package vm
import (
gmath "math"
"math/big"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/math"
"github.com/ethereum/go-ethereum/params"
)
// memoryGasCosts calculates the quadratic gas for memory expansion. It does so
// only for the memory region that is expanded, not the total memory.
func memoryGasCost(mem *Memory, newMemSize uint64) (uint64, error) {
// The maximum that will fit in a uint64 is max_word_count - 1
// anything above that will result in an overflow.
if newMemSize > gmath.MaxUint64-32 {
return 0, errGasUintOverflow
}
if newMemSize == 0 {
return 0, nil
}
newMemSizeWords := toWordSize(newMemSize)
newMemSize = newMemSizeWords * 32
if newMemSize > uint64(mem.Len()) {
square := newMemSizeWords * newMemSizeWords
linCoef := newMemSizeWords * params.MemoryGas
quadCoef := square / params.QuadCoeffDiv
newTotalFee := linCoef + quadCoef
fee := newTotalFee - mem.lastGasCost
mem.lastGasCost = newTotalFee
return fee, nil
}
return 0, nil
}
func constGasFunc(gas uint64) gasFunc {
return func(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
return gas, nil
}
}
func gasCalldataCopy(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
gas, err := memoryGasCost(mem, memorySize)
if err != nil {
return 0, err
}
var overflow bool
if gas, overflow = math.SafeAdd(gas, GasFastestStep); overflow {
return 0, errGasUintOverflow
}
words, overflow := bigUint64(stack.Back(2))
if overflow {
return 0, errGasUintOverflow
}
if words, overflow = math.SafeMul(toWordSize(words), params.CopyGas); overflow {
return 0, errGasUintOverflow
}
if gas, overflow = math.SafeAdd(gas, words); overflow {
return 0, errGasUintOverflow
}
return gas, nil
}
func gasSStore(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
var (
y, x = stack.Back(1), stack.Back(0)
val = evm.StateDB.GetState(contract.Address(), common.BigToHash(x))
)
// This checks for 3 scenario's and calculates gas accordingly
// 1. From a zero-value address to a non-zero value (NEW VALUE)
// 2. From a non-zero value address to a zero-value address (DELETE)
// 3. From a non-zero to a non-zero (CHANGE)
if common.EmptyHash(val) && !common.EmptyHash(common.BigToHash(y)) {
// 0 => non 0
return params.SstoreSetGas, nil
} else if !common.EmptyHash(val) && common.EmptyHash(common.BigToHash(y)) {
evm.StateDB.AddRefund(new(big.Int).SetUint64(params.SstoreRefundGas))
return params.SstoreClearGas, nil
} else {
// non 0 => non 0 (or 0 => 0)
return params.SstoreResetGas, nil
}
}
func makeGasLog(n uint64) gasFunc {
return func(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
requestedSize, overflow := bigUint64(stack.Back(1))
if overflow {
return 0, errGasUintOverflow
}
gas, err := memoryGasCost(mem, memorySize)
if err != nil {
return 0, err
}
if gas, overflow = math.SafeAdd(gas, params.LogGas); overflow {
return 0, errGasUintOverflow
}
if gas, overflow = math.SafeAdd(gas, n*params.LogTopicGas); overflow {
return 0, errGasUintOverflow
}
var memorySizeGas uint64
if memorySizeGas, overflow = math.SafeMul(requestedSize, params.LogDataGas); overflow {
return 0, errGasUintOverflow
}
if gas, overflow = math.SafeAdd(gas, memorySizeGas); overflow {
return 0, errGasUintOverflow
}
return gas, nil
}
}
func gasSha3(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
var overflow bool
gas, err := memoryGasCost(mem, memorySize)
if err != nil {
return 0, err
}
if gas, overflow = math.SafeAdd(gas, params.Sha3Gas); overflow {
return 0, errGasUintOverflow
}
wordGas, overflow := bigUint64(stack.Back(1))
if overflow {
return 0, errGasUintOverflow
}
if wordGas, overflow = math.SafeMul(toWordSize(wordGas), params.Sha3WordGas); overflow {
return 0, errGasUintOverflow
}
if gas, overflow = math.SafeAdd(gas, wordGas); overflow {
return 0, errGasUintOverflow
}
return gas, nil
}
func gasCodeCopy(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
gas, err := memoryGasCost(mem, memorySize)
if err != nil {
return 0, err
}
var overflow bool
if gas, overflow = math.SafeAdd(gas, GasFastestStep); overflow {
return 0, errGasUintOverflow
}
wordGas, overflow := bigUint64(stack.Back(2))
if overflow {
return 0, errGasUintOverflow
}
if wordGas, overflow = math.SafeMul(toWordSize(wordGas), params.CopyGas); overflow {
return 0, errGasUintOverflow
}
if gas, overflow = math.SafeAdd(gas, wordGas); overflow {
return 0, errGasUintOverflow
}
return gas, nil
}
func gasExtCodeCopy(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
gas, err := memoryGasCost(mem, memorySize)
if err != nil {
return 0, err
}
var overflow bool
if gas, overflow = math.SafeAdd(gas, gt.ExtcodeCopy); overflow {
return 0, errGasUintOverflow
}
wordGas, overflow := bigUint64(stack.Back(3))
if overflow {
return 0, errGasUintOverflow
}
if wordGas, overflow = math.SafeMul(toWordSize(wordGas), params.CopyGas); overflow {
return 0, errGasUintOverflow
}
if gas, overflow = math.SafeAdd(gas, wordGas); overflow {
return 0, errGasUintOverflow
}
return gas, nil
}
func gasMLoad(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
var overflow bool
gas, err := memoryGasCost(mem, memorySize)
if err != nil {
return 0, errGasUintOverflow
}
if gas, overflow = math.SafeAdd(gas, GasFastestStep); overflow {
return 0, errGasUintOverflow
}
return gas, nil
}
func gasMStore8(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
var overflow bool
gas, err := memoryGasCost(mem, memorySize)
if err != nil {
return 0, errGasUintOverflow
}
