mirror of
https://github.com/ethereum/go-ethereum.git
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54178bda9b
Consolidated and made environment a type (not an interface). This reduces a lot of tech-debt throughout the codebase where a Virtual machine environment had to be implemented in order to test or run it. The new environment is suitable to be used en the json tests, core consensus and light client.
76 lines
2.7 KiB
Go
76 lines
2.7 KiB
Go
// Copyright 2014 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 core
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import (
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"math/big"
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"github.com/ethereum/go-ethereum/common"
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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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)
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// BlockFetcher retrieves headers by their hash
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type BlockFetcher interface {
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// GetHeader returns the hash corresponding to their hash
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GetHeader(common.Hash, uint64) *types.Header
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}
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// ToEVMContext creates a new context for use in the EVM.
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func ToEVMContext(msg Message, header *types.Header, chain BlockFetcher) vm.Context {
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return vm.Context{
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CallContext: EVMCallContext{
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CanTransfer: CanTransfer,
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Transfer: Transfer,
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GetHashFn: GetHashFn(header, chain),
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},
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Origin: msg.From(),
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Coinbase: header.Coinbase,
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BlockNumber: new(big.Int).Set(header.Number),
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Time: new(big.Int).Set(header.Time),
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Difficulty: new(big.Int).Set(header.Difficulty),
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GasLimit: new(big.Int).Set(header.GasLimit),
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GasPrice: new(big.Int).Set(msg.GasPrice()),
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}
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}
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// GetHashFn returns a function for which the VM env can query block hashes through
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// up to the limit defined by the Yellow Paper and uses the given block chain
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// to query for information.
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func GetHashFn(ref *types.Header, chain BlockFetcher) func(n uint64) common.Hash {
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return func(n uint64) common.Hash {
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for header := chain.GetHeader(ref.ParentHash, ref.Number.Uint64()-1); header != nil; header = chain.GetHeader(header.ParentHash, header.Number.Uint64()-1) {
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if header.Number.Uint64() == n {
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return header.Hash()
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}
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}
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return common.Hash{}
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}
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}
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// CanTransfer checks wether there are enough funds in the address' account to make a transfer.
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func CanTransfer(db vm.StateDB, addr common.Address, amount *big.Int) bool {
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return db.GetBalance(addr).Cmp(amount) >= 0
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}
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// Transfer subtracts amount from sender and adds amount to recipient using the given Db
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func Transfer(db vm.StateDB, sender, recipient common.Address, amount *big.Int) {
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db.SubBalance(sender, amount)
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db.AddBalance(recipient, amount)
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}
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