// Copyright 2015 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 (
"encoding/hex"
"fmt"
"io"
"math/big"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/hexutil"
"github.com/ethereum/go-ethereum/common/math"
"github.com/ethereum/go-ethereum/core/types"
)
type Storage map[common.Hash]common.Hash
func (s Storage) Copy() Storage {
cpy := make(Storage)
for key, value := range s {
cpy[key] = value
}
return cpy
}
// LogConfig are the configuration options for structured logger the EVM
type LogConfig struct {
DisableMemory bool // disable memory capture
DisableStack bool // disable stack capture
DisableStorage bool // disable storage capture
Debug bool // print output during capture end
Limit int // maximum length of output, but zero means unlimited
}
//go:generate gencodec -type StructLog -field-override structLogMarshaling -out gen_structlog.go
// StructLog is emitted to the EVM each cycle and lists information about the current internal state
// prior to the execution of the statement.
type StructLog struct {
Pc uint64 `json:"pc"`
Op OpCode `json:"op"`
Gas uint64 `json:"gas"`
GasCost uint64 `json:"gasCost"`
Memory []byte `json:"memory"`
MemorySize int `json:"memSize"`
Stack []*big.Int `json:"stack"`
Storage map[common.Hash]common.Hash `json:"-"`
Depth int `json:"depth"`
Err error `json:"-"`
}
// overrides for gencodec
type structLogMarshaling struct {
Stack []*math.HexOrDecimal256
Gas math.HexOrDecimal64
GasCost math.HexOrDecimal64
Memory hexutil.Bytes
OpName string `json:"opName"` // adds call to OpName() in MarshalJSON
ErrorString string `json:"error"` // adds call to ErrorString() in MarshalJSON
}
func (s *StructLog) OpName() string {
return s.Op.String()
}
func (s *StructLog) ErrorString() string {
if s.Err != nil {
return s.Err.Error()
}
return ""
}
// Tracer is used to collect execution traces from an EVM transaction
// execution. CaptureState is called for each step of the VM with the
// current VM state.
// Note that reference types are actual VM data structures; make copies
// if you need to retain them beyond the current call.
type Tracer interface {
CaptureStart(from common.Address, to common.Address, call bool, input []byte, gas uint64, value *big.Int) error
CaptureState(env *EVM, pc uint64, op OpCode, gas, cost uint64, memory *Memory, stack *Stack, contract *Contract, depth int, err error) error
CaptureFault(env *EVM, pc uint64, op OpCode, gas, cost uint64, memory *Memory, stack *Stack, contract *Contract, depth int, err error) error
CaptureEnd(output []byte, gasUsed uint64, t time.Duration, err error) error
}
// StructLogger is an EVM state logger and implements Tracer.
//
// StructLogger can capture state based on the given Log configuration and also keeps
// a track record of modified storage which is used in reporting snapshots of the
// contract their storage.
type StructLogger struct {
cfg LogConfig
logs []StructLog
changedValues map[common.Address]Storage
output []byte
err error
}
// NewStructLogger returns a new logger
func NewStructLogger(cfg *LogConfig) *StructLogger {
logger := &StructLogger{
changedValues: make(map[common.Address]Storage),
}
if cfg != nil {
logger.cfg = *cfg
}
return logger
}
func (l *StructLogger) CaptureStart(from common.Address, to common.Address, create bool, input []byte, gas uint64, value *big.Int) error {
return nil
}
// CaptureState logs a new structured log message and pushes it out to the environment
//
// CaptureState also tracks SSTORE ops to track dirty values.
func (l *StructLogger) CaptureState(env *EVM, pc uint64, op OpCode, gas, cost uint64, memory *Memory, stack *Stack, contract *Contract, depth int, err error) error {
// check if already accumulated the specified number of logs
if l.cfg.Limit != 0 && l.cfg.Limit <= len(l.logs) {
return ErrTraceLimitReached
}
// initialise new changed values storage container for this contract
// if not present.
if l.changedValues[contract.Address()] == nil {
l.changedValues[contract.Address()] = make(Storage)
}
// capture SSTORE opcodes and determine the changed value and store
// it in the local storage container.
if op == SSTORE && stack.len() >= 2 {
var (
value = common.BigToHash(stack.data[stack.len()-2])
address = common.BigToHash(stack.data[stack.len()-1])
)
l.changedValues[contract.Address()][address] = value
}
// Copy a snapstot of the current memory state to a new buffer
var mem []byte
if !l.cfg.DisableMemory {
mem = make([]byte, len(memory.Data()))
copy(mem, memory.Data())
}
// Copy a snapshot of the current stack state to a new buffer
var stck []*big.Int
if !l.cfg.DisableStack {
stck = make([]*big.Int, len(stack.Data()))
for i, item := range stack.Data() {
stck[i] = new(big.Int).Set(item)
}
}
// Copy a snapshot of the current storage to a new container
var storage Storage
if !l.cfg.DisableStorage {
storage = l.changedValues[contract.Address()].Copy()
}
// create a new snaptshot of the EVM.
log := StructLog{pc, op, gas, cost, mem, memory.Len(), stck, storage, depth, err}
l.logs = append(l.logs, log)
return nil
}
func (l *StructLogger) CaptureFault(env *EVM, pc uint64, op OpCode, gas, cost uint64, memory *Memory, stack *Stack, contract *Contract, depth int, err error) error {
return nil
}
func (l *StructLogger) CaptureEnd(output []byte, gasUsed uint64, t time.Duration, err error) error {
l.output = output
l.err = err
if l.cfg.Debug {
fmt.Printf("0x%x\n", output)
if err != nil {
fmt.Printf(" error: %v\n", err)
}
}
return nil
}
// StructLogs returns the captured log entries.
func (l *StructLogger) StructLogs() []StructLog { return l.logs }
// Error returns the VM error captured by the trace.
func (l *StructLogger) Error() error { return l.err }
// Output returns the VM return value captured by the trace.
func (l *StructLogger) Output() []byte { return l.output }
// WriteTrace writes a formatted trace to the given writer
func WriteTrace(writer io.Writer, logs []StructLog) {
for _, log := range logs {
fmt.Fprintf(writer, "%-16spc=%08d gas=%v cost=%v", log.Op, log.Pc, log.Gas, log.GasCost)
if log.Err != nil {
fmt.Fprintf(writer, " ERROR: %v", log.Err)
}
fmt.Fprintln(writer)
if len(log.Stack) > 0 {
fmt.Fprintln(writer, "Stack:")
for i := len(log.Stack) - 1; i >= 0; i-- {
fmt.Fprintf(writer, "%08d %x\n", len(log.Stack)-i-1, math.PaddedBigBytes(log.Stack[i], 32))
}
}
if len(log.Memory) > 0 {
fmt.Fprintln(writer, "Memory:")
fmt.Fprint(writer, hex.Dump(log.Memory))
}
if len(log.Storage) > 0 {
fmt.Fprintln(writer, "Storage:")
for h, item := range log.Storage {
fmt.Fprintf(writer, "%x: %x\n", h, item)
}
}
fmt.Fprintln(writer)
}
}
// WriteLogs writes vm logs in a readable format to the given writer
func WriteLogs(writer io.Writer, logs []*types.Log) {
for _, log := range logs {
fmt.Fprintf(writer, "LOG%d: %x bn=%d txi=%x\n", len(log.Topics), log.Address, log.BlockNumber, log.TxIndex)
for i, topic := range log.Topics {
fmt.Fprintf(writer, "%08d %x\n", i, topic)
}
fmt.Fprint(writer, hex.Dump(log.Data))
fmt.Fprintln(writer)
}
}
