mirror of
https://github.com/ethereum/go-ethereum.git
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1e5725f03b
The REVERT op codes reverts the state by returning an error from the instruction. The instruction was checked during in the EVM. This error would then determine whether any gas should be consumed or not. If the error was an errRevert, no gas was further reduced and only state was reverted. This solution is error prone as you'll need an err check in multiple locations and removes the no-err check requirement of the evm. This has been solved by passing the snapshot to the interpreter and letting the interpreter do the state reverting if the operation so requires.
360 lines
13 KiB
Go
360 lines
13 KiB
Go
// Copyright 2014 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package vm
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import (
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"math/big"
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"sync/atomic"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/params"
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)
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type (
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CanTransferFunc func(StateDB, common.Address, *big.Int) bool
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TransferFunc func(StateDB, common.Address, common.Address, *big.Int)
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// GetHashFunc returns the nth block hash in the blockchain
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// and is used by the BLOCKHASH EVM op code.
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GetHashFunc func(uint64) common.Hash
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)
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// run runs the given contract and takes care of running precompiles with a fallback to the byte code interpreter.
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func run(evm *EVM, snapshot int, contract *Contract, input []byte) ([]byte, error) {
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if contract.CodeAddr != nil {
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precompiledContracts := PrecompiledContracts
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if evm.ChainConfig().IsMetropolis(evm.BlockNumber) {
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precompiledContracts = PrecompiledContractsMetropolis
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}
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if p := precompiledContracts[*contract.CodeAddr]; p != nil {
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return RunPrecompiledContract(p, input, contract)
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}
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}
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return evm.interpreter.Run(snapshot, contract, input)
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}
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// Context provides the EVM with auxiliary information. Once provided
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// it shouldn't be modified.
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type Context struct {
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// CanTransfer returns whether the account contains
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// sufficient ether to transfer the value
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CanTransfer CanTransferFunc
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// Transfer transfers ether from one account to the other
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Transfer TransferFunc
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// GetHash returns the hash corresponding to n
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GetHash GetHashFunc
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// Message information
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Origin common.Address // Provides information for ORIGIN
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GasPrice *big.Int // Provides information for GASPRICE
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// Block information
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Coinbase common.Address // Provides information for COINBASE
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GasLimit *big.Int // Provides information for GASLIMIT
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BlockNumber *big.Int // Provides information for NUMBER
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Time *big.Int // Provides information for TIME
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Difficulty *big.Int // Provides information for DIFFICULTY
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}
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// EVM is the Ethereum Virtual Machine base object and provides
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// the necessary tools to run a contract on the given state with
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// the provided context. It should be noted that any error
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// generated through any of the calls should be considered a
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// revert-state-and-consume-all-gas operation, no checks on
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// specific errors should ever be performed. The interpreter makes
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// sure that any errors generated are to be considered faulty code.
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//
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// The EVM should never be reused and is not thread safe.
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type EVM struct {
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// Context provides auxiliary blockchain related information
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Context
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// StateDB gives access to the underlying state
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StateDB StateDB
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// Depth is the current call stack
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depth int
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// chainConfig contains information about the current chain
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chainConfig *params.ChainConfig
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// virtual machine configuration options used to initialise the
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// evm.
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vmConfig Config
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// global (to this context) ethereum virtual machine
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// used throughout the execution of the tx.
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interpreter *Interpreter
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// abort is used to abort the EVM calling operations
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// NOTE: must be set atomically
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abort int32
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}
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// NewEVM retutrns a new EVM evmironment. The returned EVM is not thread safe
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// and should only ever be used *once*.
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func NewEVM(ctx Context, statedb StateDB, chainConfig *params.ChainConfig, vmConfig Config) *EVM {
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evm := &EVM{
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Context: ctx,
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StateDB: statedb,
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vmConfig: vmConfig,
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chainConfig: chainConfig,
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}
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evm.interpreter = NewInterpreter(evm, vmConfig)
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return evm
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}
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// Cancel cancels any running EVM operation. This may be called concurrently and
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// it's safe to be called multiple times.
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func (evm *EVM) Cancel() {
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atomic.StoreInt32(&evm.abort, 1)
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}
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func (evm *EVM) StaticCall(caller ContractRef, addr common.Address, input []byte, gas uint64) (ret []byte, leftOverGas uint64, err error) {
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if evm.vmConfig.NoRecursion && evm.depth > 0 {
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return nil, gas, nil
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}
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// Depth check execution. Fail if we're trying to execute above the
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// limit.
