277 lines
10 KiB
Go
277 lines
10 KiB
Go
// Copyright 2015 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 backends
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import (
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"errors"
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"fmt"
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"math/big"
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"sync"
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"github.com/ethereum/go-ethereum"
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"github.com/ethereum/go-ethereum/accounts/abi/bind"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/core"
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"github.com/ethereum/go-ethereum/core/state"
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"github.com/ethereum/go-ethereum/core/types"
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"github.com/ethereum/go-ethereum/core/vm"
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"github.com/ethereum/go-ethereum/ethdb"
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"github.com/ethereum/go-ethereum/event"
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"github.com/ethereum/go-ethereum/params"
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"golang.org/x/net/context"
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)
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// Default chain configuration which sets homestead phase at block 0 (i.e. no frontier)
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var chainConfig = ¶ms.ChainConfig{HomesteadBlock: big.NewInt(0), EIP150Block: new(big.Int), EIP158Block: new(big.Int)}
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// This nil assignment ensures compile time that SimulatedBackend implements bind.ContractBackend.
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var _ bind.ContractBackend = (*SimulatedBackend)(nil)
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var errBlockNumberUnsupported = errors.New("SimulatedBackend cannot access blocks other than the latest block")
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// SimulatedBackend implements bind.ContractBackend, simulating a blockchain in
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// the background. Its main purpose is to allow easily testing contract bindings.
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type SimulatedBackend struct {
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database ethdb.Database // In memory database to store our testing data
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blockchain *core.BlockChain // Ethereum blockchain to handle the consensus
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mu sync.Mutex
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pendingBlock *types.Block // Currently pending block that will be imported on request
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pendingState *state.StateDB // Currently pending state that will be the active on on request
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config *params.ChainConfig
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}
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// NewSimulatedBackend creates a new binding backend using a simulated blockchain
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// for testing purposes.
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func NewSimulatedBackend(accounts ...core.GenesisAccount) *SimulatedBackend {
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database, _ := ethdb.NewMemDatabase()
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core.WriteGenesisBlockForTesting(database, accounts...)
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blockchain, _ := core.NewBlockChain(database, chainConfig, new(core.FakePow), new(event.TypeMux))
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backend := &SimulatedBackend{database: database, blockchain: blockchain}
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backend.rollback()
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return backend
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}
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// Commit imports all the pending transactions as a single block and starts a
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// fresh new state.
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func (b *SimulatedBackend) Commit() {
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b.mu.Lock()
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defer b.mu.Unlock()
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if _, err := b.blockchain.InsertChain([]*types.Block{b.pendingBlock}); err != nil {
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panic(err) // This cannot happen unless the simulator is wrong, fail in that case
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}
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b.rollback()
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}
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// Rollback aborts all pending transactions, reverting to the last committed state.
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func (b *SimulatedBackend) Rollback() {
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b.mu.Lock()
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defer b.mu.Unlock()
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b.rollback()
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}
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func (b *SimulatedBackend) rollback() {
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blocks, _ := core.GenerateChain(chainConfig, b.blockchain.CurrentBlock(), b.database, 1, func(int, *core.BlockGen) {})
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b.pendingBlock = blocks[0]
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b.pendingState, _ = state.New(b.pendingBlock.Root(), b.database)
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}
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// CodeAt returns the code associated with a certain account in the blockchain.
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func (b *SimulatedBackend) CodeAt(ctx context.Context, contract common.Address, blockNumber *big.Int) ([]byte, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
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return nil, errBlockNumberUnsupported
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}
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statedb, _ := b.blockchain.State()
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return statedb.GetCode(contract), nil
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}
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// BalanceAt returns the wei balance of a certain account in the blockchain.
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func (b *SimulatedBackend) BalanceAt(ctx context.Context, contract common.Address, blockNumber *big.Int) (*big.Int, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
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return nil, errBlockNumberUnsupported
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}
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statedb, _ := b.blockchain.State()
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return statedb.GetBalance(contract), nil
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}
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// NonceAt returns the nonce of a certain account in the blockchain.
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func (b *SimulatedBackend) NonceAt(ctx context.Context, contract common.Address, blockNumber *big.Int) (uint64, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
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return 0, errBlockNumberUnsupported
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}
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statedb, _ := b.blockchain.State()
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return statedb.GetNonce(contract), nil
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}
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// StorageAt returns the value of key in the storage of an account in the blockchain.
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func (b *SimulatedBackend) StorageAt(ctx context.Context, contract common.Address, key common.Hash, blockNumber *big.Int) ([]byte, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
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return nil, errBlockNumberUnsupported
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}
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statedb, _ := b.blockchain.State()
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val := statedb.GetState(contract, key)
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return val[:], nil
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}
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// TransactionReceipt returns the receipt of a transaction.
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func (b *SimulatedBackend) TransactionReceipt(ctx context.Context, txHash common.Hash) (*types.Receipt, error) {
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return core.GetReceipt(b.database, txHash), nil
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}
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// PendingCodeAt returns the code associated with an account in the pending state.
