mirror of
https://gitlab.com/pulsechaincom/erigon-pulse.git
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208 lines
6.7 KiB
Go
208 lines
6.7 KiB
Go
// Copyright 2015 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 vm
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import (
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"github.com/holiman/uint256"
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"github.com/ledgerwatch/turbo-geth/common"
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)
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// ContractRef is a reference to the contract's backing object
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type ContractRef interface {
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Address() common.Address
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}
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// AccountRef implements ContractRef.
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//
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// Account references are used during EVM initialisation and
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// it's primary use is to fetch addresses. Removing this object
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// proves difficult because of the cached jump destinations which
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// are fetched from the parent contract (i.e. the caller), which
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// is a ContractRef.
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type AccountRef common.Address
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// Address casts AccountRef to a Address
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func (ar AccountRef) Address() common.Address { return (common.Address)(ar) }
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// Contract represents an ethereum contract in the state database. It contains
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// the contract code, calling arguments. Contract implements ContractRef
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type Contract struct {
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// CallerAddress is the result of the caller which initialised this
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// contract. However when the "call method" is delegated this value
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// needs to be initialised to that of the caller's caller.
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CallerAddress common.Address
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caller ContractRef
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self ContractRef
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jumpdests map[common.Hash][]uint64 // Aggregated result of JUMPDEST analysis.
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analysis []uint64 // Locally cached result of JUMPDEST analysis
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skipAnalysis bool
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Code []byte
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CodeHash common.Hash
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CodeAddr *common.Address
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Input []byte
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Gas uint64
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value *uint256.Int
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}
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// NewContract returns a new contract environment for the execution of EVM.
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func NewContract(caller ContractRef, object ContractRef, value *uint256.Int, gas uint64, skipAnalysis bool) *Contract {
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c := &Contract{CallerAddress: caller.Address(), caller: caller, self: object}
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if parent, ok := caller.(*Contract); ok {
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// Reuse JUMPDEST analysis from parent context if available.
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c.jumpdests = parent.jumpdests
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} else {
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c.jumpdests = make(map[common.Hash][]uint64)
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}
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// Gas should be a pointer so it can safely be reduced through the run
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// This pointer will be off the state transition
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c.Gas = gas
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// ensures a value is set
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c.value = value
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c.skipAnalysis = skipAnalysis
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return c
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}
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// First result tells us if the destination is valid
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// Second result tells us if the code bitmap was used
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func (c *Contract) validJumpdest(dest *uint256.Int) (bool, bool) {
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udest, overflow := dest.Uint64WithOverflow()
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// PC cannot go beyond len(code) and certainly can't be bigger than 64bits.
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// Don't bother checking for JUMPDEST in that case.
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if overflow || udest >= uint64(len(c.Code)) {
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return false, false
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}
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// Only JUMPDESTs allowed for destinations
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if OpCode(c.Code[udest]) != JUMPDEST {
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return false, false
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}
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if c.skipAnalysis {
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return true, false
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}
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return c.isCode(udest), true
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}
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func isCodeFromAnalysis(analysis []uint64, udest uint64) bool {
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return analysis[udest/64]&(uint64(1)<<(udest&63)) == 0
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}
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// isCode returns true if the provided PC location is an actual opcode, as
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// opposed to a data-segment following a PUSHN operation.
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func (c *Contract) isCode(udest uint64) bool {
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// Do we have a contract hash already?
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// If we do have a hash, that means it's a 'regular' contract. For regular
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// contracts ( not temporary initcode), we store the analysis in a map
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if c.CodeHash != (common.Hash{}) {
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// Does parent context have the analysis?
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analysis, exist := c.jumpdests[c.CodeHash]
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if !exist {
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// Do the analysis and save in parent context
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// We do not need to store it in c.analysis
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analysis = codeBitmap(c.Code)
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c.jumpdests[c.CodeHash] = analysis
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}
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// Also stash it in current contract for faster access
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c.analysis = analysis
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return isCodeFromAnalysis(analysis, udest)
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}
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// We don't have the code hash, most likely a piece of initcode not already
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// in state trie. In that case, we do an analysis, and save it locally, so
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// we don't have to recalculate it for every JUMP instruction in the execution
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// However, we don't save it within the parent context
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if c.analysis == nil {
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c.analysis = codeBitmap(c.Code)
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}
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return isCodeFromAnalysis(c.analysis, udest)
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}
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// AsDelegate sets the contract to be a delegate call and returns the current
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// contract (for chaining calls)
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func (c *Contract) AsDelegate() *Contract {
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// NOTE: caller must, at all times be a contract. It should never happen
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// that caller is something other than a Contract.
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parent := c.caller.(*Contract)
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c.CallerAddress = parent.CallerAddress
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c.value = parent.value
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return c
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}
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// GetOp returns the n'th element in the contract's byte array
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func (c *Contract) GetOp(n uint64) OpCode {
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return OpCode(c.GetByte(n))
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}
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// GetByte returns the n'th byte in the contract's byte array
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func (c *Contract) GetByte(n uint64) byte {
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if n < uint64(len(c.Code)) {
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return c.Code[n]
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}
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return 0
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}
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// Caller returns the caller of the contract.
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//
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// Caller will recursively call caller when the contract is a delegate
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// call, including that of caller's caller.
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func (c *Contract) Caller() common.Address {
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return c.CallerAddress
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}
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// UseGas attempts the use gas and subtracts it and returns true on success
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func (c *Contract) UseGas(gas uint64) (ok bool) {
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if c.Gas < gas {
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return false
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}
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c.Gas -= gas
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return true
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}
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// Address returns the contracts address
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func (c *Contract) Address() common.Address {
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return c.self.Address()
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}
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// Value returns the contract's value (sent to it from it's caller)
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func (c *Contract) Value() *uint256.Int {
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return c.value
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}
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// SetCallCode sets the code of the contract and address of the backing data
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// object
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func (c *Contract) SetCallCode(addr *common.Address, hash common.Hash, code []byte) {
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c.Code = code
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c.CodeHash = hash
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c.CodeAddr = addr
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}
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// SetCodeOptionalHash can be used to provide code, but it's optional to provide hash.
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// In case hash is not provided, the jumpdest analysis will not be saved to the parent context
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func (c *Contract) SetCodeOptionalHash(addr *common.Address, codeAndHash *codeAndHash) {
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c.Code = codeAndHash.code
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c.CodeHash = codeAndHash.hash
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c.CodeAddr = addr
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}
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