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if evm.depth > int(params.CallCreateDepth) {
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return nil, gas, ErrDepth
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}
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// make sure the readonly is only set if we aren't in readonly yet
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// this makes also sure that the readonly flag isn't removed for
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// child calls.
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if !evm.interpreter.readonly {
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evm.interpreter.readonly = true
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defer func() { evm.interpreter.readonly = false }()
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}
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var (
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to = AccountRef(addr)
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snapshot = evm.StateDB.Snapshot()
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)
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if !evm.StateDB.Exist(addr) {
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return nil, gas, nil
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}
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// initialise a new contract and set the code that is to be used by the
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// E The contract is a scoped evmironment for this execution context
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// only.
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contract := NewContract(caller, to, new(big.Int), gas)
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contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
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ret, err = evm.interpreter.Run(snapshot, contract, input)
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// When an error was returned by the EVM or when setting the creation code
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// above we revert to the snapshot and consume any gas remaining. Additionally
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// when we're in homestead this also counts for code storage gas errors.
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if err != nil {
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contract.UseGas(contract.Gas)
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evm.StateDB.RevertToSnapshot(snapshot)
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}
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return ret, contract.Gas, err
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}
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// Call executes the contract associated with the addr with the given input as parameters. It also handles any
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// necessary value transfer required and takes the necessary steps to create accounts and reverses the state in
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// case of an execution error or failed value transfer.
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func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int) (ret []byte, leftOverGas uint64, err error) {
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if evm.vmConfig.NoRecursion && evm.depth > 0 {
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return nil, gas, nil
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}
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// Depth check execution. Fail if we're trying to execute above the
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// limit.
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if evm.depth > int(params.CallCreateDepth) {
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return nil, gas, ErrDepth
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}
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if !evm.Context.CanTransfer(evm.StateDB, caller.Address(), value) {
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return nil, gas, ErrInsufficientBalance
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}
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var (
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to = AccountRef(addr)
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snapshot = evm.StateDB.Snapshot()
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)
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if !evm.StateDB.Exist(addr) {
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if PrecompiledContracts[addr] == nil && evm.ChainConfig().IsEIP158(evm.BlockNumber) && value.Sign() == 0 {
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return nil, gas, nil
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}
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evm.StateDB.CreateAccount(addr)
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}
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evm.Transfer(evm.StateDB, caller.Address(), to.Address(), value)
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// initialise a new contract and set the code that is to be used by the
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// E The contract is a scoped evmironment for this execution context
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// only.
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contract := NewContract(caller, to, value, gas)
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contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
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ret, err = run(evm, snapshot, contract, input)
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// When an error was returned by the EVM or when setting the creation code
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// above we revert to the snapshot and consume any gas remaining. Additionally
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// when we're in homestead this also counts for code storage gas errors.
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if err != nil {
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contract.UseGas(contract.Gas)
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evm.StateDB.RevertToSnapshot(snapshot)
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}
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return ret, contract.Gas, err
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}
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// CallCode executes the contract associated with the addr with the given input as parameters. It also handles any
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// necessary value transfer required and takes the necessary steps to create accounts and reverses the state in
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// case of an execution error or failed value transfer.
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//
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// CallCode differs from Call in the sense that it executes the given address' code with the caller as context.
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func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int) (ret []byte, leftOverGas uint64, err error) {
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if evm.vmConfig.NoRecursion && evm.depth > 0 {
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return nil, gas, nil
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}
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// Depth check execution. Fail if we're trying to execute above the
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// limit.
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if evm.depth > int(params.CallCreateDepth) {
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return nil, gas, ErrDepth
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}
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if !evm.CanTransfer(evm.StateDB, caller.Address(), value) {
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return nil, gas, ErrInsufficientBalance
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}
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var (
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snapshot = evm.StateDB.Snapshot()
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to = AccountRef(caller.Address())
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)
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// initialise a new contract and set the code that is to be used by the
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// E The contract is a scoped evmironment for this execution context
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// only.
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contract := NewContract(caller, to, value, gas)
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contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
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ret, err = run(evm, snapshot, contract, input)
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if err != nil {
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contract.UseGas(contract.Gas)
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evm.StateDB.RevertToSnapshot(snapshot)
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}
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return ret, contract.Gas, err
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}
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// DelegateCall executes the contract associated with the addr with the given input as parameters.
