// Copyright 2016 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 core import ( "math/big" "github.com/ava-labs/coreth/consensus" "github.com/ava-labs/coreth/core/types" "github.com/ava-labs/coreth/core/vm" "github.com/ava-labs/go-ethereum/common" "github.com/ava-labs/go-ethereum/log" ) // ChainContext supports retrieving headers and consensus parameters from the // current blockchain to be used during transaction processing. type ChainContext interface { // Engine retrieves the chain's consensus engine. Engine() consensus.Engine // GetHeader returns the hash corresponding to their hash. GetHeader(common.Hash, uint64) *types.Header } // NewEVMContext creates a new context for use in the EVM. func NewEVMContext(msg Message, header *types.Header, chain ChainContext, author *common.Address) vm.Context { // If we don't have an explicit author (i.e. not mining), extract from the header var beneficiary common.Address if author == nil { beneficiary, _ = chain.Engine().Author(header) // Ignore error, we're past header validation } else { beneficiary = *author } return vm.Context{ CanTransfer: CanTransfer, CanTransferMC: CanTransferMC, Transfer: Transfer, TransferMultiCoin: TransferMultiCoin, GetHash: GetHashFn(header, chain), Origin: msg.From(), Coinbase: beneficiary, BlockNumber: new(big.Int).Set(header.Number), Time: new(big.Int).SetUint64(header.Time), Difficulty: new(big.Int).Set(header.Difficulty), GasLimit: header.GasLimit, GasPrice: new(big.Int).Set(msg.GasPrice()), } } // GetHashFn returns a GetHashFunc which retrieves header hashes by number func GetHashFn(ref *types.Header, chain ChainContext) func(n uint64) common.Hash { var cache map[uint64]common.Hash return func(n uint64) common.Hash { // If there's no hash cache yet, make one if cache == nil { cache = map[uint64]common.Hash{ ref.Number.Uint64() - 1: ref.ParentHash, } } // Try to fulfill the request from the cache if hash, ok := cache[n]; ok { return hash } // Not cached, iterate the blocks and cache the hashes for header := chain.GetHeader(ref.ParentHash, ref.Number.Uint64()-1); header != nil; header = chain.GetHeader(header.ParentHash, header.Number.Uint64()-1) { cache[header.Number.Uint64()-1] = header.ParentHash if n == header.Number.Uint64()-1 { return header.ParentHash } } return common.Hash{} } } // CanTransfer checks whether there are enough funds in the address' account to make a transfer. // This does not take the necessary gas in to account to make the transfer valid. func CanTransfer(db vm.StateDB, addr common.Address, amount *big.Int) bool { return db.GetBalance(addr).Cmp(amount) >= 0 } func CanTransferMC(db vm.StateDB, addr common.Address, to common.Address, coinID *common.Hash, amount *big.Int) int { if coinID == nil { return 0 } if !db.IsMultiCoin(addr) { err := db.EnableMultiCoin(addr) log.Debug("try to enable MC", "addr", addr.Hex(), "err", err) } if !(db.IsMultiCoin(addr) && db.IsMultiCoin(to)) { // incompatible return -1 } if db.GetBalanceMultiCoin(addr, *coinID).Cmp(amount) >= 0 { return 0 } // insufficient balance return 1 } // Transfer subtracts amount from sender and adds amount to recipient using the given Db func Transfer(db vm.StateDB, sender, recipient common.Address, amount *big.Int) { db.SubBalance(sender, amount) db.AddBalance(recipient, amount) } // Transfer subtracts amount from sender and adds amount to recipient using the given Db func TransferMultiCoin(db vm.StateDB, sender, recipient common.Address, coinID *common.Hash, amount *big.Int) { if coinID == nil { return } db.SubBalanceMultiCoin(sender, *coinID, amount) db.AddBalanceMultiCoin(recipient, *coinID, amount) }