[FVM] beyond EVM part 2.2 - adding EVM emulator

fvm/evm/emulator/config.go

@@ -0,0 +1,183 @@
+package emulator
+
+import (
+	"math"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+var (
+	FlowEVMTestnetChainID = big.NewInt(666)
+	FlowEVMMainnetChainID = big.NewInt(777)
+	BlockLevelGasLimit    = uint64(math.MaxUint64)
+	zero                  = uint64(0)
+)
+
+// Config sets the required parameters
+type Config struct {
+	// Chain Config
+	ChainConfig *params.ChainConfig
+	// EVM config
+	EVMConfig vm.Config
+	// block context
+	BlockContext *vm.BlockContext
+	// transaction context
+	TxContext *vm.TxContext
+	// base unit of gas for direct calls
+	DirectCallBaseGasUsage uint64
+}
+
+// DefaultChainConfig is the default chain config which
+// considers majority of EVM upgrades (e.g. Shanghai update) already been applied
+// this has done through setting the height of these changes
+// to zero nad setting the time for some other changes to zero
+// For the future changes of EVM, we need to update the EVM go mod version
+// and set a proper height for the specific release based on the Flow EVM heights
+// so it could gets activated at a desired time.
+var DefaultChainConfig = &params.ChainConfig{
+	ChainID: FlowEVMTestnetChainID, // default is testnet
+
+	// Fork scheduling based on block heights
+	HomesteadBlock:      big.NewInt(0),
+	DAOForkBlock:        big.NewInt(0),
+	DAOForkSupport:      false,
+	EIP150Block:         big.NewInt(0),
+	EIP155Block:         big.NewInt(0),
+	EIP158Block:         big.NewInt(0),
+	ByzantiumBlock:      big.NewInt(0), // already on Byzantium
+	ConstantinopleBlock: big.NewInt(0), // already on Constantinople
+	PetersburgBlock:     big.NewInt(0), // already on Petersburg
+	IstanbulBlock:       big.NewInt(0), // already on Istanbul
+	BerlinBlock:         big.NewInt(0), // already on Berlin
+	LondonBlock:         big.NewInt(0), // already on London
+	MuirGlacierBlock:    big.NewInt(0), // already on MuirGlacier
+
+	// Fork scheduling based on timestamps
+	ShanghaiTime: &zero, // already on Shanghai
+	CancunTime:   &zero, // already on Cancun
+	PragueTime:   &zero, // already on Prague
+}
+
+func defaultConfig() *Config {
+	return &Config{
+		ChainConfig: DefaultChainConfig,
+		EVMConfig: vm.Config{
+			NoBaseFee: true,
+		},
+		TxContext: &vm.TxContext{},
+		BlockContext: &vm.BlockContext{
+			CanTransfer: core.CanTransfer,
+			Transfer:    core.Transfer,
+			GasLimit:    BlockLevelGasLimit, // block gas limit
+			BaseFee:     big.NewInt(0),
+			GetHash: func(n uint64) common.Hash { // default returns some random hash values
+				return common.BytesToHash(crypto.Keccak256([]byte(new(big.Int).SetUint64(n).String())))
+			},
+		},
+	}
+}
+
+// NewConfig initializes a new config
+func NewConfig(opts ...Option) *Config {
+	ctx := defaultConfig()
+	for _, applyOption := range opts {
+		ctx = applyOption(ctx)
+	}
+	return ctx
+}
+
+type Option func(*Config) *Config
+
+// WithMainnetChainID sets the chain ID to flow evm testnet
+func WithTestnetChainID() Option {
+	return func(c *Config) *Config {
+		c.ChainConfig.ChainID = FlowEVMTestnetChainID
+		return c
+	}
+}
+
+// WithMainnetChainID sets the chain ID to flow evm mainnet
+func WithMainnetChainID() Option {
+	return func(c *Config) *Config {
+		c.ChainConfig.ChainID = FlowEVMMainnetChainID
+		return c
+	}
+
+}
+
+// WithOrigin sets the origin of the transaction (signer)
+func WithOrigin(origin common.Address) Option {
+	return func(c *Config) *Config {
+		c.TxContext.Origin = origin
+		return c
+	}
+}
+
+// WithGasPrice sets the gas price for the transaction (usually the one sets by the sender)
+func WithGasPrice(gasPrice *big.Int) Option {
+	return func(c *Config) *Config {
+		c.TxContext.GasPrice = gasPrice
+		return c
+	}
+}
+
+// WithBaseFee sets the the base fee for each transaction
+func WithBaseFee(baseFee *big.Int) Option {
+	return func(c *Config) *Config {
+		c.BlockContext.BaseFee = baseFee
+		return c
+	}
+}
+
+// WithGasLimit sets the gas limit of the transaction
+func WithGasLimit(gasLimit uint64) Option {
+	return func(c *Config) *Config {
+		c.BlockContext.GasLimit = gasLimit
+		return c
+	}
+}
+
+// WithCoinbase sets the coinbase of the block where the fees are collected in
+func WithCoinbase(coinbase common.Address) Option {
+	return func(c *Config) *Config {
+		c.BlockContext.Coinbase = coinbase
+		return c
+	}
+}
+
+// WithBlockNumber sets the block height in the block context
+func WithBlockNumber(blockNumber *big.Int) Option {
+	return func(c *Config) *Config {
+		c.BlockContext.BlockNumber = blockNumber
+		return c
+	}
+}
+
+// WithBlockTime sets the block time in the block context
+func WithBlockTime(time uint64) Option {
+	return func(c *Config) *Config {
+		c.BlockContext.Time = time
+		return c
+	}
+}
+
+// WithGetBlockHashFunction sets the functionality to look up block hash by height
+func WithGetBlockHashFunction(getHash vm.GetHashFunc) Option {
+	return func(c *Config) *Config {
+		c.BlockContext.GetHash = getHash
+		return c
+	}
+}
+
+// WithDirectCallBaseGasUsage sets the base direct call gas usage
+func WithDirectCallBaseGasUsage(gas uint64) Option {
+	return func(c *Config) *Config {
+		c.DirectCallBaseGasUsage = gas
+		return c
+	}
+}

fvm/evm/emulator/database/database.go

@@ -395,6 +395,7 @@ func handleError(err error) error {
 		return nil
 	}
 	var atreeFatalError *atree.FatalError
+	// if is a atree fatal error or fvm fatal error (the second one captures external errors)
 	if stdErrors.As(err, &atreeFatalError) || errors.IsFailure(err) {
 		return types.NewFatalError(err)
 	}