154 lines
4.4 KiB
Go
154 lines
4.4 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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"math/big"
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"github.com/ethereum/go-ethereum/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 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 destinations // result of JUMPDEST analysis.
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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 *big.Int
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Args []byte
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DelegateCall bool
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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 *big.Int, gas uint64) *Contract {
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c := &Contract{CallerAddress: caller.Address(), caller: caller, self: object, Args: nil}
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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(destinations)
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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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return c
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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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c.DelegateCall = true
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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 contracts value (sent to it from it's caller)
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func (c *Contract) Value() *big.Int {
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return c.value
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}
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// SetCode sets the code to the contract
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func (c *Contract) SetCode(hash common.Hash, code []byte) {
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c.Code = code
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c.CodeHash = hash
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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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