Changed prev_hash to block_hash, state transition now uses vm env

* PREVHASH => BLOCKHASH( N )
* State transition object uses VMEnv as it's query interface
* Updated vm.Enviroment has GetHash( n ) for BLOCKHASH instruction
* Added GetHash to xeth, core, utils & test environments

2 files changed, 10 insertions, 3 deletions

diff --git a/xeth/pipe.go b/xeth/pipe.go
index cae6ee1de..05cefd8ad 100644
--- a/xeth/pipe.go
+++ b/xeth/pipe.go
@@ -87,7 +87,7 @@ func (self *XEth) ExecuteObject(object *Object, data []byte, value, gas, price *
 
 	self.Vm.State = self.World().State().Copy()
 
-	vmenv := NewEnv(self.Vm.State, block, value.BigInt(), initiator.Address())
+	vmenv := NewEnv(self.chainManager, self.Vm.State, block, value.BigInt(), initiator.Address())
 	return vmenv.Call(initiator, object.Address(), data, gas.BigInt(), price.BigInt(), value.BigInt())
 }
 
diff --git a/xeth/vm_env.go b/xeth/vm_env.go
index d2a21afd5..1470b9eaa 100644
--- a/xeth/vm_env.go
+++ b/xeth/vm_env.go
@@ -10,6 +10,7 @@ import (
 )
 
 type VMEnv struct {
+	chain  *core.ChainManager
 	state  *state.StateDB
 	block  *types.Block
 	value  *big.Int
@@ -18,7 +19,7 @@ type VMEnv struct {
 	depth int
 }
 
-func NewEnv(state *state.StateDB, block *types.Block, value *big.Int, sender []byte) *VMEnv {
+func NewEnv(chain *core.ChainManager, state *state.StateDB, block *types.Block, value *big.Int, sender []byte) *VMEnv {
 	return &VMEnv{
 		state:  state,
 		block:  block,
@@ -33,12 +34,18 @@ func (self *VMEnv) PrevHash() []byte      { return self.block.ParentHash() }
 func (self *VMEnv) Coinbase() []byte      { return self.block.Coinbase() }
 func (self *VMEnv) Time() int64           { return self.block.Time() }
 func (self *VMEnv) Difficulty() *big.Int  { return self.block.Difficulty() }
-func (self *VMEnv) BlockHash() []byte     { return self.block.Hash() }
 func (self *VMEnv) GasLimit() *big.Int    { return self.block.GasLimit() }
 func (self *VMEnv) Value() *big.Int       { return self.value }
 func (self *VMEnv) State() *state.StateDB { return self.state }
 func (self *VMEnv) Depth() int            { return self.depth }
 func (self *VMEnv) SetDepth(i int)        { self.depth = i }
+func (self *VMEnv) GetHash(n uint64) []byte {
+	if block := self.chain.GetBlockByNumber(n); block != nil {
+		return block.Hash()
+	}
+
+	return nil
+}
 func (self *VMEnv) AddLog(log state.Log) {
 	self.state.AddLog(log)
 }