74 lines
2.7 KiB
Go
74 lines
2.7 KiB
Go
// Copyright 2014 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/ethereum/go-ethereum/common"
|
|
"github.com/ethereum/go-ethereum/core/types"
|
|
"github.com/ethereum/go-ethereum/core/vm"
|
|
)
|
|
|
|
// BlockFetcher retrieves headers by their hash
|
|
type HeaderFetcher interface {
|
|
// 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 HeaderFetcher) vm.Context {
|
|
return vm.Context{
|
|
CanTransfer: CanTransfer,
|
|
Transfer: Transfer,
|
|
GetHash: GetHashFn(header, chain),
|
|
|
|
Origin: msg.From(),
|
|
Coinbase: header.Coinbase,
|
|
BlockNumber: new(big.Int).Set(header.Number),
|
|
Time: new(big.Int).Set(header.Time),
|
|
Difficulty: new(big.Int).Set(header.Difficulty),
|
|
GasLimit: new(big.Int).Set(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 HeaderFetcher) func(n uint64) common.Hash {
|
|
return func(n uint64) common.Hash {
|
|
for header := chain.GetHeader(ref.ParentHash, ref.Number.Uint64()-1); header != nil; header = chain.GetHeader(header.ParentHash, header.Number.Uint64()-1) {
|
|
if header.Number.Uint64() == n {
|
|
return header.Hash()
|
|
}
|
|
}
|
|
|
|
return common.Hash{}
|
|
}
|
|
}
|
|
|
|
// CanTransfer checks wether 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
|
|
}
|
|
|
|
// 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)
|
|
}
|