core, cmd/geth: improved recover functionality

`geth recover` now accepts both hashes and numbers using "#" and no
longer requires the ethereum instance.

core/chain_util.go

@@ -0,0 +1,98 @@
+package core
+
+import (
+	"bytes"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/rlp"
+)
+
+// CalcDifficulty is the difficulty adjustment algorithm. It returns
+// the difficulty that a new block b should have when created at time
+// given the parent block's time and difficulty.
+func CalcDifficulty(time int64, parentTime int64, parentDiff *big.Int) *big.Int {
+	diff := new(big.Int)
+	adjust := new(big.Int).Div(parentDiff, params.DifficultyBoundDivisor)
+	if big.NewInt(time-parentTime).Cmp(params.DurationLimit) < 0 {
+		diff.Add(parentDiff, adjust)
+	} else {
+		diff.Sub(parentDiff, adjust)
+	}
+	if diff.Cmp(params.MinimumDifficulty) < 0 {
+		return params.MinimumDifficulty
+	}
+	return diff
+}
+
+// CalcTD computes the total difficulty of block.
+func CalcTD(block, parent *types.Block) *big.Int {
+	if parent == nil {
+		return block.Difficulty()
+	}
+	d := block.Difficulty()
+	d.Add(d, parent.Td)
+	return d
+}
+
+// CalcGasLimit computes the gas limit of the next block after parent.
+// The result may be modified by the caller.
+func CalcGasLimit(parent *types.Block) *big.Int {
+	decay := new(big.Int).Div(parent.GasLimit(), params.GasLimitBoundDivisor)
+	contrib := new(big.Int).Mul(parent.GasUsed(), big.NewInt(3))
+	contrib = contrib.Div(contrib, big.NewInt(2))
+	contrib = contrib.Div(contrib, params.GasLimitBoundDivisor)
+
+	gl := new(big.Int).Sub(parent.GasLimit(), decay)
+	gl = gl.Add(gl, contrib)
+	gl = gl.Add(gl, big.NewInt(1))
+	gl.Set(common.BigMax(gl, params.MinGasLimit))
+
+	if gl.Cmp(params.GenesisGasLimit) < 0 {
+		gl.Add(parent.GasLimit(), decay)
+		gl.Set(common.BigMin(gl, params.GenesisGasLimit))
+	}
+	return gl
+}
+
+// GetBlockByHash returns the block corresponding to the hash or nil if not found
+func GetBlockByHash(db common.Database, hash common.Hash) *types.Block {
+	data, _ := db.Get(append(blockHashPre, hash[:]...))
+	if len(data) == 0 {
+		return nil
+	}
+	var block types.StorageBlock
+	if err := rlp.Decode(bytes.NewReader(data), &block); err != nil {
+		glog.V(logger.Error).Infof("invalid block RLP for hash %x: %v", hash, err)
+		return nil
+	}
+	return (*types.Block)(&block)
+}
+
+// GetBlockByHash returns the canonical block by number or nil if not found
+func GetBlockByNumber(db common.Database, number uint64) *types.Block {
+	key, _ := db.Get(append(blockNumPre, big.NewInt(int64(number)).Bytes()...))
+	if len(key) == 0 {
+		return nil
+	}
+
+	return GetBlockByHash(db, common.BytesToHash(key))
+}
+
+// WriteHead force writes the current head
+func WriteHead(db common.Database, block *types.Block) error {
+	key := append(blockNumPre, block.Number().Bytes()...)
+	err := db.Put(key, block.Hash().Bytes())
+	if err != nil {
+		return err
+	}
+	err = db.Put([]byte("LastBlock"), block.Hash().Bytes())
+	if err != nil {
+		return err
+	}
+	return nil
+}