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// 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/ethereum/go-ethereum/common"
"github.com/ethereum/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 {
// Cache will initially contain [refHash.parent],
// Then fill up with [refHash.p, refHash.pp, refHash.ppp, ...]
var cache []common.Hash
return func(n uint64) common.Hash {
// If there's no hash cache yet, make one
if len(cache) == 0 {
cache = append(cache, ref.ParentHash)
}
if idx := ref.Number.Uint64() - n - 1; idx < uint64(len(cache)) {
return cache[idx]
}
// No luck in the cache, but we can start iterating from the last element we already know
lastKnownHash := cache[len(cache)-1]
lastKnownNumber := ref.Number.Uint64() - uint64(len(cache))
for {
header := chain.GetHeader(lastKnownHash, lastKnownNumber)
if header == nil {
break
}
cache = append(cache, header.ParentHash)
lastKnownHash = header.ParentHash
lastKnownNumber = header.Number.Uint64() - 1
if n == lastKnownNumber {
return lastKnownHash
}
}
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)
}
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