1 files changed, 299 insertions, 0 deletions
diff --git a/core/vm/evm.go b/core/vm/evm.go
new file mode 100644
index 000000000..0c5d998c2
--- /dev/null
+++ b/core/vm/evm.go
@@ -0,0 +1,299 @@
+// Copyright 2014 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package vm
+
+import (
+	"math/big"
+	"sync/atomic"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+type (
+	CanTransferFunc func(StateDB, common.Address, *big.Int) bool
+	TransferFunc    func(StateDB, common.Address, common.Address, *big.Int)
+	// GetHashFunc returns the nth block hash in the blockchain
+	// and is used by the BLOCKHASH EVM op code.
+	GetHashFunc func(uint64) common.Hash
+)
+
+// Context provides the EVM with auxiliary information. Once provided it shouldn't be modified.
+type Context struct {
+	// CanTransfer returns whether the account contains
+	// sufficient ether to transfer the value
+	CanTransfer CanTransferFunc
+	// Transfer transfers ether from one account to the other
+	Transfer TransferFunc
+	// GetHash returns the hash corresponding to n
+	GetHash GetHashFunc
+
+	// Message information
+	Origin   common.Address // Provides information for ORIGIN
+	GasPrice *big.Int       // Provides information for GASPRICE
+
+	// Block information
+	Coinbase    common.Address // Provides information for COINBASE
+	GasLimit    *big.Int       // Provides information for GASLIMIT
+	BlockNumber *big.Int       // Provides information for NUMBER
+	Time        *big.Int       // Provides information for TIME
+	Difficulty  *big.Int       // Provides information for DIFFICULTY
+}
+
+// EVM provides information about external sources for the EVM
+//
+// The EVM should never be reused and is not thread safe.
+type EVM struct {
+	// Context provides auxiliary blockchain related information
+	Context
+	// StateDB gives access to the underlying state
+	StateDB StateDB
+	// Depth is the current call stack
+	depth int
+
+	// chainConfig contains information about the current chain
+	chainConfig *params.ChainConfig
+	// virtual machine configuration options used to initialise the
+	// evm.
+	vmConfig Config
+	// global (to this context) ethereum virtual machine
+	// used throughout the execution of the tx.
+	interpreter *Interpreter
+	// abort is used to abort the EVM calling operations
+	// NOTE: must be set atomically
+	abort int32
+}
+
+// NewEVM retutrns a new EVM evmironment.
+func NewEVM(ctx Context, statedb StateDB, chainConfig *params.ChainConfig, vmConfig Config) *EVM {
+	evm := &EVM{
+		Context:     ctx,
+		StateDB:     statedb,
+		vmConfig:    vmConfig,
+		chainConfig: chainConfig,
+	}
+
+	evm.interpreter = NewInterpreter(evm, vmConfig)
+	return evm
+}
+
+// Cancel cancels any running EVM operation. This may be called concurrently and it's safe to be
+// called multiple times.
+func (evm *EVM) Cancel() {
+	atomic.StoreInt32(&evm.abort, 1)
+}
+
+// Call executes the contract associated with the addr with the given input as parameters. It also handles any
+// necessary value transfer required and takes the necessary steps to create accounts and reverses the state in
+// case of an execution error or failed value transfer.
+func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int) (ret []byte, leftOverGas uint64, err error) {
+	if evm.vmConfig.NoRecursion && evm.depth > 0 {
+		return nil, gas, nil
+	}
+
+	// Depth check execution. Fail if we're trying to execute above the
+	// limit.
+	if evm.depth > int(params.CallCreateDepth) {
+		return nil, gas, ErrDepth
+	}
+	if !evm.Context.CanTransfer(evm.StateDB, caller.Address(), value) {
+		return nil, gas, ErrInsufficientBalance
+	}
+
+	var (
+		to       Account
+		snapshot = evm.StateDB.Snapshot()
+	)
+	if !evm.StateDB.Exist(addr) {
+		if PrecompiledContracts[addr] == nil && evm.ChainConfig().IsEIP158(evm.BlockNumber) && value.BitLen() == 0 {
+			return nil, gas, nil
+		}
+
+		to = evm.StateDB.CreateAccount(addr)
+	} else {
+		to = evm.StateDB.GetAccount(addr)
+	}
+	evm.Transfer(evm.StateDB, caller.Address(), to.Address(), value)
+
+	// initialise a new contract and set the code that is to be used by the
+	// E The contract is a scoped evmironment for this execution context
+	// only.
+	contract := NewContract(caller, to, value, gas)
+	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
+
+	ret, err = evm.interpreter.Run(contract, input)
+	// When an error was returned by the EVM or when setting the creation code
+	// above we revert to the snapshot and consume any gas remaining. Additionally
+	// when we're in homestead this also counts for code storage gas errors.
+	if err != nil {
+		contract.UseGas(contract.Gas)
+
+		evm.StateDB.RevertToSnapshot(snapshot)
+	}
+	return ret, contract.Gas, err
+}
+
+// CallCode executes the contract associated with the addr with the given input as parameters. It also handles any
+// necessary value transfer required and takes the necessary steps to create accounts and reverses the state in
+// case of an execution error or failed value transfer.
+//
+// CallCode differs from Call in the sense that it executes the given address' code with the caller as context.
+func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int) (ret []byte, leftOverGas uint64, err error) {
+	if evm.vmConfig.NoRecursion && evm.depth > 0 {
+		return nil, gas, nil
+	}
+
+	// Depth check execution. Fail if we're trying to execute above the
+	// limit.
