github.com/alex403s/heco-chain@v1.2.3-0.20220611014610-f10f4107d8b9/core/evm.go (about) 1 // Copyright 2016 The go-ethereum Authors 2 // This file is part of the go-ethereum library. 3 // 4 // The go-ethereum library is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU Lesser General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // The go-ethereum library is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU Lesser General Public License for more details. 13 // 14 // You should have received a copy of the GNU Lesser General Public License 15 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17 package core 18 19 import ( 20 "math/big" 21 22 "github.com/ethereum/go-ethereum/common" 23 "github.com/ethereum/go-ethereum/consensus" 24 "github.com/ethereum/go-ethereum/core/types" 25 "github.com/ethereum/go-ethereum/core/vm" 26 "github.com/modern-go/reflect2" 27 ) 28 29 // ChainContext supports retrieving headers and consensus parameters from the 30 // current blockchain to be used during transaction processing. 31 type ChainContext interface { 32 // Engine retrieves the chain's consensus engine. 33 Engine() consensus.Engine 34 35 // GetHeader returns the hash corresponding to their hash. 36 GetHeader(common.Hash, uint64) *types.Header 37 } 38 39 // NewEVMBlockContext creates a new context for use in the EVM. 40 func NewEVMBlockContext(header *types.Header, chain ChainContext, author *common.Address) vm.BlockContext { 41 var ( 42 beneficiary common.Address 43 baseFee *big.Int 44 ) 45 46 // If we don't have an explicit author (i.e. not mining), extract from the header 47 if author == nil && chain != nil { 48 beneficiary, _ = chain.Engine().Author(header) // Ignore error, we're past header validation 49 } else { 50 beneficiary = *author 51 } 52 if header.BaseFee != nil { 53 baseFee = new(big.Int).Set(header.BaseFee) 54 } 55 return vm.BlockContext{ 56 CanTransfer: CanTransfer, 57 Transfer: Transfer, 58 GetHash: GetHashFn(header, chain), 59 Coinbase: beneficiary, 60 BlockNumber: new(big.Int).Set(header.Number), 61 Time: new(big.Int).SetUint64(header.Time), 62 Difficulty: new(big.Int).Set(header.Difficulty), 63 BaseFee: baseFee, 64 GasLimit: header.GasLimit, 65 CanCreate: GetCanCreateFn(chain), 66 } 67 } 68 69 // NewEVMTxContext creates a new transaction context for a single transaction. 70 func NewEVMTxContext(msg Message) vm.TxContext { 71 return vm.TxContext{ 72 Origin: msg.From(), 73 GasPrice: new(big.Int).Set(msg.GasPrice()), 74 } 75 } 76 77 // GetHashFn returns a GetHashFunc which retrieves header hashes by number 78 func GetHashFn(ref *types.Header, chain ChainContext) func(n uint64) common.Hash { 79 // Cache will initially contain [refHash.parent], 80 // Then fill up with [refHash.p, refHash.pp, refHash.ppp, ...] 81 var cache []common.Hash 82 83 return func(n uint64) common.Hash { 84 // If there's no hash cache yet, make one 85 if len(cache) == 0 { 86 cache = append(cache, ref.ParentHash) 87 } 88 if idx := ref.Number.Uint64() - n - 1; idx < uint64(len(cache)) { 89 return cache[idx] 90 } 91 // No luck in the cache, but we can start iterating from the last element we already know 92 lastKnownHash := cache[len(cache)-1] 93 lastKnownNumber := ref.Number.Uint64() - uint64(len(cache)) 94 95 for { 96 header := chain.GetHeader(lastKnownHash, lastKnownNumber) 97 if header == nil { 98 break 99 } 100 cache = append(cache, header.ParentHash) 101 lastKnownHash = header.ParentHash 102 lastKnownNumber = header.Number.Uint64() - 1 103 if n == lastKnownNumber { 104 return lastKnownHash 105 } 106 } 107 return common.Hash{} 108 } 109 } 110 111 // CanTransfer checks whether there are enough funds in the address' account to make a transfer. 112 // This does not take the necessary gas in to account to make the transfer valid. 113 func CanTransfer(db vm.StateDB, addr common.Address, amount *big.Int) bool { 114 return db.GetBalance(addr).Cmp(amount) >= 0 115 } 116 117 // Transfer subtracts amount from sender and adds amount to recipient using the given Db 118 func Transfer(db vm.StateDB, sender, recipient common.Address, amount *big.Int) { 119 db.SubBalance(sender, amount) 120 db.AddBalance(recipient, amount) 121 } 122 123 func GetCanCreateFn(chain ChainContext) vm.CanCreateFunc { 124 if reflect2.IsNil(chain) || chain.Engine() == nil { 125 return func(db vm.StateDB, address common.Address, height *big.Int) bool { 126 return true 127 } 128 } 129 posa, isPoSA := chain.Engine().(consensus.PoSA) 130 if isPoSA { 131 return func(db vm.StateDB, address common.Address, height *big.Int) bool { 132 return posa.CanCreate(db, address, height) 133 } 134 } 135 return func(db vm.StateDB, address common.Address, height *big.Int) bool { 136 return true 137 } 138 }