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- // Copyright 2017 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 vm
- import (
- "errors"
- "github.com/ethereum/go-ethereum/common"
- "github.com/ethereum/go-ethereum/common/math"
- "github.com/ethereum/go-ethereum/params"
- )
- // memoryGasCost 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) {
- if newMemSize == 0 {
- return 0, nil
- }
- // The maximum that will fit in a uint64 is max_word_count - 1. Anything above
- // that will result in an overflow. Additionally, a newMemSize which results in
- // a newMemSizeWords larger than 0xFFFFFFFF will cause the square operation to
- // overflow. The constant 0x1FFFFFFFE0 is the highest number that can be used
- // without overflowing the gas calculation.
- if newMemSize > 0x1FFFFFFFE0 {
- return 0, ErrGasUintOverflow
- }
- 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
- }
- // memoryCopierGas creates the gas functions for the following opcodes, and takes
- // the stack position of the operand which determines the size of the data to copy
- // as argument:
- // CALLDATACOPY (stack position 2)
- // CODECOPY (stack position 2)
- // EXTCODECOPY (stack poition 3)
- // RETURNDATACOPY (stack position 2)
- func memoryCopierGas(stackpos int) gasFunc {
- return func(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
- // Gas for expanding the memory
- gas, err := memoryGasCost(mem, memorySize)
- if err != nil {
- return 0, err
- }
- // And gas for copying data, charged per word at param.CopyGas
- words, overflow := stack.Back(stackpos).Uint64WithOverflow()
- 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
- }
- }
- var (
- gasCallDataCopy = memoryCopierGas(2)
- gasCodeCopy = memoryCopierGas(2)
- gasExtCodeCopy = memoryCopierGas(3)
- gasReturnDataCopy = memoryCopierGas(2)
- )
- func gasSStore(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
- var (
- db = getDualState(evm, contract.Address())
- y, x = stack.Back(1), stack.Back(0)
- current = db.GetState(contract.Address(), x.Bytes32())
- )
- // The legacy gas metering only takes into consideration the current state
- // Legacy rules should be applied if we are in Petersburg (removal of EIP-1283)
- // OR Constantinople is not active
- if evm.chainRules.IsPetersburg || !evm.chainRules.IsConstantinople {
- // 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)
- switch {
- case current == (common.Hash{}) && y.Sign() != 0: // 0 => non 0
- return params.SstoreSetGas, nil
- case current != (common.Hash{}) && y.Sign() == 0: // non 0 => 0
- evm.StateDB.AddRefund(params.SstoreRefundGas)
- return params.SstoreClearGas, nil
- default: // non 0 => non 0 (or 0 => 0)
- return params.SstoreResetGas, nil
- }
- }
- // The new gas metering is based on net gas costs (EIP-1283):
- //
- // 1. If current value equals new value (this is a no-op), 200 gas is deducted.
- // 2. If current value does not equal new value
- // 2.1. If original value equals current value (this storage slot has not been changed by the current execution context)
- // 2.1.1. If original value is 0, 20000 gas is deducted.
- // 2.1.2. Otherwise, 5000 gas is deducted. If new value is 0, add 15000 gas to refund counter.
- // 2.2. If original value does not equal current value (this storage slot is dirty), 200 gas is deducted. Apply both of the following clauses.
- // 2.2.1. If original value is not 0
- // 2.2.1.1. If current value is 0 (also means that new value is not 0), remove 15000 gas from refund counter. We can prove that refund counter will never go below 0.
- // 2.2.1.2. If new value is 0 (also means that current value is not 0), add 15000 gas to refund counter.
- // 2.2.2. If original value equals new value (this storage slot is reset)
- // 2.2.2.1. If original value is 0, add 19800 gas to refund counter.
- // 2.2.2.2. Otherwise, add 4800 gas to refund counter.