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func (b *SimulatedBackend) PendingCodeAt(ctx context.Context, contract common.Address) ([]byte, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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return b.pendingState.GetCode(contract), nil
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}
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// CallContract executes a contract call.
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func (b *SimulatedBackend) CallContract(ctx context.Context, call ethereum.CallMsg, blockNumber *big.Int) ([]byte, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
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return nil, errBlockNumberUnsupported
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}
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state, err := b.blockchain.State()
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if err != nil {
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return nil, err
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}
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rval, _, err := b.callContract(ctx, call, b.blockchain.CurrentBlock(), state)
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return rval, err
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}
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// PendingCallContract executes a contract call on the pending state.
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func (b *SimulatedBackend) PendingCallContract(ctx context.Context, call ethereum.CallMsg) ([]byte, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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defer b.pendingState.RevertToSnapshot(b.pendingState.Snapshot())
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rval, _, err := b.callContract(ctx, call, b.pendingBlock, b.pendingState)
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return rval, err
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}
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// PendingNonceAt implements PendingStateReader.PendingNonceAt, retrieving
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// the nonce currently pending for the account.
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func (b *SimulatedBackend) PendingNonceAt(ctx context.Context, account common.Address) (uint64, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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return b.pendingState.GetOrNewStateObject(account).Nonce(), nil
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}
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// SuggestGasPrice implements ContractTransactor.SuggestGasPrice. Since the simulated
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// chain doens't have miners, we just return a gas price of 1 for any call.
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func (b *SimulatedBackend) SuggestGasPrice(ctx context.Context) (*big.Int, error) {
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return big.NewInt(1), nil
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}
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// EstimateGas executes the requested code against the currently pending block/state and
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// returns the used amount of gas.
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func (b *SimulatedBackend) EstimateGas(ctx context.Context, call ethereum.CallMsg) (*big.Int, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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defer b.pendingState.RevertToSnapshot(b.pendingState.Snapshot())
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_, gas, err := b.callContract(ctx, call, b.pendingBlock, b.pendingState)
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return gas, err
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}
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// callContract implemens common code between normal and pending contract calls.
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// state is modified during execution, make sure to copy it if necessary.
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func (b *SimulatedBackend) callContract(ctx context.Context, call ethereum.CallMsg, block *types.Block, statedb *state.StateDB) ([]byte, *big.Int, error) {
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// Ensure message is initialized properly.
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if call.GasPrice == nil {
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call.GasPrice = big.NewInt(1)
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}
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if call.Gas == nil || call.Gas.BitLen() == 0 {
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call.Gas = big.NewInt(50000000)
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}
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if call.Value == nil {
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call.Value = new(big.Int)
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}
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// Set infinite balance to the fake caller account.
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from := statedb.GetOrNewStateObject(call.From)
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from.SetBalance(common.MaxBig)
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// Execute the call.
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msg := callmsg{call}
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evmContext := core.NewEVMContext(msg, block.Header(), b.blockchain)
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// Create a new environment which holds all relevant information
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// about the transaction and calling mechanisms.
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vmenv := vm.NewEVM(evmContext, statedb, chainConfig, vm.Config{})
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gaspool := new(core.GasPool).AddGas(common.MaxBig)
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ret, gasUsed, _, err := core.NewStateTransition(vmenv, msg, gaspool).TransitionDb()
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return ret, gasUsed, err
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}
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// SendTransaction updates the pending block to include the given transaction.
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// It panics if the transaction is invalid.
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func (b *SimulatedBackend) SendTransaction(ctx context.Context, tx *types.Transaction) error {
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b.mu.Lock()
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defer b.mu.Unlock()
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sender, err := types.Sender(types.HomesteadSigner{}, tx)
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if err != nil {
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panic(fmt.Errorf("invalid transaction: %v", err))
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}
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nonce := b.pendingState.GetNonce(sender)
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if tx.Nonce() != nonce {
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panic(fmt.Errorf("invalid transaction nonce: got %d, want %d", tx.Nonce(), nonce))
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}
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blocks, _ := core.GenerateChain(chainConfig, b.blockchain.CurrentBlock(), b.database, 1, func(number int, block *core.BlockGen) {
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for _, tx := range b.pendingBlock.Transactions() {
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block.AddTx(tx)
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}
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block.AddTx(tx)
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})
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b.pendingBlock = blocks[0]
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b.pendingState, _ = state.New(b.pendingBlock.Root(), b.database)
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return nil
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}
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// callmsg implements core.Message to allow passing it as a transaction simulator.
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type callmsg struct {
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ethereum.CallMsg
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}
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func (m callmsg) From() common.Address { return m.CallMsg.From }
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func (m callmsg) Nonce() uint64 { return 0 }
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func (m callmsg) CheckNonce() bool { return false }
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func (m callmsg) To() *common.Address { return m.CallMsg.To }
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func (m callmsg) GasPrice() *big.Int { return m.CallMsg.GasPrice }
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func (m callmsg) Gas() *big.Int { return m.CallMsg.Gas }
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func (m callmsg) Value() *big.Int { return m.CallMsg.Value }
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func (m callmsg) Data() []byte { return m.CallMsg.Data }
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