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, 11 insertions, 3 deletions

diff --git a/cmd/mist/debugger.go b/cmd/mist/debugger.go
index 0e97a6652..618e31f4e 100644
--- a/cmd/mist/debugger.go
+++ b/cmd/mist/debugger.go
@@ -151,7 +151,7 @@ func (self *DebuggerWindow) Debug(valueStr, gasStr, gasPriceStr, scriptStr, data
 
 	block := self.lib.eth.ChainManager().CurrentBlock()
 
-	env := utils.NewEnv(statedb, block, account.Address(), value)
+	env := utils.NewEnv(self.lib.eth.ChainManager(), statedb, block, account.Address(), value)
 
 	self.Logf("callsize %d", len(script))
 	go func() {
diff --git a/cmd/utils/vm_env.go b/cmd/utils/vm_env.go
index 19091bdc5..acc2ffad9 100644
--- a/cmd/utils/vm_env.go
+++ b/cmd/utils/vm_env.go
@@ -10,6 +10,7 @@ import (
 )
 
 type VMEnv struct {
+	chain *core.ChainManager
 	state *state.StateDB
 	block *types.Block
 
@@ -20,8 +21,9 @@ type VMEnv struct {
 	Gas   *big.Int
 }
 
-func NewEnv(state *state.StateDB, block *types.Block, transactor []byte, value *big.Int) *VMEnv {
+func NewEnv(chain *core.ChainManager, state *state.StateDB, block *types.Block, transactor []byte, value *big.Int) *VMEnv {
 	return &VMEnv{
+		chain:      chain,
 		state:      state,
 		block:      block,
 		transactor: transactor,
@@ -35,12 +37,18 @@ 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)
 }