path: root/core/vm/interpreter.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 vm

import (
	"hash"
	"sync/atomic"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/common/math"
	"github.com/ethereum/go-ethereum/log"
)

var (
	// BuiltinAddr ...
	BuiltinAddr = common.Address{
		1, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	}
)

// Config are the configuration options for the Interpreter
type Config struct {
	Debug                   bool   // Enables debugging
	Tracer                  Tracer // Opcode logger
	NoRecursion             bool   // Disables call, callcode, delegate call and create
	EnablePreimageRecording bool   // Enables recording of SHA3/keccak preimages

	JumpTable [256]*operation // EVM instruction table, automatically populated if unset

	EWASMInterpreter string // External EWASM interpreter options
	EVMInterpreter   string // External EVM interpreter options

	ExtraEips []int // Additional EIPS that are to be enabled
}

// Interpreter is used to run Ethereum based contracts and will utilise the
// passed environment to query external sources for state information.
// The Interpreter will run the byte code VM based on the passed
// configuration.
type Interpreter interface {
	// Run loops and evaluates the contract's code with the given input data and returns
	// the return byte-slice and an error if one occurred.
	Run(contract *Contract, input []byte, static bool) ([]byte, error)
	// CanRun tells if the contract, passed as an argument, can be
	// run by the current interpreter. This is meant so that the
	// caller can do something like:
	//
	// ```golang
	// for _, interpreter := range interpreters {
	//   if interpreter.CanRun(contract.code) {
	//     interpreter.Run(contract.code, input)
	//   }
	// }
	// ```
	CanRun([]byte) bool
}

// callCtx contains the things that are per-call, such as stack and memory,
// but not transients like pc and gas
type callCtx struct {
	memory   *Memory
	stack    *Stack
	rstack   *ReturnStack
	contract *Contract
}

// keccakState wraps sha3.state. In addition to the usual hash methods, it also supports
// Read to get a variable amount of data from the hash state. Read is faster than Sum
// because it doesn't copy the internal state, but also modifies the internal state.
type keccakState interface {
	hash.Hash
	Read([]byte) (int, error)
}

// EVMInterpreter represents an EVM interpreter
type EVMInterpreter struct {
	evm *EVM
	cfg Config

	hasher    keccakState // Keccak256 hasher instance shared across opcodes
	hasherBuf common.Hash // Keccak256 hasher result array shared aross opcodes

	readOnly   bool   // Whether to throw on stateful modifications
	returnData []byte // Last CALL's return data for subsequent reuse
}

// NewEVMInterpreter returns a new instance of the Interpreter.
func NewEVMInterpreter(evm *EVM, cfg Config) *EVMInterpreter {
	// We use the STOP instruction whether to see
	// the jump table was initialised. If it was not
	// we'll set the default jump table.
	if cfg.JumpTable[STOP] == nil {
		var jt JumpTable
		switch {
		case evm.chainRules.IsApricot:
			jt = apricotInstructionSet
		case evm.chainRules.IsYoloV1:
			jt = yoloV1InstructionSet
		case evm.chainRules.IsIstanbul:
			jt = istanbulInstructionSet
		case evm.chainRules.IsConstantinople:
			jt = constantinopleInstructionSet
		case evm.chainRules.IsByzantium:
			jt = byzantiumInstructionSet
		case evm.chainRules.IsEIP158:
			jt = spuriousDragonInstructionSet
		case evm.chainRules.IsEIP150:
			jt = tangerineWhistleInstructionSet
		case evm.chainRules.IsHomestead:
			jt = homesteadInstructionSet
		default:
			jt = frontierInstructionSet
		}
		for i, eip := range cfg.ExtraEips {
			if err := EnableEIP(eip, &jt); err != nil {
				// Disable it, so caller can check if it's activated or not
				cfg.ExtraEips = append(cfg.ExtraEips[:i], cfg.ExtraEips[i+1:]...)
				log.Error("EIP activation failed", "eip", eip, "error", err)
			}
		}
		cfg.JumpTable = jt
	}

	return &EVMInterpreter{
		evm: evm,
		cfg: cfg,
	}
}

// Run loops and evaluates the contract's code with the given input data and returns
// the return byte-slice and an error if one occurred.
//
// It's important to note that any errors returned by the interpreter should be
// considered a revert-and-consume-all-gas operation except for
// ErrExecutionReverted which means revert-and-keep-gas-left.
func (in *EVMInterpreter) Run(contract *Contract, input []byte, readOnly bool) (ret []byte, err error)</