- value := common.Hash(y.Bytes32())
- if current == value { // noop (1)
- return params.NetSstoreNoopGas, nil
- }
- original := evm.StateDB.GetCommittedState(contract.Address(), x.Bytes32())
- if original == current {
- if original == (common.Hash{}) { // create slot (2.1.1)
- return params.NetSstoreInitGas, nil
- }
- if value == (common.Hash{}) { // delete slot (2.1.2b)
- evm.StateDB.AddRefund(params.NetSstoreClearRefund)
- }
- return params.NetSstoreCleanGas, nil // write existing slot (2.1.2)
- }
- if original != (common.Hash{}) {
- if current == (common.Hash{}) { // recreate slot (2.2.1.1)
- evm.StateDB.SubRefund(params.NetSstoreClearRefund)
- } else if value == (common.Hash{}) { // delete slot (2.2.1.2)
- evm.StateDB.AddRefund(params.NetSstoreClearRefund)
- }
- }
- if original == value {
- if original == (common.Hash{}) { // reset to original inexistent slot (2.2.2.1)
- evm.StateDB.AddRefund(params.NetSstoreResetClearRefund)
- } else { // reset to original existing slot (2.2.2.2)
- evm.StateDB.AddRefund(params.NetSstoreResetRefund)
- }
- }
- return params.NetSstoreDirtyGas, nil
- }
- // 0. If *gasleft* is less than or equal to 2300, fail the current call.
- // 1. If current value equals new value (this is a no-op), SLOAD_GAS is deducted.
- // 2. If current value does not equal new value:
- // 2.1. If original value equals current value (this storage slot has not been changed by the current execution context):
- // 2.1.1. If original value is 0, SSTORE_SET_GAS (20K) gas is deducted.
- // 2.1.2. Otherwise, SSTORE_RESET_GAS gas is deducted. If new value is 0, add SSTORE_CLEARS_SCHEDULE to refund counter.
- // 2.2. If original value does not equal current value (this storage slot is dirty), SLOAD_GAS gas is deducted. Apply both of the following clauses:
- // 2.2.1. If original value is not 0:
- // 2.2.1.1. If current value is 0 (also means that new value is not 0), subtract SSTORE_CLEARS_SCHEDULE gas from refund counter.
- // 2.2.1.2. If new value is 0 (also means that current value is not 0), add SSTORE_CLEARS_SCHEDULE gas to refund counter.
- // 2.2.2. If original value equals new value (this storage slot is reset):
- // 2.2.2.1. If original value is 0, add SSTORE_SET_GAS - SLOAD_GAS to refund counter.
- // 2.2.2.2. Otherwise, add SSTORE_RESET_GAS - SLOAD_GAS gas to refund counter.
- func gasSStoreEIP2200(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
- // If we fail the minimum gas availability invariant, fail (0)
- if contract.Gas <= params.SstoreSentryGasEIP2200 {
- return 0, errors.New("not enough gas for reentrancy sentry")
- }
- // Gas sentry honoured, do the actual gas calculation based on the stored value
- var (
- y, x = stack.Back(1), stack.Back(0)
- current = evm.StateDB.GetState(contract.Address(), x.Bytes32())
- )
- value := common.Hash(y.Bytes32())
- if current == value { // noop (1)
- return params.SloadGasEIP2200, nil
- }
- original := evm.StateDB.GetCommittedState(contract.Address(), x.Bytes32())
- if original == current {
- if original == (common.Hash{}) { // create slot (2.1.1)
- return params.SstoreSetGasEIP2200, nil
- }
- if value == (common.Hash{}) { // delete slot (2.1.2b)
- evm.StateDB.AddRefund(params.SstoreClearsScheduleRefundEIP2200)
- }
- return params.SstoreResetGasEIP2200, nil // write existing slot (2.1.2)
- }
- if original != (common.Hash{}) {
- if current == (common.Hash{}) { // recreate slot (2.2.1.1)
- evm.StateDB.SubRefund(params.SstoreClearsScheduleRefundEIP2200)
- } else if value == (common.Hash{}) { // delete slot (2.2.1.2)
- evm.StateDB.AddRefund(params.SstoreClearsScheduleRefundEIP2200)
- }
- }
- if original == value {
- if original == (common.Hash{}) { // reset to original inexistent slot (2.2.2.1)
- evm.StateDB.AddRefund(params.SstoreSetGasEIP2200 - params.SloadGasEIP2200)
- } else { // reset to original existing slot (2.2.2.2)
- evm.StateDB.AddRefund(params.SstoreResetGasEIP2200 - params.SloadGasEIP2200)
- }
- }
- return params.SloadGasEIP2200, nil // dirty update (2.2)
- }
- func makeGasLog(n uint64) gasFunc {
- return func(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
- requestedSize, overflow := stack.Back(1).Uint64WithOverflow()
- 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(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
- gas, err := memoryGasCost(mem, memorySize)
- if err != nil {
