core/vm/runtime: added simple execution runtime

The runtime environment can be used for simple basic execution of
contract code without the requirement of setting up a full stack and
operates fully in memory.

1 files changed, 121 insertions, 0 deletions

diff --git a/core/vm/runtime/runtime.go b/core/vm/runtime/runtime.go
new file mode 100644
index 000000000..dd3aa1b0b
--- /dev/null
+++ b/core/vm/runtime/runtime.go
@@ -0,0 +1,121 @@
+// 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 runtime
+
+import (
+	"math/big"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/state"
+	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/ethdb"
+)
+
+// Config is a basic type specifing certain configuration flags for running
+// the EVM.
+type Config struct {
+	Difficulty  *big.Int
+	Origin      common.Address
+	Coinbase    common.Address
+	BlockNumber *big.Int
+	Time        *big.Int
+	GasLimit    *big.Int
+	GasPrice    *big.Int
+	Value       *big.Int
+	DisableJit  bool // "disable" so it's enabled by default
+	Debug       bool
+
+	GetHashFn func(n uint64) common.Hash
+}
+
+// sets defaults on the config
+func setDefaults(cfg *Config) {
+	if cfg.Difficulty == nil {
+		cfg.Difficulty = new(big.Int)
+	}
+	if cfg.Time == nil {
+		cfg.Time = big.NewInt(time.Now().Unix())
+	}
+	if cfg.GasLimit == nil {
+		cfg.GasLimit = new(big.Int).Set(common.MaxBig)
+	}
+	if cfg.GasPrice == nil {
+		cfg.GasPrice = new(big.Int)
+	}
+	if cfg.Value == nil {
+		cfg.Value = new(big.Int)
+	}
+	if cfg.BlockNumber == nil {
+		cfg.BlockNumber = new(big.Int)
+	}
+	if cfg.GetHashFn == nil {
+		cfg.GetHashFn = func(n uint64) common.Hash {
+			return common.BytesToHash(crypto.Sha3([]byte(new(big.Int).SetUint64(n).String())))
+		}
+	}
+}
+
+// Execute executes the code using the input as call data during the execution.
+// It returns the EVM's return value, the new state and an error if it failed.
+//
+// Executes sets up a in memory, temporarily, environment for the execution of
+// the given code. It enabled the JIT by default and make sure that it's restored
+// to it's original state afterwards.
+func Execute(code, input []byte, cfg *Config) ([]byte, *state.StateDB, error) {
+	if cfg == nil {
+		cfg = new(Config)
+	}
+	setDefaults(cfg)
+
+	// defer the call to setting back the original values
+	defer func(debug, forceJit, enableJit bool) {
+		vm.Debug = debug
+		vm.ForceJit = forceJit
+		vm.EnableJit = enableJit
+	}(vm.Debug, vm.ForceJit, vm.EnableJit)
+
+	vm.ForceJit = !cfg.DisableJit
+	vm.EnableJit = !cfg.DisableJit
+	vm.Debug = cfg.Debug
+
+	var (
+		db, _      = ethdb.NewMemDatabase()
+		statedb, _ = state.New(common.Hash{}, db)
+		vmenv      = NewEnv(cfg, statedb)
+		sender     = statedb.CreateAccount(cfg.Origin)
+		receiver   = statedb.CreateAccount(common.StringToAddress("contract"))
+	)
+	// set the receiver's (the executing contract) code for execution.
+	receiver.SetCode(code)
+
+	// Call the code with the given configuration.
+	ret, err := vmenv.Call(
+		sender,
+		receiver.Address(),
+		input,
+		cfg.GasLimit,
+		cfg.GasPrice,
+		cfg.Value,
+	)
+
+	if cfg.Debug {
+		vm.StdErrFormat(vmenv.StructLogs())
+	}
+	return ret, statedb, err
+}