core, core/vm: implemented a generic environment (#3348)

Environment is now a struct (not an interface). This
reduces a lot of tech-debt throughout the codebase where a virtual
machine environment had to be implemented in order to test or run it.

The new environment is suitable to be used en the json tests, core
consensus and light client.

1 files changed, 24 insertions, 27 deletions

diff --git a/core/state_transition.go b/core/state_transition.go
index 8abe17b0a..48540be14 100644
--- a/core/state_transition.go
+++ b/core/state_transition.go
@@ -55,9 +55,9 @@ type StateTransition struct {
 	initialGas    *big.Int
 	value         *big.Int
 	data          []byte
-	state         vm.Database
+	state         vm.StateDB
 
-	env vm.Environment
+	env *vm.Environment
 }
 
 // Message represents a message sent to a contract.
@@ -106,7 +106,7 @@ func IntrinsicGas(data []byte, contractCreation, homestead bool) *big.Int {
 }
 
 // NewStateTransition initialises and returns a new state transition object.
-func NewStateTransition(env vm.Environment, msg Message, gp *GasPool) *StateTransition {
+func NewStateTransition(env *vm.Environment, msg Message, gp *GasPool) *StateTransition {
 	return &StateTransition{
 		gp:         gp,
 		env:        env,
@@ -116,7 +116,7 @@ func NewStateTransition(env vm.Environment, msg Message, gp *GasPool) *StateTran
 		initialGas: new(big.Int),
 		value:      msg.Value(),
 		data:       msg.Data(),
-		state:      env.Db(),
+		state:      env.StateDB,
 	}
 }
 
@@ -127,7 +127,7 @@ func NewStateTransition(env vm.Environment, msg Message, gp *GasPool) *StateTran
 // the gas used (which includes gas refunds) and an error if it failed. An error always
 // indicates a core error meaning that the message would always fail for that particular
 // state and would never be accepted within a block.
-func ApplyMessage(env vm.Environment, msg Message, gp *GasPool) ([]byte, *big.Int, error) {
+func ApplyMessage(env *vm.Environment, msg Message, gp *GasPool) ([]byte, *big.Int, error) {
 	st := NewStateTransition(env, msg, gp)
 
 	ret, _, gasUsed, err := st.TransitionDb()
@@ -217,47 +217,44 @@ func (self *StateTransition) TransitionDb() (ret []byte, requiredGas, usedGas *b
 	msg := self.msg
 	sender := self.from() // err checked in preCheck
 
-	homestead := self.env.ChainConfig().IsHomestead(self.env.BlockNumber())
+	homestead := self.env.ChainConfig().IsHomestead(self.env.BlockNumber)
 	contractCreation := MessageCreatesContract(msg)
 	// Pay intrinsic gas
 	if err = self.useGas(IntrinsicGas(self.data, contractCreation, homestead)); err != nil {
 		return nil, nil, nil, InvalidTxError(err)
 	}
 
-	vmenv := self.env
-	//var addr common.Address
+	var (
+		vmenv = self.env
+		// vm errors do not effect consensus and are therefor
+		// not assigned to err, except for insufficient balance
+		// error.
+		vmerr error
+	)
 	if contractCreation {
-		ret, _, err = vmenv.Create(sender, self.data, self.gas, self.gasPrice, self.value)
+		ret, _, vmerr = vmenv.Create(sender, self.data, self.gas, self.value)
 		if homestead && err == vm.CodeStoreOutOfGasError {
 			self.gas = Big0
 		}
-
-		if err != nil {
-			ret = nil
-			glog.V(logger.Core).Infoln("VM create err:", err)
-		}
 	} else {
 		// Increment the nonce for the next transaction
 		self.state.SetNonce(sender.Address(), self.state.GetNonce(sender.Address())+1)
-		ret, err = vmenv.Call(sender, self.to().Address(), self.data, self.gas, self.gasPrice, self.value)
-		if err != nil {
-			glog.V(logger.Core).Infoln("VM call err:", err)
-		}
-	}
-
-	if err != nil && IsValueTransferErr(err) {
-		return nil, nil, nil, InvalidTxError(err)
+		ret, vmerr = vmenv.Call(sender, self.to().Address(), self.data, self.gas, self.value)
 	}
-
-	// We aren't interested in errors here. Errors returned by the VM are non-consensus errors and therefor shouldn't bubble up
-	if err != nil {
-		err = nil
+	if vmerr != nil {
+		glog.V(logger.Core).Infoln("vm returned with error:", err)
+		// The only possible consensus-error would be if there wasn't
+		// sufficient balance to make the transfer happen. The first
+		// balance transfer may never fail.
+		if vmerr == vm.ErrInsufficientBalance {
+			return nil, nil, nil, InvalidTxError(vmerr)
+		}
 	}
 
 	requiredGas = new(big.Int).Set(self.gasUsed())
 
 	self.refundGas()
-	self.state.AddBalance(self.env.Coinbase(), new(big.Int).Mul(self.gasUsed(), self.gasPrice))
+	self.state.AddBalance(self.env.Coinbase, new(big.Int).Mul(self.gasUsed(), self.gasPrice))
 
 	return ret, requiredGas, self.gasUsed(), err
 }