool) {
 	var sb supplementedBlock
-	ok := db.bucket(bBlocks).get(id[:], &sb)
-	return sb.Block, sb.Supplement, ok
+
+	val := db.bucket(bBlocks).getRaw(id[:])
+	if val == nil {
+		return b, bs, false
+	}
+	// fallback to old encoding before panicking
+	d := types.NewBufDecoder(val)
+	sb.DecodeFrom(d)
+	if d.Err() != nil {
+		d = types.NewBufDecoder(val)
+		sb.decodeOldSupplement(d)
+	}
+	if d.Err() != nil {
+		check(fmt.Errorf("error decoding %T: %w", &sb, d.Err()))
+	}
+	return sb.Block, sb.Supplement, true
 }
 
 func (db *DBStore) putBlock(b types.Block, bs *consensus.V1BlockSupplement) {