path: root/core/vm/runtime/runtime.go

// Copyright 2015 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/crypto"
    "github.com/ethereum/go-ethereum/ethdb"
    "github.com/ethereum/go-ethereum/params"
)

// The default, always homestead, rule set for the vm env
type ruleSet struct{}

func (ruleSet) IsHomestead(*big.Int) bool { return true }
func (ruleSet) GasTable(*big.Int) params.GasTable {
    return params.GasTableHomesteadGasRepriceFork
}

// Config is a basic type specifying certain configuration flags for running
// the EVM.
type Config struct {
    ChainConfig *params.ChainConfig
    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

    State     *state.StateDB
    GetHashFn func(n uint64) common.Hash
}

// sets defaults on the config
func setDefaults(cfg *Config) {
    if cfg.ChainConfig == nil {
        cfg.ChainConfig = &params.ChainConfig{new(big.Int), new(big.Int), false, new(big.Int), common.Hash{}, new(big.Int)}
    }

    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.Keccak256([]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)

    if cfg.State == nil {
        db, _ := ethdb.NewMemDatabase()
        cfg.State, _ = state.New(common.Hash{}, db)
    }
    var (
        vmenv    = NewEnv(cfg, cfg.State)
        sender   = cfg.State.CreateAccount(cfg.Origin)
        receiver = cfg.State.CreateAccount(common.StringToAddress("contract"))
    )
    // set the receiver's (the executing contract) code for execution.
    receiver.SetCode(crypto.Keccak256Hash(code), code)

    // Call the code with the given configuration.
    ret, err := vmenv.Call(
        sender,
        receiver.Address(),
        input,
        cfg.GasLimit,
        cfg.GasPrice,
        cfg.Value,
    )

    return ret, cfg.State, err
}

// Call executes the code given by the contract's address. It will return the
// EVM's return value or an error if it failed.
//
// Call, unlike Execute, requires a config and also requires the State field to
// be set.
func Call(address common.Address, input []byte, cfg *Config) ([]byte, error) {
    setDefaults(cfg)

    vmenv := NewEnv(cfg, cfg.State)

    sender := cfg.State.GetOrNewStateObject(cfg.Origin)
    // Call the code with the given configuration.
    ret, err := vmenv.Call(
        sender,
        address,
        input,
        cfg.GasLimit,
        cfg.GasPrice,
        cfg.Value,
    )

    return ret, err
}