if gas, overflow = math.SafeAdd(gas, GasFastestStep); overflow {
return 0, errGasUintOverflow
}
return gas, nil
}
func gasMStore(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
var overflow bool
gas, err := memoryGasCost(mem, memorySize)
if err != nil {
return 0, errGasUintOverflow
}
if gas, overflow = math.SafeAdd(gas, GasFastestStep); overflow {
return 0, errGasUintOverflow
}
return gas, nil
}
func gasCreate(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
var overflow bool
gas, err := memoryGasCost(mem, memorySize)
if err != nil {
return 0, err
}
if gas, overflow = math.SafeAdd(gas, params.CreateGas); overflow {
return 0, errGasUintOverflow
}
return gas, nil
}
func gasBalance(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
return gt.Balance, nil
}
func gasExtCodeSize(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
return gt.ExtcodeSize, nil
}
func gasSLoad(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
return gt.SLoad, nil
}
func gasExp(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
expByteLen := uint64((stack.data[stack.len()-2].BitLen() + 7) / 8)
var (
gas = expByteLen * gt.ExpByte // no overflow check required. Max is 256 * ExpByte gas
overflow bool
)
if gas, overflow = math.SafeAdd(gas, GasSlowStep); overflow {
return 0, errGasUintOverflow
}
return gas, nil
}
func gasCall(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
var (
gas = gt.Calls
transfersValue = stack.Back(2).Sign() != 0
address = common.BigToAddress(stack.Back(1))
eip158 = evm.ChainConfig().IsEIP158(evm.BlockNumber)
)
if eip158 {
if evm.StateDB.Empty(address) && transfersValue {
gas += params.CallNewAccountGas
}
} else if !evm.StateDB.Exist(address) {
gas += params.CallNewAccountGas
}
if transfersValue {
gas += params.CallValueTransferGas
}
memoryGas, err := memoryGasCost(mem, memorySize)
if err != nil {
return 0, err
}
var overflow bool
if gas, overflow = math.SafeAdd(gas, memoryGas); overflow {
return 0, errGasUintOverflow
}
cg, err := callGas(gt, contract.Gas, gas, stack.Back(0))
if err != nil {
return 0, err
}
// Replace the stack item with the new gas calculation. This means that
// either the original item is left on the stack or the item is replaced by:
// (availableGas - gas) * 63 / 64
// We replace the stack item so that it's available when the opCall instruction is
// called. This information is otherwise lost due to the dependency on *current*
// available gas.
stack.data[stack.len()-1] = new(big.Int).SetUint64(cg)
if gas, overflow = math.SafeAdd(gas, cg); overflow {
return 0, errGasUintOverflow
}
return gas, nil
}
func gasCallCode(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
gas := gt.Calls
if stack.Back(2).Sign() != 0 {
gas += params.CallValueTransferGas
}
memoryGas, err := memoryGasCost(mem, memorySize)
if err != nil {
return 0, err
}
var overflow bool
if gas, overflow = math.SafeAdd(gas, memoryGas); overflow {
return 0, errGasUintOverflow
}
cg, err := callGas(gt, contract.Gas, gas, stack.Back(0))
if err != nil {
return 0, err
}
// Replace the stack item with the new gas calculation. This means that
// either the original item is left on the stack or the item is replaced by:
// (availableGas - gas) * 63 / 64
// We replace the stack item so that it's available when the opCall instruction is
// called. This information is otherwise lost due to the dependency on *current*
// available gas.
stack.data[stack.len()-1] = new(big.Int).SetUint64(cg)
if gas, overflow = math.SafeAdd(gas, cg); overflow {
return 0, errGasUintOverflow
}
return gas, nil
}
func gasReturn(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
return memoryGasCost(mem, memorySize)
}
func gasSuicide(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
var gas uint64
// EIP150 homestead gas reprice fork:
if evm.ChainConfig().IsEIP150(evm.BlockNumber) {
gas = gt.Suicide
var (
address = common.BigToAddress(stack.Back(0))
eip158 = evm.ChainConfig().IsEIP158(evm.BlockNumber)
)
if eip158 {
// if empty and transfers value
if evm.StateDB.Empty(address) && evm.StateDB.GetBalance(contract.Address()).Sign() != 0 {
gas += gt.CreateBySuicide
}
} else if !evm.StateDB.Exist(address) {
gas += gt.CreateBySuicide
}
}
if !evm.StateDB.HasSuicided(contract.Address()) {
evm.StateDB.AddRefund(new(big.Int).SetUint64(params.SuicideRefundGas))
}
return gas, nil
}
func gasDelegateCall(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
gas, err := memoryGasCost(mem, memorySize)
if err != nil {
return 0, err
}
var overflow bool
if gas, overflow = math.SafeAdd(gas, gt.Calls); overflow {
return 0, errGasUintOverflow
}
cg, err := callGas(gt, contract.Gas, gas, stack.Back(0))
if err != nil {
return 0, err
}
// Replace the stack item with the new gas calculation. This means that
// either the original item is left on the stack or the item is replaced by:
// (availableGas - gas) * 63 / 64
// We replace the stack item so that it's available when the opCall instruction is
// called.
stack.data[stack.len()-1] = new(big.Int).SetUint64(cg)
if gas, overflow = math.SafeAdd(gas, cg); overflow {
return 0, errGasUintOverflow
}
return gas, nil
}
func gasPush(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
return GasFastestStep, nil
}
func gasSwap(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
return GasFastestStep, nil
}
func gasDup(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
return GasFastestStep, nil
}