+	if evm.depth > int(params.CallCreateDepth) {
+		return nil, gas, ErrDepth
+	}
+	if !evm.CanTransfer(evm.StateDB, caller.Address(), value) {
+		return nil, gas, ErrInsufficientBalance
+	}
+
+	var (
+		snapshot = evm.StateDB.Snapshot()
+		to       = evm.StateDB.GetAccount(caller.Address())
+	)
+	// initialise a new contract and set the code that is to be used by the
+	// E The contract is a scoped evmironment for this execution context
+	// only.
+	contract := NewContract(caller, to, value, gas)
+	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
+
+	ret, err = evm.interpreter.Run(contract, input)
+	if err != nil {
+		contract.UseGas(contract.Gas)
+
+		evm.StateDB.RevertToSnapshot(snapshot)
+	}
+
+	return ret, contract.Gas, err
+}
+
+// DelegateCall executes the contract associated with the addr with the given input as parameters.
+// It reverses the state in case of an execution error.
+//
+// DelegateCall differs from CallCode in the sense that it executes the given address' code with the caller as context
+// and the caller is set to the caller of the caller.
+func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []byte, gas uint64) (ret []byte, leftOverGas uint64, err error) {
+	if evm.vmConfig.NoRecursion && evm.depth > 0 {
+		return nil, gas, nil
+	}
+
+	// Depth check execution. Fail if we're trying to execute above the
+	// limit.
+	if evm.depth > int(params.CallCreateDepth) {
+		return nil, gas, ErrDepth
+	}
+
+	var (
+		snapshot = evm.StateDB.Snapshot()
+		to       = evm.StateDB.GetAccount(caller.Address())
+	)
+
+	// Iinitialise a new contract and make initialise the delegate values
+	contract := NewContract(caller, to, caller.Value(), gas).AsDelegate()
+	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
+
+	ret, err = evm.interpreter.Run(contract, input)
+	if err != nil {
+		contract.UseGas(contract.Gas)
+
+		evm.StateDB.RevertToSnapshot(snapshot)
+	}
+
+	return ret, contract.Gas, err
+}
+
+// Create creates a new contract using code as deployment code.
+func (evm *EVM) Create(caller ContractRef, code []byte, gas uint64, value *big.Int) (ret []byte, contractAddr common.Address, leftOverGas uint64, err error) {
+	if evm.vmConfig.NoRecursion && evm.depth > 0 {
+		return nil, common.Address{}, gas, nil
+	}
+
+	// Depth check execution. Fail if we're trying to execute above the
+	// limit.
+	if evm.depth > int(params.CallCreateDepth) {
+		return nil, common.Address{}, gas, ErrDepth
+	}
+	if !evm.CanTransfer(evm.StateDB, caller.Address(), value) {
+		return nil, common.Address{}, gas, ErrInsufficientBalance
+	}
+
+	// Create a new account on the state
+	nonce := evm.StateDB.GetNonce(caller.Address())
+	evm.StateDB.SetNonce(caller.Address(), nonce+1)
+
+	snapshot := evm.StateDB.Snapshot()
+	contractAddr = crypto.CreateAddress(caller.Address(), nonce)
+	to := evm.StateDB.CreateAccount(contractAddr)
+	if evm.ChainConfig().IsEIP158(evm.BlockNumber) {
+		evm.StateDB.SetNonce(contractAddr, 1)
+	}
+	evm.Transfer(evm.StateDB, caller.Address(), to.Address(), value)
+
+	// initialise a new contract and set the code that is to be used by the
+	// E The contract is a scoped evmironment for this execution context
+	// only.
+	contract := NewContract(caller, to, value, gas)
+	contract.SetCallCode(&contractAddr, crypto.Keccak256Hash(code), code)
+
+	ret, err = evm.interpreter.Run(contract, nil)
+
+	// check whether the max code size has been exceeded
+	maxCodeSizeExceeded := len(ret) > params.MaxCodeSize
+	// if the contract creation ran successfully and no errors were returned
+	// calculate the gas required to store the code. If the code could not
+	// be stored due to not enough gas set an error and let it be handled
+	// by the error checking condition below.
+	if err == nil && !maxCodeSizeExceeded {
+		createDataGas := uint64(len(ret)) * params.CreateDataGas
+		if contract.UseGas(createDataGas) {
+			evm.StateDB.SetCode(contractAddr, ret)
+		} else {
+			err = ErrCodeStoreOutOfGas
+		}
+	}
+
+	// When an error was returned by the EVM or when setting the creation code
+	// above we revert to the snapshot and consume any gas remaining. Additionally
+	// when we're in homestead this also counts for code storage gas errors.
+	if maxCodeSizeExceeded ||
+		(err != nil && (evm.ChainConfig().IsHomestead(evm.BlockNumber) || err != ErrCodeStoreOutOfGas)) {
+		evm.StateDB.RevertToSnapshot(snapshot)
+
+		// Nothing should be returned when an error is thrown.
+		return nil, contractAddr, 0, err
+	}
+	// If the vm returned with an error the return value should be set to nil.
+	// This isn't consensus critical but merely to for behaviour reasons such as
+	// tests, RPC calls, etc.
+	if err != nil {
+		ret = nil
+	}
+
+	return ret, contractAddr, contract.Gas, err
+}
+
+// ChainConfig returns the evmironment's chain configuration
+func (evm *EVM) ChainConfig() *params.ChainConfig { return evm.chainConfig }
+
+// Interpreter returns the EVM interpreter
+func (evm *EVM) Interpreter() *Interpreter { return evm.interpreter }