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// It reverses the state in case of an execution error.
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//
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// DelegateCall differs from CallCode in the sense that it executes the given address' code with the caller as context
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// and the caller is set to the caller of the caller.
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func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []byte, gas uint64) (ret []byte, leftOverGas uint64, err error) {
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if evm.vmConfig.NoRecursion && evm.depth > 0 {
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return nil, gas, nil
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}
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// Depth check execution. Fail if we're trying to execute above the
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// limit.
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if evm.depth > int(params.CallCreateDepth) {
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return nil, gas, ErrDepth
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}
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var (
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snapshot = evm.StateDB.Snapshot()
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to = AccountRef(caller.Address())
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)
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// Iinitialise a new contract and make initialise the delegate values
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contract := NewContract(caller, to, nil, gas).AsDelegate()
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contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
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ret, err = run(evm, snapshot, contract, input)
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if err != nil {
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contract.UseGas(contract.Gas)
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evm.StateDB.RevertToSnapshot(snapshot)
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}
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return ret, contract.Gas, err
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}
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// Create creates a new contract using code as deployment code.
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func (evm *EVM) Create(caller ContractRef, code []byte, gas uint64, value *big.Int) (ret []byte, contractAddr common.Address, leftOverGas uint64, err error) {
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if evm.vmConfig.NoRecursion && evm.depth > 0 {
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return nil, common.Address{}, gas, nil
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}
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// Depth check execution. Fail if we're trying to execute above the
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// limit.
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if evm.depth > int(params.CallCreateDepth) {
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return nil, common.Address{}, gas, ErrDepth
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}
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if !evm.CanTransfer(evm.StateDB, caller.Address(), value) {
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return nil, common.Address{}, gas, ErrInsufficientBalance
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}
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// Create a new account on the state
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nonce := evm.StateDB.GetNonce(caller.Address())
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evm.StateDB.SetNonce(caller.Address(), nonce+1)
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snapshot := evm.StateDB.Snapshot()
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contractAddr = crypto.CreateAddress(caller.Address(), nonce)
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evm.StateDB.CreateAccount(contractAddr)
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if evm.ChainConfig().IsEIP158(evm.BlockNumber) {
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evm.StateDB.SetNonce(contractAddr, 1)
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}
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evm.Transfer(evm.StateDB, caller.Address(), contractAddr, value)
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// initialise a new contract and set the code that is to be used by the
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// E The contract is a scoped evmironment for this execution context
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// only.
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contract := NewContract(caller, AccountRef(contractAddr), value, gas)
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contract.SetCallCode(&contractAddr, crypto.Keccak256Hash(code), code)
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ret, err = run(evm, snapshot, contract, nil)
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// check whether the max code size has been exceeded
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maxCodeSizeExceeded := len(ret) > params.MaxCodeSize
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// if the contract creation ran successfully and no errors were returned
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// calculate the gas required to store the code. If the code could not
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// be stored due to not enough gas set an error and let it be handled
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// by the error checking condition below.
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if err == nil && !maxCodeSizeExceeded {
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createDataGas := uint64(len(ret)) * params.CreateDataGas
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if contract.UseGas(createDataGas) {
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evm.StateDB.SetCode(contractAddr, ret)
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} else {
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err = ErrCodeStoreOutOfGas
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}
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}
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// When an error was returned by the EVM or when setting the creation code
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// above we revert to the snapshot and consume any gas remaining. Additionally
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// when we're in homestead this also counts for code storage gas errors.
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if maxCodeSizeExceeded ||
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(err != nil && (evm.ChainConfig().IsHomestead(evm.BlockNumber) || err != ErrCodeStoreOutOfGas)) {
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contract.UseGas(contract.Gas)
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evm.StateDB.RevertToSnapshot(snapshot)
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}
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// If the vm returned with an error the return value should be set to nil.
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// This isn't consensus critical but merely to for behaviour reasons such as
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// tests, RPC calls, etc.
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if err != nil {
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ret = nil
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}
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return ret, contractAddr, contract.Gas, err
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}
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// ChainConfig returns the evmironment's chain configuration
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func (evm *EVM) ChainConfig() *params.ChainConfig { return evm.chainConfig }
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// Interpreter returns the EVM interpreter
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func (evm *EVM) Interpreter() *Interpreter { return evm.interpreter }
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