- return 0, err
- }
- wordGas, overflow := stack.Back(1).Uint64WithOverflow()
- 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
- }
- // pureMemoryGascost is used by several operations, which aside from their
- // static cost have a dynamic cost which is solely based on the memory
- // expansion
- func pureMemoryGascost(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
- return memoryGasCost(mem, memorySize)
- }
- var (
- gasReturn = pureMemoryGascost
- gasRevert = pureMemoryGascost
- gasMLoad = pureMemoryGascost
- gasMStore8 = pureMemoryGascost
- gasMStore = pureMemoryGascost
- gasCreate = pureMemoryGascost
- )
- func gasCreate2(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
- gas, err := memoryGasCost(mem, memorySize)
- if err != nil {
- return 0, err
- }
- wordGas, overflow := stack.Back(2).Uint64WithOverflow()
- 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 gasExpFrontier(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 * params.ExpByteFrontier // no overflow check required. Max is 256 * ExpByte gas
- overflow bool
- )
- if gas, overflow = math.SafeAdd(gas, params.ExpGas); overflow {
- return 0, ErrGasUintOverflow
- }
- return gas, nil
- }
- func gasExpEIP158(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 * params.ExpByteEIP158 // no overflow check required. Max is 256 * ExpByte gas
- overflow bool
- )
- if gas, overflow = math.SafeAdd(gas, params.ExpGas); overflow {
- return 0, ErrGasUintOverflow
- }
- return gas, nil
- }
- func gasCall(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
- var (
- gas uint64
- transfersValue = !stack.Back(2).IsZero()
- address = common.Address(stack.Back(1).Bytes20())
- )
- if evm.chainRules.IsEIP158 {
- if transfersValue && getDualState(evm, address).Empty(address) {
- gas += params.CallNewAccountGas
- }
- } else if !getDualState(evm, address).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
- }
- evm.callGasTemp, err = callGas(evm.chainRules.IsEIP150, contract.Gas, gas, stack.Back(0))
- if err != nil {
- return 0, err
- }
- if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
- return 0, ErrGasUintOverflow
- }
- return gas, nil
- }
- func gasCallCode(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
- memoryGas, err := memoryGasCost(mem, memorySize)
- if err != nil {
- return 0, err
- }
- var (
- gas uint64
- overflow bool
- )
- if stack.Back(2).Sign() != 0 {
- gas += params.CallValueTransferGas
- }
- if gas, overflow = math.SafeAdd(gas, memoryGas); overflow {
- return 0, ErrGasUintOverflow
- }
- evm.callGasTemp, err = callGas(evm.chainRules.IsEIP150, contract.Gas, gas, stack.Back(0))
- if err != nil {
- return 0, err
- }
- if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
- return 0, ErrGasUintOverflow
- }
- return gas, nil
- }
- func gasDelegateCall(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
- gas, err := memoryGasCost(mem, memorySize)
- if err != nil {
- return 0, err
- }
- evm.callGasTemp, err = callGas(evm.chainRules.IsEIP150, contract.Gas, gas, stack.Back(0))
- if err != nil {
- return 0, err
- }
- var overflow bool
- if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
- return 0, ErrGasUintOverflow
- }
- return gas, nil
- }
- func gasStaticCall(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
- gas, err := memoryGasCost(mem, memorySize)
- if err != nil {
- return 0, err
- }
- evm.callGasTemp, err = callGas(evm.chainRules.IsEIP150, contract.Gas, gas, stack.Back(0))
- if err != nil {
- return 0, err
- }
- var overflow bool
- if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
- return 0, ErrGasUintOverflow
- }
- return gas, nil
- }
- func gasSelfdestruct(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
- var gas uint64
- // EIP150 homestead gas reprice fork:
- if evm.chainRules.IsEIP150 {
- gas = params.SelfdestructGasEIP150
- var address = common.Address(stack.Back(0).Bytes20())
- if evm.chainRules.IsEIP158 {
- // if empty and transfers value
- if evm.StateDB.Empty(address) && evm.StateDB.GetBalance(contract.Address()).Sign() != 0 {
- gas += params.CreateBySelfdestructGas
- }
- } else if !evm.StateDB.Exist(address) {
- gas += params.CreateBySelfdestructGas
- }
- }
- if !evm.StateDB.HasSuicided(contract.Address()) {
- evm.StateDB.AddRefund(params.SelfdestructRefundGas)
- }
- return gas, nil
- }
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