fix 13284494

minigeth/core/fake_blockchain.go

 package core
 
 import (
+	"log"
+	"math/big"
+
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/consensus"
 	"github.com/ethereum/go-ethereum/consensus/ethash"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/oracle"
 	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/rlp"
 )
 
 type BlockChain struct {
 	// TODO: write stub BlockChain
 	chainConfig *params.ChainConfig // Chain & network configuration
 	engine      consensus.Engine
+	lastBlock   *types.Header
 }
 
-func NewBlockChain() *BlockChain {
+func NewBlockChain(parent *types.Header) *BlockChain {
 	return &BlockChain{
 		chainConfig: params.MainnetChainConfig,
 		engine:      &ethash.Ethash{},
+		lastBlock:   parent,
 	}
 }
 
@@ -30,21 +37,36 @@ func (bc *BlockChain) Engine() consensus.Engine { return bc.engine }
 // GetHeader retrieves a block header from the database by hash and number,
 // caching it if found.
 func (bc *BlockChain) GetHeader(hash common.Hash, number uint64) *types.Header {
-	return nil
+	if hash == bc.lastBlock.Hash() {
+		return bc.lastBlock
+	}
+	oracle.PrefetchBlock(big.NewInt(int64(number)), true, nil)
+
+	var ret types.Header
+	err := rlp.DecodeBytes(oracle.Preimage(hash), &ret)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	return &ret
 }
 
 func (bc *BlockChain) CurrentHeader() *types.Header {
-	return nil
+	log.Fatal("CurrentHeader")
+	// this right?
+	return bc.lastBlock
 }
 
 // GetHeaderByHash retrieves a block header from the database by hash, caching it if
 // found.
 func (bc *BlockChain) GetHeaderByHash(hash common.Hash) *types.Header {
+	log.Fatal("GetHeaderByHash", hash)
 	return nil
 }
 
 // GetHeaderByNumber retrieves a block header from the database by number,
 // caching it (associated with its hash) if found.
 func (bc *BlockChain) GetHeaderByNumber(number uint64) *types.Header {
+	log.Fatal("GetHeaderByNumber", number)
 	return nil
 }

minigeth/main.go

@@ -61,7 +61,7 @@ func main() {
 	newheader.GasLimit = oracle.Input(4).Big().Uint64()
 	newheader.Time = oracle.Input(5).Big().Uint64()
 
-	bc := core.NewBlockChain()
+	bc := core.NewBlockChain(&parent)
 	database := state.NewDatabase(parent)
 	statedb, _ := state.New(parent.Root, database, nil)
 	vmconfig := vm.Config{}

minigeth/oracle/prefetch.go

@@ -269,7 +269,10 @@ func PrefetchBlock(blockNumber *big.Int, startBlock bool, hasher types.TrieHashe
 		blockHeaderRlp, _ := rlp.EncodeToBytes(blockHeader)
 		hash := crypto.Keccak256Hash(blockHeaderRlp)
 		preimages[hash] = blockHeaderRlp
-		inputs[0] = hash
+		emptyHash := common.Hash{}
+		if inputs[0] == emptyHash {
+			inputs[0] = hash
+		}
 		return
 	}